Enhanced dispersion of edge-coated precious metal catalysts

Patent metadata

Field	Value
Publication number	US-2018071720-A1
Application number	US-201615559837-A
Country	US
Kind code	A1
Filing date	Mar 18, 2016
Priority date	Mar 20, 2015
Publication date	Mar 15, 2018
Grant date	—

Abstract

The present invention is in the field of catalysis. More particularly, the present invention is directed to supported precious metal, preferably palladium and/or gold metal catalysts, having a high degree of dispersion and a high degree of edge-coating. The present invention is further directed to a process for producing these catalysts, as well as to the use of these catalysts in chemical reactions.

First claim

1 . A precious metal catalyst, comprising nanocrystallites of at least one precious metal on a powder support,
wherein: the precious metal is palladium metal, gold metal, or a combination thereof; when the precious metal comprises the palladium metal, the precious metal catalyst comprises a palladium metal catalyst comprising nanocrystallites of palladium metal having an average size of from 1 to less than 5 nm, and the palladium metal catalyst has a surface enrichment value of from at least 6.5 to at most 150; when the precious metal comprises the gold metal, the precious metal catalyst comprises a gold metal catalyst comprising nanocrystallites of gold metal having an average size of from 3 to less than 15 nm, and the gold metal catalyst has a surface enrichment value of from at least 3 to at most 150; the surface enrichment value (SEV) is determined from the following formula (I):
SEV=(XPS wt. %−ICP wt. %)/ICP wt. %;  (I)

wherein XPS wt. % is the X-ray photoelectron spectroscopy (XPS) measurement and ICP wt. % is the inductively coupled plasma (ICP) measurement of the precious metal content in weight percent of said catalyst.

2 . The catalyst according to claim 1 , comprising the precious metal in an amount of between 0.01 and 20 wt. %, based on a weight of the catalyst.

3 . The catalyst according to claim 1 , wherein:
the palladium metal catalyst has a surface enrichment value of at least 8, and the palladium metal catalyst has a surface enrichment value of at most 120; and the gold metal catalyst has a surface enrichment factor of at least 5 and, has a surface enrichment value of at most 120.

4 . The catalyst according to claim 1 , wherein:
the nanocrystallites of the palladium metal have an average size between 1 and 4 nm; and the nanocrystallites of the gold metal have an average size between 3 and 13.

5 . The catalyst according to claim 1 , wherein the powder support is selected from the group consisting of silica, alumina, zirconia, titanium oxide, ceria, magnesium oxide, zinc oxide, metal silicates, metal aluminates, zeolites, carbon nanotubes, carbon nanofibres, graphitic carbon and activated carbon and combinations thereof.

6 . The catalyst according to claim 1 , wherein the average particle size of the powder support is between 0.1 and 500 micron.

7 . A process for preparing a precious metal catalyst, the process comprising:
reducing a precious metal compound in an aqueous solution by contacting said solution with a reducing agent, a stabilizing agent and a coordinating agent thereby forming a colloidal precious metal suspension; contacting the suspension with a powder support; and recovering the precious metal catalyst.

8 . The process according to claim 7 , wherein the precious metal is palladium metal, gold metal, or a combination thereof.

9 . The process according to claim 7 , wherein the reducing agent is selected from the group consisting of a quaternary ammonium salt, sodium formate, formic acid, sodium citrate, citric acid, hydrazine, a C 1 -C 4 alcohol, a diol, a polyol, a borohydride, formaldehyde, hypophosphite, a metal alkalyde hydrogen and combinations thereof.

10 . The process according to claim 7 , wherein the stabilizing agent is selected from the group consisting of a quaternary ammonium salt, a donor ligand, a polymer, a surfactant and combinations thereof.

11 . The process according to claim 7 , wherein the coordinating agent is urea, ammonia, or both.

12 . The process according to claim 7 , wherein the support is selected from the group consisting of silica, alumina, zirconia, titanium oxide, ceria, magnesium oxide, zinc oxide, a metal silicate, a metal aluminate, a zeolite, a carbon nanotube, a carbon nanofiber, graphitic carbon, activated carbon and combinations thereof.

13 . A precious metal catalyst obtained by the process of claim 7 .

14 . A process, comprising performing a reaction in the presence of the precious metal catalyst of claim 1 , wherein the reaction is a hydrogenation/dehydrogenation, isomerization, oxidation, hydrogenolysis or hydro-dewaxing reaction.

Assignees

• Basf Corp

Inventors

• Witte Peter
• Nollen Erica
• TERORDE Robert
• Zhang Lei

Classifications

• B01J23/44

  Palladium · CPC title

• B01J35/0013

  Operations & Transport · mapped topic

• B01J37/16

  Reducing · CPC title

• C07C29/17

  by hydrogenation of carbon-to-carbon double or triple bonds · CPC title

• B01J37/0221

  of particles · CPC title