| Summary: | 碩士 === 逢甲大學 === 綠色能源科技碩士學位學程 === 100 === This research investigated the feasibility of enhanced energy yield in gasification of rice straw by using a new prepared iron-based catalyst. The prepared iron-based catalyst contained approximately 2.34% (weight%) iron content that was manufactured from wet impregnation process with 15 impregnate time and 0.01M ferric nitrate concentration. According to the results of isothermal adsorption model, the theoretical adsorption capacity of tested zeolite was 4.22 mg Fe/g zeolite. In this research, the prepared iron-based catalyst plate was 4.5 cm in diameter that was manufactured further by operated at 900℃ calcined temperature for 3 hours. Based on the results of speciation identification, the prepared iron-based catalyst has a potential for applying in catalytic gasification due to it contained Fe2O3.
According to the results of gas composition revolution, maximum gas composition occurred in advance because the tested iron-based catalyst used in this research. In the case of lower gasification temperature, the prepared catalyst can enhance the energy yield and synthesis gas (H2 and CO) production. According to the results of improvement of synthesis gas quality, in the case of gasification temperature 800℃, the H2/CO ratio increased with an increase in prepared catalyst plate used. That is because the active iron compounds can promote water-gas shift reaction resulting in hydrogen production increasing. However, when the gasification temperature operated at 900℃, the H2/CO ratio and energy yield decreased significantly due to the surface of prepared catalyst had a melting or sintering tendency by biomass ash containing alkali metals (Ca, Mg, and K etc.) that it resulted in catalyst deactivation. In addition, according to the results of CH4 composition revolution, CH4 can produce approximately between 9.65% and 20.77% (v/v) that it is because the gasification reaction will tend to the hydrodealkylation and methanation reaction. Meanwhile, methane steam reforming reaction could not occur without enough steam provided in this research. Hence, the produced gas can yield more methane production and relatively lower in hydrogen production.
The energy density (ED) is an important index for explanation of energy yield efficiency in gasification of rice straw. In this research, in the case of gasification temperature 700℃ and 800℃, the ED increased with an increase in catalyst addition that it was approximately 65% and 56%, respectively. It can be concluded that the new prepared iron-based catalyst can enhance effectively on energy yield in gasification of rice straw operated at temperature 800℃ and below. Besides, in the case of 800℃ and 3 layers catalyst plate addition, the ED is almost equal to that of gasification temperature 900℃ condition. Based on the results of prediction for iron speciation, when gasification temperature increased between 800℃ and 900℃, the prepared iron-based catalyst used in our research can be reduced to active metal iron (Fe0). In summary, the new prepared iron-based catalyst used in this research could reform and reduce the tar production, but also has been developed as a potential catalyst for improving quality of synthesis gas in gasification of rice straw.
|
|---|
