Bio-oil production via catalytic microwave co-pyrolysis of lignin and low density polyethylene using zinc modified lignin-based char as a catalyst

In order to improve the product quality and make the process more sustainable, lignin-based char was used as a catalyst during microwave co-pyrolysis of lignin and low density polyethylene (LDPE). Lignin-based char modification using zinc transition metal proved to be beneficial by improving the porosity and selectiveness of the prepared catalyst. General selectivity of lignin-based char catalyst was observed to produce bio-oil with high selectivity of valued compounds. GC/MS analysis proved that the major chemical components of the bio-oil were hydrocarbons, ketones, alcohols, phenols and guaiacols(∼70%). A central composite experimental design (CCD) was used to optimize the product yield and component composition. The optimum condition to produce the highest quantity and quality of bio-oil was 450 °C and 12.5% LDPE/lignin ratio. GC analysis of the syn-gas revealed that the valued compounds were H2, CO and CH4, the content of which was about 40%, 20% and 5%, respectively.