Catalytic Synthesis Of N, N-dimethylcyclohexanamine Over HX Zeolite

N,N-dimethylcyclohexanamine is an important chemical. The synthesis condition of N,N-dimethylcyclohexanamine via the alkylation of cyclohexanamine with methanol has been studied by orthogonal experiment, using HX zeolite as catalyst. The effect of calcination temperature and ion-exchange degree on the acidity and cyclohexanamine alkylation activity over HX zeolite were determined. The catalyst samples were characterized by TG-DTG, XRD and TPD respectively.An ion selective electrode method was developed for determination of sodium in ion-exchange zeolite. The experiment was designed by a mathematical way and was analyzed by error. The linearity used for determination was 5×10^-5～1×10^-2mol/L, the relationship between Na⁺. concentration and electrode potential was expressed as y=81.9+54.2x(R=0.9992) and the maximum error of the method was 1.40%. The result of sodium ion selective electrode was consistent with absorption spectrophotometer's.There was no obvious effect on the crystalline structure of catalysts if the calcination temperature no more than 923K. Raising the temperature made against the acidity of catalyst, so the calcination temperature was 723K。The strength of acidity of HX zeolite, the acidity and catalytic activity appeared relatively slowly as about half of Na⁺ cation was removed. After reaching a decationization level of 65%, however, the acidity increased much more rapidly.The effect of different factors, such as the ion-exchange degree, the reaction temperature, the molar ratio and the space time, on the alkylation of cyclohexanamine with methanol has been investigated. The reaction temperature and the molar ratio were significant factors to the yield of N,N-dimethylcyclohexanamine.