【作者】 张宪；

【导师】 王日杰； 张凤宝；

【作者基本信息】 天津大学 ， 化学工程， 2008， 博士

【摘要】 乙烯是一种重要的基本有机化工原料。本文对乙醇催化脱水制乙烯反应进行了研究。采用水热晶化合成法制备了系列NiAPSO-34分子筛催化剂,采用常压连续固定床反应器对催化剂的活性和稳定性进行了评价,对催化剂进行了XRD、FT-IR、NH₃-TPD、H₂-TPR、ESR、BET、TG-DTG、SEM和XPS表征,并对反应热力学和动力学进行了研究。研究表明,以30wt%的硅溶胶为硅源,拟薄水铝石为铝源,原料配比为P/Al=1,Si/Al=1,Ni/Al=0.015,R/Al=2,晶化时间60h,晶化温度为200℃条件下制备的NiAPSO-34（Ni0.015）催化剂具有较好的活性。其与HZSM-5分子筛相比,具有较高的稳定性。通过中心复合试验设计对反应条件进行筛选,得到了乙醇转化率、乙烯选择性和反应温度、乙醇与催化剂的接触时间、乙醇分压之间的数学模型关系。试验值和预测值高度一致（对于乙醇转化率,相关系数和调整相关系数分别为99.8%和99.7%;对于乙烯选择性,相关系数和调整相关系数分别为100%和99.9%）。根据得到的数学模型对反应条件进行求优计算,得出在反应温度为385°C,乙醇与催化剂的接触时间为3.3s,乙醇分压为0.57atm条件下,当乙醇的转化率为98.4%时,乙烯选择性最大,可以达到99.3%。对乙醇脱水的热力学分析表明,高温有利于目的产物乙烯的生成,低温有利于副产物乙醚的生成。通过对乙醇脱水动力学研究,得出乙醇脱水反应属于平行-连串反应机理,推导出了乙醇脱水生成乙烯和乙醚的动力学方程,采用禁忌遗传算法计算出乙醇脱水动力学模型参数,并得到了乙醇生成乙烯、乙醇生成乙醚和乙醚生成乙烯反应的活化能和乙醇、水和乙醚吸附在催化剂表面的吸附热。更多还原

【Abstract】 Ethylene is an important material for the organic chemistry industry. Catalytic dehydration of ethanol to ethylene was studied in this thesis. A series of NiAPSO-34 catalysts were home-made by hydrothermal method and tested for dehydration of ethanol using fixed bed reactor. The catalyst samples were characterized by XRD、FT-IR、NH3-TPD、H2-TPR、ESR、BET、TG-DTG、SEM and XPS respectively. Reaction thermodynamics and kinetics were researched.Research showed that among the catalysts prepared by hydrothermal method, the Ni0.015 sample showed the best activity, whose preparation condition was as follow: 30wt% colloidal silica and pseudoboehmite were used as the sources of silicon and aluminum respectively; the molar ratio of the starting gel was P/Al=1, Si/Al=1, Ni/Al=0.015, R/Al=2; the crystallization temperature was 200°C and the crystallization time was 60h. Moreover, NiAPSO-34 catalyst showed better stability compared with HZSM-5 catalyst.Central composite experimental design was applied in catalytic dehydration of ethanol to optimize the reaction condition. The mathematical relationship of ethanol conversion and ethylene selectivity on the reaction temperature, residence time through catalyst bed, ethanol partial pressure can be approximated by polynomial models. Predicted values were found to be in good agreement with experimental values (R-Sq of 99.8% and R-Sq (adj) of 99.7% for ethanol conversion; R-Sq of 100% and R-Sq (adj) of 99.9% for ethylene selectivity). The result of optimization predicted by the model showed that ethylene selectivity presented the maximal result 99.3% at the optimal condition of reaction temperature 385°C, contact time with catalyst 3.3s, ethanol partial pressure 0.57atm, when ethanol conversion reached to 98.4%.Thermodynamics analysis for the reaction system showed that high-temperature was favorable to produce ethylene, but byproduct diethyl ether yield increased under low-temperature. Based on the kinetics research, dehydration of ethanol was parallel-consecutive reaction mechanism and the intrinsic kinetic models of dehydration of ethanol to ethylene and diethyl ether were gained. Kinetic parameters for dehydration of ethanol were calculated through tabu-hierarchy genetic algorithm. Activation energies of ethanol to ethylene, ethanol to diethyl ether, diethyl ether to ethylene and heats of adsorption of ethanol, water, diethyl ether were obtained.更多还原