Ethylbenzene
Application: To produce ethylbenzene (EB) from benzene and a poly-mer-grade ethylene or an ethylene/ethane feedstock using the Bad-ger EBMax process and proprietary ExxonMobil alkylation and trans-alkylation catalysts. The technology can be applied in the design of grassroots units, upgrading of existing vapor-phase technology plants, or conversion of aluminum chloride technology EB plants to zeolite technology.
Description: Ethylene reacts with benzene in either a totally liquid-fi lled or mixed-phase alkylation reactor (1) containing multiple fi xed-beds of ExxonMobil’s proprietary catalyst, forming EB and very small quantities of polyethylbenzenes (PEB). In the transalkylation reactor (2), PEB is con-verted to EB by reaction with benzene over ExxonMobil’s transalkylation catalyst. PEB and benzene recovered from the crude EB enter the trans-alkylation reactor.
Effl uents from the alkylation and transalkylation reactors are fed to the benzene column (3), where unreacted benzene is recovered from crude EB. The fresh benzene feedstock and a small vent stream from the benzene column are fed to the lights column (4) to reject light im-purities. The lights column bottoms is returned to the benzene column.
The bottoms from the benzene column is fed to the EB column (5) to recover EB product. The bottoms from the EB column is fed to the PEB column (6) where recyclable alkylbenzenes are recovered as a distillate and diphenyl compounds are rejected in a bottoms stream that can be used as fuel.
Catalysts: Cycle lengths in excess of four years are expected for the alkylation and transalkylation catalysts. Process equipment is fabri-cated entirely from carbon steel. Capital investment is reduced as a consequence of the high activity and extraordinary selectivity of the alkylation catalyst and the ability of both the alkylation and transalkyl-ation catalysts to operate with very low quantities of excess benzene.
Product quality: The EB product contains less than 100 ppm of C8 plus C9 impurities. Product purities of 99.95% to 99.99% are expected.
Economics:
Raw materials and steam, tons per ton of EB product:
Ethylene 0.265
Benzene 0.739
Steam, high-pressure used 0.98
Steam, medium- and low-pressured generated 1.39
Utilities can be optimized for specifi c site conditions.
Commercial plants: Since the commercialization of the Badger EB tech-nology in 1980, 45 licenses have been granted. The total licensed
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ity for the Badger EB technology exceeds 17 million mtpy. The capacity for the EBMax technology exceeds 10.6 million mtpy.
Licensor: Badger Licensing LLC.
Ethylbenzene,
continuedEthylbenzene
Application: State-of-the-art technology to produce high-purity ethylben-zene (EB) by liquid-phase alkylation of benethylben-zene with ethylene. The Lum-mus/UOP EBOne process uses specially formulated, proprietary zeolite catalyst from UOP. The process can handle a wide range of ethylene feed compositions ranging from chemical (70%) to polymer grade (100%).
Description: Benzene and ethylene are combined over a proprietary zeo-lite catalyst in a fi xed-bed, liquid-phase reactor. Fresh benzene is combined with recycle benzene and fed to the alkylation reactor (1). The combined benzene feed fl ows in series through the beds, while fresh ethylene feed is distributed equally between the beds. The reaction is highly exothermic, and heat is removed between the reaction stages by generating steam.
Unreacted benzene is recovered from the overhead of the benzene col-umn (3), and EB product is taken as overhead from the EB colcol-umn (4).
A small amount of polyethylbenzene (PEB) is recovered in the over-head of the PEB column (5) and recycled back to the transalkylation reactor (2) where it is combined with benzene over a second proprietary zeolite catalyst to produce additional EB product. A small amount of fl ux oil is recovered from the bottom of the PEB column (5) and is usually burned as fuel.
The catalysts are non-corrosive and operate at mild conditions, al-lowing for all carbon-steel construction. The reactors can be designed for 2– 6 year catalyst cycle length, and the catalyst is fully regenerable.
The process does not produce any hazardous effl uent.
Yields and product quality: Both the alkylation and trans-alkylation reactions are highly selective, producing few byproducts. The EB product has a high purity (99.9 wt% minimum) and is suitable for styrene-unit feed. Xylene make is less than 10 ppm. The process has an overall yield of 99.7%.
Economics: The EBOne process features consistently high product yields over the entire catalyst life cycle, high-product purity, low-energy con-sumption, low investment cost, and simple, reliable operation.
Investment, ISBL Gulf Coast, US$/mtpy 30 – 45 Raw material and utilities, per metric ton of EB
Ethylene, mtons 0.265
Benzene, mtons 0.738
Utilities, US$ 1
Additional utility savings can be realized via heat integration with downstream Lummus/UOP Classic SM or SMART SM styrene unit.
Commercial plants: Nineteen EBOne units are in operation throughout the world, with a total EB capacity of 5.7 million mtpy. Unit capacities range from 65,000 to 725,000 mtpy. Ethylene feedstock purity ranges from 80 to 100%. Nine additional units are either in design or under construction — the largest unit is 770,000 mtpy.
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Licensor: ABB Lummus Global and UOP LLC.
Ethylbenzene,
continuedEthylene
Application: To produce polymer-grade ethylene (99.95 vol%). Major byproducts are propylene (chemical or polymer-grade), a butadiene-rich C4 stream, C6 to C8 aromatics-rich pyrolysis gasoline and high-purity hydrogen.
Description: Hydrocarbon feedstock is preheated and cracked in the presence of steam in tubular SRT (short residence time) pyrolysis furnaces (1). This approach features extremely high olefi n yields, long runlength and mechanical integrity. The products exit the furnace at 1,500°F to 1,600°F and are rapidly quenched in the transfer line exchangers (2) that generate super high-pressure (SHP) steam. The latest generation furnace design is the SRT VI.
Furnace effl uent, after quench, fl ows to the gasoline fractionator (3) where the heavy oil fraction is removed from the gasoline and lighter fraction (liquids cracking only). Further cooling of furnace effl uents is accomplished by a direct water quench in the quench tower (4). Raw gas from the quench tower is compressed in a multistage centrifugal compressor (5) to greater than 500 psig. The compressed gas is then dried (6) and chilled. Hydrogen is recovered in the chilling train (7), which feeds the demethanizer (8). The demethanizer operates at about 100 psia, providing increased energy effi ciency. The bottoms from the demethanizer go to the deethanizer (9).
Acetylene in the deethanizer overhead is hydrogenated (10) or recovered. The ethylene-ethane stream is fractionated (11) and polymer-grade ethylene is recovered. Ethane leaving the bottom of the ethylene fractionator is recycled and cracked to extinction.
The deethanizer bottoms and condensate stripper bottoms from the charge compression system are depropanized (12). Methylacetylene and propadiene are hydrogenated in the depropanizer using CDHydro catalytic distillation hydrogenation technology. The depropanizer bottoms is separated into mixed C4 and light gasoline streams (14). Polymer-grade propylene is recovered in a propylene fractionator (13).
A revised fl ow scheme eliminates ~25% of the equipment from this conventional fl owsheet. It uses CDHydro hydrogenation for the selective hydrogenation of C2 through C4 acetylenes and dienes in a single tower;
reduces the cracked-gas discharge pressure to 250 psig; uses a single refrigeration system to replace the three separate systems; and applies metathesis to produce up to 1/3 of the propylene product catalytically rather than by thermal cracking, thereby lowering energy consumption by ~15%.
Energy consumption: Energy consumptions are 3,300 kcal/kg of ethylene produced for ethane cracking and 5,000 kcal/kg of ethylene for naphtha
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feedstocks. Energy consumption can be as low as 4,000 kcal/kg of ethyl-ene for naphtha feedstocks with gas turbine integration. As noted above, the new flow scheme reduces energy consumption by 14%.
Commercial plants: Approximately 40% of the world’s ethylene plants use Lummus’ ethylene technology. Many existing units have been sig-nificantly expanded (above 150% of nameplate) using Lummus’ MCET (maximum capacity expansion technology) approach.
Licensor: ABB Lummus Global.