Intensification of Bio-oil Yield from Waste Banana Pseudo-Stems—Experimental Studies on Catalytic Pyrolysis

Abstract

Regular generation of huge amount of solid wastes from various origin and the difficulties in obtaining a feasible management measure is a persisting problem faced by the societies of all countries. Thermochemical conversion, particularly through pyrolysis, of the abundant solid wastes to renewable energy resources and other value-added products is a sensible solution of this problem which can be adapted globally. In the present research work, non-edible parts of waste pseudo-stems of banana (Musa sp.) have been selected as the lignocellulosic feedstock for pyrolysis and its conversion to bio-oil, pyro-char and pyro-gas has been studied using temperature as a parameter. Initially, pyrolysis of raw and untreated banana pseudo-stems (BPS) has been conducted in a 50-mm-diameter and 164-mm-long semi-batch pyrolyzer under non-isothermal conditions in the temperature range of 673–1173 K. Five metal-based catalysts namely alumina, zinc oxide, sodium chloride, potassium chloride, and sodium aluminosilicate have been used to comparatively assess the enhancing effect of the catalysts on the product yields, particularly on the bio-oil yield. Pattern of the yields of bio-oil from non-catalytic and catalytic pyrolysis under same temperature range has been compared. Among the five catalysts, maximum bio-oil yield of 50 wt% at 873 K was obtained using potassium chloride (KCl). Hence, KCl is the best performing catalyst among all the other catalysts for bio-oil production using BPS. The lumped kinetic parameters for both non-catalytic and catalytic pyrolysis of BPS have been determined in the temperature range of 673–1173 K. The kinetics indicated that the weight loss increases with the increase in pyrolysis temperature due to the increased rate of pyrolysis for all experimental runs. Based on the current experimental findings, it has been recommended that lignocellulosic solid wastes can serve as excellent feedstocks for enhanced production of bio-oil through catalytic pyrolysis.