Silver catalysts with improved size and distribution density of silver particles

Patent metadata

Field	Value
Publication number	US-10040773-B2
Application number	US-201615054447-A
Country	US
Kind code	B2
Filing date	Feb 26, 2016
Priority date	Feb 27, 2015
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A silver-based ethylene epoxidation catalyst is provided that exhibits improved performance, i.e., selectivity and activity decline. The catalyst that exhibits the improved performance includes greater than about 20% by weight of silver disposed on an alpha-alumina carrier, and a promoting amount of one or more promoters disposed on the alpha-alumina carrier. The silver is present on the alpha-alumina carrier as silver particles having a diameter of greater than about 150 nm and a distribution density of about 20 particles per 1 square micron or less.

First claim

What is claimed is:

1. A silver-based ethylene epoxidation catalyst comprising:
greater than about 20% by weight of silver disposed on an alpha-alumina carrier; and
a promoting amount of one or more promoters disposed on said alpha-alumina carrier, wherein said silver is present on said alpha-alumina carrier as silver particles, said silver particles having a diameter of greater than about 150 nm and having a distribution density of about 20 particles per 1 square micron or less.

2. The silver-based ethylene epoxidation catalyst of claim 1 , wherein said one or more promoters comprise Group IIA metal promoters, one or more transition metals, one or more alkali metals or any combination thereof.

3. The silver-based ethylene epoxidation catalyst of claim 2 , wherein said one or more transition metals are selected from the group consisting of Groups 4-10 of the Periodic Table of the Elements.

4. The silver-based ethylene epoxidation catalyst of claim 3 , wherein said one or more transition metals are selected from the group consisting of molybdenum, rhenium, tungsten, chromium, titanium, hafnium, zirconium, vanadium, thorium, tantalum, and niobium.

5. The silver-based ethylene epoxidation catalyst of claim 2 , wherein said one or more transition metals comprise rhenium, molybdenum, tungsten, or any combination thereof.

6. The silver-based ethylene epoxidation catalyst of claim 2 , wherein said one or more alkali metals are selected from the group consisting of cesium, lithium, sodium, potassium, and rubidium.

7. The silver-based ethylene epoxidation catalyst of claim 6 , wherein said one or more alkali metals comprise lithium and cesium.

8. The silver-based ethylene epoxidation catalyst of claim 1 , wherein said diameter of said silver particles is from about 150 nm to about 300 nm.

9. The silver-based ethylene epoxidation catalyst of claim 1 , wherein said distribution density of said silver particles is from about 10 particles per 1 square micron to about 20 particles per 1 square micron.

10. The silver-based ethylene epoxidation catalyst of claim 1 , wherein said alpha-alumina carrier has a pore volume from 0.40 mL/gm to 0.70 mL/gm, a surface area from 0.7 m 2 /gm to 1.2 m 2 /gm, an Al 2 O 3 content of greater than 80% and has a pore size from 0.01 micrometers to 1.0 micrometer of less than 25%, pore size from 1.0 micrometer to 10 micrometers of greater than 50%, and pore size from 10 micrometers to 100 micrometers of less than 25%.

11. The silver-based ethylene epoxidation catalyst of claim 1 , wherein said alpha-alumina carrier has a pore volume from 0.33 mL/gm to 0.55 mL/gm, a surface area from 0.5 m 2 /gm to 1.0 m 2 /gm, an Al 2 O 3 content of greater than 85% and has a pore size from 0.01 micrometers to 1.0 micrometer of less than 35%, pore size from 1.0 micrometer to 10 micrometers of greater than 30%, and pore size from 10 micrometers to 100 micrometers of less than 25%.

12. The silver-based ethylene epoxidation catalyst of claim 1 , wherein said one or more promoters comprise a promoting combination of rhenium, cesium and lithium.

13. The silver-based ethylene epoxidation catalyst of claim 1 , wherein from about 20 to about 45% by weight of silver is disposed on said alpha-alumina carrier.

14. A process for the vapor phase conversion of ethylene to ethylene oxide in the presence of oxygen, said process comprising:
providing a silver-based ethylene epoxidation catalyst to an ethylene oxide reactor, wherein said silver-based ethylene epoxidation catalyst comprises:
greater than about 20% by weight of silver disposed on an alpha-alumina carrier; and
a promoting amount of one or more promoters disposed on said alpha-alumina carrier, wherein said silver is present on said alpha-alumina carrier as silver particles, said silver particles having a diameter of greater than about 150 nm and having a distribution density of about 20 particles per 1 square micron or less; and
reacting a reaction mixture comprising ethylene and oxygen in the present of said ethylene epoxidation catalyst.

15. A silver-based ethylene epoxidation catalyst comprising:
from about 20% to about 50% by weight of silver disposed on an alpha-alumina carrier; and
a promoting amount of one or more promoters disposed on said alpha-alumina carrier, wherein said silver is present on said alpha-alumina carrier as silver particles, said silver particles having a diameter of greater than about 150 nm and up to about 300 nm, and having a distribution density of from about 1 particle per 1 square micron to about 20 particles per 1 square micron.

Assignees

• Scient Design Co

Inventors

• Suchanek Wojciech L
• Rizkalla Nabil
• Rokicki Andrzej

Classifications

• B01J23/688

  with manganese, technetium or rhenium · CPC title

• B01J21/04

  Alumina · CPC title

• C07D301/10 Primary

  with catalysts containing silver or gold · CPC title

• B01J35/1009

  Operations & Transport · mapped topic

• B01J35/006

  Operations & Transport · mapped topic