Preparation of Ni/SiO2 using silicon-rich-biomass as source for acetic acid steam reforming

Abstract

In this paper, four kinds of silicon-rich biomass (rice husk, rice straw, peanut shell, corncob) were used as raw materials for SiO2 extraction by heat treatment method. And the extracted SiO2 was applied to prepare Ni/SiO2 catalyst for acetic acid (AcOH) steam reforming. Various characterization methods were used to analyze the purity, structure and specific surface area characteristics of SiO2 extracted from different sources. It was found that the silica prepared by acid washing and calcination (AWC) had larger specific surface area, abundant pore channels and larger pore volume. By water washing and calcination (WWC), K2O impurity would be remained in SiO2, which might dissolve SiO2 during the calcination process, generating an increase in the pore size and a decrease in the specific surface area. While the CaO impurity in SiO2 promoted the dispersion of the active components and enhanced the interaction between the active component and the carrier. A series of reforming catalysts were prepared by using the obtained SiO2 as carriers. It was found that the lifetime of catalyst from low to high was Ni/RS-SiO2 <Ni/PS-SiO2 <Ni/RH-SiO2, which was in the opposite order of K2O content. Acid washing was beneficial for the enhancement of Ni/RH-AC-SiO2 activity, and the increase of Ni/RS-AC-SiO2 stability. Among the four catalysts, the Ni/RH-AC-SiO2 catalyst exhibited the highest carbon conversion (100%) and hydrogen yield at 600 °C, which may be because that the acid washing removed the metal oxide impurity K2O. And its large specific surface area, the concentrated pore size distribution, and the suitable interactions between the support and carrier may also contribute to its high catalyst activity.