Abstract
The urgent need to reduce CO2 emissions requires the development of efficient catalysts for the conversion of CO2 into chemicals and fuels. In this study, a series of nickel catalysts supported on ITQ-2 and ZSM-5 zeolites have been prepared, characterized and tested in the hydrogenation reaction of CO2 towards methane. Specifically, two ITQ-2 and two ZSM 5 zeolites with different aluminum content have been studied. For both types, the higher Si/Al ratio of the material, the more active the catalyst due probably to its higher hydrophobicity. The largest difference was found for the ITQ-2 samples, being the CO2 conversion for the sample with a greater Si/Al ratio 50 points higher at 350 °C. Comparing both zeolite structures, while similar catalytic results were obtained with the samples with lower Si/Al ratio, a distinctly higher activity was found for the ITQ-2 zeolite without aluminum, pure silica. Therefore, this result suggests that the presence of aluminum is of particular relevance. Among the studied materials, the catalyst supported on the delaminated ITQ-2 zeolite without Al was the most active catalyst. Its higher activity was mainly attributed to the smaller crystallite size of nickel supported on the large external surface area presented by this zeolite.
Highlights
Due to the growing concern about climate change and its consequences, most countries worldwide seem determined to take action against this problem
For the sample supported on the ITQ-2 without Al, the absence of diffraction peaks of NiO indicates that Ni is well-dispersed in this sample with a small crystallite size (Figure 1a)
For the ITQ-2 zeolite with a Si/Al ratio of 15, the peaks corresponding to the NiO phase can be observed
Summary
Due to the growing concern about climate change and its consequences, most countries worldwide seem determined to take action against this problem. The relation of human-related activities with climate change is clear. In the fifth assessment report of the Intergovernmental Panel on Climate Change (IPCC), these human activities are stated as the dominant cause with an extreme likelihood [1]. The impact of humankind on the climate system has been evidenced one more time during the outbreak and spread of COVID-19 disease in 2020. The confinement measurements adopted by most countries to slow down the expansion of this disease have produced a significant reduction of air pollution and CO2 emissions due to the decline in human activity [2,3,4]. With the aim of unifying the response to mitigate climate change, the parties of the United Nations
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