CATALYTIC-OXIDATION OF ISOBUTANE TO METHACRYLIC-ACID WITH MOLECULAR-OXYGEN OVER ACTIVATED PYRIDINIUM 12-MOLYBDOPHOSPHATE

Isobutane was catalytically oxidized to methacrylic acid with molecula r oxygen above 300 degrees C over crystalline particles of pyridinium 12-molybdophosphates which were activated by heat-treatment under a ni trogen stream up to 420 degrees C. During the treatment two third of p yridine were released from the sample and one third remained accompani ed by the formation of orthorhombic structure. It was proved by IR stu dies that the catalyst became a reduced state by this treatment. The r educed state was highly stable even under catalytic oxidation conditio ns with molecular oxygen. 50% selectivity to methacrylic acid and 22% to acetic acid were achieved at 22% conversion of isobutane. The highl y stable reduced state and structure of the activated heteropolymolybd ophosphate catalyst seem to be responsible for the high activity for i sobutane oxidation and high selectivity to methacrylic acid formation.