Effect of acid (CH3COOH, H2SO4 and H3PO4) and basic (KOH and NaOH) impurities on glycerol valorisation by aqueous phase reforming

Abstract This work analyses and compares, under the same operating conditions (220 °C and 44 bar with a Ni-La/Al 2 O 3 catalyst), the effects of some of the most common acid (CH 3 COOH, H 2 SO 4 , H 3 PO 4 ) and basic (KOH and NaOH) biodiesel-derived impurities on the aqueous phase reforming (APR) of a 30 wt.% glycerol solution. The statistical analysis of the results revealed that the impurities did not greatly influence the initial reforming results. Conversely, they significantly influenced the catalyst deactivation, which resulted in different evolutions over time for the glycerol conversion, liquid production and the composition of the gas and liquid phases. Significant decreases over time in the glycerol conversion and liquid production were detected, the severity of the decay being as follows: H 3 PO 4 (KOH = NaOH) > H 2 SO 4 (KOH   CH 3 COOH (KOH  3 PO 4  > H 2 SO 4  > CH 3 COOH. In addition, S and P were also deposited on the catalyst, while boehmite and other new crystalline phases were detected in the spent catalyst after the APR reaction.