本文選題：柴油煙氣　切入點(diǎn)：煙氣凈化　出處：《江蘇科技大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：柴油煙氣中CO、CxHy、PM和NOx是環(huán)境污染的元兇巨惡,催化氧化—還原后處理技術(shù)是凈化柴油煙氣最行之有效的方法。研究?jī)r(jià)格低廉、催化效率好的催化劑刻不容緩。鈣鈦礦型四效催化劑對(duì)凈化柴油煙氣的催化效率高,尤其是La-K-Co-Mn-O型催化劑。本文利用化學(xué)裁剪法以K離子部分取代鈣鈦礦LaCoO3 A位上的La離子,以Mn(Mn2+、Mn3+、Mn4+、Mn5+、Mn6+、Mn7+)部分取代LaCoO3 B位上的Co(Co2+、Co3+、Co4+),采用溶膠-凝膠法、檸檬酸絡(luò)合法及溶液燃燒法合成具有鈣鈦礦結(jié)構(gòu)的四效催化劑活性組分La1-xKxCo1-yMnyO3。采用溶液浸漬法或懸濁液淤漿法將La1-xKx Co1-yMnyO3浸漬到蜂窩陶瓷載體上,得到鈣鈦礦型催化劑。通過自制的性能評(píng)價(jià)裝置及柴油機(jī)車尾氣的模擬煙氣進(jìn)行脫除CO、CxHy、PM和NOx的性能試驗(yàn),并通過BET、XRD、SEM、EDS等表征方法進(jìn)行分析。研究結(jié)果表明:選取La0.8K0.2Co0.8Mn0.2O3和La0.8K0.2Co0.7Mn0.3O3為研究對(duì)象,根據(jù)催化氧化還原CO、CxHy、PM和NOx轉(zhuǎn)化率的大小,活性組分的煅燒合成溫度排序?yàn)?750℃800℃700℃900℃600℃;750℃煅燒6 h合成的催化劑催化氧化CO、CxHy、PM的轉(zhuǎn)化率分別為99.9%、95.4%、90.3%,PM的起燃溫度為225℃,最大轉(zhuǎn)化率溫度為318℃,NOx的最大轉(zhuǎn)化率為73.6%。以750℃煅燒6 h合成的La0.8K0.2Co0.7Mn0.3O3為對(duì)象,溶液浸漬法制備的催化劑比懸濁液淤漿法負(fù)載的催化效果好。中間層γ-Al2O3的粘度強(qiáng)度和涂覆量影響催化劑活性組分浸漬量和使用壽命�；钚越M分含量決定著催化劑的催化性能。試驗(yàn)結(jié)果得出:溶液浸漬法、γ-Al2O3含量為載體質(zhì)量的10%、活性組分含量為載體質(zhì)量的10%是整體式催化劑最優(yōu)的選擇�？杖急葲Q定CO、CxHy、PM與NOx相互反應(yīng)的徹底性,實(shí)驗(yàn)室模擬試驗(yàn)表明:氣體總體積4%的氧對(duì)同時(shí)去除CO、CxHy、PM和NOx最為合適。x=0.1、0.2、0.3、0.4與y=0.1、0.2、0.3、0.4的La1-x KxCo1-yMnyO3均具有鈣鈦礦結(jié)構(gòu)晶體的特征峰,K+部分取代LaCoO3的La3+后,部分Co3+向Co4+轉(zhuǎn)變,同時(shí)存在Co3+與Co4+,Co4+離子半徑小于Co3+,晶格出現(xiàn)細(xì)微畸變。Mn取代LaCoO3的Co后,Mn3+的離子半徑小于Co3+,也出現(xiàn)晶型畸變。當(dāng)K和Mn同時(shí)取代部分La和Co時(shí),畸變程度增加。少量的晶格畸變使用空隙增大,結(jié)構(gòu)空位及空位氧數(shù)量增多,比表面積增大,有利于四效脫除CO、CxHy、PM和NOx。當(dāng)X=0.2時(shí),催化氧化PM的效果最好,達(dá)到93.8%;當(dāng)y=0.3時(shí),催化氧化還原CO、CxHy、NOx的效果最佳,分別達(dá)到100%、99.9%、75.8%。從熱力學(xué)角度看,CO、CxHy、PM和NOx相互之間反應(yīng)的吉布斯自由能變量均小于零,說明CO、CxHy、PM均可以還原NOx,但受反應(yīng)溫度的影響大;La0.8K0.2Co0.8Mn0.2O3使得催化氧化—還原CO、CxHy、PM和NOx的反應(yīng)更易進(jìn)行,吉布斯自由能變量更低。從動(dòng)力學(xué)角度看,La0.8K0.2Co0.7Mn0.3O3可加快CO、CxHy、PM和NOx被催化氧化還原的速率,四效催化效率提高。
[Abstract]:COC x Hyp PM and NOx in diesel smoke are the most serious environmental pollution. Catalytic oxidation-reduction post-treatment technology is the most effective method for purifying diesel smoke. The catalyst with good catalytic efficiency is urgent. The catalytic efficiency of perovskite-type four-way catalyst for purifying diesel smoke is high, especially for La-K-Co-Mn-O type catalyst. In this paper, K ion is used to partially replace La ion on LaCoO3 A site of perovskite by chemical tailoring method. The Co(Co2 Co _ 3 / Co _ 4 on the LaCoO3 B site was partially replaced by Mn(Mn2 Mn-3 / mn _ 4 / mn _ 5 and mn _ 6 / mn _ 7, and the sol-gel method was used to replace the Co _ (3) and Co _ (4) on the LaCoO3 B site. The active component La1-xKxCo1-yMnyO3 with perovskite structure was synthesized by citric acid complexation method and solution combustion method. La1-xKxCo1-yMnyO3 was impregnated on honeycomb ceramic carrier by solution impregnation or suspension slurry method. Perovskite type catalyst was obtained. The performance test of removing COC x Hyp PM and NOx from diesel engine exhaust gas was carried out by self-made performance evaluation device and simulated flue gas of diesel locomotive tail gas. The results showed that La0.8K0.2Co0.8Mn0.2O3 and La0.8K0.2Co0.7Mn0.3O3 were selected as research objects, and the conversion rates of CX Hydro PM and NOx were determined according to the catalytic redox activity. The order of calcination synthesis temperature of active components is: 1: 750 鈩，

本文編號(hào)：1618104