Co-pyrolysis of the Chinese liquor industry waste and bamboo waste, elucidation of the pyrolysis reaction chemistry, and TG-FTIR-MS based study of the evolved gases

Abstract

• Chinese liquor industry and bamboo industry produce huge amounts of biomass wastes. • Bioenergy potential of these waste biomasses was evaluated via pyrolysis and co-pyrolysis. • The impact of mixing on the pyrolysis behavior was elucidated. • Evolved gases were analyzed using state-of-the-art coupled TG-FTIR-GCMS. • The data demonstrated their promising potential to produce clean energy for bioeconomy. Chinese liquor and bamboo are the leading industrial enterprises in China which produce huge amounts of residual biomass. This study was aimed at assessing the potential of both residual biomasses to produce clean energy and biochemicals via pyrolysis and co-pyrolysis. Both biomasses were pyrolyzed either alone (1:0 and 0:1) or co-pyrolyzed in three combinations (1:1, 1:3, and 3:1) using a thermogravimetric analyzer at five heating rates including 10 °C min −1 , 20 °C min −1 , 30 °C min −1 , 40 °C min −1 , and 50 °C min −1 . The data were interpreted through isoconversional models namely Ozawa-Wall-Flynn (OWF), Kissenger-Akahira-Sunose (KAS), and Friedman for the elucidation of pyrolysis reaction. It was shown to be a three-stage pyrolysis where major pyrolysis occurred during stage-II, between conversions (0.2–0.7), where 59–60% of the biomass was transformed to bioproducts within the temperature range of 180 °C to 450 °C, where 17–20% of the biomass was left as char. The average activation energies for the bamboo waste (labelled as B) and the liquor industry waste (labelled as D) were shown to be 151–160 kJ mol −1 for B:D = 1:0, 192–205 kJ mol −1 for B:D = 1:1, 193–202 kJ mol −1 for B:D = 1:3, 178–188 kJ mol −1 for B:D = 3:1, and 194–201 kJ mol −1 for B:D = 1:3 computed through OWF, KAS, and Friedman methods ( R 2 = 0.98–0.99). The values of activation energy, calorific values, Gibb’s free energy, enthalpy change, and pre-exponential factors indicated that the pyrolysis of bamboo waste was energy efficient when compared to the liquor industry waste, however, mixing both biomasses in the ratio of 3:1 was shown to be the most suitable co-pyrolysis scenario. The FTIR analyses of the evolved gases showed that these gases were dominated by the functional groups related to alcohols, aromatic hydrocarbons, alkynes, aldehydes, halides, ketones, esters, phenols, and amines. While TG-FTIR-GC–MS analyses confirmed the presence of aforementioned compounds in the evolved gases indicating the substantial potential of both biomasses to produce syngas and biochemicals. In conclusion, the wastes from bamboo forests and liquor industry could be renewable and carbon neutral feedstocks to produce bioenergy and biochemicals via pyrolysis and co-pyrolysis.