Application: The Snamprogetti methyl tertiary butyl ether (MTBE) crack-ing technology allows produccrack-ing high-purity isobutylene, which can be used as monomer for elastomers (polyIsobutylene, butyl rubber), and/
or as intermediate for the production of chemicals (MMA, tertiary-butyl phenols, tertiary-butyl amines, etc.)
Feed: MTBE can be used as the feedstock in the plant; in case of high level of impurities, a purification section can be added before the reactor.
Description: The MTBE cracking technology is based on proprietary cat-alyst and reactor that carry out the reaction with excellent flexibility, mild conditions as well as without corrosion and environmental problems.
With Saipem consolidated technology, it is possible to reach the desired isobutylene purity and production with only one tubular reactor (1) filled with a proprietary catalyst characterized for the right balance between acidity and activity.
The reaction effluent, mainly consisting of isobutylene, methanol and unconverted MTBE, is sent to a counter-current washing tower (2) to separate out methanol and then to two fractionation towers to sepa-rate isobutylene from unconverted MTBE, which is recycled to the reac-tor (3) and from lights compounds (4). The produced isobutylene has a product purity of 99.9+ wt%.
The methanol/water solution leaving the washing tower is fed to the alcohol recovery section (5) where high-quality methanol is recovered.
Utilities:
Steam 5 t / t isobutylene
Water, cooling 186 m³/t isobutylene
Power 17.4 kWh / t isobutylene
Installation: Four units have been licensed by Saipem.
Licensor: Saipem contact
2
Ether
High-purity isobutene MTBE feed
MeOH 1
3
5
4 Light ends
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Isomerization
Application: C5 / C6 paraffin-rich hydrocarbon streams are isomerized to produce high RON and MON product suitable for addition to the gasoline pool.
Description: Several variations of the C5 / C6 isomerization process are available. The choice can be a once-through reaction for an inexpensive-but-limited octane boost, or, for substantial octane improvement and as an alternate (in addition) to the conventional DIH recycle option, the Ip-sorb Isom scheme shown to recycle the normal paraffins for their com-plete conversion. The Hexorb Isom configuration achieves a comcom-plete normal paraffin conversion plus substantial conversion of low (75) oc-tane methyl penoc-tanes gives the maximum ococ-tane results. With the most active isomerization catalyst (chlorinated alumina), particularly with the Albemarle /Axens jointly developed ATIS2L catalyst, the isomerization performance varies from 84 to 92: once-through isomerization -84, isomerization with DIH recycle -88, Ipsorb -90, Hexorb-92.
Operating conditions: The Ipsorb Isom process uses a deisopentanizer (1) to separate the isopentane from the reactor feed. A small amount of hydrogen is also added to reactor (2) feed. The isomerization reaction proceeds at moderate temperature producing an equilibrium mixture of normal and isoparaffins. The catalyst has a long service life. The reactor products are separated into isomerate product and normal paraffins in the Ipsorb molecular sieve separation section (3) which features a novel vapor phase PSA technique. This enables the product to consist entirely of branched isomers.
Installation: Sixty-five C5 / C6 isomerization licenses have been issued over the last 20 years, with over 27 obtained in the last five years. Twen-ty-one units are operating including one Ipsorb unit.
Reference: Axens /Albemarle, “Advanced solutions for paraffin isomerization,” NPRA Annual Meeting, March 2004, San Antonio.
“Paraffins isomerizatioin options,” Petroleum Technology Quarterly, Q2, 2005.
Licensor: Axens contact
START
C5/C6 feed
Hydrogen
Offgas
Isomerate
Recycle CW
2 3
1
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Isomerization
Application: Convert normal olefins to isoolefins.
Description:
C4 olefin skeletal isomerization (ISOmPluS)
A zeolite-based catalyst especially developed for this process pro-vides near equilibrium conversion of normal butenes to isobutylene at high selectivity and long process cycle times. A simple process scheme and moderate process conditions result in low capital and operating costs. Hydrocarbon feed containing n-butenes, such as C4 raffinate, can be processed without steam or other diluents, nor the addition of cata-lyst activation agents to promote the reaction. Near-equilibrium con-version levels up to 44% of the contained n-butenes are achieved at greater than 90% selectivity to isobutylene. During the process cycle, coke gradually builds up on the catalyst, reducing the isomerization ac-tivity. At the end of the process cycle, the feed is switched to a fresh catalyst bed, and the spent catalyst bed is regenerated by oxidizing the coke with an air/nitrogen mixture. The butene isomerate is suitable for making high purity isobutylene product.
C5 olefin skeletal isomerization (ISOmPluS)
A zeolite-based catalyst especially developed for this process pro-vides near-equilibrium conversion of normal pentenes to isoamylene at high selectivity and long process cycle times. Hydrocarbon feeds con-taining n-pentenes, such as C5 raffinate, are processed in the skeletal isomerization reactor without steam or other diluents, nor the addition of catalyst activation agents to promote the reaction. Near-equilibrium conversion levels up to 72% of the contained normal pentenes are ob-served at greater than 95% selectivity to isoamylenes.
Economics: The IsomPlus process offers the advantages of low capital investment and operating costs coupled with a high yield of isobutylene or isoamylene. Also, the small quantity of heavy byproducts formed can
easily be blended into the gasoline pool. Capital costs (equipment, labor and detailed engineering) for three different plant sizes are:
Total installed cost: Feedrate, mbpd ISBl cost, $mm 10 8
15 11 30 20
utility consumption: per barrel of feed (assuming an electric-motor-driven compressor) are:
Power, kWh 3.2
Fuel gas, mmBtu 0.44
steam, mP, mmBtu 0.002
Water, cooling, mmBtu 0.051
Nitrogen, scf 57–250
Installation: Two plants are in operation. Two licensed units are in vari-ous stages of design.
licensor: lummus Technology, a CB&I company contact
3
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Isomerization
Application: For more refiners, the issue of benzene in the gasoline pool is one of managing benzene production from the catalytic reformer. The two primary strategies to accomplish this goal include the minimization of benzene and benzene precursors in the catalytic reformer feed, or elimination of the benzene from the reformate after it is formed. The UOP BenSat process can be applied in either of these strategies. The process can operate in stand-along mode or in conjunction with C5 – C6 isomerization such as the UOP Penex-Plus process configuration.
Description: The UOP BenSat process was developed as a low-cost stand-alone option to treat C5 – C6 feedstocks that are high in benzene.
Benzene is saturated to C6 naphthenes. The catalyst used in this process is highly selective for benzene saturation to C6 naphthenes.
Makeup hydrogen is provided in an amount slightly above the stoi-chiometric level required for benzene saturation. The heat of reaction associated with benzene saturation is carefully managed to control tem-perature rise across the reactor. Use of a relatively high space velocity in the reactor contributes to the unit’s cost-effectiveness.
Feed: Typical feeds include hydrotreated light straight-run (LSR) naphtha or light reformate streams. The Ben Sat process is designed to handle 30 vol% or more benzene in the feed. Sulfur suppresses activity, as ex-pected for any noble-metal-based catalyst. However, the suppression effect is fully reversible by subsequent processing with clean feedstocks.
Yields: For feeds with 5–10 vol% benzene, the C5+ volumetric product yields are 101–106% of the feed. Because of high catalyst selectivity, hydrogen consumption is minimized and is near the stoichiometric level of three moles of hydrogen per mole of benzene saturated. The BenSat process saturates benzene without an increase in Rvp.
Installation: The first BenSat unit was started in 1994. Since then 13 additional units have been commissioned either as a stand-alone unit or integrated with the Penex process in a Penex-Plus configuration. Several additional units are in design and construction.
Licensor: UOP, A Honeywell Company contact
Makeup hydrogen
Preheater (for startup only)
Feed/effluent exchanger
Reactor
Light ends to FG Stabilizer
Feed
Product