Effect of support of Co-Na-Mo catalysts on the direct conversion of CO2 to hydrocarbons

Abstract

This study of the effect of support of Co-Na-Mo based catalysts on the direct hydrogenation of CO2 into hydrocarbons (HC) provides guidelines for the design of catalysts for CO2 conversion.We demonstrate that the surface area of the support and the metal-support interaction have a key role determining the cobalt crystallite size and consequently the activity of the system. Cobalt particles with sizes < 2 nm supported on MgO present low reverse water gas shift conversion with negligible Fischer-Tropsch activity. Increasing the cobalt particle size to ~ 15 nm supported on SiO2 and ZSM-5 supports not only substantially increases the CO2 conversion but it also provides high HC selectivities. Further increase of the cobalt particle size to 25-30 nm has a detrimental effect on the global CO2 conversion with HC:CO ratios below 1, however, lower methane selectivity and enhanced formation of unsaturated HC products are achieved. Additionally, the metal-support interaction potentially also has a strong effect on the growth chain probability of the formed hydrocarbons, increasing as the metal-support interaction increases. These evidences demonstrate that CO2 conversion and hydrocarbon distribution can be tuned towards desired products by controlled catalyst design.2

Greenhouse gas CO2 hydrogenation to fuels: A thermodynamic analysis

“…Here, it is important to note that there is no significant effect of pressure on the conversion of CO 2 below 270°C. This fact indicates that CO 2 ‐FT reaction will yield desirable results with bit lower chain HCs at low pressure and low temperature, which is supported by various experimental studies conducted at atmospheric pressure . However, increase in temperature up to 477°C is favorable for long chain HCs synthesis at higher pressure .…”

“…Owen et al . have reported the formation of HCs from CO 2 on Cobalt catalsyts at atmospheric pressure with a significant conversion. In the view of above studies, CO 2 hydrogenation provides new opportunities for the development of catalytic processes and sustainable energy.…”

“…Wei et al [12] have reported 22% CO 2 conversion to gasoline range HC with 4% CH 4 selectivity on the fixed bed of Na-Fe 3 O 4 /HZSM-5 catalyst. Owen et al [13][14][15][16] have reported the formation of HCs from CO 2 on Cobalt catalsyts at atmospheric pressure with a significant conversion. In the view of above studies, CO 2 hydrogenation provides new opportunities for the development of catalytic processes and sustainable energy.…”

A Critical Look at Direct Catalytic Hydrogenation of Carbon Dioxide to Olefins

“…[34] However,they are poor RWGS catalysts,a nd thus unsuitable for CO 2 hydrogenation.T he C 2 -C 4 hydrocarbon productioni sl imited,w ith methane as main product. [66] Despite this, cobalt was used as dopanti nF e/K catalysts. Adding a small amount of Co (2.6 wt %) to aF e( 12.4 wt %) catalyst showedh igher CO 2 conversion than an unpromotedF ec atalyst.…”

Metallic bionanocatalysts: potential applications as green catalysts and energy materials

“…Precious metals (Pd, Pt, Ru, Rh) on SiO 2 have been used in the reverse water gas shift reaction, while catalysts for the Fischer-Tropsch process are usually Fe or Cobased, with recent innovations towards one-pot reactions (see e.g. Mattia et al, 2015;Owen et al, 2016;Prieto, 2017) following early work (Dorner et al, 2010) that showed conversion of CO 2 to hydrocarbons (41% conversion and a C2-C5+ selectivity of 62%) using a doped Fe-based system. The potential for using biogenic catalysts has not been explored although a paradigm hybrid bio-magnetite/Pd(0) catalyst has been reported .…”