Pyrolysis and Thermogravimetric Study to Elucidate the Bioenergy Potential of Novel Feedstock Produced on Poor Soils While Keeping the Environmental Sustainability Intact

Abstract

This work focused on exploring the bioenergy potential of biomass produced on salt-affected soils by growing two types of grasses, namely Parthenium hysterophorus (carrot grass) and Pennesetum benthiumo (mott grass), without using fertilizers or pesticides. The whole plant biomass of both grasses was pyrolyzed at three heating rates (10, 30, and 50 °C min−1) in a joined Thermogravimetry–Differential Scanning Calorimetry (TGA–DSC) analyzer under an inert (nitrogen) environment. The pyrolysis of both grasses was shown to occur in a three-stage process, while most of the thermal transformation occurred at the temperature range of 240–400 °C. The pyrolytic behavior was assessed by estimating the kinetic parameters, using the isoconversional models of Kissenger–Akahira–Sunose and Ozawa–Flynn–Wall. The average values of the activation energy of carrot and mott grasses were shown to be 267 kJ mol−1 (R2 ≥ 0.98) and 188 kJ mol−1 (R2 ≥ 0.98), indicating the suitability of both grasses for co-pyrolysis. Whereas, the difference in the values of enthalpy change and the activation energy was shown to be <~5 kJ mol−1 at each fractional point, which indicated that the product formation was being favored. Moreover, the high heating values of carrot grass (18.25 MJ kg−1) and mott grass (18.63 MJ kg−1) have shown a remarkable bioenergy potential and suitability of co-pyrolysis for both grasses. This study will lead to establishing an energy-efficient and cost-effective process for the thermal transformation of biomass to bioenergy.

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“…All combustible compounds were oxidized at this stage where the sample reacted with oxygen to produce ash. The DSC curves show that the overall decrease in heat flow indicating that the main components of biomass are actively changing at a temperature of <600°C is similar as reported [42], [43].…”

Kinetic Pyrolysis of Some Herbaceous Biomasses- Two Kinds of Grasses

“…The average activation energies were 296.29-290.69 and 216.75-215.07 kJ.mol -1 for CS and JIL samples, by KAS and FWO methods, respectively (Table 3). CS biomass showed similar Ea when compared to carrot grass [11]. Whereas, the Ea average of JIL grass were so similar to the mean activation energies of elephant grass (218-227 kJ mol −1 ), rice husk (221-229 kJ mol −1 ) [15], Laminaria japonica (207.7 kJ mol −1 ), Sargassum pallidum (202.9 kJ mol −1 ) [26] and Enteromorpha prolifera (228.1 kJ mol −1 ) [27].…”

“…Among these materials, grasses can be transformed into high energy content biofuels. Kinetic pyrolysis of different types of grasses has been studied, such as Switch grass [7][8][9], carrot grass (congress grass) [10][11], Camel grass [12], Para grass [13], and Elephant grass [14][15][16].…”