铜磷铝分子筛的合成及其对苯液相氧化制苯酚的催化性能

Synthesis of Cu-AlPO_4-5 Molecular Sieve and Its Catalytic Perfor-mance for Liquid-Phase Oxidation of Benzene to Phenol

以水热法合成了铜磷铝分子筛 (Cu AlPO4 5 ) ,并用XRD ,ICP ,SEM ,FT IR ,NH3 TPD ,H2 TPR ,ESR和N2 吸附 脱附等手段对样品进行了表征 .结果表明 ,所合成的Cu AlPO4 5分子筛具有AFI拓扑结构 ,结晶度高 ,无结晶态杂质 ;Cu2 + 进入到分子筛的骨架结构中 ,并使其Lewis酸和Br¨onsted酸中心数量增加 ,弱酸性中心大大增强 ,强酸性中心消失 ;样品中的Cu存在多种形式 ,以骨架Cu物种为主 ,还存在有骨架外CuO和双核Cu物种 ,部分样品具有缺陷结构 .Cu AlPO4 5分子筛中存在着骨架Cu和缺陷结构两种可能的活性中心 ,对苯液相氧化具有良好的催化性能 ,苯酚选择性可达 96 % ,收率可达 6 9% .

Cu\|substituted aluminophosphate molecular sieve (Cu-AlPO 4-5) was synthesized hydrothermally and its physicochemical properties were characterized by XRD, ICP, SEM, FT-IR, NH 3-TPD, H 2-TPR, ESR and N 2 adsorption-desorption. The results showed that the Cu atoms had incorporated into the AlPO 4-5 framework. The synthesized samples possessed AFI topology structure and their crystallinity was high without crystalline impurities. The Lewis and Brnsted acid sites on Cu-AlPO 4-5 were much increased and the weak acid sites were much enhanced compared with AlPO 4-5, while the strong acid sites disappeared. There were several kinds of Cu species in the Cu-AlPO 4-5 molecular sieve. Most Cu atoms had incorporated into the framework, other Cu species were extra-framework CuO and binuclear Cu species. There was defect structure in the Cu-AlPO 4-5 molecular sieve. The catalytic activity of Cu-AlPO 4-5 for liquid-phase oxidation of benzene by hydrogen peroxide to phenol was measured. The yield of phenol was 6 9% with a selectivity as high as 96%. The framework Cu species and the defect structure of the Cu-AlPO 4-5 molecular sieve might be two types of active sites for the oxidation of benzene to phenol.