Research On Fractionation Of Pyrolysis-oil From Agricultural And Forestry Biomass And Characterization Of Pyrolytic Lignin

Pyrolysis-oil botainted from agricultural and forestry biomass is a good raw material for preparing high value-added chemicals and liquid fuels due to its abundant chemical composition. However, the pyrolysis-oil utilization is not high due to the complexity of compounds and heterogeneity of composition distribution. Fractionation is an effective way to achieve efficient usage of pyrolysis-oil according to the different characteristics among the composition. In this paper, Softwood (larch) pyrolysis-oil, hardwood (yellow poplar) pyrolysis oil and herb (corn stalk) pyrolysis oil were studied. The physico-chemical properties, chemical composition and component distribution of pyrolysis oil were analyzed via a variety of analytical methods, such as GC-MS, solvent extraction, and etc. The formaldehyde consumption was used as an indicator to examine chemical reactivity of phenolic fraction. Radical scavenging activity was used as an indicator to examine oxidation activity of water-soluble fraction and phenolic fraction. Furthermore, the weight loss characteristics and product formation rule of pyrolytic lignin were studied by TG-FTIR and Py-GC/MS. The main conclusions are as follows:(1) Moisture content of pyrolysis-oil was 19%～27%, pH value in the range of 2.5 to 3.8, and kinematic viscosity was 30～50 mPa-s. The main components were phenols, ketones, aldehydes, acids, esters and sugars.(2) The relative content of ether-souble fraction (acids, aldehydes, ketones), ether-insoluble fraction (sugars), dichloromethane-souble fraction (phenolic compounds) and dichloromethane-insouble fraction (pyrolytic lignin) were 18%～23%,32%～38%,15%～20% and 6%-9%.(3) The biological activity analysis showed that the water-souble fraction and phenolic fraction of purolysis-oil both had antioxidant activity, and gradually increased with the increasing of the sample concentration.(4) The chemical reactivity of phenolic components and pyrolytic lignin analysis showed that the chemical reactivity with formaldehyde of the two fractions were up to 80% and 25% compared to phenol.(5) The Py-GC/MS and TG-FTIR analysis showed that pyrolytic lignin was easier to depolymerize compared with MWL, and the pyrolysis degree and liquid yield were higher. The main product was phenolic compounds, which relative content was higher than that of alkali lignin pyrolysis products.