Vapour phase oxidn of hydrocarbons - over vanadium and molybdenum oxide catalyst regenerated with cpds. of phosphorus and or molybdenum

摘要

Vapour-phase oxidn. of hydrocarbons to dicarboxylic acids or dicarboxylic acid anhydrides, by contacting hydrocarbon with a V-Mo-O catalyst which gradually loses its activity, takes place by process in which the catalyst is admixed with pref. 0.0012 (0.00004-0.0008) moles, w.r.t. moles V in catalyst, of P halide having formula:- PX'n (I) (where X' is Cl, Br, I or F and n is 3 to 5) or an organo-P cpd. (II) having one of formulae:- (where R is Ph or 1-6C alkyl and X is H or R) and/or pref. >0.000005 moles of a cpd. of Mo, Ni, Co, Mn, U, or their mixts., w.r.t. g. atom V in V-Mo-O catalyst/day. Process is pref. used for oxidising 4-8C hydrocarbons to deicarboxylic anhydrides, esp. for oxidising 4-6C hydrocarbons, more pref. benzene, to maleic anhydride. Catalyst can be regenerated and stabilised in situ. Catalyst clogging is prevented.