Promoting effect of oxometallic acids, heteropoly acids of Mo, W and their salts on rhodium catalyzed methanol carbonylation

Oxometallic acids, heteropoly acids (HPAs) of Mo, W and their sodium salts were investigated as promoters for homogeneous rhodium catalyzed methanol carbonylation. The experiments were carried out under low water conditions. All of the catalysts with the promoters demonstrate better catalytic activity than the pristine Monsanto catalyst. And the promoting effects of acids upon reaction rates are generally better than the salts. The catalysts with the salts of HPAs as promoters have the best stability in the reactions. The catalytic rate can be effectively enhanced by increasing the content of the promoters, especially at low content level.