CO2 Hydrogenation to Methanol with Ga- and Zn-Doped Mesoporous Cu/SiO2 Catalysts Prepared by the Aerosol-Assisted Sol-Gel Process

Abstract

The preparation of copper-based heterogeneous catalysts dedicated to the hydrogenation of CO2 to methanol typically relies on multi-step procedures carried out in batch. These steps are precisely tailored to introduce the active phase (Cu) and the promoters (e.g. zinc, gallium) onto a preformed support, to maximize catalyst performance. However, each process step – often carried out in batch – can be associated with the formation of waste and with the consumption of energy, thereby negatively impacting the environmental performance of the overall catalyst preparation procedure. Here, we propose a direct and continuous production process for the synthesis of efficient catalysts for the CO2 to methanol reaction. Gallium- and zinc-promoted mesoporous Cu-SiO2 catalysts are prepared in one step by the aerosol-assisted sol-gel process. The catalysts consist of spherical microparticles and feature high specific surface area and pore volume, with interconnected pores of about 6 nm. A strong promoting effect of Ga and Zn is highlighted, boosting the selectivity for methanol at the expense of CO. Upon calcination, we show that Cu species – initially trapped in the silica matrix – undergo a migration towards the catalyst surface and a progressive sintering. After optimization, the catalysts obtained via such direct route compete with the best catalysts reported in the literature and obtained via multi-step approaches. <br>

Highly dispersed mesoporous Au/SiO2 catalysts obtained by a direct aerosol-assisted sol-gel process

“…This contrasts with the case of Cu-SiO2 catalysts, where a migration of Cu towards the external surface was observed, together with a progressive sintering, when calcination temperature was increased. 31 Here, the relatively low Au surface concentration suggests that the gold NP remain partly trapped in the mesoporous silica matrix. The gold particle size of each sample was also evaluated by X-ray diffractometry.…”

“…Recently, a series of Cu-SiO2 catalysts was prepared by AASG, showing high activity in the CO2 to methanol reaction. 31 Such one-pot aerosol strategy has never been reported for Au-SiO2 materials.…”

Ethanol dehydrogenation to acetaldehyde with mesoporous Cu-SiO2 catalysts prepared by aerosol-assisted sol–gel

“…This allows the one-step and continuous production of nanomaterials with desired properties. Aerosol processes have been used to develop catalysts for a wide range of reactions, such as Mo-based catalysts for olefin metathesis 33 , TiO2 catalyst supports for CO2 methanation 34 , Cu-based materials for CO2 hydrogenation to methanol 35 , Au based catalysts for CO oxidation 36 or RuO2 based catalysts for electrocatalysis 37 . While this technique has never been used to synthesize Cu-based catalysts for ethanol non-oxidative dehydrogenation, we surmised that the control offered in terms of Cu dispersion and texture could offer decisive advantages regarding intrinsic activity and stability.…”

Mechanochemical Effect in Mixing Sponge Copper with Amorphous ZrO2Creates Effective Active Sites for Methanol Synthesis by CO2Hydrogenation

“…To solve such problems, several superior catalysts for CO 2 hydrogenation, such as In 2 O 3 , − Cu–ZrO 2 , − Cu–Ga 2 O 3 , , Cu–TiO 2 , , and modified Cu–Zn catalysts, − have been reported. Although these catalysts show high activity for methanol synthesis by CO 2 hydrogenation, further improvements are desired.…”