TY - JOUR
T1 - Investigating the correlation between deactivation and the carbon deposited on the surface of Ni/Al2O3 and Ni/La2O3-Al2O3 catalysts during the biogas reforming reaction
AU - Charisiou, N. D.
AU - Tzounis, L.
AU - Sebastian, V.
AU - Hinder, S. J.
AU - Baker, M. A.
AU - Polychronopoulou, K.
AU - Goula, M. A.
N1 - Funding Information:
VS acknowledges financial support from CIBER-BBN (financed by the Instituto de Salud Carlos III with assistance from the European Regional Development Fund). KP acknowledges the financial support from the Abu Dhabi Educational Council ( ADEC ) through the Award for Research Excellence ( B3111 ) and from the Abu Dhabi Department of Education and Knowledge ( ADEK ) through the Award for Research Excellence” ( AARE 2017 ).
Publisher Copyright:
© 2018 Elsevier B.V.
PY - 2019/4/30
Y1 - 2019/4/30
N2 - Ni/Al2O3 and Ni/La2O-Al2O3 catalysts were investigated for the biogas reforming reaction using CH4/CO2 mixtures with minimal dilution. Stability tests at various reaction temperatures were conducted and TGA/DTG, Raman, STEM-HAADF, HR-TEM, XPS techniques were used to characterize the spent samples. Graphitized carbon allotrope structures, carbon nanotubes (CNTs) and amorphous carbon were formed on all samples. Metallic Ni0 was recorded for all (XPS), whereas a strong peak corresponding to Ni2O3/NiAl2O4, was observed for the Ni/Al sample (650–750 °C). Stability tests confirm that the Ni/LaAl catalyst deactivates at a more gradual rate and is more active and selective in comparison to the Ni/Al for all temperatures. The Ni/LaAl exhibits good durability in terms of conversion and selectivity, whereas the Ni/Al gradually loses its activity in CH4 and CO2 conversion, with a concomitant decrease of the H2 and CO yield. It can be concluded that doping Al2O3 with La2O3 stabilizes the catalyst by (a) maintaining the Ni0 phase during the reaction, due to higher dispersion and stronger active phase-support interactions, (b) leading to a less graphitic and more defective type of deposited carbon and (c) facilitating the deposited carbon gasification due to the enhanced CO2 adsorption on its increased surface basic sites.
AB - Ni/Al2O3 and Ni/La2O-Al2O3 catalysts were investigated for the biogas reforming reaction using CH4/CO2 mixtures with minimal dilution. Stability tests at various reaction temperatures were conducted and TGA/DTG, Raman, STEM-HAADF, HR-TEM, XPS techniques were used to characterize the spent samples. Graphitized carbon allotrope structures, carbon nanotubes (CNTs) and amorphous carbon were formed on all samples. Metallic Ni0 was recorded for all (XPS), whereas a strong peak corresponding to Ni2O3/NiAl2O4, was observed for the Ni/Al sample (650–750 °C). Stability tests confirm that the Ni/LaAl catalyst deactivates at a more gradual rate and is more active and selective in comparison to the Ni/Al for all temperatures. The Ni/LaAl exhibits good durability in terms of conversion and selectivity, whereas the Ni/Al gradually loses its activity in CH4 and CO2 conversion, with a concomitant decrease of the H2 and CO yield. It can be concluded that doping Al2O3 with La2O3 stabilizes the catalyst by (a) maintaining the Ni0 phase during the reaction, due to higher dispersion and stronger active phase-support interactions, (b) leading to a less graphitic and more defective type of deposited carbon and (c) facilitating the deposited carbon gasification due to the enhanced CO2 adsorption on its increased surface basic sites.
KW - Biogas reforming reaction
KW - Carbon nanotubes
KW - Catalytic deactivation
KW - Lanthana doping
KW - Nickel catalysts
KW - Syngas production
UR - http://www.scopus.com/inward/record.url?scp=85047422928&partnerID=8YFLogxK
U2 - 10.1016/j.apsusc.2018.05.177
DO - 10.1016/j.apsusc.2018.05.177
M3 - Article
AN - SCOPUS:85047422928
SN - 0169-4332
VL - 474
SP - 42
EP - 56
JO - Applied Surface Science
JF - Applied Surface Science
ER -