Home – Home – Jornals – Chemistry for Sustainable Development 2018 number 4

Cu-Mo/ZSM-5 catalysts with Мо content 4.0 mass % and Сu 0.05 to 1.0 mass % were prepared by dry mechanical mixing of ZSM-5 zeolite with nanosized powders (NSP) of molybdenum and copper. To carry out comparative tests, Cu-Mo/ZSM-5 systems were prepared from 4.0 % Мо/ZSM-5 catalyst by impregnation with Cu(NO₃)₂ solution and mechanical mixing with copper oxide (CuO). The acid characteristics of thus prepared samples were investigated by means of temperature-programmed desorption of ammonia. The concentration and strength of the acid sites of the catalysts were measured. It was established that the addition of 0.1 % copper NSP to the 4.0 % Mo/ZSM-5 catalyst promotes a decrease in the concentration of strong acid sites to 140 mmol/g, while further increase in the fraction of copper NSP causes an increase in their concentration (to 153 mmol/g). The activity of the catalysts in methane conversion decreases in comparison with the sample containing 0.1 % Cu NSP. Methane conversion degree after reaction for 20 min with 4.0 % Мо/ZSM-5 and 0.1 % Сu-4.0 % Мо/ZSM-5 catalysts was 16.1 and 18.9 %, respectively. The effect of the temperature of methane conversion on its conversion degree in the presence of the 0.1 % Сu-4.0 % Мо/ZSM-5 catalyst was studied. It was demonstrated that temperature rise from 650 to 750 °С is accompanied by an increase in methane conversion. For instance, within the first 20 minutes of reaction at a temperature of 750 °C and 650 °C is 18.9% and 7.9% respectively. It was shown that the optimal feed space velocity of methane during its conversion over the 1.0% Cu-Mo/ZSM-5 catalyst is 1000 h^-1.