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Tytuł pozycji:

Impacts of alkali or alkaline earth metals addition on reaction intermediates formed in methanation of CO2 over cobalt catalysts.

Tytuł:
Impacts of alkali or alkaline earth metals addition on reaction intermediates formed in methanation of CO2 over cobalt catalysts.
Autorzy:
Zhang, Zhanming
Zhang, Xiao
Zhang, Lijun
Gao, Jingxu
Shao, Yuewen
Dong, Dehua
Zhang, Shu
Liu, Qing
Xu, Leilei
Hu, Xun
Temat:
METHANATION
COBALT catalysts
ALKALINE earth metals
ADDITION reactions
CATALYTIC activity
ALKALIES
Źródło:
Journal of the Energy Institute (Elsevier Science); Aug2020, Vol. 93 Issue 4, p1581-1596, 16p
Czasopismo naukowe
Additives affect the physiochemical properties of the catalyst as well as the evolution of the reaction intermediates produced during the reaction process such as the methanation of CO 2. In this study, Co/Al 2 O 3 catalysts modified with Na, K, Mg or Ca were prepared and the reaction intermediates formed during CO 2 methanation were investigated. The results showed that Na, K or Mg species reacted with alumina, forming Al(OH) 3 or MgAl 2 O 4 spinel structure, leading to the re-structure of the catalysts and a remarkable decrease of the specific surface area. The increased alkalinity of the catalyst did not promote the catalytic activity for methanation but promoted CO formation. The addition of Na or K enhanced the affinity of the catalyst to the reaction intermediates of HCOO* and CO 3 2−, slowing down their further reduction to CH 4 and leading to the lower catalytic activity. The evolution of HCOO* and CO 3 2− species strongly correlated with the catalytic activity, while the direct correlation between the capability for the absorbance of CO 2 * as well as the C–O functionality and the catalytic activity was not found. In addition, the addition of Na or K to Co/Al 2 O 3 could also induce the formation of a significant amount of the coke species in the nanotube form. Image 1 • Na or K addition to Co/Al 2 O 3 forms Al(OH) 3 phase and reduces specific area. • Mg or Ca prevents the sintering of cobalt species while Na or K promotes. • Na or K enhances accumulation of HCOO* and CO 3 2−, decreasing catalytic activity. • HCOO*/CO 3 2− strongly correlate to catalytic activity, while CO 2 */C–O* did not. • Na or K addition to Co/Al 2 O 3 induce carbon nanotube formation during methanation. [ABSTRACT FROM AUTHOR]
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