Catalytic Method for N-Methyl-4-pyridone Synthesis in the Presence of ZnAl2O4

A composite oxide ZnAl2O4 was prepared by microwave-assisted hydrothermal treatment, a precursor mixture of hydroxides obtained by precipitation of aluminium and zinc nitrates. Characterization by TEM, XRD and textural studies shows that ZnAl2O4 is nanosized and is a micro/mesoporous material with large a surface area (140 m2/g). The gas phase catalytic methylation of 4-hydroxypyridine in the presence of the ZnAl2O4 catalyst was performed in a continuous process at atmospheric pressure in the temperature range of 240–360 °C. A mixture of O- and N-alkylated products, namely 4-methoxypyridine and N-methyl-4-pyridone were obtained. The alkylation of 4-hydroxypyridine with methanol at 345 °C offered 87.6% selectivity towards N-methyl-4-pyridone with about 89% 4-hydroxypyridine conversion.