Abstract
Supported nickel catalysts were synthesized, characterized, and employed in the carbon oxides co-methanation process. Five NiO/CeO2-ZrO2 mixed oxides, with the same Ni content and different Ce/Zr molar ratios, were prepared by the soft-template method. They were characterized through ICP-AES, N2 adsorption, XRD, and TPR. Reduced Ni/CeO2-ZrO2 catalysts were obtained by submitting the oxide systems to reduction treatment in H2 at 400 °C. They were characterized by XRD, H2-TPD, and CO2 adsorption microcalorimetry and their catalytic performances in the carbon oxides co-methanation were investigated. Catalytic tests were performed in a fixed-bed continuous-flow microreactor at atmospheric pressure. The effect of experimental conditions (reaction temperature, space velocity, reactants molar ratio) was also studied. Almost complete CO conversion was obtained on any catalyst, whereas CO2 conversion was much lower and increased with Ce content, at least up to Ce/Zr = 1. The beneficial effect of the Ce content could be related to the increased NiO reducibility and to the higher ability to adsorb and activate CO2. However, at high Ce/Zr ratios, it is probably counterbalanced by an interplay of reactions involving CO and CO2.
Highlights
Due to the depleting nature of oil and natural gas reserves, the production of a valuable fuel such as synthetic natural gas (SNG) has been attracting increasing attention
When syngas or hydrogen is obtained from renewable resources, carbon oxides methanation presents the additional advantage of reducing greenhouse gases emissions
NiO/Cex Zr1−x O2, where x is the nominal CeO2 molar fraction in the (CeO2 )x -(ZrO2 )1−x support. Their chemical composition was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES)
Summary
Due to the depleting nature of oil and natural gas reserves, the production of a valuable fuel such as synthetic natural gas (SNG) has been attracting increasing attention. SNG can be obtained by hydrogenation of CO and/or CO2 [1]. When syngas or hydrogen is obtained from renewable resources, carbon oxides methanation presents the additional advantage of reducing greenhouse gases emissions. Reformed gases deriving from the steam reforming of oil fractions or from coal gasification contain both CO and CO2. Carbon oxides can be simultaneously hydrogenated to methane (co-methanation). Several studies have been devoted to the methanation of either CO [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]
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