Mg,Al-mixed oxide system: Synthesis under hydrothermal conditions, physico-chemical characterisation and application as an efficient catalyst for imidazole methylation

Abstract

Mg,Al-mixed oxide catalyst with molar ratio 1:2 was prepared hydrothermally from magnesium acetate and basic aluminium nitrate. The obtained sample was characterised by XRD, HRTEM and nitrogen adsorption. The basic sites density was determined by temperature-programmed desorption of CO 2 combined with mass spectrometry (TPD-MS). Moreover, test reactions for acid–base characterisation (i.e. 2-propanol and cyclohexanol transformations) were used. The prepared catalyst proved to be selective and active for monoalkylation of imidazole leading to 1-methylimidazole. The gas phase catalytic alkylation of imidazole with methanol on Mg,Al-mixed oxide catalyst was carried out in a continuous process at atmospheric pressure in the temperature range of 225–350 °C. 1-Methylimidazole was efficiently obtained with selectivity reaching up to 97.4% at an imidazole conversion of 93.0% (at temperature 340 °C).