Experimental Study On The Influence Of Soaked-potassium Salts On The Pyrolysis Of Biomass Components

As the clean and renewable energy, the utilization of biomass attracted increasing concern. Pyrolysis can convert biomass to solid char, liquid oil, and biogas. Biomass is mainly consisted of cellulose, hemicellulose and lignin and inorganic compounds(alkali and alkaline earth metal salts). During biomass pyrolysis, there exists strong influence of inorganic species on biomass pyrolysis. This study is focused on the influence of potassium salts on the pyrolysis of three major constituents of biomass, thus provided referred solutions to relative problems theoretically.First, the existence form and transformation behavior of potassium biomass components was analyzed. The pyrolysis of biomass samples was carried out in a micro fixed-bed and the products of char, coke, heavy oil, light oil, bio-gas was collected in term of exploration the char, gas, and tar characteristics. The mount of potassium in different potassim speciations was analyzed using the microwave dissolver and ICP-MS. Investigate The mechanism of potassium influence on the biomass pyrolysis was analyzed.Then, the influence of K on pyrolytic products was investigated, the results showed that K2SO4 is the most appropriate salt to represent the influence of potassium on the pyrolysis of biomass components among the soaked potassium salts, which is increase the yield of char, gas, and decrease the yield of bio-oil. The chemical composition of solid products was characterized by Fourier transform infrared spectroscopy(FTIR), elemental analysis, and X-ray photoelectron spectroscopy(XPS). The liquid products were analyzed by gas chromatography-mass spectrometry(GC-MS). The contents of the gas products determined by Four-Channels Micro-Gas Chromatograph(GC). According to the difference between the products, the influence of potassium salts on the pyrolysis of biomass was analyzed. During pyrolysis process, cellulose and hemi-cellulose underwent decomposition through heterolytic fission of glucosidic bond under transglycosylation reaction and open-loop forming the fatty chain structure, the presence of potassium promote the fatty chain structure form the benzene and the dence-ring of it to release H2, prevent it escape as the volatiles to form the coke. On the other hand, the presence of potassium promote the transformation of ether bond to aldehyde group, and inhibit it to carboxyl group to increase the yield of carbon monoxide, and decrease the yield of carbon dioxide. The formation of carbon dioxide from carboxyl group during the pyrolysis of hemicellulose was evidently promoted.