Combustion dispersion of CuO-ZnO-Al2O3 nanocatalyst over HZSM-5 used in DME production as a green fuel: Effect of citric acid to nitrate ratio on catalyst properties and performance

A series of CuO-ZnO-Al2O3/HZSM-5 nanocatalysts was synthesized with combustion synthesis method for direct conversion of syngas to dimethyl ether process. Various citric acid/nitrate molar ratios of 0.5, 1, 2 and 4 have been used to investigate the effect of the fuel content on physicochemical properties of synthesized catalysts. The phase evolution, morphology, functional groups, surface area and reducibility were investigated via XRD, FESEM, FTIR, BET and H2-TPR, respectively. Increasing the fuel/nitrate ratio has enhanced the surface area and reducibility of catalysts. Furthermore, the results indicated interesting cave shaped porous morphology with a wide nanometric pore size distribution. The catalytic performance test resulted the highest catalytic activity for the sample of the fuel/nitrates molar ratio of 4 among all the samples through all the operating conditions. Furthermore, the best catalytic activity for the reaction was resulted at 300 °C and 40 bar. The time on stream test of the nanocatalyst introduced negligible activity lost over the 1060 min.236