Thermochemical conversion of silkworm by-product into syngas

Abstract

This study explored the valorisation of silkworm by-product, a major by-product of the silk industry (sericulture), which amounts to 16 million tonnes annually. The focus was on transforming waste into energy resources through pyrolysis under CO₂ conditions. In one-stage pyrolysis, the evolution of syngas under N₂ was found to be comparable to that under CO₂. A notable allocation of carbon to biocrude rather than syngas was observed. The two-stage pyrolysis resulted in increased syngas production. However, achieving a homogeneous reaction between CO₂ and the volatiles liberated from silkworm byproduct proved challenging. Indeed, the reaction kinetics governing CO₂ reactivity was not fast although the temperature windows of the reaction were aligned in the two-stage pyrolysis. To address this issue, pyrolysis was performed using a Ni-based catalyst to expedite the reaction kinetics. Consequently, syngas formation, particularly CO formation, was significantly enhanced under CO₂ conditions compared to that under N₂ conditions. The syngas yield under CO₂ was 36.42 wt% which was 2-fold higher than that of N₂. This suggested the potential of CO₂ altering the carbon distribution from biocrude to syngas. This strategy would contribute to the establishment of sustainable production of silk by converting sericulture by-product into energy/chemical resources.

Keywords: Pyrolysis; Textile industry by-product; Waste-to-energy.