Iso:alkene prodn. from N-alkene(s) - by isomerisation with fluorinated alumina catalyst in presence of water

摘要

Isomerisation of n-alkenes (I) to isoalkenes (II) is effected at 250-550 deg.C using a fluorinated alumina catalyst, with the improvement that (i) the reaction is effected in the presence of 0.5-150 (pref. 2-130)wt.% water, based on the wt. of (I); (ii) fluorine lost from the catalyst is continuously or periodically replaced by means of a volatile F cpd. (esp. HF); and (iii) the catalyst is regenerated by burning off coke deposits with an O2-contg. gas in the presence of steam. The process is esp. useful for converting n-butenes to isobutene (IIa), which is an intermediate for methyl t.-butyl ether (fuel component) or methyl methacrylate. Addn. of water moderates the activity of the catalyst, giving increased selectivity for (II) and increased stability (longer time between regenerations).