Process and apparatus for ethylbenzene production and transalkylation to xylene
AssigneeUop LLC
InventorRobert B. James, Jr.
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Abstract
The use of two transalkylation catalysts to react aromatic compounds of carbon number nine (and heavier carbon numbers) with benzene to form carbon number eight aromatics is disclosed. The two catalyst system preserves ethyl-group species on the heavier aromatics that would otherwise de-ethylate over most gas-phase transalkylation catalysts to form undesired ethane gas with benzene or toluene. Thus, by using a transalkylation step to save ethylbenzene, a greater yield of para-xylene or other carbon number eight aromatics may be achieved within an integrated complex. An apparatus and process for the two transalkylation catalyst system is disclosed with a liquid-phase unit and a gas-phase unit.
Claims18
A dual transalkylation process for conversion of aromatic hydrocarbons into xylenes comprising:
- a) providing a stream including benzene and C9+ alkylaromatics;
- b) passing the stream of step (a) to a first-transalkylation unit, wherein said stream is contacted with a first-transalkylation catalyst under first-transalkylation conditions to produce a first-transalkylation product stream comprising ethylbenzene;
- c) combining at least a portion of the first-transalkylation product stream with at least a portion of second-transalkylation product stream;
- d) separating the combined streams of (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, which is recovered as a product from the process, and a C9+ alkylaromatic-enriched stream;
- f) providing a toluene feed stream;
- g) combining at least a portion of the C9+ alkylaromatic-enriched stream of step (e) with at least a portion of the toluene stream;
- and
- h) passing at least a portion of the combined streams of step (g) to a second-transalkylation unit, wherein said streams are contacted with a second-transalkylation catalyst under second-transalkylation conditions to produce the second-transalkylation product stream of step (c).
A process for conversion of aromatic hydrocarbons into para-xylene comprising:
- a) providing a stream of 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 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 (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, wherein the para-xylene production unit produces para-xylene, which is recovered as ε, product from the process;
- g) providing a toluene stream;
- h) combining the toluene stream with 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 steam 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 an 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.