Oxygen vinyl acetate monomer process

A gold-palladium catalyst which includes potassium acetate is very well established for the production of vinyl acetate monomer (VAM) from ethene, acetic acid and oxygen in selectivities as high as 96% (see Section 8.4). VAM is an important intermediate used in the production of polyvinyl acetate, polyvinyl butyral and a variety of other polymers, and the gold-catalysed process followed many years of industrially focused research and patent activity in a number of large industrial companies 39-43... 

Leap A process for making vinyl acetate monomer. It uses a fluidized bed of a new catalyst in powder form the reactants are acetic acid, ethylene, and oxygen. Developed by BP Amoco and first operated in Hull, England, in 2001. The catalyst is a supported gold-palladium alloy made by... 

The effect of oxygen on the polymerization characteristics of the monomer is quite dramatic. In bulk polymerization of reasonably purified vinyl acetate, the process is autoaccelerated from the start and goes nearly to completion with a residual monomer content of 2-4%. When the monomer distillation is carried out in contact with air, inhibiting impurities form quite rapidly. These lead to dead-end polymerizations with 30-40% unreacted monomer left in the product [17]. 

L. B. Levy, "The Effect of Oxygen on Vinyl Acetate and Acrylic Monomer Stabilization," Process Safety Progress, 12, No. 1,47 (January 1993). 

The major route for the industrial production of vinyl acetate, the monomer of polyvinyl acetate (emulsion paints, adhesives) and its hydrolysis product, polyvinyl alcohol (textiles, food packaging) is closely related to the Wacker acetaldehyde process, but the industrial catalysts are heterogeneous. A mixture of ethene, oxygen and acetic acid is passed over a palladium catalyst supported on alumina at 100-200°C. The overall reaction is H C=CH2-hCHjCO H-hyO ->H2C=CHC02CH3 -hH O. Ethene is no longer cheap, so that work is being pursued to make vinyl acetate from synthesis gas (p. 384). 

Some rubbers, acetal resins, and a variety of polyethers are prepared on a commercial scale by cationic polymerization. Vinyl ethers are among the easiest monomers to polymerize by the cationic process. The carbonium ion is readily formed because the pendant oxygen participates in delocalization of the positive charge. When polymerization of isobutyl vinyl ether is carried out at temperatures in the range of — 80°C using boron trifluoride etherate as initiator, isotactic crystalline polymer can be produced. Ethyl and isobutyl ethers produce polyvinyl ethers with low 7 s, and are used in pressure-sensitive adhesives. 

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