Vanadia-titania metal molybdate dual catalyst bed system and process using the same for methanol oxidation to formaldehyde

摘要

A process and a catalyst reaction zone comprising one or more fixed bed reactors for oxidizing methanol in a reactant gas feed stream to formaldehyde. According to one embodiment, the process comprises introducing the reactant gas feed stream into an upstream region containing a vanadia-titania first catalyst (substantially free of a volatile MoO₃ species) under oxidizing conditions to form a partially oxidized reactant gas feed stream which is then introduced under oxidizing conditions into a downstream region containing a metal molybdate second catalyst to further oxidize any residual methanol contained therein. According to another embodiment, a fixed bed reactor comprising an upstream region and a downstream region containing the aforementioned vanadia-titania and metal molybdate catalysts, respectively, is utilized to implement the inventive process to yield a product gas stream containing formaldehyde preferably at a conversion of 85% or more and a selectivity of 90% or more.