Alkali Earth Metal Molybdates - Selectivity and Stability as Catalysts for the Selective Oxidation of Methanol to Formaldehyde

Formaldehyde is the most important aldehyde commercially available as it is an irreplaceable C₁ building block for higher-valued products [1]. The annual global production of formaldehyde is expected to increase with 4.8-5.8% per year and reach 36.6 million tons by 2026 [2, 3]. Formaldehyde is mainly produced through either the silver process or the Formox process [1].
In the Formox process, methanol is selectively oxidized over an iron molybdate catalyst (MoO₃/Fe₂(MoO₄)₃), which achieve high selectivities (92-95%) at high conversions (>99%) [1]. The catalyst is however not stable under the reaction conditions due to formation of volatile molybdenum compounds [4]. The alkali earth metal molybdates have been reported to have high thermal stability [5], with expected lower volatility of Mo in MeOH atmosphere, and their properties as catalysts for selective oxidation of methanol are scarcely investigated in the literature.