Aromatics transalkylation to ethylbenzene and xylenes
AssigneeUop LLC
InventorsPaula L. Bogdan, Robert B. James, Jr., Gregory F. Maher
Life of this patent
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Abstract
The use of transalkylation catalysts to react heavy aromatic compounds of carbon number nine (and heavier carbon numbers) with benzene to form carbon number eight aromatics is disclosed. The catalyst system preserves ethyl-group species on the heavier aromatics that are otherwise de-ethylated over most gas-phase transalkylation catalysts to form undesired ethane gas with benzene or toluene. The catalyst system also promotes methyl-group species transalkylation at selected conditions. Thus, by using the transalkylation system, a greater yield of para-xylene or other carbon number eight aromatics may be achieved overall within an integrated aromatics complex.
Claims10
A process for conversion of aromatic hydrocarbons into para-xylene comprising:
- a) providing a stream including benzene and C9+ alkylaromatics;
- b) passing the stream of step (a) to a liquid-phase transalkylation unit, wherein said streams are contacted with a first transalkylation catalyst under first transalkylation conditions without added hydrogen to produce a first transalkylation product stream comprising ethylbenzene and at least 1 wt-% xylene calculated on a net effluent basis;
- c) combining at least a portion of the first-transalkylation-product stream with a second-transalkylation-product stream;
- d) separating the combined streams of step (c) in a fractionation zone comprising at least one column to produce a fractionated-benzene stream and a xylene-plus stream;
- e) separating the xylene-plus stream in a xylene column to produce a xylene enriched stream and a C9+ alkylaromatic-enriched stream;
- f) passing the xylene enriched stream to a para-xylene production unit to produce para-xylene, which is recovered as a product from the process;
- g) providing a toluene stream;
- h) combining the toluene stream with at least part of the C9+ alkylaromatic-enriched stream of step (e);
- i) separating the combined streams of step (h) in a heavy aromatics column to produce a stream rich in C7, C9 and C10 alkylaromatics and a stream rich in C11+ alkylaromatics;
- j) passing the stream rich in C7, C9 and C10 alkylaromatics to a gas-phase transalkylation unit, wherein said stream is contacted with a second transalkylation catalyst under second transalkylation conditions to produce ar unstabilized transalkylation stream;
- and
- k) separating the unstabilized transalkylation stream in a transalkylation stabilizer column to produce a gas stream and the second transalkylation product stream of step (c).
Dependencies are inferred from the claim text.