Experimental Study On Biomass Pyolysis In Molten Salt Media For Bio-Oil Production

Bio-oil is a focal point of research in the cleaning utilization technology of biomass energy. For convenience, there are two approaches for the bio-oil production technology, fast pyrolysis and high-pressure liquefaction. In this paper, an innovative way, thermal pyrolysis of biomass in molten salt media, was proposed for its potential to produce fuels and chemicals.The chemical quantitative analysis method improved on the basis of X.H.Boqinnuoke’s method was established. Contents of cellulose, hemicellulose and lignin in six kinds of biomass raw materials were determined. Three trace elements （potassium, calcium and iron） in those biomass raw materials were also determined by ICP-MS after H₂SO₄-H₂O₂ digestion.The investigations on the pyrolysis process of hydroxypropyl methylcellulose and rice stalk were carried out by thermogravimetry（TG）. The differences during the pyrolysis process of biomass raw materials were compared and the influences of heating rate on pyrolysis process were analyzed. The pyrolysis kinetic laws of these two kinds of biomass were developed with integral method and the kinetic parameters were calculated. Three kinds of metal salts （FeCl₂·4H₂O, CuCl and 34.0mol%CuCl-KCl） were introduced in to mixed with biomass materials and their influences on pyrolysis process were deeply studied. Thus, basic datas for the pyrolysis mechanism research were provided.The cooling curves of mixed salts were plotted and their melting points were determined by thermal analysis method. Pyrolysis experiments were carried out in a self-designed reactor, fed with a controlled flow rate of nitrogen and equipped with accessories to collect liquid. Several kinds of mixed molten salts were used as thermal pyrolysis media and two kinds of biomass were used as feedstock. The pyrolysis process was performed under atmospheric pressure and 400-600℃. The influences of the molten salt type, feed type, and reaction conditions, including temperature and space velocity, on yield of liquid product were investigated. Bio-oils were analyzed by GC-MS method and FTIR method. The components of bio-oil were very complexity, while furan was relatively high.