NaNbO3 Nanocubes: Perovskite Catalysts for Methanol Polymerization

Polyoxymethylene dimethyl ethers (PODEs) are a class of oxygenated fuels with promising applications in energy production and emission reduction. They are often utilized as a diesel fuel additive or substitute, which reduces the formation of harmful emissions such as polycyclic aromatic hydrocarbons (PAH), soot, nitrogen oxides (NOx), and carbon monoxide (CO). The oxidative polymerization of methanol presents a promising route for the formation of PODEs. NaNbO3, a type of perovskite oxide, was synthesized with a well-defined nanocubic structure through solvothermal synthesis using a Nb2O5 precursor. The catalytic potential of both the NaNbO3 nanocubes and the well-studied Nb2O5 precursor was assessed for the oxidative polymerization of methanol into PODEs. NaNbO­3 demonstrated catalytic performance comparable to Nb2O5 as both catalysts produced formaldehyde and dimethyl ether, which are precursors to PODE. Powder X-ray diffraction, scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller (BET) surface area confirmed the crystalline nature and desired cubic morphology of the NaNbO3 nanocubes. Additionally, Nb2O5 precursors with an orthorhombic, as opposed to a monoclinic or hexagonal crystal system were determined to produce NaNbO3 nanocubes successfully. Effective shape control of the NaNbO3 nanocubes makes this catalyst an intriguing material to understand and apply in heterogenous catalysis.