柠檬酸处理对ZSM-5分子筛甲缩醛气相羰基化性能的影响  

Effect of Citric Acid Modification of ZSM-5 Zeolite on Vapor-Phase Dimethoxymethane Carbonylation

作　　者：孙泽平 武建兵 李鹏 赵永祥[1,2] SUN Ze-ping;WU Jian-bing;LI Peng;ZHAO Yong-xiang(School of Chemistry&Chemical Engineering,Shanxi University,Taiyuan 030006,China;Engineering Research Center for Fine Chemicals of Ministry of Education,Taiyuan 030006,China;Synfuels China Technology Inner Mongolia Institute Co.,Ltd.,Taiyuan 030006,China)

机构地区：[1]山西大学化学化工学院,山西太原030006 [2]精细化学品教育部工程研究中心,山西太原030006 [3]中科合成油内蒙古技术研究院有限公司,山西太原030006

出　　处：《分子催化》2021年第1期22-30,I0002,共10页Journal of Molecular Catalysis(China)

基　　金：国家自然科学基金项目(21703127)。

摘　　要：采用柠檬酸对晶种法制备的低硅铝比ZSM-5纳米晶聚集体进行改性处理,并将其应用于催化甲缩醛(DMM)气相羰基化合成甲氧基乙酸甲脂(MMAc)反应.结果表明,通过调控柠檬酸处理时间可以有效地改进所制备ZSM-5分子筛的催化羰基化性能.其中,使用0.2 mol/L柠檬酸在80℃下处理12 h后的ZSM-5分子筛可获得59.5%DMM转化率和59.3%的MMAc选择性,MMAc收率从16.9%提高到35.3%.通过SEM、 TEM、 ICP、 N_(2)-BET、 P_(y)-FTIR、 NH_(3)-TPD等表征手段对分子筛进行详细表征分析,发现适当调控柠檬酸处理时间,可使得纳米晶聚集体ZSM-5分子筛酸强度降低,并暴露出更多的中强B酸位点,同时增大分子筛比表面积及孔道体积.酸性位点的增多促使DMM转化率提高,而酸强度的降低、比表面积及孔道体积的增加,有助于调控中间物种的反应路径及扩散程度,进而抑制部分副反应,提高目标产物MMAc的选择性.The nanocrystalline aggregate ZSM-5 zeolites with low Si/Al ratio were synthesized by a seeding technique and modified by citric acid. Their catalytic performance in the vapor-phase carbonylation of dimethoxymethane(DMM) to produce methyl methoxyacetate(MMAc) was investigated. The results indicated that the catalytic performance of the ZSM-5 zeolite could be effectively improved by adjusting the citric acid treatment time. Zeolite treated with 0.2 mol/L citric acid at 80 ℃ for 12 h could obtain 59.5% DMM conversion and 59.3% MMAc selectivity, MMAc yield increased from 16.9% to 35.3%. Various characterization results of SEM, TEM, ICP, BET, P_(y)-FTIR and NH_(3)-TPD show that the acid strength could be reduced, more medium-strong Br∅nsted acid sites were exposed, the specific surface area and pore volume were increased by changing citric acid treatment time. With the increase of acidic sites, the DMM conversion rate was increased;while with the decrease of acid strength, the increase of specific surface area and pore volume, the reaction path and diffusion of intermediate species were regulated, some side reactions were weakened and the MMAc selectivity was improved.

关 键 词：ZSM-5分子筛 柠檬酸处理 羰基化 甲缩醛 甲氧基乙酸甲酯 

分 类 号：O643.32[理学—物理化学]