Experimental Study On Production And Properties Of Bio-oil By Catalytic Pyrolysis Biomass

With the rapid development of industrialization and population in the world, the contradiction between the demand for the energy and lack of the traditional fossil fuels become more and more prominent. The development of new energy and renewable energy is particularly urgent topic. The bio-oil generated by the pyrolysis liquefaction process has the potential alternatives to fossil fuels, but the appropriate modification and upgrade quality is needed before industrial applications. The catalytic pyrolysis process, due to the simple equipment and the moderate operating conditions, has been investigated widespreadly.The experiments of the rice husk pyrolysis were performed in a fixed-bed reactor to produce bio-oil. The effects of the different operation factors such as pyrolysis temperature、sweeping gas (N2) flow rates and ZnO catalyst mixing ratio on the yields of three products and the characteristics of bio-oil were investigated. The maximum liquids yield of49.91%was obtained at550℃pyrolysis temperature with a heating rate of25℃/min and nitrogen flow rate of150mL/min. The liquid yield decreased with the increase of the catalyst mixing ratio. The results of thermal gravimetric analysis indicated that the devolatilization of main pyrolysis reactions occurred in the range of200～385℃. When the temperature reached500℃, the volatile matter in biomass almost has been released completely.The bio-oils yielded with and without catalyst were characterized by FT-IR and GC/MS. The results showed that the main identified compounds of bio-oils were phenols, phenol derivatives and long-chain aliphatic compounds. A series of rheological tests were performed for the two kinds of bio-oil with cone and plate rheometer. The results indicated that both types of bio-oil were typical non-Newtonian and strongly-shear thinning liquids in the flow behavior. The viscosity of the ZnO-treated bio-oil was significantly lower than that of the bio-oil without any catalyst.Thermogravimetric and differential thermal analysises were introduced to study the combustion behavior of the bio-oils. The kinetic parameters of bio-oil combustion were obtained by Coats-Redfern model and the results showed that the bio-oil by catalytic processing contained more volatile small molecule compounds and the addition of catalyst could improve the combustion behavior of bio-oil. The activation energy of the combustion reactions of the bio-oil after the catalytic process decreased significantly. Solid products from the pyrolysis of residual carbon was analyszed by elemental analysis, approximate analysis, SEM and XRD methods and the results showed that the pyrolysis temperature had a great influence on surface morphology of the coke, pyrolysis temperature of550℃was sufficient to make the raw materials to complete pyrolysis. With the increasing of pyrolysis temperature, the silicate crystal structure was observed at the coke surface.