Study On Synthesis Of Cycloaliphatic Amides From Aromatic Amides Hydrogenation Over Supported Ru Catalyst

Synthesis of cycloaliphatic amides from aromatic amides hydrogenation on supported Ru catalyst was studied, including quantitative analysis of the TDA hydrogenation products, thermodynamic analysis of the hydrogenation reaction, the choice of catalysts and optimization of operating conditions for aromatic amine hydrogenation.Based on qualitative analysis of aniline, OMA, MPD hydrogenation products with GC, TDA hydrogenation products was determined by GC-MS and spacious structure analysis.Thermodynamic analysis of the TDA hydrogenation system was done by the group contribu -tion approach. This was an exothermic reaction with thermodynamic superiority and side reactions equilibrium constants were all greater than that of the main reaction. The by-product MCHA was mainly formed by deamination of the main product MCHD.Ru/γ-Al2O3(4% load), aromatic amine hydrogenation catalyst, was prepared with aniline hydrogenation as the probe reaction. Aniline hydrogenation was studied with single factors test and the optimal operating conditions were as follows: w(aniline) /w(catalyst) was 100:1(mass ratio), 7MPa, 160℃, 4h. Under the conditions, aniline conversion was 98.2% and aniline selectivity (cyclohexylamine to aniline) was 91.4%.OMA hydrogenation was studied with orthogonal experiment and the optimal conditions were: w(OMA) /w(catalyst) was 100:1, 8MPa, 170℃, 4h, OMA conversion was 99.4%. The selectivity (OMCHA to OMA) was 97.9%.MPD hydrogenation was studied with single factors test. The optimal conditions were: w(MPD) /w(catalyst) was 25:1, THF (solvent) 20ml, high pressure, low temperature and short time. The selectivity (DACH to MPD) could reach 49.5%.TDA hydrogenation was studied with the above optimal conditions. Calcination temperature of the catalyst has the greatest influence on selectivityof the main product (MCHD). The optimal selectivity was 71.3% with the calcination temperature 400℃.