Preparation of Highly Dispersed Ni-Ce-Zr Oxides over Mesoporous <i>γ</i>-Alumina and Their Catalytic Properties for CO₂ Methanation

Abstract

Highly dispersed Ni-Ce-Zr mixed oxides supported on mesoporous γ-alumina (Ni-Ce-Zr/γ-MA) were prepared by a citric acid (CA)-assisted impregnation method and evaluated as catalysts for the methanation of CO2 with H2. The effects of the CA content of the reaction solution on the physicochemical properties and the catalytic performance of the Ni-Ce-Zr/γ-MA catalysts were investigated in detail. The addition of CA promoted the dispersion of the Ni-Ce-Zr oxide species on the γ-alumina surface and improved the interactions between the Ni oxide species and the support, resulting in the formation of homogeneously dispersed Ni nanoparticles in the γ-MA frameworks upon reduction with H2. The resulting Ni-Ce-Zr/γ-MA catalysts were highly active and showed almost 100% selectivity for CH4 during the methanation of CO2 at temperatures in the range of 150-400°C. Notably, the catalytic activity increased as the molar ratio of CA/(Ni + Ce + Zr) increased in the range of 0-2. This effect was most likely caused by the associated decrease in the Ni particle size and the improved electronic and structural properties of the Ni-Ce-ZrOx species. The results of a stability test for the Ni-Ce-Zr/γ-2803

Promising Catalytic Systems for CO2 Hydrogenation into CH4: A Review of Recent Studies

“…Wang-Xin et al [88] prepared highly dispersed Ni-Ce-Zr/γ-Al 2 O 3 catalysts by citric acid assisted impregnation. The addition of citric acid in the preparation procedure promoted the dispersion of the Ni-Ce-Zr oxide species over the γ-Al 2 O 3 surface and improved metal-support interactions.…”

Solvent-Free Ball-Milling-Derived Ni-CeO2/SiO2 Catalysts for CO2 Methanation

“…Table summarizes CeO 2 -doped or CeO 2 -supported Ni-based CO 2 methanation catalysts reported in the literature. Most catalysts were prepared by impregnation methods, ,− with a minority synthesized by deposition-precipitation, ammonia evaporation, and hydrothermal. , The feedstock consists of either a mixture of H 2 and CO 2 , ,,,,,, or a mixture of H 2 , CO 2 , and an inert gas (N 2 or He), ,,,,, with the GHSV ranging from 3000 to 86 000 mL/(g·h). In addition, the reaction temperature varies from 250 to 400 °C, with most studies focusing on 350–400 °C. ,,− ,− , Depending on catalysts, feedstock composition, and reaction temperature, the CO 2 conversion varies widely from 55 to 94%, while the CH 4 selectivity consistently remains high (95–100%).…”

“…82 However, the feedstock contained an extraordinarily low amount of CO 2 (1%) relative to H 2 (50%), along with 49% of He; thus, the space-time yield of CH 4 would be rather low. In two other studies with CO 2 conversion above 90%, 81,86 although the feedstock comprised H 2 and CO 2 in a molar ratio of 4:1, the GHSV was relatively low (≤12000 mL/(g•h)). In contrast, 30Ni-1CeO 2 /SiO 2 (0.15) developed in this study achieves 81% CO 2 conversion and 99% CH 4 selectivity at 350 °C using H 2 and CO 2 (4:1) with a high GHSV of 60 000 mL/ (g•h), surpassing the performance of most CeO 2 -incoporated Ni-based catalysts reported to date.…”

“…Most catalysts were prepared by impregnation methods, 35,77−85 with a minority synthesized by deposition-precipitation, 36 ammonia evaporation, 65 and hydrothermal. 86,87 The feedstock consists of either a mixture of H 2 and CO 2 , 35,36,80,81,83,84,86 or a mixture of H 2 , CO 2 , and an inert gas (N 2 or He), 65,78,79,82,85,87 with the GHSV ranging from 3000 to 86 000 mL/(g•h). In addition, the reaction temperature varies from 250 to 400 °C, with most studies focusing on 350−400 °C.…”

“…In addition, the reaction temperature varies from 250 to 400 °C, with most studies focusing on 350−400 °C. 35,36,[78][79][80][81][83][84][85]87 Depending on catalysts, feedstock composition, and reaction temperature, the CO 2 conversion varies widely from 55 to 94%, while the CH 4 selectivity consistently remains high (95−100%).…”