纳米薄层SAPO-5分子筛的离子热合成及催化性能

Ionothermal synthesis of nanosheets SAPO-5 molecular sieves and its catalytic performances

摘要:

以小剂量的丁二酸、氯化胆碱和四乙基溴化铵复配形成的低共熔混合物为溶剂和模板，以水热法合成的纳米薄层SAPO-5分子筛作为晶种，使用离子热法在微波加热功率为400W、温度为180℃和晶化时间为20min的条件下，高效合成了具有六角花瓣状的纳米薄层SAPO-5分子筛。采用XRD、SEM、N2物理吸/脱附和NH3-TPD对合成样品的物相、形貌、孔结构和酸性进行了分析。N2物理吸/脱附分析结果表明：所合成的样品SC2-T180-t20-P400是一种同时含有微孔-介孔-大孔结构的多级孔SAPO-5分子筛，其外表面积高达85 m2/g。分子筛产物中无机物的原子利用率 达到88%。最重要的是，该样品在苯与苯甲醇的烷基化反应中苯甲醇转化率和二苯甲烷选择性分别达到99.9%和93.9%，表现出比传统水热法合成的纳米薄层SAPO-5催化剂更为优异的催化性能。

Abstract:

Hexagonal petal SAPO-5 zeolite was synthesized by ionothermal method with high efficiency under the conditions of microwave heating power of 400W, temperature of 180 °C and crystallization time of 20 min, in which a low-dosage eutectic mixture based on succinic acid, choline chloride and tetraethyl ammonium bromide was used as the solvent and template, nanosheets SAPO-5 molecular sieve synthesized by hydrothermal method acted as seeds.The product phase, morphology, pore structure and acidity of the synthesized samples were fully analyzed by XRD, SEM, N2 physical adsorption/ desorption and NH3-TPD techniques. The results of N2 physical adsorption/desorption analysis show that the synthesized sample SC2-T180-t20-P400 is a hierarchically porous SAPO-5 molecular sieve with micro-meso-macropore structure inside, and its external surface area is up to 85 m2/g.The atomic utilization efficiency of inorganic substances in zeolite products can reach 88%. Most importantly, the conversion of benzyl alcohol and the selectivity of diphenylmethane in the alkylation of benzene with benzyl alcohol reached 99.9% and 93.9% respectively, showing better catalytic performance than the traditional hydrothermally synthesized counterpart.