【摘要】：CO2等溫室氣體的大量排放導(dǎo)致全球氣候變暖,CO2減排成為重大緊迫需求。O2/CO2循環(huán)燃燒技術(shù)能大規(guī)模降低燃煤CO2排放,但制氧的高昂成本限制該技術(shù)發(fā)展。一種利用鍋爐排出煙氣中的二氧化碳和鈣鈦礦反應(yīng),生成氧氣濃度較高的O2/CO2混合氣體的鏈?zhǔn)街蒲跫夹g(shù)很有發(fā)展前景。為尋找一種釋氧性能良好且結(jié)構(gòu)穩(wěn)定的鈣鈦礦型載氧體,本文通過正交實(shí)驗(yàn)改進(jìn)了微波輔助溶膠凝膠法,合成了不同A位/B位組成的Ba-Co-O系列鈣鈦礦型金屬氧化物,并通過固定床實(shí)驗(yàn)結(jié)合XRD和ESEM等分析手段對其反應(yīng)特性以及循環(huán)性能等進(jìn)行了實(shí)驗(yàn)研究。主要的實(shí)驗(yàn)內(nèi)容和結(jié)論如下:固定床實(shí)驗(yàn)結(jié)果表明,A位、B位取代摻雜對鈣鈦礦載氧體的釋氧性能有很大影響,A位應(yīng)選擇離子勢小、離子半徑大的堿土金屬Ba,而B位應(yīng)選擇可變價(jià)離子勢小的Co,BaCoO3-δ的釋氧性能最好;BaCoO3-δ反應(yīng)前后的ESEM圖和XRD圖得出,反應(yīng)前樣品蓬松多孔,主要是鈣鈦礦結(jié)構(gòu);反應(yīng)后樣品出現(xiàn)明顯團(tuán)聚,主要為BaCO3、Co3O4和CoO。BaCoO3-δ型載氧體與CO2反應(yīng)釋氧的最佳吸附、脫附溫度都是850℃左右,釋氧量隨著吸附溫度和脫附溫度的增加先增加后減小;釋氧量隨著氧吸附時(shí)間增加而增加,超過30 min后增加緩慢;反應(yīng)壓力對反應(yīng)影響很大,氧脫附量幾乎隨著壓力增加呈線性增長。由正交實(shí)驗(yàn)得出微波輔助溶膠凝膠法的最佳條件為:pH值8,微波時(shí)間25 min,微波功率77%(額定功率700 W),馬弗爐煅燒溫度500℃,影響因素的主次順序?yàn)?pH微波時(shí)間煅燒溫度微波功率。ESEM圖和XRD圖分析得出正交實(shí)驗(yàn)制得的BaCoO3-δ均為鈣鈦礦相,偏酸性或強(qiáng)堿性前驅(qū)體溶液均不適合BaCoO3-δ鈣鈦礦晶體的生長,長時(shí)間大功率微波以及高溫煅燒會(huì)使樣品表面發(fā)生燒結(jié)。BaCoO3-δ的循環(huán)釋氧性能良好,循環(huán)前后的ESEM圖和BET結(jié)果表明循環(huán)后BaCoO3-δ樣品變化不大,空隙減少不明顯,能夠?yàn)镺2/CO2循環(huán)燃燒供給穩(wěn)定的O2/CO2混合氣體。
[Abstract]:Due to the large amount of greenhouse gas emissions such as CO2, global warming CO2 emission reduction becomes an urgent need. O2 / CO2 cycle combustion technology can greatly reduce CO2 emissions from coal combustion, but the high cost of oxygen production limits the development of this technology. A chain-type oxygen-making technology which uses the reaction of carbon dioxide and perovskite from flue gas from boiler to produce O2/CO2 mixed gas with high oxygen concentration has a good prospect. In order to find a perovskite-type oxygen carrier with good oxygen release performance and stable structure, the microwave-assisted sol-gel method was improved to synthesize Ba-Co-O series perovskite-type metal oxides with different A / B sites. The reaction characteristics and cyclic properties were studied by means of fixed bed experiment combined with XRD and ESEM. The main experimental contents and conclusions are as follows: the results of the fixed bed experiment show that the doping at the B site at the A site has a great influence on the oxygen release performance of perovskite oxygen carriers. The ion potential at the A site should be small. The Ba, of alkali earth metal with large ion radius and Co,BaCoO3- 未 with small variable valence ion potential should be chosen as the best oxygen releasing property. The ESEM and XRD diagrams before and after the reaction show that the sample is fluffy and porous, mainly perovskite structure. After the reaction, the samples showed obvious agglomeration, mainly the best adsorption of BaCO3,Co3O4 and CoO.BaCoO3- 未 oxygen carriers to CO2. The desorption temperature was about 850 鈩，

本文編號(hào)：2226239