Monsanto Company

Earle C Makin

Jerry L Price

Yu Wen Wei

K Keith Okamoto

Crude vanillin is purified by supercritical extraction of impurities. The process is especially useful in purifying crude vanillin obtained from paper mill waste liquors. Preferred supercritical extraction fluid is CO.sub.2.

Purification of vanillin

There is provided an improved continuous homogeneous catalytic carbonylation process wherein a mixed gas stream is removed from the carbonylation reactor, condensable liquids separated from said gas stream and said gas stream vented, the improvement comprising contacting said gas stream with a plurality of hollow fiber membranes selectively permeable to hydrogen under conditions substantially non-degrading of the membranes to generate a non-permeated gas stream of higher carbon monoxide content and recycling said non-permeated gas stream to the carbonylation process reactor. There is also provided for the recovery and recycle to the process of carbonylation products such as acetic or propionic acids by adsorption and removal from a solid adsorbent or absorption in a liquid absorbent.

Carbonylation process

An improved methanol synthesis process is provided wherein synthesis gas containing hydrogen and carbon dioxide is passed over a methanol synthesis catalyst, cooled to condense methanol and water in the reacted gas, the liquids separated, a purge gas stream removed while the remaining reacted gas is recycled to the synthesis catalyst, the purge gas separated by contacting the outer surfaces of a plurality of hollow fiber membranes selectively permeable to hydrogen and carbon dioxide to form a permeant gas depleted in hydrogen and carbon dioxide and a permeate gas enriched in said gases and the enriched permeate gas is combined with the synthesis gas. In an optional embodiment, methanol vapor is first recovered from the purge gas prior to contacting the selectively permeable membranes, preferably by a water scrub.

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Dickinson, TX, United States of America

Earle C Makin