Bio-oil production via catalytic microwave pyrolysis of model municipal solid waste component mixtures

摘要

In this study, microwave assisted co-pyrolysis of mixtures of cellulose, paraffin oil, kitchen waste and garden waste that closely mimic municipal solid wastes (MSW) is conducted at different reaction conditions. Experiments were conducted in a multimode microwave reactor using ten different microwave absorbing materials (or susceptors) such as aluminium, activated carbon, garnet, iron, silica beads, cement, SiC, TiO2, fly ash and graphite. Pyrolysis was conducted up to 600 degrees C, and the effects of feed to susceptor ratio and composition of the model MSW mixture on (i) overall bio-oil, gas and char yields, (ii) heating value of the bio-oil, and (iii) composition of the bio-oil and gases, were evaluated. Besides greatly affecting the yields of bio-oil, gases and char, the susceptors played a catalytic role in altering the selectivity of the various components in bio-oil. The bio-oil contained oxygenated compounds (furans, phenolics, cyclo-oxygenates), aliphatic and aromatic hydrocarbons (mono and polycyclics). Aromatic hydrocarbons were the key products of interaction among the model components. Highest bio-oil yield of 53 wt% was achieved with an equal composition mixture at 1 : 1 wt/wt of MSW : graphite. This corresponded to nearly 95% energy recovery and 85% deoxygenation in bio-oil. High selectivities of monoaromatics such as benzene, toluene, xylene and styrene, and C8-C20 aliphatic hydrocarbons, and low selectivity of polycyclic aromatics were obtained with a majority of the susceptor-MSW combinations. Methane, ethylene, propylene, isobutylene and hydrogen were the major gaseous products, whose selectivities varied with MSW composition. This study shows that microwave assisted pyrolysis is a promising strategy to derive value added organics from MSWs.