过渡金属磷钼钒杂多化合物的表征及催化性能  

CHARACTERIZATION AND CATALYTIC PROPERTIES OF TRANSITION METAL MOLYBDOVANADOPHOSPHORIC HETEROPOLY COMPOUNDS

作　　者：徐静[1] 赵振波[1,2,3] 李正[2] 杨向光[3] 

机构地区：[1]长春工业大学,吉林长春130012 [2]中国石油吉林石化公司研究院,吉林吉林132021 [3]中国科学院长春应用化学研究所,吉林长春130022

出　　处：《石油学报（石油加工）》2008年第5期526-532,共7页Acta Petrolei Sinica(Petroleum Processing Section)

基　　金：长春工业大学基础研究基金;吉林省教育厅科技发展计划项目(吉教科合字[2003]第42号)资助

摘　　要：采用水热合成的方法制备了4种过渡金属磷钼钒杂多化合物M11PV1Fe、M11PV1Cu、M11PV1Cr和M11PV1Mn。采用傅里叶变换红外光谱(FT-IR)、紫外可见光漫反射光谱(DRSUV-Vis)、X射线衍射(XRD)、热分析(TG-DSC)、程序升温还原(TPR)及程序升温脱附(NH3-TPD)方法对所制备过渡金属磷钼钒杂多化合物进行了表征。结果表明,所制备的过渡金属磷钼钒杂多化合物具有Keggin结构,其中,V取代了部分Mo,进入了杂多酸一级结构,而过渡金属没有进入一级结构,仅占据在抗衡正离子的位置。过渡金属可调变磷钼钒杂多化合物的氧化还原能力,引起酸强度及酸量的改变。将4种过渡金属磷钼钒杂多化合物作为催化剂,用于H2O2为氧化剂的苯羟化合成苯酚的反应中,都表现出较好的催化性能。以M11PV1Mn为催化剂,考察了H2O2/C6H6摩尔比(n(H2O2)/n(C6H6))、反应溶剂、反应温度以及反应时间对苯羟化反应的影响,获得了优化的反应条件。在优化的反应条件下,即在n(H2O2)/n(C6H6)=1.5、乙腈为溶剂、反应时间3h、反应温度60℃的条件下,苯酚收率大于50%,选择性高于90%。Four transition metallic molybdovanadophosphoric heteropoly compounds MllPVIFe, M11PV1Cu,M11PV1Cr and M11PVIMn were synthesized by hydrothermal method, which were characterized by Fourier transform infrared spectroscopy （FT-IR）, UV-Vis diffuse reflectance spectroscopy（DRS UV-Vis）, X-ray diffraction（XRD）, thermal analysis（TG-DSC）, H2-TPR and NH3-TPD. The results showed that the prepared heteropoly compounds were of Keggin structure, in which some Mo atoms in the primary structure of the heteropolyacid were substituted by V atoms, while transition metals have not entered the primary structure and hold only at the cation position. Transition metals could change the redox ability of the molybdovanadophosphoric heteropoly compounds, resulting in the change of acid strength and acid quantity. These four heteropoly compounds showed high catalytic activity in the hydroxylation of benzene to phenol with aqueous hydrogen peroxide as oxidation agent. The effects of reaction conditions on the hydroxylation catalyzed by M11PVIMn were investigated to obtain optimal ones, i. e. , n （H2O2）/ n（C6H6） =1.5, acetonitrile as solvent, reaction time for 3 h, temperature at 60℃, under which the yield of phenol was over 50% and the selectivity of phenol was over 90%.

关 键 词：过渡金属 KEGGIN结构 杂多化合物 氧化 苯 苯酚 

分 类 号：O643.32[理学—物理化学]