F-T合成校正综合动力学模型

考虑了烯烃、醇与酸的再吸附及其非本征效应(烯烃、醇与酸在催化剂孔道中的扩散作用、物理吸附及溶解度效应)对产物分布的影响,推导了基于详细反应机理的亚甲基插入的烷基机理F-T合成校正综合动力学模型.利用文献数据对动力学模型进行了回归,获得了与文献报道结果相一致的动力学参数.由校正动力学模型计算的烷烃、烯烃、醇与酸产物分布及烯烃比、醇烃比及酸烃比与实验数据较好地吻合.动力学计算结果表明,在铁锰催化剂上,烷烃、烯烃、醇与酸生成的反应是平行竞争反应,烯烃、醇与酸在催化剂表面的再吸附及二次反应导致产物分布偏离了ASF分布.动力学研究还表明,相同碳数的醇与酸产物在催化剂表面上再吸附及二次反应的机会比相同碳数的烯烃大.通过比较相同碳数的烯烃、醇与酸的分子体积及沸点,指出了在铁锰催化剂上,低碳数的烯烃、醇与酸的再吸附及二次反应对产物分布影响的非本征效应中,烯烃、醇与酸的扩散阻力不是主导效应.

A Corrected Comprehensive Kinetic Model of Fischer-Tropsch Synthesis

A corrected comprehensive Fischer-Tropsch synthesis kinetic model was developed on the basis of the CH2 insertion alkyl mechanism,in which readsorption and secondary reactions of olefins,alcohols,and acids and their non-intrinsic effects(diffusion,physisorption,and solubility) were involved.The values of kinetic parameters estimated by the regression between the corrected kinetic model and the data in the literature are within the ranges reported in the literature.The predicted paraffin,olefin,alcohol,and acid distributions and the corresponding olefin/hydrocarbon,alcohol/hydrocarbon,and acid/hydrocarbon ratios fit well with the experimental data.It further suggests that paraffin,olefin,alcohol,and acid formation reactions over the Fe-Mn catalyst are parallel competitive reactions.The higher constant of alcohol and acid readsorption and secondary reactions than that of olefin indicates that alcohols and acids have more propensity to readsorb over the catalyst surface and have more chances to take part in chain growth reactions and can be hydrogenated to corresponding paraffins.Diffusion effects of olefins and oxygenates with low carbon numbers on product distributions are not the dominant reason for the readsorption and secondary reactions of olefins,alcohols,and acids according to the comparison of their liquid molecular volumes and boiling points with low carbon numbers.