Supported Ni catalysts are active in CO2 methanation. It is important to understand the reaction mechanism for the development of highly-active catalysts. In this study, we investigated the reaction pathways of CO2 methanation over Ni/Y2O3 and Ni/Al2O3 based on the adsorbates observed by diffuse reflectance infrared Fourier transform spectroscopy. For Ni/Al2O3, linear and bridged CO adsorbates were converted to nickel carbonyl hydride and/or formyl species, which would be further hydrogenated to methane. In contrast, the formation of formate adsorbates was specifically confirmed over Ni/Y2O3 under the CO2 methanation condition. The hydrogen molecule was activated by dissociatively-adsorbing on Ni particles. Then, the hydrogenation of formate adsorbates by the activated hydrogen species proceeded sequentially to form methane. The observed bridged CO species would not be a major intermediate for Ni/Y2O3.
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http://dx.doi.org/10.1039/d0cp06257j | DOI Listing |
Environ Res
January 2025
Department of Civil and Smart Construction Engineering, Shantou University, Shantou, Guangdong 515063, China. Electronic address:
Landfill gas (LFG) has become the second-largest anthropogenic source of methane (CH) emissions globally. CH is the second most significant greenhouse gas after carbon dioxide (CO), thus it is crucial to mitigate the methane emission of landfills. The soil in landfill cover layers is rich in methane-oxidizing bacteria (MOB), which use CH as their sole carbon and energy source.
View Article and Find Full Text PDFJ Environ Manage
January 2025
Bioenergy Research Institute - IPBEN, UNESP, Institute of Chemistry, Araraquara, SP, Brazil; São Paulo State University (UNESP), Institute of Chemistry, Campus Araraquara, Department of Engineering, Physics and Mathematics, Rua Prof. Francisco Degni, 55, 14800-900, Araraquara, SP, Brazil. Electronic address:
Waste-to-energy technologies involve the conversion of several wastes to useful energy forms like biogas and biochar, which include biological and thermochemical processes, as well as the combination of both systems. Assessing the economic and environmental impacts is an important step to integrate sustainability and economic viability at anaerobic digestion systems and its waste management. Energy production, CO emissions, cost analysis, and an overall process evaluation were conducted, relying on findings from both laboratory and pilot-scale experiments.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Department of Chemical and Bimolecular Engineering, National University of Singapore, 117576 Singapore.
Biogas, primarily composed of methane (CH) and carbon dioxide (CO), is considered an alternative renewable energy resource. Efficient CO/CH separation is essential for biogas upgrading to increase energy density, and in this context, metal-organic frameworks (MOFs) have demonstrated significant potential. Here, we integrate multiscale modeling with cross-diversity machine learning (ML) to unveil MOFs with open copper sites (OCS-MOFs) that exhibit exceptional CO/CH separation performance.
View Article and Find Full Text PDFChemistry
January 2025
Ningbo University, School of Material Science and Chemical Engineering, Rokkakubashi, Kanagawa-ku, Yokohama-shi, Kanagawa, 221-8686, Japan., 315211, Ningbo, CHINA.
Direct oxidation of methane to methanol utilizing molecular oxygen under mild conditions is an important yet challenging process due to the difficulty in activation of methane under such conditions. In this research, we report zeolitic octahedral metal oxides based on cobalt vanadotungstates, which act as the catalysts for oxidation of methane using molecular oxygen as the oxidant without co-reductants at a low temperature of 90 oC even as low as 60 oC. This catalytic process results in the high-yield production of methanol as the major product.
View Article and Find Full Text PDFPLoS One
January 2025
Environmental Molecular Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America.
Coastal wetlands, including freshwater systems near large lakes, rapidly bury carbon, but less is known about how they transport carbon either to marine and lake environments or to the atmosphere as greenhouse gases (GHGs) such as carbon dioxide and methane. This study examines how GHG production and organic matter (OM) mobility in coastal wetland soils vary with the availability of oxygen and other terminal electron acceptors. We also evaluated how OM and redox-sensitive species varied across different size fractions: particulates (0.
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