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Mn and Na additives have been widely studied to improve the efficiency of CO2 hydrogenation to valuable olefins on Fe catalysts, but their effects on the catalytic properties and mechanism are still under vigorous debate. This study shows that Fe‐based catalysts with moderate Mn and Na contents are highly selective for CO2 hydrogenation to olefins, together with low selectivities for both CO and CH4 and much improved space‐time olefin yields compared to state‐of‐the‐art catalysts. Combined kinetic assessment and quasi in situ characterizations further unveil that the sole presence of Mn suppresses the activity of Fe catalysts because of the close contact between Fe and Mn, whereas the introduction of Na mediates the Fe–Mn interaction and provides strong basic sites. This subtle synergy between Na and Mn sheds light on the importance of the interplay of multiple additives that could bring an enabling strategy to improve catalytic activity and selectivity. [ABSTRACT FROM AUTHOR]

Enhancing the intrinsic activity and space time yield of Cu based heterogeneous methanol synthesis catalysts through CO2 hydrogenation is one of the major topics in CO2 conversion into value-added liquid fuels and chemicals. Here we report inverse ZrO2/Cu catalysts with a tunable Zr/Cu ratio have been prepared via an oxalate co-precipitation method, showing excellent performance for CO2 hydrogenation to methanol. Under optimal condition, the catalyst composed by 10% of ZrO2 supported over 90% of Cu exhibits the highest mass-specific methanol formation rate of 524 gMeOHkgcat−1h−1 at 220 °C, 3.3 times higher than the activity of traditional Cu/ZrO2 catalysts (159 gMeOHkgcat−1h−1). In situ XRD-PDF, XAFS and AP-XPS structural studies reveal that the inverse ZrO2/Cu catalysts are composed of islands of partially reduced 1–2 nm amorphous ZrO2 supported over metallic Cu particles. The ZrO2 islands are highly active for the CO2 activation. Meanwhile, an intermediate of formate adsorbed on the Cu at 1350 cm−1 is discovered by the in situ DRIFTS. This formate intermediate exhibits fast hydrogenation conversion to methoxy. The activation of CO2 and hydrogenation of all the surface oxygenate intermediates are significantly accelerated over the inverse ZrO2/Cu configuration, accounting for the excellent methanol formation activity observed. Enhancing the intrinsic activity and space time yield of Cu based heterogeneous methanol synthesis catalysts is one of the major topics in CO2 hydrogenation. Here the authors develop a highly active inverse catalyst composed of fine ZrO2 islands dispersed on metallic Cu nanoparticles. [ABSTRACT FROM AUTHOR]

A one-step ligand-free method based on an adsorption-precipitation process was developed to fabricate iridium/cerium oxide (Ir/CeO2) nanocatalysts. Ir species demonstrated a strong metal-support interaction (SMSI) with the CeO2 substrate. The chemical state of Ir could be finely tuned by altering the loading of the metal. In the carbon dioxide (CO2) hydrogenation reaction it was shown that the chemical state of Ir species-induced by a SMSI-has a major impact on the reaction selectivity. Direct evidence is provided indicating that a single-site catalyst is not a prerequisite for inhibition of methanation and sole production of carbon monoxide (CO) in CO2 hydrogenation. Instead, modulation of the chemical state of metal species by a strong metal-support interaction is more important for regulation of the observed selectivity (metallic Ir particles select for methane while partially oxidized Ir species select for CO production). The study provides insight into heterogeneous catalysts at nano, sub-nano, and atomic scales. [ABSTRACT FROM AUTHOR]

[Display omitted] • CL-DRM reaction activity was verified on mesoporous NiMCeOx (M = Co, Zr or La). • CL-DRM is composed with catalytic CH 4 decomposition successive CO 2 activation step. • NiLaCeOx showed stable activity due to stronger Ni-Ce interaction with La 2 O 3 promoter. Highly ordered mesoporous NiLaCeOx mixed metal oxides were investigated as effective catalysts for the chemical looping-based dry reforming of methane (CH 4) with carbon dioxide (CO 2) (CL-DRM). This catalyst exhibited an excellent catalytic activity and stability in the decomposition of CH 4 to form H 2 with surface carbons subsequently activated by CO 2 via reverse Boudouard reaction to form CO. Among the NiMCeOx catalysts with various promoter (M = Co, Zr, or La), the optimal NiLaCeOx catalyst preserved its original highly ordered mesoporous structures, leading to the higher dispersion of smaller Ni nanoparticles. This was attributed to the stronger Ni-Ce interactions facilitated by the La 2 O 3 metal oxide promoter. The NiLaCeOx demonstrated a higher rate of H 2 formation and successive CO production in the CL-DRM reaction, resulting in a H 2 /CO ratio above 1.0. Additionally, the NiLaCeOx catalyst exhibited superior structural stability over 5 cyclic CL-DRM reactions for CH 4 decomposition (>85 %) and CO 2 activation (>45 %), with minimal deposition of cokes. [ABSTRACT FROM AUTHOR]