Molecular characterization of organic aerosol particles from biomass pyrolysis

Organic aerosol (OA) particles, as important parts of biomass pyrolysis tar, have a negative effect on the quality of pyrolysis oil by coking, while their physical and chemical properties are rarely reported. In this work, the flash and fast pyrolysis of lignocellulosic biomass and its individual components (cellulose, xylan and lignin) were conducted in a microfluidized-bed reactor (MFBR) and a U-shaped fixed-bed reactor (U-FBR), respectively. A vacuum ultraviolet photoionization aerosol mass spectrometer (VUV-PI-AMS) was used for the online characterization of chemical components of OA particles, and their size distributions were determined by a scanning mobility particle size spectrometer (SMPS). The effect of feedstock types, pyrolysis temperatures and heating rates on the properties of OA particles from biomass pyrolysis was investigated and discussed. The experimental results show that the chemical components of OA particles from biomass pyrolysis dominated by carboxylic acids, furans, pyrans, lignin monomers and oligomers. The sizes of biomass-derived OA particles center at about 110 and 240 nm for the flash and fast pyrolysis, respectively. All detected OA particles exist in the form of liquid state. The high heating rate would improve the formation of lignin oligomers in particle phase.