Influence of preparation method on the activity of molecular sieve KA catalysts modified with zinc and phosphorus oxides in the non-oxidative thermocatalytic conversion of ethanol to aromatic hydrocarbons

Abstract

The activity of catalysts based on KA modified with zinc and phosphorus oxides and the effect of the method of catalyst preparation on its activity in the non-oxidative thermocatalytic conversion of ethanol to aromatic hydrocarbons was studied in this work. The ZnO-P2O5/KA catalyst was prepared by capillary impregnation and solution-combustion methods and characterized by SEM, TEM, TPD-NH3, and TPR-H2. The results showed that the method of preparation affects both the reducibility, dispersity, as well as the acidity of the catalyst. The preparation of the ZnO-P2O5/КА catalyst by the "solution combustion" method, in comparison with capillary impregnation, leads to an increase in the dispersion of particles. In the composition of the ZnO-P2O5/КА (SC) catalyst, nanoparticles with sizes from 2 nm are observed. The results of TPD-ammonia showed that catalysts based on KA modified with zinc oxides have weak and strong Lewis acid sites, and Bronsted acid sites. Modification of ZnO-P2O5/КА with phosphorus oxide leads to an increase in the number of weak and strong acid sites. The highest ethanol conversion (85%) and the concentration of aromatic hydrocarbons (23 vol.%) was obtained for the ZnO-P2O5/КА (SC) catalyst, which has the highest acidity of 1206 µmol/g.