Effects of Silica Modification (Mg, Al, Ca, Ti, and Zr) on Supported Cobalt Catalysts for H₂-Dependent CO₂ Reduction to Metabolic Intermediates

Abstract

Serpentinizing hydrothermal systems generate H 2 as a reductant and harbor catalysts conducive to geochemical CO 2 conversion into reduced carbon compounds that form the core of microbial autotrophic metabolism. This study characterizes mineral catalysts at hydrothermal vents by investigating the interactions between catalytically active cobalt sites and silica-based support materials on H 2 -dependent CO 2 reduction. Heteroatom incorporated (Mg, Al, Ca, Ti, and Zr), ordered mesoporous silicas are applied as model support systems for the cobalt-based catalysts. It is demonstrated that all catalysts surveyed convert CO 2 to methane, methanol, carbon monoxide, and low-molecular-weight hydrocarbons at 180 °C and 20 bar, but with different activity and selectivity depending on the support modification. The additional analysis of the condensed product phase reveals the formation of oxygenates such as formate and acetate, which are key intermediates in the ancient acetyl-coenzyme A pathway of carbon metabolism. The Ti-incorporated catalyst yielded the highest concentrations of formate (3.6 mM) and acetate (1.2 mM) in the liquid phase. Chemisorption experiments including H 2 temperature-programmed reduction (TPR) and CO 2 temperatureprogrammed desorption (TPD) in agreement with density functional theory (DFT) calculations of the adsorption energy of CO 2 suggest metallic cobalt as the preferential adsorption site for CO 2 compared to hardly reducible cobalt−metal oxide interface species. The ratios of the respective cobalt species vary depending on the interaction strength with the support materials. The findings reveal robust and biologically relevant catalytic activities of silica-based transition metal minerals in H 2 -rich CO 2 fixation, in line with the idea that autotrophic metabolism emerged at hydrothermal vents.

Confining Co-Based Nanocatalysts by Ultrathin Nanotubes for Efficient Transfer Hydrogenation of Biomass Derivatives

“…Furthermore, H 2 -TPR profiles of the CoAl NT 160‑O and Co 3 O 4 /am-Al 2 O 3 in Figure d exhibited two reduction peaks. For CoAl NT 160‑O , the first wide reduction peak in a temperature range of 239.3–453.8 °C was attributed to the reduction of bulk Co 3 O 4 to CoO. , In addition, the small shoulder peak centered at 520.9 °C could be assigned to the reduction of CoO, which interacted weakly with Al 2 O 3 , to metallic Co. , The higher reduction peak above 550 °C could be assigned to the reduction of a large amount of CoO with stronger interaction with Al 2 O 3 to metallic Co NPs. ,, Obviously, all of the reduction peaks of CoAl NT 160‑O presented higher temperature than that of the supported Co 3 O 4 /am-Al 2 O 3 , indicating the strong interaction between Co species and amorphous Al 2 O 3 nanotubes. On the whole, H 2 -TPR characterization realized direct evidence that the interaction between Co species and amorphous Al 2 O 3 of CoAl NT 160‑H was stronger than that of Co/am-Al 2 O 3 , which could contribute to improving the stability and dispersity of the electropositive Co NPs and facilitate the CTH process of LA.…”

“…49 In order to further demonstrate the strong interaction between Co species and Al 50,51 In addition, the small shoulder peak centered at 520.9 °C could be assigned to the reduction of CoO, which interacted weakly with Al 2 O 3 , to metallic Co. 52,53 The higher reduction peak above 550 °C could be assigned to the reduction of a large amount of CoO with stronger interaction with Al 2 O 3 to metallic Co NPs. 52,54,55 Obviously, all of the reduction peaks of CoAl NT 160-O 57 which might be due to the interaction between NH 3 and the larger Co species. The number of acidic and basic sites of the obtained catalysts are listed in Table S2.…”

Linking Catalysis in Biochemical and Geochemical CO2 Fixation at the Emergence of Life

“…A recent study by our team further addressed the effect of surrounding minerals on H 2 -dependent CO 2 reduction with supported native transition metal catalysts at 180 °C and 20 bar. [45] The hydrothermal vent minerals were simulated by the design of porous silica-based materials (SBA-15) modified with different cations (Mg, Al, Ca, Ti, and Zr). As seen in Figure 3, the silica-supported Co nanoparticles catalyzed the formation of formate, acetate, and ethanol in mM range in the liquid phase.…”

“…b) Gas phase products CH 4 , methanol, CO, and hydrocarbons detected by gas chromatography (GC). Reproduced from ref [45] . Copyright (2022), with permission from the American Chemical Society.…”

Recycling of iron from vanadium titanium magnetite tailings and its application in an asymmetric supercapacitor

“…The valuable metal recycling, mineral processing, blast furnace smelting and electrochemical strategy are mainly used for the recovery of valuable elements from the tailings. [7][8][9] The valuable elements (Fe, Ti, V, and so on) in VTMT have high comprehensive utilization value, not only in the traditional industrial manufacturing field 10 but also in the current booming energy storage conversion and electrocatalytic field, including fuel cell, 11 CO 2 electrocatalytic reduction, 12 lithium-ion battery 13 supercapacitor, 14 electrocatalytic water decomposition, 15 metal-air battery, 16,17 aqueous zinc-ion batteries, 18 and ammonium ion energy storage. 19 As emerging energy-powering sources, supercapacitors (SCs) hold a distinctive position owing to their high power density, good cycling stability as well as fast charge/discharge process, bridging the gap between batteries and traditional capacitors.…”