Wacker Chemie Ag

Willibald Dafinger

Peter Holl

Marc Eckert

Johann Wagner

Guenther Rudolf

Heribert Westermayer

Mehmet Guenaltay

Peter Schultheiss

Brigitte Patsch

Wilhelm Kaiser

Günther Rudolf

Martin Schönleben

Friedrich Frank

Jürgen Guba

Fouling of the acetic acid saturator by recycle gas in the continuous gas phase process for manufacture of vinyl acetate is reduced by adding an N-oxyl fouling inhibitor to the saturator and/or at one or more other addition sites in the process, in amounts such that the concentration of N-oxyl compound which accumulates in the saturator bottoms is from 10 to 100 ppm. The amount of N-oxyl compound in the saturator is preferably from 10-50 ppm. The reduction in fouling is evidenced by lessening the lowering of the heat transfer coefficient of the saturator over time.

Method for producing vinyl acetate

The invention relates to a method for removing oxygen from hydrocarbon-containing gas mixtures, characterized in that a hydrocarbon-containing gas mixture containing 50 vol % of one or more hydrocarbons, 2 to 10 vol % of oxygen, and possibly one or more gases from the group comprising nitrogen, noble gases, hydrogen, carbon dioxide, carbon monoxide, and water is introduced into an isothermally operated reactor, in which the oxygen contained in the hydrocarbon-containing gas mixture is at least partially converted into carbon dioxide and water in the presence of one or more catalysts, wherein the specifications in vol % relate to the total volume of the hydrocarbon-containing gas mixture introduced into the reactor and add up to 100 vol % in total.

Removal of oxygen from hydrocarbon-containing gas mixtures

Oxygen is effectively removed from hydrocarbon-containing gas streams while minimizing danger of explosion by contacting the gas stream with a catalyst comprising shaped bentonite supports having an outer shell containing catalytic metals gold, and at least one of palladium platinum, rhodium, or iridium.

Process for removing oxygen from a gas mixture comprising hydrocarbon and oxygen

The invention provides a process for preparing vinyl acetate in a heterogeneously catalyzed, continuous gas phase process by reacting ethylene with acetic acid and oxygen and subsequently working up the product gas stream, with inhibition of the polymerization of vinyl acetate during the workup of the product gas mixture by addition of one or more N-oxyl compounds which contain at least one N-oxyl radical group &#x2014;N&#x2014;O. as inhibitors which comprises adding the N-oxyl compound as a 50 to 85% by weight strength aqueous solution.

Process for preparing vinyl acetate with inhibited by-product formation

The invention provides a process for preparing vinyl acetate monomer (VAM) by reacting ethylene with acetic acid and oxygen in a tube bundle reactor in a heterogeneously catalysed, continuous gas phase process, characterized in that a high-performance catalyst with a space-time yield of more than 700 g of VAM/l of catalyst&#xd7;hour is used for catalysis, and in that the tube bundle reactor comprises tubes with a ratio of inner surface area to volume of &#x2267;130 m.

Process and apparatus for preparing vinyl acetate monomer

The invention relates to a method for producing vinyl acetate in a heterogeneously catalyzed, continuous gas-phase process by reacting ethylene with acetic acid and oxygen in a reactor, and a) separating the product gas flow essentially containing ethylene, vinyl acetate, acetic acid, water, carbon dioxide, and other inert gases, and b) feeding a circulating gas flow containing ethylene and COback into the reactor, c) the circulating gas flow being compressed in a circulating gas compressor before being fed back into the reactor, and d) a partial flow of the circulating gas is branched off on the suction side or the pressure side of the circulating gas compressor and is fed to a COscrubbing process, and e) is scrubbed in a water scrubber before the COscrubbing process, characterized in that f) after the COscrubbing process, the partial flow, together with ethylene as a propellant, is fed, by means of a jet compressor, to the circulating gas on the pressure side of the circulating gas compressor and downstream of the point where the partial flow is removed for COscrubbing, and/or g) the bottom product from the water scrubber is fed directly to the pre-dehydration column.

Method for producing vinyl acetate monomer

A method for producing vinyl acetate in a heterogeneously catalyzed, continuous gas phase process by reacting ethylene with acetic acid and oxygen in a reactor and separating the product gas stream substantially comprising ethylene, vinyl acetate, acetic acid, water, carbon dioxide and inert gases.

A process for preparing unsaturated carboxylic esters includes reaction of alkenes having 2 to 6 carbon atoms with alkanecarboxylic acids having 1 to 6 carbon atoms in the presence of an oxygenous gas and in the presence of a heterogeneous noble metal catalyst by means of a continuous homogeneous gas phase process in a reactor. A gaseous phase (cycle gas) is circulated, and the cycle gas is laden with alkanecarboxylic acid in an acid saturator before entry into the reactor. In a presaturator connected upstream of the acid saturator, the cycle gas is laden with a portion of the amount of alkanecarboxylic acid used for saturation, and then it is transferred to the acid saturator and laden there with the remaining amount of alkanecarboxylic acid.

Process for preparing unsaturated carboxylic esters

The efficiency of vinyl acetate production is increased by scrubbing of off gas followed by COabsorption. A portion of the off gas containing substantial quantities of ethylene is recycled to the process, whereas another portion is employed in another ethylene consuming reaction. Despite not removing non-reactive gases, selectivity and yield based on ethylene are both increased.

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Röhrnbach, Germany

Willibald Dafinger