焙烧条件对Ni-Sn-Cr/AC催化乙酸甲酯气相羰基化合成醋酐反应性能的影响

以活性炭(AC)为载体,采用等体积浸渍法制备了Ni-Sn-Cr/AC催化剂,在连续流动固定床反应器上考察了焙烧温度、焙烧时间和焙烧气氛等热处理条件对该催化剂催化乙酸甲酯气相羰基化合成醋酐反应性能的影响;同时用扫描电子显微镜、X射线衍射和N_2物理吸附等方法表征了该催化剂的结构。实验结果表明,焙烧温度和焙烧时间对催化剂活性的影响较为显著,而焙烧气氛对催化剂活性的影响不大。在N_2气氛中于600℃下焙烧4 h后的Ni-Sn-Cr/AC催化剂具有较高的羰基化活性;在n(CO):n(H_2)=8、n(CH3COOCH3):n(CH_3I)=7、n(CO):n(CH_3COOCH_3)=4、反应温度205℃、反应压力5.5 MPa、气态空速1 200 h~(-1)的条件下,乙酸甲酯的转化率、醋酐的选择性和收率分别达到38.8%,81.1%,31.5%。

Effect of Calcination Conditions on Activity of Ni-Sn-Cr/AC Catalyst in Vapor Phase Carbonylation of Methyl Acetate to Acetic Anhydride

Ni-Sn-Cr/active carbon(AC)catalyst was prepared by incipient impregnation.Influences of calcination temperature,calcination time and calcination atmosphere on vapor phase carbonylation of methyl acetate to acetic anhydride over the Ni-Sn-Cr/AC catalyst were investigated in a continuous flow fixed-bed reactor.The surface morphology,crystalline structure and textural property of catalyst were characterized by means of SEM,XRD and N_2 physical adsorption.Calcination temperature and time imposed significant effect on activity of catalyst.However,catalytic activities of the catalysts calcined in different inert atmospheres hardly showed any differences.Ni-Sn-Cr/AC catalyst calcined at 600 ℃ for 4 h under N_2 atmosphere exhibited higher activity than the other catalysts.Under the reaction conditions of n(CO):n(H_2) 8,n(CH_3COOCH_3):n(CH_3I) 7,n(CO):n(CH_3COOCH_3) 4,reaction temperature 205 ℃,reaction pressure 5.5 MPa and GHSV 1 200 h~(-1),conversion of methyl acetate,selectivity to acetic anhydride and its yield could reach 38.8%,81.1% and 31.5%,respectively.