Getting the lead out

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IPIECA

International Petroleum Industry Environmental Conservation Association

Getting the lead out

Downstream strategies and resources

for phasing out leaded gasoline

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Introduction

IPIECA position on leaded gasoline phase out 4

General references 6

The benefits of unleaded gasoline 6

Progress on leaded gasoline phase out: where are we now? 6

Background

Lead basics: why was lead added to gasoline? 7

Vehicle basics: bridging the octane gap 7

Refining basics: refinery structure and unleaded gasoline 8

Lead phase-out programmes: general considerations 9

Vehicle requirements: valve seat recession 10

Phase-out strategies

Immediate transition 11

Medium- and long-term transitions 12

Table 1: Key advantages and disadvantages associated with 13 each transition option

Summary: deciding on a phase-in strategy 14

Taking account of VSR in an unleaded gasoline phase-in strategy 15 Table 2: Some common additives for use in

unleaded gasoline and lead replacement gasoline 16

The use of manganese to replace lead in unleaded gasoline 16

Ethers and alcohols: the use of oxygenates as a 17

blending component in unleaded gasoline

Downstream strategies and resources

for phasing out leaded gasoline

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Refining options for the production of unleaded gasoline 18

General issues

Taxation incentives to encourage adoption of unleaded gasoline 19

Media relations and information strategies 19

The final step

Decommissioning of lead alkyl facilities 22

Annexes

Annex 1: Lead basics: why lead was used in gasoline 24

Annex 2: Valve seat recession (VSR): 26

is the risk real and what are the strategies for protection

Annex 3: The use of oxygenates in moving to unleaded gasoline 29 Annex 4: Refining options for the production of unleaded gasoline 33

CD-ROM / other sources of information 37

This document is also available on the IPIECA CD-ROM of the same title which includes additional material on the subject. Contact IPIECA for further information.

Links are provided in the text to related information throughout the document and also to resources on the Internet. All links are in blue underlined text.

© IPIECA 2003. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior consent of IPIECA.

Acknowledgements

This document was compiled by the IPIECA Fuels and Vehicles Working Group (Project Manager: Rob Cox) with the assistance of the following:

Steven McArragher (Shell) Frederick Villforth (ChevronTexaco) Mario Camarsa (Enstrat International)

Brian Doll (ExxonMobil) Miguel Moyano (ARPEL)

and the officers and members of the IPIECA Fuels and Vehicles Working Group:

Chairs: Bill Flis (ExxonMobil) and Stewart Kempsell (Shell) Roger Organ (ChevronTexaco)

Olivier Alexandre and Benoit Chague (Total)

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Introduction

This document provides background and ‘starting-point’ references and resources to help regulators, engineers, refiners and marketers plan and execute the phase out of leaded gasoline. It features extracts from documents written by IPIECA members, non-governmental organizations (NGOs) and environmental protection agencies, refiners, marketers, commercial organizations and consultants. Experience has shown the need to tailor lead phase out and unleaded gasoline (ULG) introduction strategies to the individual circumstances of a given region or country to its unique economic, social, cultural and technological infrastructure. In some cases (e.g. with certain vehicle fleets, or in the case where no refining activity is present in the country), this task is greatly simplified and the switch to unleaded gasoline can occur relatively rapidly. In other cases, the task is more complex and requires a longer phase-in period.

Downstream strategies and resources for phasing out leaded gasoline

IPIECA’s Fuels and Vehicles Working Group addresses environmental issues related to the refining and distri- bution of fuels, in particular working towards the elimination worldwide of the use of lead as an addi- tive in motor gasoline. IPIECA believes that the worldwide development of catalytic car exhaust tech- nology, which leads to cleaner air in urban areas, should not be inhibited and that the developing world should benefit from modern fuels which are available now in most countries. The removal of lead is impor-

tant to public welfare because it will allow the intro- duction of widely available vehicle catalytic exhaust technology to improve air quality.

In this regard, IPIECA members encourage govern- ments in countries still using leaded gasoline to develop lead phase-out action plans and finally mandate the elimination of lead as an additive. In pursuing this objective, we recognize that affordable energy supplies are just one of many other issues crit- ical to the health and public welfare of people,

IPIECA position on leaded gasoline phase out

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The IPIECA position on leaded gasoline phaseout (see box below) recognizes this and frames the discussion in the context of the various national and regional priorities (providing potable water, housing, sanitation, agricultural development, etc.) that compete for investment funds when considering lead phase out. At the time of writing, more than 85 per cent of world gasoline supply is unleaded. However, this encouraging statistic masks the fact that this has been achieved mostly in the developed world, where almost all gasoline is now unleaded. On a ‘per country’ basis, the phase-out picture is very different—a large part of the remaining leaded volumes are concentrated in the developing world where the existing refining infrastructure is often weak, and the potential to attract investment is marginal. Difficult choices and compromises will therefore need to be made in order to achieve global phase out of leaded gasoline in the timeframe suggested by recent intergovernmental declarations and resolutions. This document brings together information on leaded gasoline phase out throughout the supply chain, and provides further direction to more detailed references.

Because many of the decisions that need to be made as part of a phase-out programme are contingent on the market into which these fuels will be distributed, this document considers lead phase-out issues in ‘reverse order’, that is, backwards through the fuel supply chain from vehicle requirements to retail marketing and point of sale, through distribution and terminals to refining and supply. More general issues, such as tax incentives and public information and education programmes are covered towards the end of the document.

particularly in countries of the developing world. We understand that each country faces other issues and must set their own priorities and timetables according to these issues. Therefore, we intend to approach lead phase out constructively to support the elimination of lead, whilst also taking due consideration of customer satisfaction, vehicle performance, environmental quality improvement and the overall benefit to people in economically challenged countries. We will work with governments, car manufacturers and other

industries to address the economic, political and supply barriers to quick action.

Additionally, IPIECA will support and participate in

global and regional initiatives geared towards imple-

menting lead phase-out action plans, with the

ultimate objective of achieving global elimination of

leaded gasoline.

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General references

A good general reference to lead phase-out options is given in the United States Environmental Protection Agency (US EPA) document Implementers’ Guide to Phasing Out Lead in Gasoline (supplied on the IPIECA CD-ROM, Getting the Lead Out) which identifies broad strategies in the context of the refining and marketing infrastructure of developing countries. Reference should also be made to the UNEP/OECD document Phasing Lead out of Gasoline: An Examination of Policy Approaches in Different Countries, available from the UNEP website at www.unepie.org/home/html.

The benefits of unleaded gasoline

The most significant benefit of introducing unleaded gasoline is that it enables the introduction of catalytic converters, which are the single most effective method of reducing harmful exhaust emissions from vehicles. This alone could justify the introduction of unleaded gasoline and the elimination of leaded fuels to prevent any mis-fuelling. In addition, the reduction of lead compounds in the atmosphere, and the consequent lead drop out into the soil, reduces the overall lead burden on people and the environment.

The benefits for the motorist of changing to ULG are well documented and can include lower service costs, extended oil change intervals, cleaner spark plugs and a potential for increased fuel economy by reducing the likelihood of misfires. Although studies show a wide variation in the resulting cost savings, the benefits are tangible.

Progress on leaded gasoline phase out: where are we now?

The degree to which leaded gasoline has been phased out varies widely from region to region, country to country and, in certain cases, between urban and rural areas within a given country. While on a volume basis the overall lead phase-out situation looks encouraging, the data belies the fact that there are still areas where the leaded gasoline grades represent the majority (or in some cases the totality) of the gasoline consumption.

A useful survey of lead phase-out progress is periodically conducted by the International

Fuel Quality Center (IFQC). The current version of this document is available on the

IPIECA CD-ROM, Getting the Lead Out.

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Background

Lead basics: why was lead added to gasoline?

Lead and octane

Gasoline requires a certain octane quality to prevent the engine from ‘knock’, which is the uncontrolled combustion of the last part of the fuel/air mixture in the combustion chamber. Knock can reduce engine efficiency, reduce power, increase heat load on the cooling system and increase hydrocarbon emissions; it can also cause engine damage. Lead was found to be an economically effective means of increasing gasoline octane and so controlling engine knock. See Annex 1 for more background on why lead additives were used.

Lead and health

The use of lead alkyl continued through the 1970s, at which time mounting concern over the increasing recognition of the health effects of airborne lead eventually caused successive governments and regions (e.g. the EU) to ban the use of lead additives in gasoline. Lead is now believed to be a cumulative toxin that can be harmful if ingested at any age.

A major factor in banning lead was the introduction of exhaust catalysts to meet vehicle exhaust emissions limits aimed at improving air quality. Catalysts are quickly rendered inactive when lead from the anti-knock additives, carried in the exhaust gases, is deposited on the active catalyst sites, ‘poisoning’ the catalyst. Vehicle emissions increase substantially when the catalyst is poisoned. For more information on vehicle catalysts, see www.meca.org or http://auto.howstuffworks.com.

Vehicle basics: bridging the octane gap

ULG grades have been made available worldwide with a broad range of octane

numbers. The main grades (the only grade in some countries) or the grade attracting

the highest demand, have Research Octane Number (RON) values ranging from 88

to 98. However, a more careful analysis seems to suggest that about 85–90 per cent of

the volumes of unleaded gasoline have RON values ranging from 90–92 in developing

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economies and around 94–95 in developed economies. Because of concerns that the switch to ULG will result in undesirable increases in fuel benzene and aromatics contents, in almost every case, ULG grades have been, and are being, introduced in conjunction with gasoline compositional limits in terms of benzene and total aromatics content in a two-step process as follows:

■ Step one: capping the level of benzene and aromatics in the newly introduced unleaded grade at existing levels (usually around 5 and 50 per cent by volume respectively, but occasionally higher).

■ Step two: gradually reducing, in later stages, the benzene content of the new gasoline to levels ranging between 1 and 2 per cent, and the aromatics content to values between 40 and 50 per cent. A few countries have legislated an aromatics cap of 35 per cent maximum, however it should be noted that Category 1 of the World Wide Fuel Charter (the auto manufacturers’ consensus document on fuel quality) allows up to 50 per cent aromatics with no cap on olefin content.

Because the developed economies usually started the lead phase-out process earlier, most have by now achieved substantial reductions of both the benzene and the aromatics contents of their ULG grades. In these countries, the maximum allowed benzene is most often limited to 1 per cent, while the maximum limits on total aromatics range between 30 and 45 per cent. These different stages in the evolution towards ULG with higher RON and lower benzene and aromatics contents are a reflection of the refinery structure and complexity of the various geographical areas.

Refining basics: refinery structure and unleaded gasoline

The need to introduce ULG while attempting to control aromatics in gasoline is one of the key factors influencing the configuration of developing country refineries. The other major factor is the trend towards lower-sulphur gasoline. In general, developing country refineries are the least complex with:

■ very little or no alkylation or isomerization capacity; and

■ relatively small reforming capacity (in the 2–3 per cent range, expressed as

percentage of crude throughput).

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These refineries have little flexibility in general and this limits gasoline blending options to naphtha and a small amount of reformate. As a consequence, any move to ULG would result in a lower octane number and/or higher aromatics and benzene, unless one of the following avenues is pursued:

■ The purchase of high octane, low aromatics or aromatics-free blending components (e.g., methyl tertiary butyl ether (MTBE), other oxygenates, or alkylates).

■ Capital investment in an isomerization unit in order to upgrade some of the naphtha from a RON of 63–68 to a RON of 82–85. Isomerization plants are generally considered to be a lower-cost route to obtain the additional octane.

■ Investment in an alkylation plant, if the refinery already has a catalytic cracking unit and hence the feedstock necessary for these plants. This is potentially a capital intensive option.

An alternative strategy could be the use of methylcyclopentadienyl manganese tricarbonyl (MMT) which can cost-effectively provide an increase in octane number.

Although this strategy is sometimes used, it is has caused controversy because of uncertainties over alleged effects of MMT on health and vehicle exhaust emissions equipment (see page 16).

Sufficient reforming capacity to manufacture ULG exists in most regions. However, for the reasons stated previously most developing regions have a limited ability to produce sufficient pool octane while keeping benzene and aromatics to reasonable levels.

‘Reasonable’ in this instance should be viewed in the context of the associated removal of lead. At the moment, many of these refineries use oxygenated components—for example, ethers or alcohols—in their blends to help them achieve the required octane.

Lead phase-out programmes: general considerations

A number of factors should be considered in determining how best to eliminate the use of lead in gasoline. These include:

■ the reasons lead is being banned (i.e. whether the primary reason is to enable vehicle technology; concern over levels of lead in urban areas; supply;

availability; cost; or regional harmonization of gasoline specifications);

■ in-country and regional vehicle requirements;

■ current and envisioned refining, supply and distribution infrastructure;

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■ in-country resources available to manage the transition; and

■ the need for lead replacement gasoline (LRG).

Strategies for leaded gasoline phase out need to take account of a complex mix of factors relating to population density, transport policy, infrastructure, economics and resources which, in turn, relate to fuel supply, vehicle age and usage, as well as refining and retail distribution capability. All of the above are influenced, and need to be driven by, the political will to implement government policies that eliminate leaded gasoline.

Lessons learned from strategies employed in other lead phase-out programmes can help provide information for each country that begins such a programme.

There is no single ‘magic solution’ to this issue, because there are both multiple product quality variables (e.g the use of oxygenates and metallic additives, the levels of sulphur, aromatics and benzene) and vehicle issues (such as age, turnover rate, technology level and maintenance standards) that need to be juggled to arrive at a satisfactory compromise in each and every case. What is certain, however, is that the lead phase-out process should be specific to the situation in each country or region and great care must be taken to ensure that the solutions proposed are workable and appropriate for the market into which they are introduced; wholesale ‘importation’ of solutions from other countries or regions (for example, the USA or Europe) are rarely appropriate without modification.

Vehicle requirements: valve seat recession

Due to the high temperature of exhaust gases, exhaust valves operate in a hot

environment and valve seats are therefore susceptible to ‘recession’—where the valve

seats recede into the cylinder head. When unleaded fuel is used in engines with

susceptible valve seats, valve seat recession (VSR) may occur to some degree. Driving

conditions, engine condition and cooling system effectiveness all affect VSR. As

engine speed, load and temperature rise, so does the rate of valve seat wear. Although

experience with ULG phase-in programmes has demonstrated that VSR problems are

almost never seen in practice, it is possible to carry out a risk assessment prior to

introduction of ULG to assess the likely percentage of vehicles that could

theoretically suffer from VSR under extraordinary circumstances.

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Phase-out strategies

Several basic strategies are commonly identified when discussing lead phase out:

■ an immediate transition—with or without octane enhancement;

■ a medium-term transition (< 5 years); or

■ a longer-term transition (5–10 years).

Immediate transition

In this approach, the addition of lead alkyl to the fuel is stopped and the existing gasoline lead concentrations decline as the lead additive is flushed through the distribution system and storage tanks. Eventually the concentrations will fall below the maximum limit specification for ULG—commonly 0.013 g/l lead. In practice this is achieved in a matter of weeks to months, depending on the off-take volumes and frequencies from the various sites. During this process, samples should be taken at depots, terminals and at individual retail sites to confirm when the unleaded specification is achieved.

This option achieves lead phase out in the fastest and cheapest way possible for the marketer, but consideration of whether and how to make up the lost octane still needs to be made. In practice, unless planning horizons are long (e.g. 3–4 years) the loss of octane can rarely be made up at the local refinery because the timescales involved are too short to implement any more than minor changes. The most common strategies are to make up this shortfall with imports of high octane blending components, to realign the octane grades offered at the pump to match vehicle requirements (rather than consumer expectations), and to take the opportunity to reformulate the fuel slate (for example, with oxygenates or the addition of additives).

In cases where the octane shortfall is made up solely by increasing the reformate

blending stream, some increase in aromatics and benzene concentrations in the fuel is

to be expected. Consequently, where the country’s car population is made up of a low

percentage of vehicles with catalytic converters, average emissions of aromatics,

including benzene, may rise. As more catalyst-equipped vehicles are introduced into

the country, emissions of these and other pollutants will decline.

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If a significant proportion of the existing vehicle population at the time of changeover has susceptible valve seats, and if the road network is conducive to high- speed driving or high-loads are common for older cars, an anti-valve-seat-recession (AVSR) additive may be recommended. Depending on the circumstances, this may be introduced as an aftermarket product—where it is added by the motorist or the service station attendant on the forecourt—or in bulk at the refinery or terminal.

Obviously, when the additive is marketed in bulk, it should be suitable for all the vehicles into which it is likely to be introduced and it is worth noting that some VSR additives are unsuitable for use with vehicles equipped with catalytic converters.

Depending on how fuel is reformulated and, in particular the levels of aromatics in the final blend, as well as the materials used in the supply and distribution system, some problems with seal swelling and fuel leakage could occur. A review of the elastomeric materials employed in the gasoline supply chain should be undertaken.

The likelihood of seal leaks in vehicles is low, and an increase in the incidence of engine fires as a result of the introduction of ULG, although documented, has generally been overstated. Nonetheless it may be helpful to include some information or caution for owners of older vehicles as part of a public information campaign.

Medium- and long-term transitions

In a medium- or long-term transition, a dual distribution system is arranged and leaded gasoline is dispensed side by side with ULG. Because a parallel/segregated distribution system is required at refineries, terminals and retail sites to keep unleaded and leaded products separate, a medium- to long-term transition may incur considerable costs. Depending on the arrangement of existing tankage it may be possible to convert some retail sites at minimum expense, but in retail sites with only one tank for each product, extra investment will be required unless an octane grade is sacrificed. In addition to refinery and terminal storage infrastructure, additional costs may be incurred for tank truck fleet segregation, pipeline transport, additional retail tanks/pump islands and segregated vapour recovery equipment, where mandated.

In this arrangement, the opportunities for product co-mingling are high

throughout the gasoline supply chain and catalyst poisoning and deactivation are

probable for even low concentrations of lead mixtures that get into catalyst equipped

cars. Separate lead replacement gasoline, where the VSR prevention additive is added

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Strategy

Immediate:

lead additions ceased: existing lead levels drop rapidly over several months until unleaded conversion is achieved.

Medium-term:

Segregated distribution system is arranged from existing system or new parallel system constructed. Phase out takes place over several (<5) years.

Long-term:

Segregated distribution system is arranged from existing system or new parallel system constructed.

ULG is introduced at selected sites and is gradually introduced countrywide as newer catalyst-equipped vehicles are introduced. Phase out takes place over 5–10 year timeframe.

Advantages

●

Most cost-effective option for the fuel distributor. Few set-up costs, duplication of retail

infrastructure is not required.

●

Extensive public education effort and differential taxation scheme not required. Potential for mis-fuelling is eliminated.

●

Total lead emissions are minimized under this option.

●

Operators of older vehicles which cannot use ULG have an extended timeframe to either make modifications to existing vehicle or to purchase new vehicle.

●

Local refiners have a realistic timeframe to upgrade facilities.

Same as for medium-term advantages plus:

●

Change in fuels closely matched to vehicles that can best use them: fleet emission profiles (e.g.

of aromatics) are the least under this option.

●

Potentially the least-cost option for owners of older vehicles.

●

Lag times consistent with refinery upgrade project planning and construction.

Disadvantages

●

Actual rate and cost of phase out is tied to octane replacement through imports (e.g. of alkylate), increased severity of refinery processing, or detuning of vehicles requiring premium grades (see text).

●

Aromatics and benzene levels may rise slightly.

●

Older vehicles may require aftermarket additives if VSR is identified as an issue.

●

Depending on reformulation strategy, storage and supply chain elastomeric materials compatibility and fire protection arrangements may require review.

●

High costs due to segregated infrastructure required for storage, transfer and retail operations.

●

Very real possibility for mis-fuelling and damage to catalytic converters.

Same as for medium-term disadvantages plus:

●

Extended subsidy costs to Government if differential tax/pricing scheme is in place.

●

Owners do not receive financial benefits of lower-cost maintenance with ULG.

●

Total lead emissions are highest under this option.

Table 1: Key advantages and disadvantages associated with each transition option

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in bulk, is a possibility under this option, which gives vehicle owners a fuel that should be satisfactory for older cars. In practice, many vehicle owners will need a financial incentive to buy unleaded gasoline and, if leaded gasoline is less expensive, misfuelling will inevitably occur. A differential pricing strategy or tax rebate may be needed to encourage migration from leaded to unleaded product for those owners whose cars normally use leaded gasoline, but can also use unleaded.

However, with a long-term transition phase out the costs of a subsidy may become onerous. An advantage of the dual grade approach is that the growth in ULG sales can take place at a rate commensurate with the introduction of catalyst equipped vehicles, thereby more closely matching lead-free fuel to the vehicles that can take best advantage of it. However, the lead phase-out process is extended in this process;

historically, the USA and Europe took between 10 and 20 years to complete the lead phase-out process and it is widely acknowledged that this was too long. In addition to delaying the phase out of lead in motor fuels, the total costs to both government and the energy companies were unnecessarily high. In addition, vehicle owners were not encouraged to take advantage of the financial benefits that might have arisen from lower-cost maintenance following a switch to ULG. A rapid phase in would have increased those potential benefits.

Table 1 on page 13 summarizes the key advantages and disadvantages associated with each option.

Summary: deciding on a phase-in strategy

In summary, the adopted ULG phase-in strategy should consider all relevant factors:

■ The age distribution profile and country of manufacture of the gasoline-engine vehicle population; this will in turn dictate the percentage of vehicles:

• equipped with catalytic converters; or

• likely to be equipped with catalytic converters soon after elimination of leaded fuel.

■ A realistic appraisal as to whether VSR is likely to be a concern given the vehicle population and road network in question, and the experience to date in other countries with similar car populations and road networks.

■ The resources available to segregate leaded and unleaded fuels in the fuel supply chain.

■ The potential for mis-fuelling if catalyst-equipped cars are available.

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■ The availability of funds to subsidize unleaded gasoline to make it price- attractive to customers, and whether such an approach is likely to succeed given local cultural factors.

■ Market factors, the availability of imports and the timescales for local/regional refiners to supply ULG.

Notwithstanding the above, experience has shown that in countries without a refining infrastructure, immediate (rapid) phase out is almost always the best option.

In countries with a refining infrastructure, rapid phase out may be the best option depending on local circumstances.

Taking account of VSR in an unleaded gasoline phase-in strategy

Although VSR is a real and demonstrated effect in the laboratory, it is increasingly less of an issue for countries moving to ULG (see Annex 2), principally because, in countries where lead has been phased out, the experience has been that VSR problems rarely occur. Where it is suspected that VSR may be an issue however, lead replacement gasoline (LRG) may be considered as a protection strategy in ULG transitions when:

■ a risk assessment has signalled that a significant proportion of the vehicle population cannot safely use ULG;

and

■ the country infrastructure supports high-speed, high-load driving for extended periods.

LRG was a useful strategy in some developed countries that satisfied the above conditions and which had a retail distribution network that could accommodate additional gasoline grades at the pump. However, the costs involved in providing this option need to be carefully weighed against the actual, rather than the perceived, risks to older vehicles from the use of ULG.

Historically, LRGs have been formulated with a number of metallic additives—

principally sodium, potassium, phosphorous and manganese—but none has been found

to protect as well as lead under all conditions. Sodium additives (and to a lesser extent

potassium additives) have been associated with hot corrosion mechanisms in valves and

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turbochargers and are not recommended. Of the remaining additives, it is generally accepted that the protection hierarchy is phosphorous>potassium>manganese, although all these additives will provide protection under certain conditions.

Phosphorous additives are not recommended for vehicles equipped with catalytic converters, because phosphorous, like lead, is a catalyst poison; however, the World Wide Fuel Charter committee has approved potassium additives for VSR control where it might be deemed necessary. Table 2 lists some common brand names for additives used in the transition to ULG and LRG—note that not all of these are equivalent in design: some improve octane, some provide VSR protection, and others provide both. Please refer to the respective manufacturer for additional information.

Table 2: Some common additives for use in ULG and LRG

Product Manufacturer Type

Valvemaster Octel Phosphorous

Formula Shell Shell Potassium

MMT Ethyl Manganese

Powershield Lubrizol Potassium

PLUTOcen Octel Iron

The use of manganese to replace lead in unleaded gasoline

Like many, if not most, ULG additizing strategies, controversy exists regarding the use of methylcyclopentadienyl manganese tricarbonyl (MMT). MMT is attractive to both refiners and fuel marketers, not only because it provides a modest octane boost but also because it has a proven AVSR effect.

The controversy centres around concerns over the possibility of health effects and

the effects on vehicle exhaust emissions equipment. Many engine and vehicle test

programmes have been conducted to determine the effect on emissions. Some well-

designed studies show that MMT protects catalysts from sulphur and phosphorous

deactivation. In most test programmes, vehicle emissions of hydrocarbons increased and

NO

_x

emissions decreased when MMT was used in modern technology cars; catalyst

conversion efficiency improved even though engine-out emissions seemed to be higher.

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A 2002 report (www.autoalliance.org/mmt_program.htm) giving results of a multi- year, two-phase vehicle test programme compared the effects on vehicle emissions of MMT-fuelled (8.3 mg/l manganese) and clear-fuelled cars. That work indicated that MMT did not interfere with on-board diagnostic (OBD) equipment or oxygen sensors.

However, as in other programmes, hydrocarbon emissions were higher for the cars using fuel containing MMT. Engine-out NO

_x

emissions were higher for MMT-fuelled cars, but tailpipe emissions were lower because catalyst efficiency was increased. The report indicated that increased catalyst efficiency did not make up for higher engine-out hydrocarbon emissions and that, at very high mileage for the California LEV-certified vehicles, all regulated emissions were higher for the MMT-fuelled cars. The report leads to the conclusion that fuel with MMT should not be used in the most sophisticated emission systems if very low emission levels are required. However, for older emission technology vehicles some deterioration of catalysts might be acceptable if the use of MMT led to accelerated lead phase-out programmes and prevented mis- fuelling of catalyst equipped vehicles.

Although the overall health and technical issues surrounding MMT remain somewhat unclear, it clearly should be considered as an option in transition to unleaded gasoline. In this regard, every refinery situation is different. The operator must consider all the options and risks: more severe processing; refinery investments;

purchase of high-octane components; the use of additives, potentially including MMT, and the risk of catalyst poisoning through cross-contamination, mis-fuelling and/or fuel adulteration practices where leaded gasoline is still available. Each strategy carries attendant risks, benefits and costs, and consideration of these options on a case-by-case basis in order to expedite the removal of lead is vital.

Ethers and alcohols: the use of oxygenates as a blending component in unleaded gasoline

Typically, oxygenates utilized as components of automotive gasoline are either alcohols (mainly ethanol) or an ether (mainly MTBE). Occasionally, both may be present in a given gasoline. The use of ethanol is technically feasible, but usually involves the use of subsidies to make its use economically viable. Due to concerns over groundwater contamination, the use of MTBE is being phased out in the USA.

However, it is still the most common oxygenate in use worldwide. See Annex 3 for

more technical information on the use of oxygenates.

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Switching to unleaded gasoline

Refining options for the production of unleaded gasoline

The octane gap

A finished base gasoline without lead has a lower octane number than if lead were added, because lead is highly effective in increasing the octane number. Typically, moving to unleaded gasoline from a lead level of 0.15 g/l gives an octane shortfall of 3 RON, while, if the lead level was previously 0.40 g/l, the RON shortfall would be about 5 numbers.

It could be desirable or necessary to maintain pool octane number to prevent widespread engine knocking and customer dissatisfaction. There are several refinery streams and imported high octane blending components that could be used to that purpose, but their attractiveness depends on individual refinery configuration. A simple topping/reforming refinery will have fewer types of processing units and blending streams with which to maintain octane number compared to a complex refinery with fluid catalytic cracking and/or hydrocracking units (FCCU/HCU).

Reformulating to maintain octane number

The process of selecting the optimal blending components to maintain the octane number of the ULG grades must take into account several parameters, the most important of which are:

■ blending octane number of the new components/volume required for necessary octane increase;

■ impact on meeting other gasoline specifications (volatility, chemical composition) and providing acceptable vehicle performance; and

■ component availability and cost.

The latter point is greatly affected by the operating conditions and processing

units of each individual refinery, and by the economics of local product procurement

and security of supply. Additional consideration will need to be given to the economic

and social costs associated with alternatives such as direct importation, as well as the

supply situation for finished fuels and blending components. See Annex 4 for more

information on refining options for the production of ULG.

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General issues

Taxation incentives to encourage adoption of unleaded gasoline

A switchover to ULG is almost always accompanied by taxation incentives to effectively subsidize the production of ULG which is more expensive to produce.

Hence, ULG can be sold more cheaply at the pump to encourage uptake, even in vehicles that are not equipped with a catalytic converter. Such taxation mechanisms have been commonly applied in developed countries. However, in developing countries, this cross subsidy in pricing has, in some cases, been seen as an unfair penalty levied on owners of older vehicles using leaded fuel.

The distinction here is relevant in an ‘un-catalysed’ dual grade market (where both leaded and unleaded fuel are available) and where a tax subsidy is designed to encourage drivers of vehicles that can use ULG (but do not) to switch to ULG. In doing this, care should be taken to avoid the perception that drivers of vehicles that cannot use ULG—generally older vehicles owned by less affluent sections of the population—are being penalized.

In at least one case this has resulted in a reversal of the tax subsidy philosophy and the pegging of ULG prices at a level where they are not attractive to the consumer, with consequent poor market penetration of ULG. The lesson is clear: individual countries need defined ULG implementation strategies based on local needs, cultures and infrastructure rather than wholesale importation of ‘Northern’ or ‘Western’

strategies. Various mechanisms which can be used to encourage the adoption of lead phase-out programmes are given in World Bank Technical paper 397, ‘Phasing Out Lead from Gasoline’.

Media relations and information strategies

Experience from other countries has shown that serious public disquiet can result if

the appropriate steps are not taken to educate and reassure all stakeholders

concerning the product quality and safety of ULG when it is introduced. This is

particularly the case where the changeover is rapid rather than phased.

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Although there have been isolated incidents of small-community public health hysteria during the introduction of ULG/reformulated gasoline (the Alaska MTBE incident being amongst the most famous), ULG introduction has mostly proved uneventful with minimum adverse public reaction where a few simple steps were taken to communicate with the public.

Whereas, in larger countries, information on the introduction of ULG may be provided by the oil companies and auto associations themselves, in smaller countries, particularly those with state-owned refining or marketing assets, it is usually helpful to devise some form of cross-functional, multi-stakeholder steering committee with responsibility for ensuring the smooth introduction of ULG into the marketplace.

This committee could be comprised of representatives from government, industry, motor manufacturers, refiners, distributors, etc. It may be beneficial to form several subcommittees when considering technical issues such as refinery performance planning, importation and supply, etc.

Activities associated with ULG phase-in could include, but are not limited to:

■ Pre-launch communications: these would include letters to car dealers, informing them of plans for the phase out of leaded fuel, and requesting them to compile data on models and model years, compatibility with ULG, and octane requirements. These details will be required for publication of

information for the motorist. Additional communications should be made to oil companies and independent service station dealers in order that they can begin the process of staff training to minimize incidents such as mis-fuelling, and to answer customer enquiries.

■ Preparation of an information booklet and/or Internet site: this would include published data on vehicle compatibility with ULG, material for FAQ

(frequently asked questions) and information on LRG or availability of aftermarket additive packages (where used). Information should be targeted at specific groups (e.g. motorists, garages or retail sites). An example of a

publication issued to motor dealers in New Zealand is available on the IPIECA CD-ROM, Getting the Lead Out.

■ Public campaign: an evaluation will need to be made regarding the need for a

structured marketing campaign designed to guide consumers and reassure

them regarding the new fuel. The benefits of such a campaign are many-fold,

and include:

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• informing and educating consumers on the environmental benefits of ULG;

• maximizing consumer confidence in the quality of the product and it’s suitability for their vehicle;

• introducing ULG smoothly and cost-effectively into the marketplace; and

• addressing potential consumer public health

concerns over ULG and any additives or oxygenated components (e.g. MTBE, MMT, etc.) early on to prevent unfounded concern.

This may involve the need for a marketing consultant and/or advertising agency; liaison on press releases and advertorials; design, production and distribution of the information booklet and other advertorial material; preparation of press releases; the compilation of technical information on the additizing strategies;

and briefing material for government departments and other agencies. Additionally, if a ‘hotline’ or internet information site is to be set up, this will need to be professionally managed.

Identified target audiences (‘stakeholders’) for the campaign could include:

■ the motoring public and commercial vehicle drivers;

■ private and fleet vehicle importers, dealers, distributors, and servicers;

■ motoring/transport organizations and associations;

■ service station dealers;

■ relevant government departments and agencies; and

■ the media.

Public information

materials should give

details of which

vehicles can be used

with which grades of

the new fuel

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The final step

Decommissioning of lead alkyl facilities

An often-overlooked aspect of the change to ULG is the need to safely dismantle redundant lead alkyl facilities, as well as the clean-up and remediation of the area where the lead additizing operations took place. Abandoned lead additive handling facilities represent a potential hazard to the environment and human health, and a plan to effect site closure should form part of any scheduled plan to introduce ULG.

Reputable suppliers of lead alkyl have recognized these potential dangers and are

available to advise on safe site clearance procedures where required.

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Annexes

Annex 1: Lead basics: why lead was used in gasoline 24

Annex 2: Valve Seat Recession (VSR): is the risk real and 26 what are the strategies for protection?

Annex 3: The use of oxygenates in moving to unleaded gasoline 29

Annex 4: Refining options for the production of unleaded gasoline 33

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Lead basics: why lead was used in gasoline

Using a single-cylinder laboratory test engine method established in 1929, gasoline octane is determined by comparing the anti-knock performance of a particular sample to blends of iso-octane (2,2,4, trimethyl pentane) and normal heptane. Iso-octane is assigned a value of 100 and normal heptane is assigned a value of zero; blends are made to make intermediate values. Using different operating conditions a Research Octane Number (RON) and a Motor Octane Number (MON) can be assigned to a fuel. The higher the octane number, the greater the fuels’ resistance to knock. The widespread use of lead alkyl additives in motor gasoline followed the 1921 discovery by General Motors engineers of its ability to increase octane rating and hence the anti-knock properties of a gasoline to which it was added.

Despite advances in refining technology, this approach remained a more cost- effective option for increasing octane than the intensive refinery processing that is required without the use of the additive. In addition to increasing gasoline octane, an unexpected benefit of lead alkyl additives was that the lead acts as a lubricant between the contact surfaces of the exhaust valves and the valve seats in the cylinder head. This proved to be an advantage, as valve seats could be machined directly into the ductile iron of cylinder heads without the need for expensive and thermally inefficient hardened inserts: the lead additive provided all the required protection. Without this protection, accelerated valve seat wear called ‘valve seat recession’ (VSR) may theoretically occur, which could eventually lead to engine failure.

Annex 1

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What happens when lead is removed?

When lead is no longer added to the gasoline pool, octane number is reduced.

Pool octane can be increased by using higher octane blending streams made by increased processing at the refinery, by blending oxygenates (e.g. methyl tertiary butyl ether (MTBE), or ethanol) into the fuel, or by using metallic additives. While no gasoline additive is as effective as lead in preventing VSR, engines in normal operation can be protected by additives containing phosphorous, manganese or potassium. Some additives may have a detrimental effect on catalyst efficiency, and in some cases, several concurrent effects (on emissions and on catalyst performance and durability) are suspected, making determination of net effects particularly difficult.

Website references for further reading www.ethyl.com

www.octel-corp.com

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Valve Seat Recession (VSR):

is the risk real and what are the strategies for protection

Although VSR is a real and demonstrated effect in the laboratory, it is increasingly less likely to be an issue in most countries moving to ULG, for three reasons:

■ With some exceptions, engines with susceptible valve seats have not been manufactured since the late 1980s. With every year that passes, the percentage of these vehicles in a given car population will decrease as older vehicles with hardened valve seats are scrapped and replaced by newer ones.

■ Engines in older cars may not operate for sustained periods of time under the constant ‘high load’ or ‘high speed’ conditions that are reported to cause VSR in older vehicles. This is particularly true in countries where the road network does not support more than ‘mixed road driving’, which includes periods of idling and low speed/low load operation. Under these conditions the effects of VSR will probably not be seen, particularly in vehicles that have built up a ‘lead memory’ effect (see below).

■ Experience from countries where lead has been phased out, is that VSR problems rarely occur.

Despite this, many countries do carry out a risk assessment prior to ULG introduction to determine whether VSR could be an issue. A publication on risk assessment procedures is available from Environment Canada (report number EPS 3/TS/1, October 1999).

When decisions are made regarding the need for VSR protection, accurate data on the vehicle population is required, as assumptions that are valid in other countries may not apply in the country eliminating leaded gasoline. As

Annex 2

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an example, the ownership of older vehicles may not decrease exponentially because the average age of the vehicle fleet is increasing, or it could be that imports of used vehicles confuses the statistics for new registrations. Care should also be taken when determining potential susceptibility of vehicle models to VSR in a given in-country fleet due to regional and national variations in models and equipment levels. Useful data may be obtained from vehicle and additive manufacturer websites.

If a risk assessment of the type described above shows that VSR is a potential issue in a given vehicle population, there are certain strategies that can be employed, including the use of anti-valve seat recession (AVSR) additives:

■ Phosphorous compounds have been shown to provide a high level of VSR protection (sodium, manganese and potassium compounds also show VSR protection) and are used in lead replacement gasoline. Phosphorous compounds are poisonous to catalytic converters and vehicle manufacturers do not recommend their use for catalyst-equipped cars. They should be segregated in the gasoline supply chain as if they were leaded.

■ The alkali metals (e.g. sodium and potassium) have been shown to

provide a measure of protection against VSR. However, a number of

side effects have been encountered when using high concentrations of

alkali metals for VSR protection. The two most significant effects are

inlet-valve sticking (which may occur in critical vehicles at low

temperatures and can lead to starting difficulties in cold weather) and

the formation of a corrosive flux of metal salts, leading to exhaust valve

burning and hot corrosion of turbocharger rotors. Because the presence

of lead exacerbates this effect, alkali metal AVSR additives should only

be used with unleaded gasoline. Furthermore, the use of LRG

containing alkali metal AVSR additives can potentially lead to mis-

fuelling in markets where owners unwittingly use such an LRG

interchangeably with a leaded grade. For this reason, LRG and leaded

products should not be marketed in the same area.

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■ One manganese compound, methylcyclopentadienyl manganese

tricarbonyl (MMT) also provides some VSR protection, and can provide octane number increases of between 1 and 2, depending on how much is added.

The ‘lead memory’ effect

In an engine running on leaded gasoline, lead deposits on valves and seats are simultaneously worn away and replenished from the fuel. If an engine has run for some time on leaded fuel, and then is switched to ULG, the onset of VSR is delayed by a ‘lead memory’ made up of existing deposits of lead bound to the valve and valve seat. The memory ‘length’ depends on the subsequent driving mode: moderate and mixed-road driving may extend the effect for some thousands of kilometres; however under severe high-speed high-load conditions, this memory effect will disappear almost immediately.

Annex 2 (continued)

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The use of oxygenates in moving to unleaded gasoline

This Annex will mainly consider the effects of MTBE-oxygenated gasoline, although the other ethers (ETBE, TAME) have similar properties. The following table gives some examples of common gasoline oxygenates.

Annex 3

Common gasoline oxygenates

Alcohol Ether

methanol MTBE (methyl tertiary butyl ether) ethanol ETBE (ethyl tertiary butyl ether) IPA (isopropanol) TAME (tertiary amyl methyl ether)

Currently, the limits surrounding the use of oxygenates in gasoline are based on:

■ the oxygen contributed to the gasoline (i.e., chemical leaning of the fuel/air mixture);

■ the vapour pressure of the blend (in the case of ethanol addition); and

■ fire fighting precautions at terminal.

In practice, the oxygen content of gasolines should be limited to about 2.7 per cent maximum from all sources, otherwise driveability problems can be encountered from lean fuel/air mixtures. The higher the oxygen content, the lower the stoichiometric air-fuel ratio and the leaner the gasoline/air mixture when combusted in the engine. Symptoms of these driveability problems include rough idle, hesitation, stumble, surge or stalling on acceleration.

Older cars are more susceptible to these driveability problems than the newer

cars that have oxygen sensors in the exhaust stream. These oxygen sensors

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Annex 3 (continued)

measure the oxygen in the exhaust and adjust the air-fuel mixture in the engine so that it operates close to the stoichiometric ratio where all the fuel is burned. The oxygen contribution of three oxygenates (MTBE, methanol and ethanol) can be found in the table below.

From the above, it is evident that a greater percentage volume of MTBE is acceptable than methanol or ethanol. In the USA, a 10 per cent ethanol blend is called ‘gasohol’ and is legal in a number of states. Ethanol, and particularly methanol can cause fuel system corrosion, elastomer compatibility problems, emulsions and phase separation with water. However, extensive experience gathered from ethanol use in Brazil and South Africa over the past twenty years has demonstrated that ethanol blends can be safely and successfully marketed given appropriate distribution precautions.

Per cent oxygen in gasoline mixture

% Vol. MTBE methanol ethanol

1 0.18 0.53 0.37

2 0.36 1.06 0.73

3 0.54 1.59 1.10

4 0.72 2.12 1.47

5 0.90 2.65 1.84

6 1.08 3.19 2.20

7 1.26 3.72 2.57

8 1.62 4.78 2.94

10 1.80 5.31 3.67

12 2.17 6.37 4.41

15 2.71 7.96 5.51

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With the exception of certain purpose-built flexibly fuelled vehicles, Methanol fuels are not recommended by any vehicle manufacturer and many warranties are voided by its use.

In addition, from a product (as opposed to an environmental) point of view, MTBE is a preferred gasoline blendstock to the alcohols because it has a lower affinity for water. Water contamination has caused problems in the past. If there is water in the tank then the alcohol will be extracted from the gasoline phase into the water phase causing a number of undesirable effects, including:

■ A lower concentration of alcohol in the gasoline reduces the octane.

■ As alcohol is absorbed by the water phase (which settles to the bottom of the tank because its density is higher than gasoline) the volume of the water-alcohol phase increases and its level can reach the pickup tube and be transferred to the motorist’s tank.

■ A larger water-alcohol phase in the vehicle tank is likely to be picked up by the fuel pump and cause the engine to run rough or stall.

■ The alcohol-contaminated water bottoms from the gasoline distribution system tanks need to be specially treated to get rid of the alcohol.

Vehicle manufacturers have, in the past, been cautious over the use of oxygenates, particularly for the most advanced emission control systems because the emissions system can under-correct for the additional oxygen in the fuel. This can lead to degraded driveability and an increase in emissions.

Where oxygenates are used, the automakers express a preference for ethers rather than alcohols although their consensus document—the World Wide Fuel Charter—does permit ethanol use within certain parameters (see www.autoalliance.org). Ethanol based fuels have been used successfully in some countries (e.g. Brazil) for many years.

If the vapour pressure (RVP, Reid Vapour Pressure) of the gasoline/oxygenate

mixture is not controlled properly, hot running problems can occur.

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Annex 3 (continued)

Symptoms can include hard starting after hot shutdown, rough idle, surge and vapour lock. Alcohols (especially methanol) result in a dramatic increase in the RVP of a gasoline. However, the blending vapour pressure of MTBE (50–65 kPa) is lower than that of finished gasoline which may allow additional butane to be used in the blend without exceeding the RVP specification.

ETBE has an even lower blending RVP.

The effects on driveability and performance are dependent on a number of factors: the specific vehicle; the composition of the fuel; whether it is leaded or unleaded; and the method of the test. Vehicles not fitted with exhaust emission controls such as catalytic converters may show an inferior driveability performance when using gasolines containing oxygenates, particularly if they are set to operate as lean as possible for fuel economy and emissions reasons.

Properly maintained and adjusted vehicles should operate satisfactorily on 10 per cent MTBE. They will probably also operate satisfactorily on 15 per cent MTBE.

Sensitivities—i.e. Research Octane Number (RON) minus Motor Octane

Number (MON)—of oxygenates are high. When MON is a critical

specification point, it may result in exceeding the RON specification (i.e. the

so-called ‘quality giveaway’). In this situation, blending components with low

sensitivities (e.g., alkylate or isomerate) may be needed.

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Refining options for the production of unleaded gasoline

The process of selecting the optimal blending components to maintain the octane number of the new unleaded gasoline (ULG) grades must take into account several parameters, the most important of which are:

■ blending octane number of the new components/volume required for necessary octane increase;

■ impact on meeting other gasoline specifications (volatility, chemical composition) and providing acceptable vehicle performance; and

■ component availability and cost.

Additional consideration will need to be given to the economic and social costs associated with alternatives such as direct importation, as well as the supply situation for finished fuels, and the use of blending components such as MTBE and additives such as MMT. Due to variations in the configuration of existing refineries and their individual economic and supply situations, it is almost impossible to give generic guidelines on this subject, however the options for simple and complex refineries are discussed here in general terms.

Options for simple refineries

Simple topping/reforming refineries rely on catalytic reforming of naphtha as their major source of octane. These reformers are key units used to increase pool octane and to supply the hydrogen needed for hydro-desulphurization operations if production of lower-sulphur fuels is required. Reformers can be operated at different levels of severity, typically producing aromatic hydrocarbons, including benzene, with Research Octane Numbers (RON) ranging from 90 to 98. Therefore, as they stand, simple topping/reforming refineries may not be able to make unleaded gasoline if low aromatics limits are in place at the same time as the lead phase-out initiative.

Annex 4

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Annex 4 (continued)

In order to overcome such a situation, these refineries would have to consider one of the following options:

■ Import of methyl tertiary butyl ether (MTBE—see Annex 3): MTBE is a high-octane blending component with a blending RON of between 115 and 120, depending on the composition of the gasoline into which it is blended.

Topping/reforming-only refineries must import MTBE because, without a catalytic cracking unit, they would not have isobutene available as feedstock to make their own MTBE. Because MTBE is typically added in significant volumes (commonly 10 per cent) and is essentially sulphur free, a reduction in gasoline sulphur content can be achieved as an incidental benefit.

■ Building a new isomerization unit to convert straight-chain pentane and hexane to the corresponding branched hydrocarbons, which have a much higher octane number: this process effectively upgrades light naphtha with a RON of about 65 to isomerate with a RON of 82 to 84, for units without effluent recycle, or a RON of 90 for plants with effluent recycle. However the latter are significantly more expensive.

■ Upgrading the fixed-bed reformer with the addition of a new heater and circulating catalyst final reactor and regenerator. The additional unit provides a step change in octane while the lower operating pressures and reduced severity applied to the fixed bed reactors will tend to reduce benzene concentrations, providing that the input concentrations of benzene precursors are controlled; the UOP ‘CycleX’ system is a good example of this approach.

These measures can keep the level of total aromatics in the final gasoline blend within currently acceptable limits. They will also reduce the benzene content of the gasoline.

These steps may not be sufficient if very low benzene levels are required. In

this case the benzene content of the reformate must be further reduced

through the following steps:

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■ The use of reformer feedstocks with a cut point in the range of 85 to 90 degrees C, rather than the more usual 65 degrees C. This approach routes part of the benzene precursor stream to light naphtha or to isomerization feedstock.

■ The use of reformate splitting, followed by light reformate benzene saturation and once through isomerization. This is a more effective approach (down to 1 per cent benzene and below), and is applicable to all types of refinery configuration. The isomerization step is needed because the saturation of benzene (to cyclohexane) results in the loss of about 18 RON points, which can be recovered by isomerization of cyclohexane and straight chain paraffins of the hydrosaturated light reformate. The Axens ‘Benfree’ technology is a good example of this approach.

Options for complex refineries

Fluid catalytic cracking (FCC) units provide more flexibility to refineries, because they are able to increase the overall yield of gasoline while, at the same time, increasing octane number. However, only light- and mid-range fractions of FCC naphtha are valuable as a gasoline blending component.

Heavy FCC fractions have a tendency to high sulphur and aromatics contents, precisely the product components that are increasingly under regulatory scrutiny in modern gasolines.

However, complex refineries have the potential for making good use of the octane blending advantages provided by the mid-range FCC naphtha and for investing in units that upgrade both the light and heavy ends as follows:

■ The olefins from the light FCC naphtha can be used as a feedstock for alkylation units or for MTBE production plants. Alkylate is a high octane, aromatics-free blending component and is valuable as a ULG blendstock.

■ The heavy end of the FCC naphtha can be hydrotreated, fractionated

out of the gasoline component, or used as feedstock for a hydrocracker,

if this unit is available at the refinery.

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Annex 4 (continued)

Overall, complex refineries have a larger selection of options available for bridging the octane gap in ULG production, as they can potentially use all the options available to simpler refineries, plus those provided by the availability of the FCC naphtha.

Impact on refinery hydrogen balance

The above demonstrates that lead phase out coupled with the need to maintain or reduce the levels of aromatics and benzene in gasoline require some very substantial changes in the gasoline production and blending practices of essentially all refineries.

In particular, the following observations may be made and are broadly true for most situations and refinery configurations when converting to ULG production:

■ Increasingly, there is less reliance on the reformate for providing the octane quality needed by the final blend.

■ There is a greater use of iso-paraffins, alkylates, and oxygenates.

■ There is more saturation of aromatics in general, and of benzene in particular.

The net effect of the above is that increasing amounts of hydrogen will be required in the refinery. However, this requirement highlights two concurrent factors: firstly, the reduction of the relative role of the major (in some cases the only) source of hydrogen in the refinery, namely the reformer;

and secondly, the trend towards increased hydrotreating of distillate fuels in order to lower sulphur content. The net effect of this is that while less hydrogen is being produced internally, more is being consumed, and the result is an increased need to invest in capital and energy-intensive hydrogen plants, to address this production versus demand imbalance.

At a recent conference on Sub Saharan African Refining, IPIECA asked two

major process licensors to provide their thoughts on cost-effective options for

refining upgrades: presentations by Axens and UOP are available on the

IPIECA CD-ROM, Getting the Lead Out.

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Downstream strategies and resources for phasing out leaded gasoline

HOW TO USE THIS CD-ROM:

Insert CD-ROM, launch the PDF file called ‘index’ and follow the instructions provided. (Requires Adobe Acrobat Reader v.4 or later)