Process for obtaining olefins directly from unsaturated aldehydes, by catalytic hydrogenation

摘要

Olefins are obtained by the direct treatment of a -b -unsaturated aldehydes of the formula FORM:0813839/IV (b)/1 in which R and R1 are the same or different and each is hydrogen, or an alkyl, or an aryl group, in the vapour phase at normal pressure with hydrogen with a hydrogenation catalyst which is also a dehydrogenation catalyst. The catalyst is preferably copper silicate or copper oxide, preferably reduced, on a silica carrier, using as a dehydrating activator alumina, silica, thorium oxide, tin dioxide, inorganic sulphates, aromatic amine sulphates, zinc chloride, aluminium silicate, graphite, aluminium phosphate, phosphorus pentoxide, boric anhydride, sulphuric acid or sulphonic acids. The working temperature is preferably 150 DEG to 350 DEG C. and the amount of hydrogen employed 1-20 times the stoichiometric quantity. In an example, ethylhexene is made by mixing ethylpropylacrolein with 5 times the stoichiometric amount of hydrogen and passing at 250 DEG C. over reduced copper silicate.