铋钼催化剂上丁烯氧化脱氢制丁二烯的本征动力学

Kinetic Modeling for Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene over Bi_(2)MoO_(6) Nanosheet and BiMoV_(0.15) Catalysts

采用水热法制备了Bi_(2)MoO_(6)纳米片催化剂、共沉淀法制备了BiMoV0.15催化剂,在固定床反应器中研究了两种催化剂上丁烯氧化脱氢制丁二烯的本征动力学。采用幂函数模型对不同条件下测得的动力学数据进行了拟合,建立了本征动力学模型,并得到了活化能和反应级数等相关参数。结果表明:由于不同的反应温度区间拥有不同的速率控制步骤,Bi_(2)MoO_(6)纳米片催化剂和BiMoV_(0.15)催化剂均在653 K左右存在活化能转折现象;且不论在何温度区间,Bi_(2)MoO_(6)纳米片催化剂的活化能均低于BiMoV_(0.15)催化剂的活化能,表明Bi_(2)MoO_(6)纳米片催化剂能有效降低反应能垒,使得反应更易进行;经检验,所得的本征动力学模型可靠性良好。进一步将动力学实验结果与Mars van Krevelen(MvK)机理相结合,阐明了动力学唯象规律和反应机理的内在联系。

Bi_(2)MoO_(6)nano sheet catalyst was prepared by hydrothermal method and BiMoV_(0.15) catalyst was prepared by coprecipitation method.And the intrinsic kinetics was studied for oxidative dehydrogenation of 1-butene to 1,3-butadiene over Bi_(2)MoO_(6)nanosheet and BiMoV_(0.15) catalysts in a fixed-bed reactor.The power-law model was used to fit the experimental data,and the model parameters were fitted by non-linear regression.Results showed the existence of two reaction temperature-dependent kinetic regimes for we found that there was a break in the activation energy around 653 K.And regardless of the temperature range,the activation energy of the Bi_(2)MoO_(6)nanosheet catalyst was lower than that of the BiMoV_(0.15) catalyst,indicating that the Bi_(2)MoO_(6)nanosheet catalyst could effectively reduce the reaction energy barrier and make the reactants easier to react with each other..The statistical test results showed that the models were able to describe the oxidative dehydrogenation process adequately for the respective temperature regimes.Meanwhile,a series of mechanism-based derivations were made,revealing the relationship between the reaction order and oxygen coverage on the catalyst surface.