多级孔NiMo负载Beta沸石催化剂的制备及加氢脱氧性能

Preparation and hydrodeoxygenation performance of multi-stage hole NiMo loaded Beta zeolite catalyst

摘要:

以廉价的硅藻土和偏铝酸钠为原料，采用水热法制备Beta沸石。通过软模板法、有机碱（尿素）处理、无机碱（NaOH）处理等方式对沸石的酸性和孔结构进行调节，合成多级孔Beta分子筛，并通过超声辅助浸渍法负载非贵金属Ni、Mo制备了双金属负载Beta沸石催化剂（NiMo/Beta）。利用XRD、SEM、N2吸脱附、NH3-TPD、H2-TPR对催化剂晶体结构、微观形貌、孔结构、酸性和金属还原性进行表征。考察了改性处理方式和工艺条件（反应温度、H2压力、溶剂正十二烷用量、反应时间）对催化剂催化愈创木酚加氢脱氧反应性能的影响。结果表明，在300 ℃、H2压力4 MPa、反应时间3 h、溶剂正十二烷20 mL的条件下，在6.0 g硅藻土中加入3.0 g的CTAB改性后的NiMo/Beta-3.0CB表现出最佳的催化活性，愈创木酚转化率为99.8%，环己烷选择性为92.7%；NiMo/Beta-3.0CB循环使用3次后，愈创木酚转化率为85.7%。

Abstract:

Beta zeolite was prepared via hydrothermal method using cheap diatomite and sodium meta-aluminate as raw material. The acidity and pore structure of the zeolite were adjusted by soft template method, organic alkali (urea) treatment and inorganic alkali (NaOH) treatment to synthesize multi-stage hole Beta molecular sieve, and bimetallic-loaded Beta zeolite catalyst (NiMo/Beta) was prepared by loading non-noble metals Ni and Mo via ultrasound-assisted impregnation method. The crystal structure, micromorphology, pore structure, acidity and metal reducibility of the catalyst were comprehensively characterized by XRD, SEM, N2 adsorption-desorption, NH3-TPD and H2-TPR. The effects of modified treatment methods and process conditions (reaction temperature, reaction H2 pressure, solvent n-dodecane amount, reaction time) on the catalyst"s catalytic performance in the hydrodeoxygenation of guaiacol were investigated. The results showed that under the conditions of 300 ℃, H2 pressure 4 MPa, reaction time 3 h and solvent n-dodecane 20 mL, the NiMo/Beta-3.0CB modified with 3.0 g CTAB in 6.0 g diatomite exhibited the best catalytic activity, and the conversion of guaiacol was 99.8%，the selectivity of cyclohexane was 92.7%; and after three times of recycling of the NiMo/Beta-3.0CB, the conversion of guaiacol was 85.7%.