Thermocatalytic Hydrogenation of CO2 to Methanol Using Cu-ZnO Bimetallic Catalysts Supported on Metal–Organic Frameworks

Abstract

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.

Enhanced Photocatalytic Degradation of Tetracycline-Class Pollutants in Water Using a Dendritic Mesoporous Silica Nanocomposite Modified with UiO-66

“…The morphology of UiO-66@NH 2 -DFNS is typical of DFNS-corresponding spherical nanoparticles with a homogeneous particle size distribution (some are illustrated as red circles in Figure b) Figure d,e obviously indicates the mounted UiO-66 crystalline shells on spherical DFNS nanoparticles . Hollow-nature of the spherical DFNS nanoparticles is revealed by the contrast between the dark center and the pale edge in the nanospheres (some shown as blue circles in Figure e) …”

“…65 Figure 6d,e obviously indicates the mounted UiO-66 crystalline shells on spherical DFNS nanoparticles. 66 Hollow-nature of the spherical DFNS nanoparticles is revealed by the contrast between the dark center and the pale edge in the nanospheres (some shown as blue circles in Figure 6e). 65 Figure 6d, demonstrates that the UiO-66 shells are porous structures with estimated pore sizes of below 10 nm.…”

“…UiO-66 nanocrystal aggregation is also portrayed as a green rectangle. 66 The UiO-66 nanocrystals grew inside and outside the pores of DFNS, forming a layer on the DFNS surface in which the growth path was demonstrated as a yellow dashed arrow. 67 On the surface of DFNS, the UiO-66 nanocrystals did not grow further due to the high concentration of Zr-ligands used, but it sounds like the UiO-66 nanocrystals gradually fill the gaps between the crystals.…”

Biogas improvement as renewable energy through conversion into methanol: A perspective of new catalysts based on nanomaterials and metal organic frameworks

“…4) Contrarily to the conversion of methane to methanol, there are scarce references on the mechanisms of these reactions, especially in the case of gas-phase conditions. For instance, Duma et al (2022) reports the results using copper-zinc bimetallic catalysts supported on a Zirconium-based MOF, where using advanced techniques they revealed the presence of copper active sites after impregnation and thermal activation. In general, research is clearly focused on having highly active sites to destabilize the molecules of carbon dioxide and hydrogen, where Ni, Co, Ru, Rh, and Pd are the most used materials (Cheng et al, 2021).…”

Clustering-Evolved Frontier Orbital for Low-Temperature CO2 Dissociation

“…Massive CO 2 emission from fossil fuel combustion has dramatically increased the CO 2 concentration in the atmosphere, which has aroused global concerns about climate change . Thermocatalytic CO 2 reduction has become an important methodology for CO 2 emission abatement. , Consequently, dissociative activation of CO 2 has been widely explored. − From the viewpoint of molecular frontier orbital characteristics of CO 2 , there are two key activation measures, namely, electron injection into its anti-σ orbital (LUMO) and electron donation from its lone pair (HOMO) to the active site of the employed catalyst . Unfortunately, the high molecular orbital symmetry of single atoms often hinders the dissociation of CO 2 .…”