(87d) Efficient Hydrogen-Rich Syngas Production Via Microwave-Induced Gasification of Bio-Char Derived From Agricultural Residues

Rice straw and corn stover are the major agricultural residues produced in large quantities in China, and most of them are consumed as conventional household fuels for stoves. Until recently, China is strongly encouraging the use of biomass for energy purposes, and the pyrolysis of biomass is an attractive option, for it provides a highly efficient way to produce bio-fuels. The bio-char, as a by-product in the pyrolysis of biomass during bio-oil production, is qualified to be used for syngas production due to its high carbon content. Compared with carbon monoxide, hydrogen energy is not only a clean, highly efficient and promising energy, but also can be used as material for hydrogenation to upgrade bio-oil quality, thus comprehensive and systematic investigation on hydrogen-rich syngas production from bio-char is needed.

A potential problem related to char reactivity, in large gasification systems, is that char particles might exit the system prior to their complete conversion. Main reasons for this incomplete conversion include in uneven temperature distribution in the reactor results in the presence of low temperature zones, which subsequently results in low reaction rates to provide poor conversion rates of the char. As microwave energy is transferred directly to the material that is heated, the temperature inside the material is usually higher than the temperature of the surrounding atmosphere, unlike conventional heating. Microwave radiation is known to have the potential to increase the rate of reaction, selectivity and yield of catalytic heterogeneous reactions. The improvement observed under microwave heating is normally attributed to various thermal effects, although the presence of microplasmas or hot spots within the catalyst bed, which are at higher temperature than the average temperature, may be the main reason for the improvement in gas-solid reactions. Microwave heating offers a number of advantages over conventional heating, such as non-contacting heating, rapid and selective heating of materials, higher flexibility, and reducing processing time. So, it could provide a more homogeneous temperature and random microplasmas in different reaction sites, which increases the conversion rates of the char.

The gasification of rice straw and corn stover chars with different oxidizing agents will be investigated in a fixed-bed reactor in a microwave irradiation environment. This exploratory study focuses on the gas composition, concentration of hydrogen, and the carbon conversion efficiency. Meanwhile, it is also expected to determine the influence of char structure and operating condition on gas yields, and find the role of the inherent catalyst in the reaction, thus lay the foundation for engineering application.