Lithium-modified zeolite catalyst for alkane cracking

Patent metadata

Field	Value
Publication number	US-11780788-B2
Application number	US-202117473108-A
Country	US
Kind code	B2
Filing date	Sep 13, 2021
Priority date	Sep 13, 2021
Publication date	Oct 10, 2023
Grant date	Oct 10, 2023

Abstract

Methods for cracking a hydrocarbon feed stream include contacting a hydrocarbon feed stream with a catalyst system in a catalytic cracking unit having a flowing gas stream to obtain a cracking product containing light olefins. The catalyst system includes at least a base catalyst. The base catalyst includes a pentasil zeolite. The pentasil zeolite includes from 0.01% to 5% by mass lithium atoms, as calculated on an oxide basis, based on the total mass of the pentasil zeolite. The flowing gas stream comprises hydrogen and, optionally, at least one additional carrier gas.

First claim

What is claimed is:

1. A method for cracking a hydrocarbon feed stream, the method comprising
contacting the hydrocarbon feed stream with a catalyst system in a catalytic cracking unit having a flowing gas stream to obtain a cracking product containing light olefins,

wherein:
the catalyst system comprises a pentasil zeolite;
the pentasil zeolite consists of ZSM-5 and from 0.01% to 5% by mass lithium atoms, as calculated on an oxide basis, based on the total mass of the pentasil zeolite; the hydrocarbon feed stream comprises C 4 -C 6 saturated hydrocarbons;
the flowing gas stream comprises hydrogen; and
the pentasil zeolite has a silica-to-alumina ratio from 20:1 to 100:1.

2. The method of claim 1 , wherein the pentasil zeolite comprises from 0.01% to 2% by mass lithium atoms, as calculated on an oxide basis, based on the total mass of the pentasil zeolite.

3. The method of claim 1 , wherein the pentasil zeolite comprises from 0.1% to 1% by mass lithium atoms, as calculated on an oxide basis, based on the total mass of the pentasil zeolite.

4. The method of claim 1 , wherein the light olefins comprise ethylene, propylene, and butylenes.

5. The method of claim 1 , wherein the flowing gas stream further comprises a carrier gas.

6. The method of claim 5 , wherein the carrier gas comprises steam, nitrogen, argon, or combinations thereof.

7. The method of claim 1 , wherein the flowing gas stream comprises hydrogen and nitrogen at a volumetric flow-rate ratio H 2 :N 2 from 1000:1 to 1:50.

8. The method of claim 1 , wherein the catalytic cracking unit is a fixed-bed reactor.

9. The method of claim 1 , wherein:
the contacting occurs at a reaction temperature from 500° C. to 650° C., at a reaction pressure from 0.01 bar to 10 bar, with a residence or contact time from 0.1 seconds to 60 seconds, with a weight hour space velocity from 0.5 h −1 to 4 h −1 , and with a catalyst to oil ratio from 1:4 to 2:1.

10. The method of claim 1 , further comprising:
separating from the cracking product a first stream including hydrocarbons with four or fewer carbon atoms, a second stream including saturated hydrocarbons, and a third stream including C 4 -C 12 unsaturated hydrocarbons; and
recycling the second and third streams to the catalytic cracking unit.

11. The method of claim 1 , further comprising:
recovering hydrogen from the cracking product; and
recycling the recovered hydrogen to the catalytic cracking unit.

12. The method of claim 1 , wherein the flowing gas stream comprises hydrogen and nitrogen at a volumetric flow-rate ratio H 2 :N 2 from 50:23 to 2:72.

13. The method of claim 1 , wherein:
the pentasil zeolite comprises from 0.1% to 1% by mass lithium atoms, as calculated on an oxide basis, based on the total mass of the pentasil zeolite;
the pentasil zeolite is ZSM-5; and
the flowing gas stream comprises hydrogen and nitrogen at a volumetric flow-rate ratio H 2 :N 2 from 50:23 to 2:72.

14. The method of claim 1 , wherein the catalyst system consists of the pentasil zeolite and the lithium atoms.

15. The method of claim 1 , wherein the flowing gas stream comprises hydrogen and nitrogen at a volumetric flow-rate ratio H 2 :N 2 from 30:43 to 2:72.

16. The method of claim 1 , wherein the flowing gas stream comprises hydrogen and nitrogen at a volumetric flow-rate ratio H 2 :N 2 from 30:43 to 10:63.

Assignees

• Saudi Arabian Oil Co

Inventors

• Al-Daous Mohammed Abdulmajeed
• Bahlouli Hussam A

Classifications

• C07C4/06 Primary

  Catalytic processes {(C07C4/025 takes precedence)} · CPC title

• B01J8/02

  with stationary particles, e.g. in fixed beds · CPC title

• B01J19/2465

  externally, i.e. the mixture leaving the vessel and subsequently re-entering it · CPC title

• B01J29/061

  containing metallic elements added to the zeolite · 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