Na盐修饰的Cu/SiO_(2)催化丙烯环氧化反应研究  

Propylene epoxidation catalyzed by Na salts modified Cu/SiO_(2) catalysts

作　　者：马应圆 魏新煜 高晶晶 苏暐光[1] MA Ying-yuan;WEI Xin-yu;GAO Jing-jing;SU Wei-guang(State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering,School of Chemistry and Chemical Engineering,Ningxia University,Yinchuan 750021,China)

机构地区：[1]宁夏大学化学化工学院,省部共建煤炭高效利用与绿色化工国家重点实验室,宁夏银川750021

出　　处：《现代化工》2024年第4期140-145,共6页Modern Chemical Industry

基　　金：国家自然科学基金项目(21463018);宁夏自然科学基金项目(2022AAC03039)。

摘　　要：通过浸渍法制备了6种Na盐修饰的Cu/SiO_(2)催化剂,利用XRD、TEM和XPS对其晶相结构、粒径大小和Cu物种价态进行了分析,考察了Na盐促进剂种类和摩尔分数对Cu/SiO_(2)催化剂上丙烯氧气环氧化反应性能的影响。结果表明,6种Na盐可以不同程度地还原Cu^(2+)物种,生成不同含量的Cu^(0)或Cu^(+)物种。6种Na盐都可以提高Cu/SiO_(2)的丙烯环氧化活性,而且Na_(2)CO_(3)最有利于环氧丙烷的生成。适量的Na_(2)CO_(3)可以促进Cu^(+)物种的形成,有利于丙烯环氧化反应的进行,但过量的Na_(2)CO_(3)会导致Cu~0物种的产生以及Cu物种的聚集,反而不利于环氧丙烷的生成。Cu^(+)物种摩尔分数越高,Cu/SiO_(2)的丙烯环氧化活性和环氧丙烷的形成速率也越大。小粒径的Cu^(+)物种具有最高的丙烯环氧化活性,是丙烯氧气环氧化反应的活性中心。Cu/SiO_(2) catalysts modified with six kinds of Na salts respectively are synthesized through an incipient wetness impregnation method,and their crystalline phase,particle size and Cu species valence state are characterized by means of XRD,TEM and XPS.The influences of the variety and mole fraction of Na salts on the activity of Cu/SiO_(2) catalysts in propylene epoxidation is investigated in detail.It is found that Cu^(2+)species may be reduced to varying degrees by six kinds of Na salts,which can produce different amount of Cu0 species or Cu^(+)species.All these six kinds of Na salts can improve the activity of Cu/SiO_(2) for propylene epoxidation,and Na_(2)CO_(3) is the most favorable for the formation of propylene oxide.The appropriate amount of Na_(2)CO_(3) is able to promote the formation of Cu^(+)species and facilitate the epoxidation of propylene,but too much amount of Na_(2)CO_(3) results in the generation of Cu0 species and the aggregation of Cu species,which is not conducive to the formation of propylene oxide.The higher the Cu^(+)species mole fraction,the higher the activity of Cu/SiO_(2) in propylene epoxidation and the higher the formation rate of propylene oxide.Cu^(+)species with small size have the most activity for propylene epoxidation and are the main active sites for propylene epoxidation reaction.

关 键 词：丙烯环氧化 Cu/SiO_(2) Cu^(+)物种 Na_(2)CO_(3) Na盐促进剂 

分 类 号：O643.32[理学—物理化学]