| Biomass is a rich, environmentally friendly and renewable resource which can be converted to high-quality liquid fuels or high value-added chemicals using thermochemical means. Bio-syngas can also be produced from biomass gasification and bio-oil reforming. The development and application of biomass renewable energy is receiving great attention. However, there are still some problems for the utilization of biomass energy, especially, how to increase the efficiency to make biomass energy become the complement of petroleum. The main points of present work were focused on the items as follows:1. Studies on hydrogen-rich bio-syngas production from bio-oil steam reforming.A carbon nanofibers supported Ni catalyst was prepared for hydrogen production from bio-oil steam reforming. The effects of reforming temperature and S/C on bio-oil conversion, hydrogen yield and gas compositions were investigated. Results show that the increasing temperature and S/C can significantly promoted the bio-oil conversion. During our investigated range (the temperature ranges from350℃to550℃, and the S/C ranges from2to7), the maximum bio-oil conversion and hydrogen yield reached about94.7%and92.1%respectively. The main contents in the syngas were hydrogen and carbon dioxide, reaching about a volume fraction of69%and26%. Besides, a small amount of carbon monoxide and a trace of methane were detected in the bio-syngas.2. Studies on the process of bio-syngas conditioning using biomass charThe present work proposed a new method of CO2-rich bio-syngas conditioning by using biomass char. The work aims to decrease the content of CO2and increase the content of CO in the conditioned syngas for producing liquid fuels through the reaction of biomass char and the excess CO2in the unconditioned syngas. The effects of catalyst/char (the mass ratio of catalyst and char), temperature and gas flow were investigated in the process of CO2-rich bio-syngas conditioning. The CO2conversion, CO yield, CO2/CO ratio and the gas compositions of the conditioned syngas were employed for evaluating the performance of conditioning. Results show that CO2conversion and CO yield reached about71.1%and0.88respectively at800℃, the CO2/CO ratio decreased from6.33to0.28, and the gas compositions of the conditioned syngas were suitable for conventional liquid fuels synthesis from syngas. To make clear the process of conditioning, the present work was also studied the two main paths (i.e. CO2+C=CO and CO2+H2=CO+H2O) by using model gases of CO2and CO2/H2. Furthermore, the activated carbon (AR), husk char and sawdust char were used for the conditioning of CO2-rich syngas, indicating that biomass char as well as activated carbon can be used for the conditioning. In addition, the results show the current can greatly improve the performance of conditioning in terms of CO2conversion and CO yield. At4A and600℃, the CO2conversion reaches about82%, the CO2/CO ratio drops to about0.11, when further increased the temperature to600℃, CO2was almost completely converted.3. Methanol and dimethyl ether synthesis from the unconditioned and conditioned bio-syngasTo certify the effects of the present conditioning, two model syngases corresponding to the unconditioned and the conditioned bio-syngas were used for methanol and dimethyl ether (DME) synthesis. Results show that, for methanol synthesis from the unconditioned bio-syngas during our investigated ranges, the maximum carbon conversion and space time yield of methanol are12%and0.44kg/(kgcatalyst h), and increase to23.9%and1.32kg/(kgcatalyst h) after conditioning. Similarly, for DME synthesis from the unconditioned syngas, the maximum carbon conversion and DME yield were15.1%and12.7%, which increased to84.8%and60.1%respectively from the conditioned syngas. |
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