Process for the alkylation of aromatic hydrocarbons with olefins

Patent metadata

Field	Value
Publication number	US-9012696-B2
Application number	US-201214127421-A
Country	US
Kind code	B2
Filing date	Jun 21, 2012
Priority date	Jun 23, 2011
Publication date	Apr 21, 2015
Grant date	Apr 21, 2015

Abstract

Process for the alkylation of aromatic hydrocarbons by means of olefins containing from 2 to 8 carbon atoms, which comprises feeding the hydrocarbon, olefin, and possibly water, to the head of a fixed-bed reactor, operating with a “trickle flow” regime, containing at least one layer of a catalyst comprising a medium-or large-pore zeolite.

First claim

The invention claimed is:

1. A process for the alkylation of aromatic hydrocarbons by means of olefins containing from 2 to 8 carbon atoms comprising:
feeding the hydrocarbon, the olefin, and optionally water, to the head of a fixed-bed reactor, operating under “trickle flow” regime, containing at least one layer of a catalyst comprising a medium-pore zeolite or a large-pore zeolite.

2. The process according to claim 1 , carried out continuously, which comprises:
(a) mixing, in liquid phase, at least one aromatic hydrocarbon (A), a C 2 -C 8 olefin (B), a recycled stream (C) coming from a discharge section of the alkylation reactor, and optionally water;
(b) feeding the mixture obtained in step (a), pre-heated to the reaction temperature, to the head of the fixed-bed alkylation reactor, operating under “trickle flow” regime, containing at least one layer of a catalyst comprising a medium-pore or large-pore zeolite;
(c) cooling the reaction mixture in a discharge section to obtain an organic phase, comprising the alkylated aromatic hydrocarbon; and
(d) subdividing the organic phase into a recycled stream (C), sent to the head of the alkylation reactor for the mixing phase with the reagents, and a final stream, comprising the alkylated aromatic hydrocarbon.

3. The continuous process according to claim 1 , which comprises:
(a) mixing, in liquid phase, at least one aromatic hydrocarbon (A), and the C 2 -C 8 olefin (B), with molar ratios A/B higher than 1;
(b) diluting the mixture coming from step (a) with a recycled stream coming from a discharge section of the alkylation reactor, and optionally water, so as to have a recycling weight ratio C/AB between the recycled stream (C) and the reagent mixture (AB) ranging from 1.5:1 to 10:1;
(c) feeding the final mixture obtained, preheated to the reaction temperature, to the head of the fixed-bed alkylation reactor, operating under “trickle flow” regime, containing at least one layer of catalyst comprising a zeolite selected from medium-pore zeolites and large-pore zeolites;
(d) cooling the reaction mixture, directly downstream of the alkylation reactor, in a discharge section, to obtain an organic phase, comprising the alkylated aromatic hydrocarbon; and
(e) subdividing the organic phase into a recycled stream (C), sent to the head of the alkylation reactor for the mixing phase with the reagents, and a final stream, comprising the alkylated aromatic hydrocarbon.

4. The process according to claim 1 , wherein in the alkylation reactor, the aromatic hydrocarbon and olefin are in gas phase and the alkylation products are in liquid phase.

5. The process according to claim 3 , wherein the recycling weight ratio C/AB between the recycled stream (C) and the reagent mixture (AB) ranges from 2:1 to 6:1.

6. The process according to claim 1 , wherein the flow-rate of the reagents to the alkylation reactor is such as to provide a WHSV (Weight Hourly Space Velocity) ranging from 1 to 8 hrs −1 .

7. The process according to claim 1 , wherein the reaction temperature inside the alkylation reactor ranges from 160 to 250° C. and the internal pressure ranges from 1 to 10 MPa.

8. The process according to claim 1 , wherein the aromatic hydrocarbon is selected from benzene, toluene and xylene.

9. The process according to claim 1 , wherein the olefin is selected from ethylene and propylene.

10. The process according to claim 1 , wherein the zeolite is a large-pore zeolite and is selected from zeolites of the type MTW, FAU, BEA, MAZ, MOR, OFF, SAPO-5, or SAPO-11.

11. The process according to claim 10 , wherein the zeolite is of the MTW, FAU or BEA type.

12. The process according to claim 1 , wherein the zeolite is a medium-pore zeolite and is MCM-22 zeolite.

13. The process according to claim 1 , wherein the water added is in an amount lower than or equal to 6% w/w with respect to the total mixture fed to the reactor.

14. The process according to claim 1 , wherein the olefin is used in a mixture with the corresponding alcohol having the same number of carbon atoms as the olefin and which provides the same alkyl substituent by alkylation.

15. A process for the preparation of phenol, comprising the following steps:
(a) alkylating benzene with propylene to give cumene, carried out in accordance with claim 1 ,
(b) oxidating the cumene thus obtained,
(c) treating cumyl-hydroperoxide with acids in order to obtain a mixture of phenol and acetone,
(d) hydrogenerating acetone to isopropanol, and
(e) dehydrating isopropanol to propylene which is recycled to step (a).

16. The process according to claim 2 , wherein:
in step (a) water is added to the mixture fed to the reactor; and
in step (c) an aqueous phase is formed after cooling the reaction mixture, in addition to the organic phase.

17. The process according to claim 3 , wherein:
in step (b) water is added to the mixture fed to the reactor; and
in step (d) an aqueous phase is formed after cooling the reaction mixture, in addition to the organic phase.

Assignees

• Calaresu Paolo
• Del Seppia Alessandro
• Bencini Elena
• Fois Giovanni Antonio
• Casalini Alessandro
• Versalis Spa

Inventors

• Calaresu Paolo
• Del Seppia Alessandro
• Bencini Elena
• Fois Giovanni Antonio
• Casalini Alessandro

Classifications

• C07C2529/70

  of types characterised by their specific structure not provided for in groups C07C2529/08 - C07C2529/65 · CPC title

• C07C2/66 Primary

  Catalytic processes · CPC title

• C07C37/08

  by decomposition of hydroperoxides, e.g. cumene hydroperoxide · CPC title

• C07C29/143

  of ketones · CPC title

• C07C15/085

  Isopropylbenzene · CPC title