Study On Conversion Of Biomass To Hydrogen-Rich Gas By Catalytic Pyrolysis

Presently, hydrogen is produced mainly by catalytic steam reforming of natural gas. However, in order to have environment friendly hydrogen, it must be produced by renewable methods. A number of ways and a variety of resources for producing renewable hydrogen are being investigated.Of all the renewable resources, biomass holds the greatest promise for hydrogen production in the near future. Thermochemical biomass gasification has been identified as a potential technology for producing renewable hydrogen.The effects of two types of acid (sulfuric acid, hydrochloric acid and acetic acid mixed solution) have been investigated on pyrolysis of several biomass (slegume stalk, rice husk, pine) by thermal analysis experiments under10K/min heating rate. The terminal temperature of furnace is1173K and the high pure N2is used as reacting and protecting gas. The results show that:sulfuric acid processing of biomass removed the hemicellulose and changed the chemical structure of lignin which reduced the initial thermal decomposition temperature. The mixed solution of hydrochloric acid and acetic acid removed some of the alkaline ions of biomass ash, and improved their porous structure to promote the thermal decomposition reaction that produced more volatile and increased the maximum decompose rate.In order to investigate the research on the effect of its operating conditions on pyolysis characteristics, a fluidized bed as a simulated pyrolysis reactor, was made for it. The effect of operating conditions, such as, gas velocity of flow, height of bed and kinds of particles on fluidized status were determinated to obtain the optimum operating condition of the fluidized bed and provide the necessary foundation experimental data for pyrolysis experiments.In this phase, catalytic pyrolysis of four kinds of biomass was carried out to produce hydrogen gas by using a powder-paticle fluidized bed, in which used different medium particles (SiO2, Al203,NiMo-A,CoMo-A), the effects of the medium particles and the kinds of biomass on the pyrolysis product distribution and yield were investigated respectively. It is found that in the case of the inert particle, the yield of hydrogen gas was controlled by the temperature, and the yield of rice husks reached1.33wt%,daf at1173K under the nitrogen gas. In the course of the catalytic pyrolysis for hydrogen gas, NiMo/A12O3catalyst promoted the decomposition of tar and light aromatic hydrocarbon compounds from the primary decompositions, and significantly declined the temperature of the secondary phase reaction. Meanwhile, the yields of gas products and hydrogen increased in the presence of NiMo/A12o3catalyst which keeps high activity and good stability during pyrolysis process. The catalytic performances of NiMo/A12O3catalyst to the woody biomass were better than strawy one. Selected pine as raw material, in the use of NiMo-A catalyst, hydrogen yield reached up to3.18wt%,daf and the conversion rate of hydrogen rised to52.22%at the medium temperature of873K.