Influence of CO2 addition on Catalytic partial oxidation of methane in a heat recirculation reactor

• Main Authors: Shih-Cheng Lin, 林士誠
• Other Authors: Shyh-Jiun Liu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/68118153416102924471

碩士 === 國立臺南大學 === 綠色能源科技學系碩士班 === 102 === The reaction phenomena of catalytic partial oxidation of methane (CPOM) in a Swiss-roll reactor are studied numerically where a rhodium-based catalyst bed is embedded at the center of the reactor. The advantages of the Swiss-roll reactor include heat recovery, small volume, and saving energy. CO2 addition in the feed gas for the purpose of CO2 utilization is also considered in the study. The present study consists of two parts to explore the influences of important parameters on the performance of CPOM; the energy efficiency of the reaction is also taken into account. In the first part of the study, the influences of CO2 addition and heat recovery on CPOM are studied where the feed gas is preheated in the Swiss-roll reactor to implement higher reaction performance and syngas production. The mole ratio of O2 to CH4 (O2/CH4 ratio) is fixed at 0.5 and the mole ratio of CO2 to O2 (CO2/O2 ratio) is in the range of 0-2. The results reveal that CO2 addition into the influent has a slight effect on methane combustion, but significantly enhances dry reforming and suppresses steam reforming. Compared to the reactor without excess enthalpy recovery, heat recirculation drastically increases the maximum reaction temperature and CH4 conversion in the catalyst bed; it also intensifies the H2 selectivity, H2 yield, CO2 conversion, and syngas production rate. The predictions indicate that the heat recirculation is able to improve the syngas formation up to 45%. In second part, the impact of the O2/CH4 ratio and CO2/O2 ratio are in the ranges of 0.4-0.6 and 0-2, respectively. The results show that the O2 content in the feed gas is the main cause affecting methane combustion reaction, whereas the impact of CO2 content is slight. CO2 addition significantly increases the reaction rate of dry reforming, CO2 consumption, and improves the energy efficiency. However, CO2 conversion decreases with increasing CO2 addition. The higher methane conversion and hydrogen yield occur high oxygen contents. Meanwhile, because of higher reaction temperatures at higher O2 concentrations, steam reforming and dry reforming are intensified. In summary, CO2 addition in a Swiss-roll reactor can be a potentially route to reuse CO2, and can improve the energy efficiency up to 3.1%.