Experimental Study of the Effect of Spray Medium on the Collection of Bio-Oil Produced from Biomass Fast Pyrolysis

The yield and properties of bio-oil are influenced by the species of spray medium used in the biomass fast pyrolysis. In this study, the GC-MS analysis of the whole bio-oil and of the mixture with isoparaffin and ethanol respectively gave information about the influence of spray medium on bio-oil composition. It is found that isoparaffin, compared with ethanol, has a slighter impact on the bio-oil composition, especially on its polar components. A series of experiments on biomass fast pyrolysis with different kinds of spray medium were carried out. The use of isoparaffin, an economic and safe solvent commonly used in industry, led to a higher bio-oil yield as compared with the use of ethanol and deionized water spray medium. For example, the yield of Pterocarpus indicus pyrolysis oil was 52.2 wt% and 47.5 wt% when using isoparaffin and deionized water respectively. As a result, isoparaffin was considered as an ideal spray medium for biomass fast pyrolysis in our study. Meantime, physical properties and chemical composition of bio-oil collected in different stages, spray condenser and surface type condenser, were analyzed. Sugars and phenols were enriched in the stage of spray condenser and surface type condenser respectively, indicating the bio-oil fractional separation could be realized by spray cooling, and providing a reference of bio-oil chemical extraction in the future.