Hydrogen production by reforming of acetic acid using La–Ni type perovskites partially substituted with Sm and Pr

Abstract

The condensation of gases from the pyrolysis of biomass leads to a liquid compound called bio-oil. This oil can be divided into two fractions: one aqueous and another non-aqueous. The aqueous fraction does not have a high market value and it is usually discarded. However, this mixture has considerable amounts of organic compounds, which can be potential renewable sources of hydrogen. Steam reforming has been the most studied reaction to produce hydrogen from the aqueous fraction of bio-oil. Due to the diversity of organic compounds found in this aqueous fraction, model compounds have usually been used to study this mixture. Among the compounds used to represent the aqueous fraction of bio-oil, acetic acid is the most popular. Nickel-based catalysts are traditionally used for reforming reactions. An alternative to combine high Ni content employed in catalysts, this kind of process with desirable values of dispersion is to use perovskite-type precursors (LaNiO3). Therefore, the objective of this study was to investigate the production of hydrogen from the aqueous fraction of bio-oil. More specifically, in this work, LaNiO3, LaPrNiO3 and LaSmNiO3 were tested as precursors for catalysts in the reaction of steam and oxidative reforming of acetic acid. During the reaction, the catalysts showed the formation of the same products: H2, CO, CH4, CO2, C3H6O, but with different selectivities. All samples presented good selectivity for hydrogen formation, and the presence of Pr and Sm just slightly affected the catalytic performance. Due to the large accumulations of coke observed during the reaction of steam reforming, a small amount of O2 was added to the mixture. The presence of this oxidant improved catalytic activity without reducing the amount of hydrogen produced. Furthermore, it helped to reduce the deposits of coke, maintaining the catalytic activity during 24h of reaction.