Vinyl acetate, production

Suspension polymerization produces beads of plastic for styrene, methyl methacrviaie. viny l chloride, and vinyl acetate production. The monomer, in which the catalyst must be soluble, is maintained in droplet fonn suspended in water by agitation in the presence of a stabilizer such as gelatin each droplet of monomer undergoes bulk polymerization. In emulsion polymerization, ihe monomer is dispersed in water by means of a surfactant to form tiny particles held in suspension I micellcsK The monomer enters the hydrocarbon part of the micelles for polymerization by a... 

Another route to the diol monomer is provided by hydroformylation of allyl alcohol or allyl acetate. Allyl acetate can be produced easily by the palladium-catalyzed oxidation of propylene in the presence of acetic acid in a process similar to commercial vinyl acetate production. Both cobalt-and rhodium-catalyzed hydroformylations have received much attention in recent patent literature (83-86). Hydroformylation with cobalt carbonyl at 140°C and 180-200 atm H2/CO (83) gave a mixture of three aldehydes in 85-99% total yield. 

In the United States, Celanese has obtained a license from Bayer to expand their vinyl acetate production. In addition, National Distillers has developed an alternative vapor-phase process and will use it in a new plant nearing completion. The adoption by Celanese of the Bayer vapor-phase process has led to patent infringement litigation among National Distillers, Celanese, and Bayer (6). 

Supported liquid-phase catalysts (SLPCs) combine the salient features of both homogeneous and heterogeneous catalysis for enhanced catalytic and/or process efficiency (337). SLPC catalysts, in which a liquid-phase (homogeneous) catalyst is dispersed within a porous support, have been used in Wacker-type ethylene oxidation for acetaldehyde and vinyl acetate production (337, 338). In the former case, a traditional homogeneous Wacker catalyst (vide supra) consisting of a chlorinated solution of Pd and Cu chlorides retained on a support with monomodal pore size distribution... 

Vinyl acetate is a dear colorless liquid. It has a boiling point of 72 °C and a flash point of -9 °C. In 1977 vinyl acetate production in the United States was 1.60 x 10 pounds (1 ). This gave vinyl acetate a rank of 45 among the 50 top-volume chemicals produced in the United States during 1977. The major end uses of vinyl acetate were adhesives (30 ), paints (20 ), textile finishes (15%), and paper coatings (10 ). Approximately 15 of the vinyl acetate produced was exported (2). 

Vinyl Acetate. Vinyl acetate (VAM, for vinyl acetate monomer) production is the latest consumer of acetic acid worldwide. In North America, vinyl acetate production in 2000 was 1.7 billion lb. Growth in North America in the period 2000-2005 is expected to be 1.0 percent/ year and for the world, 2.4 percent/year. 

Acetaldehyde is an intermediate in acetic acid and vinyl acetate production. Since 1916 it has been produced from the addition of water to acetylene, a reaction catalyzed by divalent mercury in sulphuric acid (20%)/water. Acetylene was made from coal. In Germany in particular, a lot of research was carried out on the use of acetylene as a chemical feedstock. 

Catalyst selectivity (SEL) determines the fraction of the ethylene consumed that makes the desired vinyl acetate product,... 

Step 5. The azeotropic distillation column does not produce the final salable vinyl acetate product. Its primary role is to recover and recycle unreacted acetic acid and to remove from the process all of the vinyl acetate and water produced. So we want little acetic acid in the overhead because this represents a yield loss. Also, the bottoms stream should contain no vinyl acetate since it polymerizes and fouls the heat-exchange equipment at the elevated temperatures of the column base and the vaporizer. Hence we have two control objectives base vinyl acetate and top acetic acid compositions. And we have two manipula-... 

Diphenyl carbonate from dimethyl carbonate and phenol Dibutyl phthalate from butanol and phthalic acid Ethyl acetate from ethanol and butyl acetate Recovery of acetic acid and methanol from methyl acetate by-product of vinyl acetate production Nylon 6,6 prepolymer from adipic acid and hexamethylenediamine MTBE from isobutene and methanol TAME from pentenes and methanol Separation of close boiling 3- and 4-picoline by complexation with organic acids Separation of close-boiling meta and para xylenes by formation of tert-butyl meta-xyxlene Cumene from propylene and benzene General process for the alkylation of aromatics with olefins Production of specific higher and lower alkenes from butenes... 

Several authors [298-300] reported on the preparation of platimun and palladium nanoparticles having a preferential diameter from about 1 to 2 nm stabihzed by polymeric carbo-, phospho-, and sulfobetaines for fuel-cell catalysts and vinyl acetate production. 

A recent article gave the following market figures for 1965 and estimates for 1970 for vinyl acetate production (12) ... 

The commercial process for vinyl acetate production has evolved over the years. Early in the 1930s, Wacker developed a process based upon the gas-phase conversion of acetylene and acetic acid over a zinc acetate catalyst supported on activated carbon. Later, in 1960s, a more economically favourable gas-phase process was introduced involving the acetoxylation of ethene over a Pd-based silica supported catalyst. Ethene, acetic acid and oxygen reacted to form vinyl acetate and water [122,237-242] ... 

An interesting approach to overcome these limits and thus combine the advantages of homogeneous and heterogeneous catalysis is that of supported liquid phase catalysts (SLPC or SLP). In SLPC the organometallic complex active components are dissolved in a small quantity of liquid phase dispersed in the form of an isle or film on the surface of supports. A SLPC has been applied successfully for several chemical transformations [113], particularly in the Wacker-type ethylene oxidation to acetaldehyde and vinyl acetate production by ethylene acetoxylation [114], and in other reactions catalyzed by Pd-complexes such as the Heck reaction [115]. 

Vinyl acetate production is mostly based on acetylene as follows ... 

Pd-Au/Al203 or Si02 Vinyl acetate production Pentane PEGDE/Genapol 26-L-60 NazPdCU HAuCU 114... 

Reactor effluent contains vinyl acetate, unreacted ethylene, acetic acid, carbon dioxide, water vapor, and by-products. By-products of this reaction are methyl acetate, ethyl acetate, and acetaldehyde. The effluent is partially condensed and enters the absorber. Uncondensed vinyl acetate in the vapor phase is recovered with recycle acetic acid. The liquid phase, containing most of the vinyl acetate product, is removed from the bottom of the absorber. The vapor is sent to a scrubber where additional vinyl acetate is recovered by water wash. The gas from the scrubber overhead containing unreacted ethylene, carbon dioxide, acetic acid, and water vapor is compressed for removal of carbon dioxide. 

Crude vinyl acetate is separated from acetic acid and water in an azeotropic distillation system. Acetic acid is recycled to the acetic acid vaporizer and the vinyl acetate product is separated from other by-products in a two-column recovery section. Light ends are removed in the first column followed by a heavy ends in the final column. The light ends, primarily methyl acetate, and the heavy ends, mostly ethyl acetate and acetaldehyde, are incinerated. The vinyl acetate product from the overhead of the heavy ends column is cooled and sent to storage. 

Table 17 Vinyl Acetate. Production Cost (550 MM Pounds per Year)...

Pd-catalyzed acetoxylation of ethylene with acetic acid and Oj accounts for approximately 80% of todays vinyl acetate production [1]. Vinyl acetate has a worldwide production capacity of about 6 million tons/year (2007) and is used to prepare a number of important polymers (e.g., PVA, EVA, PVCA). 

Alkene derivatives such as alkenylboronic acids and alkenylzir-conanes reacht with PhI(OAc)2 to furnish alkenyliodonium salts (eq 46). These transformations proceed with retention of olefin configuration. Similarly, alkenylboron species add to PhI(OAc)2 in the presence of Nal to give vinyl acetate products (eq 47). In these examples, ( )-alkenylboronates give stereochemically pure (Z)-configured enol acetates. ... 

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