Supported silver and copper catalysts in the oxidative dehydrogenation of methanol to formaldehyde: a comparative study under industrially relevant conditions

Abstract

In this study, we compare and assess the performance of silver and copper species in methanol oxidative dehydrogenation (ODH) to formaldehyde. Methanol ODH over polycrystalline silver catalysts is a major industrial synthesis route for formaldehyde today. Ag/SiO₂, Ag/TiO₂, Ag/ZrO₂, Cu/SiO₂, Cu/TiO₂ and Cu/ZrO₂ catalysts were prepared by strong electrostatic adsorption (SEA) and employed in the methanol ODH. All catalysts showed metal species homogenously distributed over the metal support and metal weight fractions up to 3.86% Ag and 7.96% Cu after sequential SEA steps. The silica-supported catalysts revealed the best performance in methanol ODH with the highest formaldehyde selectivities and stable conversions after seven hours time-on-stream. For these catalysts, the performance of silver and copper species in methanol ODH was further studied and compared close to industrial operating conditions. At low methanol feed concentrations, the Ag/SiO₂ catalyst revealed a superior performance while at higher methanol feed fractions, the Cu/SiO₂ catalyst showed improved performance and higher formaldehyde yields.