合成氣中13X分子篩吸附捕捉二氧化碳

氣化程序後的合成氣（Syngas）含有CO、H2、CO2、CH4、CmHn、N2等成分，透過觸媒催化反應生成甲醇可作為生物質與其他化合物的中間物，最大用途為石化工業的原料，亦可間接加入汽油或直接作為交通運輸之燃料，但合成氣中的CO2在甲醇催化反應過程中會產生水的副產物，造成後續觸媒壽命及催化效能的影響。為了解決水的副產物及提高甲醇催化效能，需透過二氧化碳捕捉系統去除不需要的氣體以提高H2比例，故本研究使用13X分子篩作為氣體吸附劑，在單一組成氣體混合物及合成氣組成氣體混合物的實驗條件下，以氣相層析儀（GC-TCD）進行動態吸附實驗分析。根據動態吸附研究結果，13X分子篩在合成氣中有效選擇性捕捉二氧化碳。在單成分氣體對進料流速、床體溫度及CO2進料濃度等操作參數進行討論，結果得出最佳條件為進料流速150ml/min、床體溫度25℃及CO2入口濃度25%時有最大CO2吸附量135.75 mg/g。在多成分氣體條件下，以相同的最佳參數進行吸附可得最大CO2吸附量128.96 mg/g，證明在含有CO的條件下幾乎不會影響CO2的吸附能力。最後藉由增加吸附劑量改變吸附床高使CO2吸附量明顯提高及貫流時間增加，對於未來工業設計上貫流時間可提供何時需更換吸附材的重要資訊。

關鍵字

13X分子篩；合成氣；二氧化碳；動態吸附；貫流曲線

並列摘要

The gasified syngas contains CO, H2, CO2, CH4, CmHn, N2 and other components, and can be used as an intermediate between biomass and other compounds to generate methanol through catalytic reaction. The largest use of methanol is as a petrochemical feedstock. It can also be added indirectly or directly to gasoline for use as a transportation fuel. However, the CO2 in the syngas will produce water by-product during the methanol catalytic reaction, which will affect the subsequent catalyst life and catalytic performance. In order to solve the by-product of water and improve the catalytic efficiency of methanol, it is necessary to remove unnecessary gases through a carbon dioxide capture system and increase the composition of H2 in syngas. Therefore, molecular sieve 13X was used as the gas adsorbent in this study. The dynamic adsorption experiments were analyzed using a gas chromatograph (GC-TCD) under the experimental conditions of single-component gas mixture and syngas component gas mixture. According to the results of dynamic adsorption studies, 13X molecular sieves are effective for the selective capture of carbon dioxide in syngas. Operating parameters such as feed flow rate, bed temperature and CO2 feed concentration are discussed in single component gas. The results show that the optimum conditions are that the maximum adsorption capacity of CO2 is 135.75mg/g when the feed flow rate is 150ml/min, the bed temperature is 25℃, and the CO2 inlet concentration is 25%. Under the condition of multi-component gas, the maximum CO2 adsorption capacity of 128.96 mg/g can be obtained under the same optimal parameters, which proves that the CO2 adsorption capacity is hardly affected under the condition of CO containing. Finally, by increasing the amount of adsorbent and changing the height of the adsorption bed, the CO2 adsorption capacity was significantly improved and the breakthrough time was increased. For future industrial designs, breakthrough time can provide important information on when to replace the sorbent.