TPA/SnO2固体酸催化油酸甲酯化反应研究

采用等体积浸渍法制备了不同磷钨酸（TPA）负载量的TPA/SnO2固体酸催化剂，用XRD、BET 和Hammett指示剂法进行表征，研究其在甲醇与油酸酯化反应中的催化性能，考察催化剂焙烧温度、TPA负载量、醇油比、反应时间和催化剂用量等因素对油酸转化率的影响。XRD和BET表征结果表明：TPA负载量较低（质量分数5%~30%）时，TPA均匀分散在SnO2表面；TPA负载量（w）高于30%时，TPA在SnO2表面发生聚结。当催化剂焙烧温度为450℃时，少量TPA在SnO2表面聚结；当焙烧温度为500℃时，TPA在SnO2表面均匀分散；当焙烧温度达550 ℃时，TPA分解成WO3。催化剂比表面积随着焙烧温度的增大而减小；随着TPA负载量的增大，比表面积呈先增大后减小的趋势，负载量（w）为15%时比表面积最大。酯化反应结果表明，30-TPA/SnO2(500)催化剂在油酸与甲醇的酯化反应中具有良好的催化活性。在n(甲醇)/n(油酸)=12、m(催化剂)/m(油酸)=0.08、反应温度68℃、反应时间6 h的条件下，油酸转化率可达90%以上。该反应符合准二级反应动力学方程，表观活化能为69.06 kJ/mol，指前因子为4.30×1010 L/(mol?h)。

INVESTIGATION OF ESTERIFICATION OF OLEIC ACID AND METHANOL OVER TPA/SnO2 SOLID ACID

A series of solid acid catalysts were synthesized by incipient wetness impregnation method with varying 12-tungstophosphoricacid (TPA) loading on tin oxide. The prepared catalysts were characterized by Hammett indicator、XRD，BET and its catalytic performance of the esterification reaction of oleic acid and methanol. The effecting factors of the catalyst preparation were discussed in detail. The results show that loading amount and calcinations both can affect the metal distribution and surface area. The 30-TPA/SnO2(500) catalyst shows good catalytic activity on the esterification. Under the reaction conditions of m(catalyst)/m(oleic acid) 8%, reaction time 8h and methanol:oleic acid molar ratio 12, the yield of oleic acid methyl ester exceeds 90%. A pseudo second order model was applied to calculate the kinetic parameters from the experimental data. The activation energy of the catalysts is 69.06 kJ/mol, pre-exponential factor is 4.30×1010 mol/(L?h).