Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Silicon containing or process of making
Reexamination Certificate
1999-06-23
2001-08-14
Geist, Gary (Department: 1623)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Silicon containing or process of making
C560S208000, C560S261000, C502S328000
Reexamination Certificate
active
06274531
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to new and improved catalysts for the production of vinyl acetate by reaction of ethylene, oxygen and acetic acid.
2. Background Information Including Description of Related Art
It is known to produce vinyl acetate by reaction of ethylene, oxygen and acetic acid using a catalyst consisting of metallic palladium and gold supported on a carrier. While the process utilizing such a catalyst is capable of producing vinyl acetate at fair levels of productivity, such productivity levels are limited by the production of undesirable by-products, particularly carbon dioxide. The production of any product or by-product can be expressed as percent selectivity, defined as the amount of such product expressed as a percentage of the theoretical maximum which could be produced from the reactants. Thus, any expedient which results in a reduced production of carbon dioxide expressed as lower percent CO
2
selectivity, is very desirable.
The following references may be considered material to the invention claimed herein.
U.S. Pat. Nos. 3,775,342 issued Nov. 27, 1973, and 3,822,308 issued Jul. 2, 1974, both to Kronig et al., each discloses a method of making vinyl acetate catalysts comprising treating a support simultaneously or successively with a solution A containing dissolved salts of noble metals such as palladium and gold, and a solution B containing compounds able to react on the support with the noble metal salts to form water insoluble compounds of the metals, treating such water-insoluble compounds with a reducing agent to convert the water-insoluble noble metal compounds to the metals, washing the catalyst to remove water-soluble compounds, and applying an alkali metal compound e.g. an alkali metal carboxylate before or after treatment with the reducing agent. Solution A can optionally also contain salts of any of several other metals, including copper.
U.S. Pat. No. 5,332,710, issued Jul. 26, 1994, to Nicolau et al., discloses a method of preparing a catalyst useful for the production of vinyl acetate by reaction of ethylene, oxygen and acetic acid, comprising impregnating a porous support with water soluble salts of palladium and gold, fixing the palladium and gold as insoluble compounds on the support by immersing and tumbling the impregnated support in a reactive solution to precipitate such compounds, and subsequently reducing the compounds to their metallic form.
U.S. Pat. No. 5,347,046, issued Sep. 13, 1994, to White et al., discloses catalysts for the production of vinyl acetate by reaction of ethylene, oxygen, and acetic acid, comprising a palladium group metal and/or a compound thereof, gold and/or a compound thereof, and copper, nickel, cobalt, iron, manganese, lead or silver, or a compound thereof, preferably deposited on a support material.
SUMMARY OF THE INVENTION
In accordance with this invention, a catalyst is provided useful for the production of vinyl acetate by reaction of ethylene, oxygen and acetic acid with low carbon dioxide selectivity, comprising a porous support on the porous surfaces of which are deposited catalytically effective amounts of metallic palladium and gold, and cupric acetate. The copper in the cupric acetate is believed to effect a lower carbon dioxide selectivity, which is often accompanied by a higher vinyl acetate productivity, than when no cupric acetate is present in the catalyst.
REFERENCES:
patent: 3775342 (1973-11-01), Kronig et al.
patent: 3822308 (1974-07-01), Kronig et al.
patent: 5332710 (1994-07-01), Nicolau et al.
patent: 5347046 (1994-09-01), White et al.
patent: 5731457 (1998-03-01), Nicolau et al.
patent: 5948724 (1999-09-01), Nicolau et al.
patent: 5969869 (1999-10-01), Nicolau et al.
patent: WO 94/08714 (1994-04-01), None
Broussard Jerry A.
Colling Philip M.
Nicolau Ioan
Celanese International Corporation
Deemie Robert W.
Geist Gary
Spiering M. Susan
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