分子筛表面酸性对微波固相法制备的ZnCl_2/HY催化剂的影响  

Effects of Surface Acid Properties of Y Zeolite on ZnCl_2/HY Catalyst Prepared by Solid State Interaction under Microwave Irradiation

作　　者：银董红[1] 尹笃林[1] 伏再辉[1] 李谦和[1] 

机构地区：[1]湖南师范大学化学化工学院,湖南长沙410081

出　　处：《催化学报》2002年第6期567-570,共4页

基　　金：教育部留学回国人员科研启动基金资助项目 ([2 0 0 1] 498号 );湖南省教育厅资助项目 (0 1C164 )

摘　　要：采用XRD和原子吸收光谱法研究了微波作用下分子筛表面酸性对ZnCl2 与Y分子筛固态相互作用的影响 .结果表明 ,微波辐射可显著促进ZnCl2 在分子筛表面分散 ,其分散阈值与分子筛表面酸性有关 .随着分子筛表面酸量和酸强度增加 ,ZnCl2在分子筛表面的最大分散量减少 ,分散的ZnCl2 与Y分子筛的固态离子交换量也减少 ;NaY型分子筛比HY分子筛更容易发生固态离子交换反应 .考察了微波固相法制备的ZnCl2 /HY催化剂在苯甲醚与乙酰氯酰化反应中的催化性能 .结果表明 ,在分子筛表面分散的ZnCl2 具有更高的催化活性及对甲氧基苯乙酮选择性 .The effects of surface acid properties of Y zeolite on the solid state interaction between ZnCl2 and Y zeolite with different ion-exchange degrees of Na+ by H+ under microwave irradiation (MWI) were investigated. The XRD patterns indicated that ZnCl2 dispersed completely on the surface of HY-98 zeolite (the number denotes ion-exchange degree) with ZnCl2 loading of 0.45 mmol/g under MWI. The dispersion threshold of Zn-Cl-2 on the surface of HY-98 is in the range from 0.45 to 0.70 mmol/g. With the increase of the acid centers and the acid strength on the surface of Y zeolite, the dispersion threshold of ZnCl2 decreased, which can be attributed to low absorption of microwave energy for low Na+ content in Y zeolite. The ZnCl2/HY samples (ZnCl2 loading 0.45 mmol/g) with different ion-exchange degrees were washed with water completely, and then the amounts of Zn2+ and Na+ in the solution after filtration and retained in the zeolite were analysed by atomic absorption spectroscopy. Zn2+ in the solution and in the zeolite were supposed to be the amounts of ZnCl2 dispered and ion-exchanged by solid state, respectively. The amount of ZnCl2 ion-exchanged by solid state with HY zeolite decreases with the increase of its surface acid properties. It is concluded that the ion-exchange by solid state with NaY zeolite is easier than that with HY zeolite under MWI. ZnCl2/HY catalyst prepared by MWI showed the highest catalytic activity and selectivity for p-methoxyl acetophenone in acylation of anisole and acetyl chloride. The ZnCl2/NaY and ZnCl2/HY-25 samples showed little catalytic activity owing to the ion-exchange by solid state between ZnCl2 and NaY zeolite under MWI during the catalyst preparation. However, when ZnCl2 is dispersed as the predominant status, its catalytic activity increases significantly.

关 键 词：表面酸性 固相法 制备 ZnCl2/HY催化剂 氯化锌 Y分子筛 微波辐射 固态相互作用 苯甲醚 乙酰氯 酰化 对甲氧基苯乙酮 

分 类 号：O643.3[理学—物理化学]