DEHYDRATION OF ALCOHOLS ON POISONED ACIDIC CATALYSTS

摘要

The present invention is a process for the dehydration of an alcohol having at least 2 carbon atoms to make the corresponding olefin, comprising: a) introducing in a reactor a stream (A) comprising at least an alcohol, optionally water, optionally an inert component, b) contacting said stream with an acidic catalyst in said reactor at conditions effective to dehydrate at least a portion of the alcohol to make an olefin, c) recovering from said reactor a stream (B) comprising : the inert component and at least an olefin, water and optionally unconverted alcohol, d) optionally fractionating the stream (B) to recover the unconverted alcohol and recycling said unconverted alcohol to the reactor of step a), e) optionally fractionating the stream (B) to recover the inert component, water and the olefin and optionally recycling said inert component and optionally a part of the water to the reactor of step a), wherein, f) an effective amount of a component capable to neutralize a part of the catalyst active site is introduced in stream (A) or directly in the dehydration reactor and g) optionally the temperature of the dehydration reactor is adjusted to increase the alcohol conversion or the olefin yield or both. In another embodiment at step f) an effective amount of a component capable to increase the selectivity for the desired corresponding olefin is introduced in stream (A) or directly in the dehydration reactor. The component introcuced at step f) can be chosen from the group consisting of ammonia, organic ammonium salts, hydrazine, nitriles, amines (including pyridines, pyrrols, pyrrolydones and pyrrolidines), amides, imines, di-imines, imides, cyanates, isocyanates, nitrites and nitroso compounds, aldehydes, ketones, carboxylic esters, and their corresponding thio-compounds (thiols, sulphides, disulfides).