纳米固体碱催化酯交换反应动力学

摘要

Mg-Al hydrotalcite nanoparticles were synthesized by coprecipitation using urea as precipitating agent, and subsequently calcined.The calcined particles were characterized by XRD, FT-IR and SEM.They were further used as nanocatalyst to produce biodiesel, and its transesterification kinetics was studied.Results showed that the characteristic XRD diffraction peak d(003 ) partly disappeared,the symmetric degree of carbonate anions decreased and the particles were agglomerated to form layer structure after the fresh nanoparticles were calcined at 500℃ for 6 h.With the catalyst, the transesterification reaction order was 1.5 with apparent activation energy of 25.92 kJ/mol.At the optimized condition,biodiesel yield was 95.4％.%尿素为沉淀剂制备纳米Mg-Al水滑石,对其高温煅烧物进行X射线衍射、傅里叶变换红外光谱和扫描电子显微镜表征,以其煅烧物为催化剂催化制备生物柴油,并系统研究酯交换反应动力学.研究结果表明:纳米Mg-Al水滑石500℃煅烧6 h,水滑石特征衍射峰d(003)部分消失,柱撑阴离子碳酸根离子对称性降低,晶粒团聚成层状结构.纳米固体碱催化酯交换反应的表观反应级数为1.5,表观活化能Ea=25.92 kJ/mol,在最优条件下,生物柴油转化率高达95.4%.