La1−x(Ce, Sr)xNiO3 perovskite-type oxides as catalyst precursors to syngas production through tri-reforming of methane

Abstract

LaNiO3 (LN), La0.95Ce0.05NiO3 (LCN) and La0.95Sr0.05NiO3 (LSN) perovskites were synthesized by the polymeric precursor method to act as catalyst precursors for the Tri-reforming of methane (TRM). The majority phase determined for the LCN perovskite was LaNiO3, whereas, for LN and LSN, it was La2NiO4. It was not possible to determine segregated strontium phases for LSN, but LCN presented a small amount of CeO2. All the catalysts presented similar methane conversions (around 75%), however differed in CO2 conversion. LCN was the sample with the highest CO2 conversion (32%), while the values recorded for the LN and LSN samples were 21.9 and 17.1%, respectively. The partial substitution of La3+ by Ce4+ leads to a higher CO2 conversion due to the redox properties of cerium, which promotes CO2 disproportion at the oxygen vacancies generated by cerium, providing more oxygen species that oxidize the coke at the surface. The most active sample for CO2 conversion (LCN) was also the least selective for hydrogen, generating a synthesis gas with an H2/CO ratio of 1.2, while the less active LN and LSN samples were more selective for hydrogen (H2/CO = 1.5–1.6). Thus, it is possible to generate synthesis gas suitable for different applications depending on the metal incorporated into the LaNiO3 perovskite.