Activity of amorphous V-AlPO4 and Co-AlPO4 in the selective synthesis of N-monoalkylated aniline via alkylation of aniline with methanol or dimethyl carbonate

Abstract

The vapour phase catalytic alkylation of aniline with methanol or dimethyl carbonate (DMC) on amorphous AlPO4 and M-AlPO4 (M = Cu, Ni, Fe, Co and V) has been studied. V-AlPO4 and Co-AlPO4 showed high selectivity towards N-monomethylation of aniline. Further studies on the alkylation reactions have been carried out using AlPO4 and M-AlPO4 (M = V and Co) as catalysts at different temperatures and molar ratio of aniline to methanol or DMC. V-AlPO4 is found to show 100% selectivity for N-monomethylation of aniline, irrespective of the temperature or the molar ratio of the reactants. On the other hand, Co-AlPO4 shows 100% selectivity for N-monomethylated product only when the aniline-to-methanol (or DMC) molar ratio is 2∶1. Aniline conversion towards N-methylaniline(NMA) was found to be 39%. DMC has been found to be a better methylating agent than methanol with respect to the percentage conversion of aniline to N-methylaniline.