The thermocatalytic hydrogenation of carbon dioxide (CO₂) to methanol is considered as a potential route for green hydrogen storage as well as a mean for utilizing captured CO₂, owing to the many established applications of methanol. Copper–zinc bimetallic catalysts supported on a zirconium-based UiO-66 metal–organic framework (MOF) were prepared via slurry phase impregnation and benchmarked against the promoted, co-precipitated, conventional ternary CuO/ZnO/Al₂O₃ (CZA) catalyst for the thermocatalytic hydrogenation of CO₂ to methanol. A decrease in crystallinity and specific surface area of the UiO-66 support was observed using X-ray diffraction and N₂-sorption isotherms, whereas hydrogen-temperature-programmed reduction and X-ray photoelectron spectroscopy revealed the presence of copper active sites after impregnation and thermal activation. Other characterisation techniques such as scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis were employed to assess the physicochemical properties of the resulting catalysts. The UiO-66 (Zr) MOF-supported catalyst exhibited a good CO₂ conversion of 27 and 16% selectivity towards methanol, whereas the magnesium-promoted CZA catalyst had a CO₂ conversion of 31% and methanol selectivity of 24%. The prepared catalysts performed similarly to a CZA commercial catalyst which exhibited a CO₂ conversion and methanol selectivity of 30 and 15%. The study demonstrates the prospective use of Cu-Zn bimetallic catalysts supported on MOFs for direct CO₂ hydrogenation to produce green methanol.

Green methanol is a viable alternative for the storage of hydrogen and may be produced from captured anthropogenic sources of carbon dioxide. The latter was hydrogenated over Cu-ZnO catalysts supported on an aluminum fumarate metal-organic framework (AlFum MOF). The catalysts, prepared via slurry phase impregnation, were assessed for thermocatalytic hydrogenation of CO₂ to methanol. PXRD, FTIR, and S_BET exhibited a decrease in crystallinity of the AlFum MOF support after impregnation with Cu-Zn active sites. SEM, SEM-EDS, and TEM revealed that the morphology of the support is preserved after metal loading, where H₂-TPR confirmed the presence of active sites for hydrogen uptake. The catalysts exhibited good activity, with a doubling in Cu and Zn loading over the AlFum MOF, resulting in a 4-fold increase in CO₂ conversions from 10.8% to 45.6% and an increase in methanol productivity from 34.4 to 56.5 g_MeOH/Kg_cat/h. The catalysts exhibited comparatively high CO selectivity and high yields of H₂O, thereby favoring the reverse water-gas shift reaction. The selectivity of the catalysts towards methanol was found to be 12.9% and 6.9%. The performance of the catalyst supported on AlFum MOF further highlights the potential use of MOFs as supports in the heterogeneous thermocatalytic conversion of CO₂ to value-added products.

Dry reforming of methane (DRM) is a reaction of methane and carbon dioxide to produce synthesis gas (syngas), a hydrogen and carbon monoxide (H₂/CO) mixture, which can have applications in the petrochemicals sector. While DRM is topical at face value, it does produce a syngas with a low H₂/CO ratio not typically used by the industry. This article highlights a desktop literature survey of practical application of a progressive approach to technology investment decisions. Key technical and business risks associated with funding the development of a high-performance DRM catalyst was identified. The study indicated the cost implications of integrating DRM technology with a Fischer-Tropsch (FT) plant where a deficit of H₂ in the syngas, >1, requires external supply to increase it to an applicable ratio of 2. The article also compares DRM and its hydrogen-lean syngas with existing syngas production technologies such as steam methane reforming (SMR) and partial oxidation (PO). It also includes an overview of the reactions that influence DRM’s catalyst performance and an integrated impact assessment of DRM when applied to a specific use application.