利用改質氧化鈣吸附二氧化碳之效?探討; Investigation on CO2 capture efficiencies achieved with modified calcium oxides materials

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Please use this identifier to cite or link to this item: http://ir.lib.ncu.edu.tw/handle/987654321/61302

Title:	利用改質氧化鈣吸附二氧化碳之效?探討;Investigation on CO2 capture efficiencies achieved with modified calcium oxides materials
Authors:	曾怡玲;Lin,Chen-yi
Contributors:	環境工程研究所在職專班
Keywords:	二氧化碳捕獲;吸附劑;氧化鈣;熱重分析;CO2 capture;Ca-Al-CO3;Adsorbents;Thermal gravimetric analysis
Date:	2013-07-25
Issue Date:	2013-08-22 12:17:55 (UTC+8)
Publisher:	國立中央大學
Abstract:	隨著地球暖化逐漸加劇，降低CO2排放為現今世界各國努力的目標，而發展CO2捕獲關鍵技術為減排技術之重要研究方向。中高溫捕獲CO2可降低能損，並具有吸附質含量高(約10-15% CO2)之優點，此技術又以含氧化鈣材料最具有優勢。因此，利用高性能吸附材料進行CO2捕獲，未來也必然成為重要趨勢之一。文獻指出高溫劣化為氧化鈣捕獲CO2之缺點，將嚴重降低捕碳劑之長期穩定性。本研究針對二氧化碳捕捉技術開發，探討含氧化鈣中高溫吸附材料製備及其CO2吸脫附效率。利用共沉法將三種鈣離子前驅物與鋁離子前驅物共沉後，再經由高溫?燒處?，以生成層狀Ca-Al-CO3吸附劑。同時針對自製層狀Ca-Al-CO3吸附劑進行BET、XRD、SEM 等特性分析及利用TGA 測試CO2吸附效率，以進行二氧化碳吸附效能之評估。結果顯示三種吸附劑係為中孔洞吸附劑之吸附行為。由實驗結果得知，三種吸附劑最適吸附溫度皆落在750°C，起始吸附量以(Ca-Al-CO3/CaO) (55.8%)最高，其次Ca(OAc)2-LDH (52.1%)，最差者為Ca(NO3)2-LDH (46.9%)。(Ca-Al-CO3/CaO)不但具有最佳的捕碳性能，經過40 次的吸脫附測試後，仍維持96%穩定性之優越性能。未來若能將此技術用於含氧化鈣之礦物改質，將成為極具有潛力之碳捕獲技術。關鍵字：二氧化碳捕獲；吸附劑；氧化鈣；Ca-Al-CO3；熱重分析 Combustion of fossil fuel causes increasing atmospheric CO2 concentration and induces man-made greenhouse effect, hence, developing effective technique for CO2 capture to mitigate its emission has become an important issue. The medium-high temperature CO2 capture technique has the major advantage of decreasing the energy penalty and is of a high capture efficiency at a high CO2 concentration (ca. 15-50%CO2). Material containing CaO is a promising candidate for adsorbing CO2 under elevated temperature, which should be a promising trend in the future. Previous study indicates that the sintering of CaO at high temperature is the major reason for the decay of CO2 capture, resulting in the poor stability of sorbent. This research aims to develop an effective CO2 capturing technology via the preparation and testing of CaO-based layer double hydroxides (LDHs) sorbents. This study focuses on the development of a Ca-Al-CO3 sorbent derived from three kinds of precursors: (I) (Ca-Al-CO3/CaO) (II) Ca(OAc)2-LDH and (III) Ca(NO3)2-LDH. Ca+2 ions are incorporated into layered structure by co-precipitation of Al (NO3)3?9H2O and Na2CO3 under alkaline conditions. The characteristics of synthesized sorbents such as surface area, morphology/particle size and crystalline are determined by BET (Quantachrome), SEM (Hitachi) and PXRD (Bruker), respectively. Sorption properties of CO2 on CaO are monitored by recording weight change of sorbent with a Thermo-gravimetric analyzer (TGA, Netzsch) operated at alternately cycling experiments of adsorption and desorption for CO2 capture. The results showed that the microscopic characters of sorbents were mainly mesoporous. CO2 sorption capacities (g CO2/g sorbent) at 750 °C were in the range of 0.524-0.672 and they were significantly related to sorbents, wherein (Ca-Al-CO3/CaO) (55.8%) >Ca(OAc)2-LDH (52.1%) > Ca(NO3)2-LDH (46.9%). The best Ca-Al-CO3 sorbent was from (Ca-Al-CO3/CaO) that provided at least 96% CO2 sorption recovery after 40 adsorption/desorption cycles. These materials are worthy to be further studied for the modification of alkaline minerals as a potential CO2 sorbent. Keywords: CO2 capture Adsorbents CaO Ca-Al-CO3 Thermal gravimetric analysis(TGA).
Appears in Collections:	[Executive Master of Environmental Engineering] Electronic Thesis & Dissertation

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