Valorization of a regional waste employing a modified natural zeolite

Abstract

The goal of this study was the valorization and recycling of residual biomass from the agro-alimentary industry with the aim of promoting the circular economy. Peanut shells (PS) were selected as feedstock since they lack value added applications and their abundance and local concentration make them of easy availability. Considering that clinoptilolite is the most abundant natural zeolite on Earth, it can be used for the development of low-cost catalysts. In this sense, clinoptilolites were modified by iron (Fe) incorporation and employed as heterogeneous catalysts for in-situ PS catalytic pyrolysis. The metal was incorporated to the zeolites by ion exchange. The material obtained was extensively characterized by means of X-Ray Diffraction, Infrared Fourier Transform Spectroscopy, BET surface area, UV?vis Diffuse Reflectance Spectra and Temperature Programmed Reduction. PS pyrolysis and bio-oil upgrade were simultaneously carried out in a fixed bed glass reactor at 500 °C, for 10 min. Chemical composition of the bio-oil was assessed by the GC-MS technique. Results showed an important reduction in organic acids? yield, from 43 wt% in thermal runs, to 8 wt% in catalytic runs and a significant increase in selectivity towards phenols and alcohols; from 14 wt% to 24 wt% and 20 wt% to 27 wt%, respectively.