不同前驱体制备的SO_4^(2-)/AC催化剂在二甲醚直接氧化合成聚甲氧基二甲醚中的反应性能  

Performance of SO_4^(2-)/AC catalysts prepared with different precursors in the synthesis of polyoxymethylene dimethyl ethers from dimethyl ether direct oxidation

作　　者：高秀娟[1,2] 王文峰[1,2] 顾颖颖[1,2] 张振洲[1,2] 张清德[1] 韩怡卓[1] 谭猗生[1] 

机构地区：[1]中国科学院山西煤炭化学研究所煤转化国家重点实验室,山西太原030001 [2]中国科学院大学,北京100049

出　　处：《燃料化学学报》2017年第9期1114-1121,共8页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(21373253;20903114);中国科学院青年创新促进会(2014155)资助~~

摘　　要：分别用硫酸、硫酸铵作为前驱体,活性炭(AC)作为载体,采用浸渍法制备了SO_4^(2-)/AC双功能催化剂(SO_4^(2-)离子和AC载体分别提供催化剂的酸性和氧化还原性),考察了其在二甲醚(DME)直接氧化合成聚甲氧基二甲醚(DMMx)反应中的催化性能。结果表明,不同前驱体制备的SO_4^(2-)/AC催化剂表现出显著的催化活性差异。40%H_2SO_4/AC催化剂具有较好的反应活性,DME转化率为8.4%,DMM1-2的选择性达到59.7%,并且没有COx的生成;而在40%(NH_4)_2SO_4/AC催化剂上,反应主要生成了COx,DMM选择性仅2.7%,且无DMM2生成。XRD、BET、NH_3-TPD及O_2-TPD-MS等表征结果显示,H_2SO_4/AC催化剂中适量的弱酸性位和氧化还原性位有利于DME直接氧化合成DMMx。经过SO_4^(2-)修饰的催化剂促进了O2在活性炭表面的活化;前驱体H_2SO_4的加入提高了催化剂表面的弱酸性位数量,而(NH_4)_2SO_4的引入却促使催化剂表面产生中强酸性位。A series of SO4^2-/AC bifunctional catalysts,in which SO4^2- and AC acted as the acid sites and redox sites,respectively,are prepared by impregnation with H2SO4 and（NH4）2SO4 as precursors and active carbon as support;their catalytic performance in the direct oxidation of dimethyl ether（DME） to polyoxymethylene dimethyl ethers（DMMx） was investigated.The results show that the catalytic performance of SO4^2-/AC catalysts is significantly related to the precursor used.Over the 40% H2SO4/AC catalyst,the selectivity to DMM1-2 reaches 59.7%,with a DME conversion of 8.4%;in addition,there is no COx observed in the products.However,a large amount of COx by-product is formed over the 40%（NH4）2SO4/AC catalyst;meanwhile,the selectivity to DMM is only 2.7% and no DMM2 is formed.The XRD,N2 sorption,NH3-TPD and O2-TPD-MS characterization results illustrate that the suitable amount of weak acid sites and redox sites of the H2SO4/AC catalyst is beneficial to the formation of long chain DMMx from DME oxidation.The modification of AC with SO4^2- promotes the activation of O2 over the surface of AC support,whereas the introduction of H2SO4 improves the weak acid sites of the catalyst.On the contrary,the number of medium-strong acid sites of the catalyst is increased by modifying AC with（NH4）2SO4.

关 键 词：二甲醚 聚甲氧基二甲醚 直接氧化 前驱体 SO2-4/AC 

分 类 号：O643[理学—物理化学]