Journal
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
Volume 44, Issue 18, Pages 9291-9306Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijhydene.2019.02.129
Keywords
Methanation; Nickel loading; Ni/Al2O3 catalyst; In-situ DRIFTS; Reaction intermediates
Categories
Funding
- Strategic International Scientific and Technological Innovation Cooperation Special Funds of National Key R&D Program of China [2016YFE0204000]
- Program for Taishan Scholars of Shandong Province Government
- Recruitment Program of Global Young Experts (Thousand Youth Talents Plan)
- Natural Science Fund of Shandong Province [ZR2017BB002]
- Australia Research Council [DP180101788]
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In this study, methanation of CO2 over Ni/Al2O3 with varied nickel loading (from 0 to 50 wt %) was evaluated, striving to explore the effects of nickel loading on catalytic behaviors and the reaction intermediates formed. The results showed that agglomeration of nickel particles were closely related to interaction between nickel and alumina. Increasing nickel loading resulted in the increased proportion of nickel having medium strong interaction with alumina, the reduced reduction degree of NiO, the increase of medium to strong basic sites, the enhanced activity for methanation and the competition between reverse water gas shift (RWGS) reaction and methanation. Lower nickel loading promoted RWGS reaction while methanation of CO2 dominated at higher nickel loading. The catalyst with a nickel loading around 25% achieved the best activity for methanation. The in-situ DRIFTS studies of methanation of CO2 showed that CO2 could be absorbed on surface of metallic Ni, NiO or alumina. More metallic nickel species on alumina suppressed formation of carbonate species while promoted further conversion of HCOO* species and *CH3 species, achieving a higher catalytic efficiency. Moreover, more metallic nickel species was crucial for gasifying the carbonaceous intermediates, prevented aggregation of the intermediates to coke and achieving a higher catalytic stability. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
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