钼、钨类水滑石材料的合成、结构及催化环氧化性能  

Synthesis and Characteristic of Catalytic Epoxidation of W,Mo-containing Hydrotalcite-like Materials

作　　者：周春晖[1] 谢华丽[1] 杜泽学[2] 范永仙[1] 葛忠华[1] 李小年[1] 

机构地区：[1]浙江工业大学化工与材料学院,浙江杭州310032 [2]中国石化石油化工科学研究院,北京100083

出　　处：《高校化学工程学报》2009年第3期516-521,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金(20773110,20541002);浙江省自然科学基金(Y405064,Y405064,Y407200,Y405025);中石化公司科技项目(X504034)

摘　　要：通过与大体积的有机阴离子对甲基苯磺酸根预柱撑的镁铝类水滑石(HTL)进行离子交换,制备了不同层间离子交换量(W/Al摩尔比和Mo/Al摩尔比分别为7:6,7:20,7:60)的钨、钼-类HTL催化材料,并用IR、UV-Vis、PXRD、SEM、TGA、XPS等表征结构。以H2O2为氧化剂,氯丙烯为底物,初步考察了W、Mo-HTL催化氯丙烯环氧化性能。结果表明,随着负载量的增大,有机阴离子红外吸收峰的强度随之减弱,钨、钼物种对应的红外吸收峰增强,证实层间有离子交换作用发生。钼-HTL中钼呈多种配位状态;钨-HTL中,仅当负载量比较高的时候,钨-HTL中钨呈现多种配位形态。材料系层状结构,随钨、钼量的增加,层间距有不同程度的增大。实验条件下,钨、钼-HTL对氯丙烯环氧化均有活性,钨-HTL比钼-HTL的活性高;对于W、Mo-HTL,较高选择性分别为85.2%和77.3%,双氧水转化率为41.2%～94.3%。材料中多种配位形态存在,可致使H2O2有效利用率降低。Tungsten （W）, molybdenum （Mo）-intercalated hydrotalcite-like materials （HTL） were synthesized by ionic exchange reaction with Mg/Al HTL precursors, during which the interlayer of the used precursors were enlarged by large organic molecules ofp-toluenesulfonate. The M/Al （M=W, Mo） molar ratio of the prepared W, Mo-intercalated HTL （W, Mo-HTL） are 7：6, 7：20 and 7：60, respectively, and they were characterized by IR, UV-Vis, PXRD, SEM, TGA and XPS, respectively. In the IR spectra of the synthesized W, Mo-HTL, the absorbance ofp-toluenesulfonate appears and the absorbance intensities ofp-toluenesulfonate decrease with the increase of the M/Al ratio in W, Mo-HTL, these indicate that the intercalation of Mo and W into the interlayer of HTL occurs. The UV-Vis analyses show that the diverse coordination state exists in the prepared Mo-HTL, while the prepared W-HTL has diverse coordination only when the W/AI ratio in it is high. The XRD patterns and SEM micrographs show that the synthesized W, Mo-HTL materials have layered structure and morphology, and their gallery heights increase with the increase of M/Al ratio in the prepared W, Mo-HTL. The catalytic performance of the prepared W, Mo-HTL was studied through the epoxidation reaction with the allyl chloride as substrate, H2O2 （30%） as oxidant and acetonitrile as solvent. The experimental epoxidations of allyl chloride were conducted at 50℃ and for 2 h, and the W, Mo-HTL used as catalyst are active to some extent for the epoxidation reaction. The highest selectivity of epichlorohydrine is 85.2% and 77.3% over the W-HTL and Mo-HTL, respectively; and the conversion of H202 are in the range of 41.2% to 94.3%. The lower H202 conversion efficiency may impute to the existent of the diverse coordination state of Mo or W in the W, Mo-HTL which leads to the catalytic decomposition of H2O2.

关 键 词：水滑石 钨酸盐 钼酸盐 过氧化氢 环氧化 环氧氯丙烷 

分 类 号：TQ424.25[化学工程] TQ426.64