Pyrolysis of lignocellulosic and algal biomasses in a fixed‐bed reactor: A comparative study on the composition and application potential of bioproducts

Abstract

The pyrolysis of six biomass samples consists of Rice husk (RH), Coconut shell (CS), and Walnut shell (WS) as lignocellulosic biomasses and Cladophora glomerata (CG), Gracilaria gracilis (GG), and Azolla filiculoides (AF) as algal biomasses were investigated at a constant operating condition in a fixed-bed reactor. The effect of biomass biochemical structure on the yields and composition of pyrolysis products and their potential for future applications were discussed. CS, AF, and CG showed respectively the highest yield of bio-oil (50.25 wt%), biogas (33.70 wt%), and biochar (40.21 wt%). WS, AF, and RH-derived gas products had a medium level of LHV (10-13 MJ/Nm3), and CG and GG algae samples had a very suitable H2/CO ratio close tow. Characterization of bio-oils showed that CS, WS had a high content of hydrocarbon components (23.5%, 17.6%, and 17%, respectively), and phenols (35.3% and 35.6%, respectively). Furthermore, useful nitrogen-containing components such as pyridine, nitrile, indole, and derivatives were detected in algae bio-oils. Biochar characterization showed the highest surface area and total pore volume for AF. Also, CG's biochar with a high concentration of carboxylic and carbonyl groups in their structure may be suitable for absorbing water and soil contaminants.