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以活性炭、三氧化二铝、二氧化硅作载体制备了一系列负载的钼催化剂 ,并对甲醇常压下直接气相羰基化进行了研究 ,实验发现载体对催化剂的羰化性能非常敏感。活性炭是最佳的催化剂载体 ;Mo/γ Al2 O3 催化剂虽甲醇转化率高 ,但羰化产物选择性低 ;而Mo/SiO2 催化剂不仅甲醇转化率低、而且羰化选择性几乎为零。实验对催化剂的CO、NH3化学吸附与羰基化性能的关系进行了分析 ,结果表明 :催化剂的酸性对甲醇的转化十分重要 ,催化剂对CO的化学吸附是决定羰化反应选择性的关键。此外 ,本文提出了甲醇裂解成甲基正离子与一氧化碳作用的直接气相羰基化的催化机理
A series of supported molybdenum catalysts were prepared by using activated carbon, aluminum oxide and silica as support. The direct carbonylation of methanol under atmospheric pressure was studied. The results showed that the support was very sensitive to the carbonylation performance of the catalyst. Activated carbon is the best catalyst support. Mo / γ Al 2 O 3 catalyst has high conversion of methanol but low selectivity of carbonylation products. However, Mo / SiO 2 catalyst not only has low methanol conversion, but also almost no carbonylation selectivity. The relationship between CO and NH3 chemisorption and carbonylation performance was analyzed experimentally. The results showed that the acidity of the catalyst was very important for the methanol conversion. The chemical adsorption of CO on the catalyst was the key factor in the selectivity of carbonylation. In addition, the catalytic mechanism of direct gas-phase carbonylation of methanol to methyl cation and carbon monoxide is proposed