Electroplating sludge-derived metal and sulfur co-doping catalyst and its application in methanol production by CO2 catalytic hydrogenation

Electroplating sludge is a hazardous waste and its recycling is a hot topic. Electroplating sludge usually contains plenty of transition metals and multi-hetero atoms, which are potential resources. For the first time, this work synthesized spinel catalyst from Zn- and Cr-containing electroplating sludges by a simple calcination method, and applied the obtained catalysts in CH3OH production by CO2 catalytic hydrogenation. The spinel was doped by various heteroatoms, including Fe, Mn, Cu, and even S. According to detailed characterizations, the metal doping increased the low-temperature conversion efficiency of CO2 but decreased the CH3OH selectivity at the same time. After a further doping of S, although CO2 conversion efficiency was slightly decreased, the selectivity of CH3OH was significantly in-creased. After all, the optimized catalyst attained a conversion efficiency of 8.6% (CO2) as well as a selectivity of 73.3% (CH3OH) at 250 degrees C and 3 MPa. As a result, above results realized high-value-added utilization of hazardous waste and producing valuable product at the same time, which was in favor of circular development.