水和载体对K_2CO_3催化甲醇与CO_2合成碳酸二甲酯反应的影响

Effect of water and supports on synthesis of dimethyl carbonate from methanol and CO_2 using K_2CO_3 as catalyst

K2CO3催化剂在CO2与甲醇直接合成碳酸二甲酯(DMC)反应中表现出较高的催化活性,但催化作用机理仍不够明确,尤其是水在反应中的作用。实验考察了无脱水剂情况下向反应体系中加入少量水以及不同的载体对DMC合成反应的影响。结果表明:少量水的存在可以增加催化活性,但并不改变生成DMC的反应平衡,水在其中起到溶解K2CO3,增加其在甲醇中的溶解性的作用,从而增加其催化活性;载体对K2CO3催化剂活性有明显影响,以煤质柱状活性炭为载体的催化剂活性最高,且负载后的催化剂反应条件更温和。

K2CO3 exhibited high catalytic activity in the direct synthesis of dimethyl carbonate （DMC） from methanol and CO2, but the catalytic mechanism was still ambiguous, especially the role of the water. The effects of small amount of water and supports on the DMC synthesis were investigated with the supported K2CO3 as catalysts by adding different volume water into the reaction system without dehydrating agent. The results indicated that the small amount of water increased the catalytic activity of K2CO3 by increasing it＇s solubility in the methanol but didn＇t affect the equilibrium of the reaction; and the supports obviously influenced the activity of the catalysts, and the coal-based columnar activated carbon supported K2CO3 showed the highest catalytic activity in a more modest reaction condition.