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

Abstract

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, TiO 2 , fly ash and graphite. Pyrolysis was conducted up to 600 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.

Evaluation of synthesized green carbon catalyst from waste date pits for tertiary butylation of phenol

“…A further increase in the temperature results in a decrease in the phenol conversion, and this can be attributed to thermodynamics of alkylation and de-alkylation reaction at higher temperatures [24]. Furthermore, it can be also related to the fact that at a higher temperature, several parallel reactions start occurring which consumes olefins in side reactions resulted from dehydration of tertiary-butanol, such as oligomerization, alkylation, and cracking [27]. While it is a sure fact that cracking is dominant at high temperatures, this causes a decrement in phenol conversion [27].…”

“…A maximum acidic strength was observed to be 4.9 mmol/g [26]. Shihai et al synthesized sulphonated carbon catalysts from char produced by pyrolysis of waste biomass for bio-oil production, and accredited it to low cost feedstock acid catalysts [27].…”

Microwave pyrolysis of biomass for bio-oil production: Scalable processing concepts

“…Microwave pyrolysis of biomass has demonstrated the potential to produce a unique grade of products owing to the unique thermal gradients that exist during processing [38][39][40][41][42][43][44]. In fact, the exceptional cooler surroundings during microwave heating enables the preservation of much larger amounts of easily-cracking compounds such as carbohydrate derivatives.…”

“…The rotating cavity comprises a main body, a microwave absorbing layer (55) -made from SiC or partially stabilized zirconia-, and an insulating layer (18) between the body and absorbing layer -which is composed by non-microwave absorbing materials (Al2O3, SiO2, mullite)-. An important reported issue is the need for a careful design of the exit port (40) to allow the removal of the processed material and to avoid microwave leakages. Figure 9 depicts the electromagnetic evaluation of the rotating kiln concept during the microwave pyrolysis of biomass using the method described in [52].…”

Microwave pyrolysis of lignocellulosic biomass––a contribution to power Africa

“…However, with microwave-assisted pyrolysis, the lignocellulose components decomposed at lower temperature (around 100-150°C lower) [115,125]. Generally, the lignocellulosic biomass components under microwave-assisted pyrolysis would produce more bio-oil than electrical heating pyrolysis [124,126].…”