Method for preparing p-xylene and co-producing propylene with high selectivity

Patent metadata

Field	Value
Publication number	US-10099973-B2
Application number	US-201415315603-A
Country	US
Kind code	B2
Filing date	Jun 4, 2014
Priority date	Jun 4, 2014
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

A method for preparing p-xylene and co-producing propylene with a high selectivity, comprising:
a) bringing a raw material containing toluene and methanol and/or dimethyl ether into contact with a catalyst in a reaction system for reaction; returning an ethylene-enriched C 2 − component discharged from the reaction system to the reaction system, and continuing the reaction with the raw material on the catalyst to produce propylene; b) separating a C 6 + component discharged from the reaction system to obtain a product p-xylene; and c) separating a C 3 component discharged from the reaction system to obtain a product propylene.

First claim

What is claimed is:

1. A method for preparing p-xylene and co-producing propylene with a high selectivity, comprising the steps of:
a) continuously bringing a raw material comprising toluene and at least one of methanol and dimethyl ether into contact with a catalyst in a reaction system to obtain a resultant;
b) separating the resultant into a C 6 + component, a C 4 -C 5 component, a C 3 component, and an ethylene-enriched C 2 — component respectively;
c) returning the ethylene-enriched C 2 — component to the reaction system to react the ethylene-enriched C 2 component with the raw material on the catalyst to produce propylene;
d) separating p-xylene from the C 6 + component; and
e) separating propylene from the C 3 component,
wherein the catalyst comprises a ZSM-5 and/or ZSM-11 molecular sieve that is hydrothermally treated under an atmosphere of saturated steam at 500-700° C. for 3-6 hours and further subjected to a surface modification by contact with a siloxanyl compound having a formula as shown below:

wherein R 1 , R 2 , R 3 , and R 4 are each independently a C 1-10 alkyl group.

2. The method according to claim 1 , wherein the reaction system comprises a reactor or a plurality of reactors connected in series and/or in parallel.

3. The method according to claim 2 , wherein the reactor is one or more selected from a fixed bed reactor, a fluidized bed reactor, and a moving bed reactor.

4. The method according to claim 1 , wherein 1-10 wt % Si is loaded on the catalyst during the surface modification.

5. A method for preparing p-xylene and co-producing propylene with a high selectivity in a reaction system, wherein the reaction system comprises a first reaction zone and a second reaction zone, and the method comprises the steps of:
a) continuously bringing a raw material comprising toluene and at least one of methanol and dimethyl ether into contact with a catalyst I in the first reaction zone, and then into contact with a catalyst II in the second reaction zone to obtain a resultant;
b) separating the resultant into a C 6 + component, a C 4 -C 5 component, a C 3 component, and an ethylene-enriched C 2 — component respectively;
c) returning the ethylene-enriched C 2 — component to the second reaction zone, and reacting the ethylene-enriched C 2 — component with methanol and/or dimethyl ether in the raw material within the second reaction zone on the catalyst II to produce propylene;
d) separating p-xylene from the C 6 + component; and
e) separating propylene from the C 3 component,
wherein each of the catalyst I and the catalyst II independently comprises a ZSM-5 and/or ZSM-11 molecular sieve that is hydrothermally treated under an atmosphere of saturated steam at 500-700° C. for 3-6 hours and further subjected to a surface modification by contact with a siloxanyl compound having a formula as shown below:

wherein R 1 , R 2 , R 3 , and R 4 are each independently a C 1-10 alkyl group.

6. The method according to claim 5 , wherein the first reaction zone and the second reaction zone are in the same reactor.

7. The method according to claim 5 , wherein the first reaction zone comprises a reactor or a plurality of reactors connected in series and/or in parallel; the second reaction zone comprises a reactor or a plurality of reactors connected in series and/or in parallel; and the first reaction zone and the second reaction zone are connected in series.

8. The method according to claim 5 , wherein 1-10 wt % Si is loaded on the catalyst I and on catalyst II during the surface modification.

9. A method for preparing p-xylene and co-producing propylene with a high selectivity in a reaction system, wherein the reaction system comprises a first reaction zone and a second reaction zone, and the method comprises the steps of:
a) bringing toluene and a first portion of methanol and/or dimethyl ether into contact with a catalyst I in the first reaction zone to obtain a resultant A;
b) separating the resultant A into a C 6 + component, a C 4 -C 5 component, a C 3 component, and an ethylene-enriched C 2 — component respectively from a separation system;
c) bringing the ethylene-enriched C 2 — component and a second portion of methanol and/or dimethyl ether into contact with a catalyst II in the second reaction zone to obtain a resultant B comprising propylene, and feeding the resultant B into the separation system;
d) separating a p-xylene from the C 6 + component; and
e) separating propylene from the C 3 component,
wherein each of the catalyst I and the catalyst II independently comprises a ZSM-5 and/or ZSM-11 molecular sieve that is hydrothermally treated under an atmosphere of saturated steam at 500-700° C. for 3-6 hours and further subjected to a surface modification by contact with a siloxanyl compound having a formula as shown below:

wherein R 1 , R 2 , R 3 , and R 4 are each independently a C 1-10 alkyl group.

10. The method according to claim 9 , wherein the first reaction zone comprises a reactor or a plurality of reactors connected in series and/or in parallel; the second reaction zone comprises a reactor or a plurality of reactors connected in series and/or in parallel; and the first reaction zone and the second reaction zone are connected in parallel.

11. The method according to claim 5 , wherein 1-10 wt % Si is loaded on the catalyst I and on catalyst II during the surface modification.

Assignees

• Dalian Inst Chem & Physics Cas

Inventors

• Xu Lei
• Liu Zhongmin
• Zhang Xinzhi

Classifications

• C07C2529/80

  Mixtures of different zeolites · CPC title

• C07C2/865

  the non-hydrocarbon is an ether · CPC title

• C07C15/08

  Xylenes · CPC title

• C07C2/864 Primary

  the non-hydrocarbon is an alcohol · CPC title

• B01J29/40

  of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively · CPC title