Studies on the Catalyst for the Production of N, N-Dimethyl (Long-chain Alkyl Amines)

Abstract

N, N-dimethyl(long-chain alkylamines)are one of the most important fatty chemicals, far example, as the industrial intermediates which are derived to many commercial products such as the quarternary ammonium salts, amine oxide and so forth. These N, N-dimethyl (long-chain alkylamines)have been synthesized from the corresponding alcohols economically over many kinds of heterogeneous catalysts. But these catalysts are not satisfactory enough both in activity and selectivity.The mechanism of the amination of alcohols has been investigated for a long time, and required the dehydrogenation and hydrogenolysis abilities of the catalysts used in this reaction.We, in this work, planned to use copper as the catalyst for dehydrogenation and nickel as that far hydrogenolysis, and found Cu-Ni catalyst supported on SiO2/Al2O3 gave very high activity and selectivity in the amination of dodecyl alcohol. When the weight ratio of Cu/Ni was 4/1, it gave the maximum of activity and selectivity.The valence states of surface metals of the catalyst were analyzed by using ESCA. Copper was reduced to Cu0 or Cu+ in the hydrogen atmosphere at 200°C. Nickel was not reduced in the same atmosphere.When there was much amount of Ni2+ on the catalyst surface, the selectivity for the amination reaction was low, Ni2+ was seemed to accelerate the disproportionation of dimethylamine (DMA).