An integrated approach to the valorization of pyrolysis products from lignocellulosic residues and by-products

Abstract

Pyrolysis of biomass waste enables the generation of energy and products, although the sustainability of this process requires an integral valorization of all produced fractions. This paper presents a study on the valorization of all pyrolysis products from selected biomass wastes, such as hemp hurd (HH), olive stone (OS) and almond shell (AS), and two technical lignins, focusing on the effect of the biopolymeric composition on the potential applications of the different pyrolysis streams. The stablished correlation between the lignocellulosic biomass composition and the properties of each of the pyrolysis products obtained (bio-oil, biochar and gases) in relation to their potential applications (in addition to the distribution of pyrolysis products and yields) represents the main novelties of this work. The results obtained demonstrate that it is possible to obtain energy to sustain an autothermal pyrolysis process from these residues at operation temperatures above 500 °C. Residual biomass materials with high lignin content deliver gases with higher heating values (up to 23 MJ/m3), higher yields of solids (ca. 58 %), and bio-oil with lower acid and higher phenolic content (up to 19.9%m/m.). Agricultural residues, especially hemp hurd, which contains lower lignin amount, produce chars with narrow microporosity, matching the requirements to selectively adsorb CO2 from biogas and steam reforming streams, achieving CO2/CH4 selectivity values as high as 53.