Effective Cu/ZnO/Al2O3 Catalyst for Methanol Production: Synthesis, Activation, Catalytic Performance, and Regeneration

Abstract

A precursor CuO/ZnO/Al2O3 catalyst for methanol synthesis has been prepared at room temperature by introducing a ternary salt solution into the excess of sodium carbonate solution following the reverse co-precipitation method. The catalyst was tested for the synthesis of methanol from synthesis gas. The composition (vol. %) has been presented: CO, 22; CO2, 5.8; N2, 5.5; H2, balance. The methanol productivity was recorded to be 2.7 kg kgcat–1 h–1 at a temperature of 260 °С, a pressure of 3 MPa, and a space velocity of 61,700 l (kgcat)–1 h–1. The possibility of regenerating the activity of a catalyst subjected to conditions of artificial aging (overheating in a syngas environment) has been tested: approximately 92% of the initial activity could be restored. Physicochemical studies were conducted using the thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), the scanning electron microscopy (SEM), and the X-ray diffraction (XRD) techniques using the Cu, Zn, and Al oxides obtained following the co-precipitation method. X-ray studies revealed that an amorphous phase was obtained from the Al oxide that was synthesized following both the direct and reverse co-precipitation methods. The calcination temperature was 300 °C. Individual oxides of Cu and Zn obtained following the reverse co-precipitation method form crystalline phases when calcined at 300 °C. When all three ingredients are present, calcination of the sample at 300 °C helps obtain an X-ray amorphous structure of the catalyst characterized by a high specific surface area. High-temperature carbonates are formed from samples prepared using a ternary mixture of nitrate salts when these are calcined at 300 °C.