Catalytic Synthesis Of N, N-dimethylcyclohexanamine Over Ce-HX Zeolite

N,N-dimethylcyclohexanamine is an important chemical. The synthesis of N, N-dimethylcyclohexanamine from the N-methylation of cyclohexanamine and methanol over Ce-HX zeolites as catalyst was studied by Box-Behnken experiment design.A series of the modified Ce-HX with various amount of Ce were prepared by ion-exchange method and characterized by means of thermal analysis, XRD and NH3-TPD, respectively. The reaction between cyclohexanamine and methanol to N,N-dimethylcyclohexanamine was carried out in a fixed-bed reactor in the presence of Ce-HX. The effect of Ce amount on the zeolite framework, acidity and cyclo- hexanamine alkylation activity was studied.The results showed that the modified Ce-HX with up to 2.0wt% Ce maintained the zeolite framework; Ce-HX containing 1.5% Ce exhibited the strongest acid strength and the most sites, and the best activity.The effect of the factors including the reaction temperature, LHSV and the molar ratio of the reactants on the alkylation of cyclohexanamine was investigated by Box-Behnken design and the optimum reaction condition was ascertained. At the optimum condition of reaction temperature 340℃, LHSV 1.4h-1 and the molar ratio of cyclohexanamine to methanol 1:6, N,N-dimethylcyclohexanamine yield attained 65.17%, close to the predicted value 64.64%.