Carbon Dioxide Hydrogenation into Higher Hydrocarbons and Oxygenates: Thermodynamic and Kinetic Bounds and Progress with Heterogeneous and Homogeneous Catalysis

Under specific scenarios, the catalytic hydrogenation of CO₂ with renewable hydrogen is considered a suitable route for the chemical recycling of this environmentally harmful and chemically refractory molecule into added-value energy carriers and chemicals. The hydrogenation of CO₂ into C₁ products, such as methane and methanol, can be achieved with high selectivities towards the corresponding hydrogenation product. More challenging, however, is the selective production of high (C₂₊ ) hydrocarbons and oxygenates. These products are desired as energy vectors, owing to their higher volumetric energy density and compatibility with the current fuel infrastructure than C₁ compounds, and as entry platform chemicals for existing value chains. The major challenge is the optimal integration of catalytic functionalities for both reductive and chain-growth steps. This Minireview summarizes the progress achieved towards the hydrogenation of CO₂ to C₂₊ hydrocarbons and oxygenates, covering both solid and molecular catalysts and processes in the gas and liquid phases. Mechanistic aspects are discussed with emphasis on intrinsic kinetic limitations, in some cases inevitably linked to thermodynamic bounds through the concomitant reverse water-gas-shift reaction, which should be considered in the development of advanced catalysts and processes.

A gold nanodendrite-decorated layered double hydroxide as a bifunctional electrocatalyst for hydrogen and oxygen evolution reactions in alkaline media

In this work, a gold nanodendrites-CuMgFe layered double hydroxide composite (AuNDs@LDH) was introduced as a bifunctional electrocatalyst for hydrogen and oxygen evolution reactions (HER and OER, respectively) in alkaline media.

Formation of C2oxygenates and ethanol from syngas on an Fe-decorated Cu-based catalyst: insight into the role of Fe as a promoter

Fe-decorated Cu bimetallic catalyst exhibits a high selectivity to ethanol.

Efficient Synthesis of Ethanol from CH4 and Syngas on a Cu-Co/TiO2 Catalyst Using a Stepwise Reactor

Ethanol synthesis from CH4 and syngas on a Cu-Co/TiO2 catalyst is studied using experiments, density functional theory (DFT) and microkinetic modelling. The experimental results indicate that the active sites of ethanol synthesis from CH4 and syngas are Cu and CoO, over which the ethanol selectivity is approximately 98.30% in a continuous stepwise reactor. DFT and microkinetic modelling results show that *CH3 is the most abundant species and can be formed from *CH4 dehydrogenation or through the process of *CO hydrogenation. Next, the insertion of *CO into *CH3 forms *CH3CO. Finally, ethanol is formed through *CH3CO and *CH3COH hydrogenation. According to our results, small particles of metallic Cu and CoO as well as a strongly synergistic effect between metallic Cu and CoO are beneficial for ethanol synthesis from CH4 and syngas on a Cu-Co/TiO2 catalyst.

The effect of an Fe promoter on Cu/SiO2 catalysts for improving their catalytic activity and stability in the water-gas shift reaction

By adding a small amount of iron, the catalytic activity and stability of Cu/SiO₂ are effectively improved.

Effect of preparation method on performance of Cu–Fe/SiO2catalysts for higher alcohols synthesis from syngas

Cu–Fe/SiO₂catalyst prepared by ultrasound-assisted impregnation exhibits higher CO conversion and alcohols yield than those by the other methods.

Nanoparticles of Cu–Co alloy derived from layered double hydroxides and their catalytic performance for higher alcohol synthesis from syngas

A series of layered double hydroxides (LDHs) with different Cu/Co ratios were prepared according to the co-precipitation method and used as catalyst precursors for higher alcohol synthesis.

Effects of metal promotion on CuMgFe catalysts derived from layered double hydroxides for higher alcohol synthesis via syngas

Schematic of the triple-active-site model and the linear relationship between alcohol selectivity and copper content.