CO2 hydrogenation over 5%Ni/CeO2–Al2O3 catalysts: effect of supports composition

• Published in: Research on chemical intermediates 2024-07, Vol.50 (7), p.3305-3325
• Main Authors: Mosayebi, Amir, Ranjbar, Atieh, Eghbal Ahmadi, Mohammad Hosein
• Format: Article
• Language: English
• Subjects: Aluminum oxide; Carbon dioxide; Catalysis; Catalysts; Catalytic converters; Cerium oxides; Chemisorption; Chemistry; Chemistry and Materials Science; Coke; Composition effects; Deposition; Hydrogenation; Inorganic Chemistry; Nickel; Physical Chemistry; Surface stability; Thermal analysis; Thermal stability; Thermogravimetric analysis; X-ray diffraction; X-ray fluorescence
• ISSN: 0922-6168; 1568-5675
• DOI: 10.1007/s11164-024-05312-7

In current work, the investigation centered on assessing the impact of the CeO 2 to Al 2 O 3 ratio in a 5%Ni/CeO 2 –Al 2 O 3 catalyst on the CO 2 hydrogenation reaction within the temperature range of 240–400 °C. The primary aim was to achieve enhanced conversion rates, while minimizing coke deposition on the catalyst surface. Nickel was incorporated into the CeO 2 –Al 2 O 3 supports via the deposition–precipitation method. The various physicochemical properties of fresh, reduced and spent catalysts were studied using techniques such as thermal gravimetric analysis (TGA), X-ray diffraction (XRD), N 2 adsorption/desorption, temperature programmed reduction (TPR), H 2 -chemisorption, X-ray fluorescence (XRF), and CHNS analyzer. XRD results revealed that the addition of CeO 2 to the Ni/Al 2 O 3 catalyst and the increase in ceria loading in the hybrid support had no obvious effect on the crystalline structure. However, several properties including reducibility, coke deposition, and coke formation quantity, coke structure on the catalyst surface, catalytic performance, and thermal stability were altered. The CO 2 conversion remained relatively stable (41.25%) up to 35 h initial on stream for Ni/Al 2 O 3 catalyst, indicating no significant deactivation. Conversely, Ni/CeO 2 –Al 2 O 3 catalyst exhibited high stability up to 45 h initial. The highest CO 2 conversion (58%) was achieved with the Ni/CeO 2 (50%)–Al 2 O 3 (50%) at 400 °C, primarily attributed to a lower interaction between nickel species and the support, along with a higher reduction degree. Ni/CeO 2 –Al 2 O 3 catalysts displayed higher methane selectivity and lower CO selectivity compared to both Ni/Al 2 O 3 and Ni/CeO 2 catalysts across the entire temperature range of 240–400 °C.