Effect of impurities of CH3OH, CH3COOH, and KOH on aqueous phase reforming of glycerol over mesoporous Ni–Cu/CeO2 catalyst

Abstract

Impurities are inevitable in crude glycerol, a by-product of biodiesel, which has a great influence on aqueous phase reforming (APR). This work investigates three impurities (CH3OH, CH3COOH, and KOH) in the aqueous phase reforming of glycerol (GAPR) using a mesoporous Ni–Cu/CeO2 catalyst at three temperatures. The experiment results indicate that the increase of temperature is beneficial to the conversion of glycerol into gas products, but not favor to the proportion of H2 in the gas phase. The presence of CH3OH almost has not affected the total gas volume, while CH3COOH and KOH decreased and increased the gas volume, respectively. The deactivation of the catalyst occurs under acidic conditions because the active phase Ni on the catalyst surface is lost in the hydrogen evolution reaction. KOH has the greatest influence on the gas phase composition, which greatly increases the H2 production and the proportion of H2. The results of liquid-phase solution analysis show that the addition of CH3COOH promoted the dehydration of glycerol, which is contrary to the results obtained by adding KOH. CH3OH, as the final product of glycerol dehydrogenation and decarbonization, is added to the initial solution, which will be conducive to the dehydration reaction. The addition of CaO can increase the H2 production in the APR of glycerol solution containing impurities.