Design of highly active cobalt catalysts for CO₂ hydrogenation via the tailoring of surface orientation of nanostructures

Abstract

Catalyst design by tuning surface structures to suppress unreactive species in order to achieve higher reactivity for CO2 conversion.

Stability of Cobalt Particles In and Outside HZSM‐5 under CO Hydrogenation Conditions Studied by ex situ and in situ Electron Microscopy

“…Typical reaction conditions cover a pressure range between 1 and more than 20 bar, as well as temperatures between 200 and 350 °C, depending on the desired hydrocarbon chain length. Low pressures and high temperatures favor methane formation, while low temperatures and high pressures are typical for FT synthesis for the formation of higher hydrocarbons [4,10–13] . The catalysts used under technical conditions consist of cobalt nanoparticles supported on porous substrates, such as silica or alumina [14–17] .…”

Influence of Coordination Environment of Anchored Single‐Site Cobalt Catalyst on CO2 Hydrogenation

“…Furthermore, the apparent activation energy for CO 2 hydrogenation over the as synthesized Co/SiO 2 SSC was 25.7 kJ/mol, consistent with the activation energy observed for the reverse water gas shift reaction (RWGS), shown in Figure S3. Furthermore, since the formation of CH 4 generally occurs via the dissociative CO 2 mechanism where CO is an intermediate, the performance of the Co/SiO 2 SSC was explored at high conversion via decreasing the space velocity, shown in Figure S3, where even at high CO 2 conversion (>50 %) the selectivity towards CO remained constant at ∼95 %. The stable selectivity towards CO is unique to the Co/SiO 2 SSC catalyst, whereas the Co/SiO 2 IMP catalyst run under identical conditions resulted in both higher catalytic activity and a selectivity towards methane that increases with temperature, indicating the reduction of the surface into metallic cobalt under higher temperatures, shown in Figure S5.…”

The Influence of Preparation Method on the Physicochemical Characteristics and Catalytic Activity of Co/TiO2 Catalysts

“…The surface of TiO 2 was negatively charged in that pH and started to adsorb Co 2+ (aq) ions. The Co 2+ ions concentration decreased due to the adsorption process, and Equations (1) and (2) shifted to the left. The positive charge in the interfacial region and the surface of TiO 2 increased due to the accumulation of Co 2+ ions.…”

“…Cobalt-supported catalysts are quite promising for many reactions of environmental and industrial interest such as volatile organic compounds oxidation [1], CO 2 hydrogenation [2], the Fischer-Tropsch process [3,4], and electrocatalysis [5].…”

“…Finally, it was found that impregnation pH was the most important parameter for the deposition of Co(II) species. Higher pH resulted in a higher amount of Co(II) deposited onto the titania surface; however, pH higher than 8 should be avoided, as Co(II) precipitates either as Co(OH) 2 or Co(OH)NO 3 in bulk solution. That study focused on the impregnation step and deposition mechanism of Co(II) onto the titania surface.…”