2,4-二硝基甲苯无外加溶剂的加氢表观动力学

Macro-Kinetics of Catalytic Hydrogenation of 2,4-Diaminotoluene without Extra Solvent

在自行设计的反应装置中以骨架镍为催化剂，在无外加溶剂的环境下催化2，4-二硝基甲苯（DNT）加氢合成2，4-甲苯二胺（TDA）。考察了温度（100～140℃）、氢气压力（1．0～3．0MPa）、催化剂质量浓度（0．03％～2．0％）、TDA质量浓度（30％～70％）对反应的影响。该反应的表观动力学研究表明，反应速率跟氢气压力成正比；DNT加氢反应在高浓度区（DNT浓度大于7．14mol／m^3）为吸附脱附控制，催化剂浓度与反应速率成正比，DNT浓度对反应速率无影响；而在低浓度区（DNT浓度小于7．14mol／m^3）该反应为界面反应控制；催化剂浓度在一定范围内对反应速率影响不大，DNT浓度对反应速率影响为一级。DNT低浓度区和高浓度区的活化能分别为17．62kJ／mol和15．67kJ／mol，表明无外加溶剂条件下催化剂可大幅降低反应活化能而使反应更易进行；在实验条件范围内TDA含量对反应速率基本无影响。

The process and kinetics of liquid phase hydrogenation of 2,4-dinitrotoluene （2, 4-DNT） to 2,4-toluenediamine （TDA） without extra solvent were investigated in a self-designed device under the conditions of 100--140 ℃, and 1.0-3.0 Mpa, and Reney Ni catalyst mass fraction of 0.03%--2.0% and TDA mass fraction of 30%--70%. The experimental results indicated that the reaction showed different performances in the low DNT content region （CDNT;7. 14 mol/m^3, LDCR） from that in the high DNT content region （CDNT〉7. 14 mol/m^3 , HDCR）. In HDCR , the reaction was controlled by adsorptive process and the reaction rate was in direct proportion to the catalyst concentration while was almost no effected by DNT concentration. In LDCR, the reaction was controlled by interface reaction process, and the reaction rate was in direct proportion to DNT concentration and was no effected by the catalyst concentration in a certain range. In both regions the reaction rate was about in direct proportion to hydrogen pressure. The apparent activation energies of the reaction in both regions were also obtained, 17. 62 kJ/mol and 15. 67 kJ/mol respectively, which revealed that the reaction is more easily occurred than that in the extra solvent environment. The reaction rate was no effected by the content of TDA. The macro-kinetics was obtained through data fitting. An good agreement between the model predictions and the experimental data was observed.