甲醇气相合成碳酸二甲酯的催化反应条件分析

Analysis of Influencing Factors on Gas Phase Catalytic Synthesis of Dimethyl Carbonate from Methanol

在较大范围内考察了催化剂预处理、反应温度、反应压力、原料配比及原料中水含量等因素对PdCl2-CuCl2-KOAc/AC催化剂上甲醇氧化羰基化合成碳酸二甲酯反应活性及选择性的影响。以含氯有机物对催化剂进行处理,可改变催化剂的表面组成,提高催化剂的活性和稳定性。最佳反应条件:反应温度140～160℃,反应压力0.3MPa,甲醇与一氧化碳和氧气的摩尔比为4:2:1。压力对反应有显著影响,提高反应压力可明显促进催化反应活性。当压力超过0.3MPa时,催化剂活性下降。XRD和XPS表征结果表明催化剂表面草酸铜结晶的产生,是造成催化剂活性下降的主要原因。原料中过高的水含量会加速一氧化碳和甲醇的完全氧化副反应的发生,造成反应选择性下降。反应过程的水含量应控制在摩尔分率1%以下。

Effects of pretreatment of catalysts, reaction temperature, molar ratio of the feeds, reaction pressure and water content in the feeds on the reaction properties of PdCl_2-CuCl_2-KOAc/AC catalysts has been studied in a wider range. Pretreatment of catalysts by organic cloride compound can change the composition of elements on the surface of catalyst samples and improve the activity and stability. It was found experimentally that the suitable reaction temperature is within a range of 140～160℃,the optimal pressure is 0.3Mpa,the optimal molar ratio of MeOH, CO and O_2 is (4∶2∶1). Dimethyl Carbonate By means of X photcelectron spectrum (XPS) alysis, it was showed that the reason for deactivation of the catalyst under high pressure was the formation of copper oxalate crystalline. In addition, high water content in the feed greatly promoted the complete oxidation reaction of CO and methanol.Therefore, the molar percentage of water in the feed would be controlled less than 1%.