Insights Into The Co-pyrolysis Of Oil Sands And Biomass Using Microwave Irradiation

Pyrolysis is an efficient resource conversion technology.It is widely used in the processing of fossil resources and biomass resources.Researchers have payed attention on microwave-assisted pyrolysis because of its unique heating characteristics and influence mechanism.In this study,in order to convert the oil sands and biomass（sawdust）into value-added chemicals in an efficient way,we studied co-pyrolysis behaviors of raw materials using microwave radiation.For one thing,compared with conventional pyrolysis,we explored the effect of microwave radiation.For another,compared with theoretical values,we explored co-pyrolysis synergies.Infrared spectrometer was first used to research the thermal decomposition behaviors of raw materials.The weight-loss ratios at different temperature points were also studied.The results showed that the main weight-loss temperature range of the oil sands was 220-500°C and 750-900°C.For sawdust,it was 250-410°C.In the process of co-pyrolysis,the weight loss rate of different mixed materials at the same temperature point is different.The infrared spectrometer was used to study the evolution curves of different gas.In fact,the evolution rates of CH₄ and C_mH_n reached their maximum at 538°C.And the evolution rates of CO₂and CO reached their maximum at 800°C for oil sands,while it was 438°C for sawdust.The influence of operating conditions on the product yields for microwave-assisted pyrolysis was explored,and the optimal operating conditions were determined for subsequent co-pyrolysis experiments to explore the synergistic effect.The research results showed that,compared with the theoretical values,liquid yields showed negative synergies,while gas yields showed positive synergies.And the solid product yield of raw material（mixed with 20.0 wt.%sawdust）showed negative synergies,and it showed positive synergies along with the increase of sawdust ratio.A horizontal pyrolyzing furnace was used to conduct pyrolysis experiments of oil sands and sawdust in order to understand the difference of product characteristics between conventional pyrolysis and microwave-assisted pyrolysis.The average experimental value of the liquid yield obtained from microwave-assisted pyrolysis was 21.8 wt.%,which was 8.3 wt.%lower than that produced by conventional pyrolysis.However,the average gas yield was 33.7 wt.%,which was 10.9 wt.%higher.Compared with conventional pyrolytic oils,the molecular weight distributions and product compositions of microwave pyrolytic oils were different,with fewer phenols and more aromatic hydrocarbons.Because microwave irradiation can both crack the chemical bonds in large molecules,such as long-chain,branched-chain,and heterocyclic compounds and convert them into small-molecule fractions.By analyzing the surface morphology and pore size of chars,more fine particles and mesopores were found on the surface of chars from MW pyrolysis,but conventional chars performed big particle aggregates.Besides,recycling of porous MW-produced chars as MW absorbers is environmentally friendly.In this paper,the conversion of fossil fuels with biomass into higher-value energy products under microwave can potentially improve the application prospects of microwave pyrolysis technology,as microwave irradiation is effective and energy efficient in areas of oil upgrading and high quality chars producing.Furthermore,the synergistic effect of the co-pyrolysis process also provides reference for the quality upgrading of pyrolysis products.