Process for preparing 2-butenolide

A process for preparing 2-butenolide which comprises reacting furan with oxygen in the vapor phase in the presence of a catalytically effective amount of a catalyst comprising a mixed metal oxide containing titanium, boron and molybdenum values;

• said mixed metal oxide being obtained by reacting titanium halide with ammonium heptamolybdate, reacting the resulting product with boric acid or alkyl borate and thereafter calcining the recovered solid in an inert or oxygen-containing atmosphere, or by reacting titanium halide with boric acid or alkyl borate to provide a titanium borate, reacting said titanium borate with ammonium heptamolybdate and thereafter calcining and recovered solid in an inert or oxygen-containing atmosphere.