Tuning interactions of surface‐adsorbed species over Fe−Co/K−Al2O3 catalyst by different K contents: selective CO2 hydrogenation to light olefins

Selective CO2 hydrogenation to light olefins over Fe−Co/K−Al2O3 catalysts was enhanced by tuning bonding strengths of adsorbed species by varying the content of the K promotor. Increasing the K/Fe atomic ratio from 0 to 0.5 increased the olefins/paraffins (O/P) ratio by 25.4 times, but then slightly raised upon ascending K/Fe to 2.5. The positive effect of K addition is attributed to the strong interaction of H adsorbed with the catalyst surface caused by the electron donor from K to Fe species. Although the Fe−Co/K−Al2O3 catalyst with K/Fe=2.5 reached the highest O/P ratio of 7.6, the maximum yield of light olefins of 16.4 % was achieved by the catalyst promoted with K/Fe of 0.5. This is explained by the considerable reduction of amount of H2 adsorbed on the catalyst surface with K/Fe=2.5

Comparison of Packed-Bed and Micro-Channel Reactors for Hydrogen Production via Thermochemical Cycles of Water Splitting in the Presence of Ceria-Based Catalysts

Hydrogen production via two-step thermochemical cycles over fluorite-structure ceria (CeO2) and ceria-zirconia (Ce0.75Zr0.25O2) materials was studied in packed-bed and micro-channel reactors for comparison purposes. The H2-temperature program reduction (H2-TPR) results indicated that the addition of Zr4+ enhanced the material’s reducibility from 585 µmol/g to 1700 µmol/g, although the reduction temperature increased from 545 to 680 °C. Ce0.75Zr0.25O2 was found to offer higher hydrogen productivity than CeO2 regardless of the type of reactor. The micro-channel reactor showed better performance than the packed-bed reactor for this reaction

Process Intensification of Methane Production via Catalytic Hydrogenation in the Presence of Ni-CeO2/Cr2O3 Using a Micro-Channel Reactor

A slight amount of Cr2O3 segregation in 40 wt% NiO/Ce0.5Cr0.5O2 was presented at the surface. The best catalytic performance towards the reaction was achieved at 74% of CO2 conversion and 100% CH4 selectivity at 310 °C, the reactant (H2/CO2) feed molar ratio was 4, and the WHSV was 56,500 mlN·h−1·g−1cat. The mechanistic pathway was proposed through carbonates and formates as a mediator during CO2 and H2 interaction. Activation energy was estimated at 4.85 kJ/mol, when the orders of the reaction were ranging from 0.33 to 1.07 for nth-order, and 0.40 to 0.53 for mth-order

Tuning Interactions of Surface‐adsorbed Species over Fe−Co/K−Al 2

Selective CO2 hydrogenation to light olefins over Fe−Co/K−Al2O3 catalysts was enhanced by tuning bonding strengths of adsorbed species by varying the content of the K promotor. Increasing the K/Fe atomic ratio from 0 to 0.5 increased the olefins/paraffins (O/P) ratio by 25.4 times, but then slightly raised upon ascending K/Fe to 2.5. The positive effect of K addition is attributed to the strong interaction of H adsorbed with the catalyst surface caused by the electron donor from K to Fe species. Although the Fe−Co/K−Al2O3 catalyst with K/Fe=2.5 reached the highest O/P ratio of 7.6, the maximum yield of light olefins of 16.4 % was achieved by the catalyst promoted with K/Fe of 0.5. This is explained by the considerable reduction of amount of H2 adsorbed on the catalyst surface with K/Fe=2.5