Patent ID: 8822717

Claim:
A method for the production of vinyl acetate, said method comprising: (a) reacting (i) 65 to 80 mol. % of ethylene, (ii) 10 to 25 mol. % of acetic acid, and (iii) 5 to 15 mol. % of an oxygen-containing gas in the presence of a palladium gold catalyst in a reactor to produce vinyl acetate; (b) withdrawing from the reactor a gas stream comprising ethylene, acetic acid, vinyl acetate, water, and carbon dioxide; (c) separating the gas stream into an ethylene stream comprising ethylene and carbon dioxide, and a primary vinyl acetate product stream comprising vinyl acetate, water, and acetic acid; (d) separating the ethylene stream into a recovered ethylene stream and a carbon dioxide stream; (e) separating the primary vinyl acetate product stream into a vinyl acetate product stream and a recovered acetic acid stream; (f) recycling the recovered ethylene stream of step (d) and the recovered acetic acid stream of step (e) to the reactor in step (a); (g) measuring the concentration of a component involved in or associated with one or more of the above steps by Raman spectroscopic analysis wherein the measuring step includes the step of identifying the Raman shifts and intensity of the component involved in or associated with one or more of the above steps; and (h) adjusting the conditions in the reactor or in any of the subsequent steps in response to the measured concentration of the component to achieve a proper control of the reaction or any of the subsequent steps.