Pr、La和Ce摻雜對釩鈦基SCR催化劑性能影響的研究
發(fā)布時間：2018-08-02 14:07
【摘要】：氮氧化物(NOx)是大氣主要污染物之一,當前,實現(xiàn)NOx控制排放的主流技術(shù)是選擇性催化還原(SCR)技術(shù),其中催化劑是核心,常用的SCR催化劑為V2O5-WO3(MoO3)/TiO2體系。在工程應(yīng)用時,SCR催化劑運行一段時間后,催化活性逐漸下降,但是在非電力行業(yè),由于催化劑的運行溫度較低,催化劑表面會生成硫酸氫銨,附著于催化劑表面,堵塞催化劑活性位點,致使催化劑活性降低。同時,飛灰或煙氣中的堿金屬、砷等也是催化劑活性降低的原因。因此,探究不同金屬雜質(zhì)對釩鈦催化劑NH3-SCR活性的影響以及催化劑上NH4HSO4的分解規(guī)律,對催化劑的工程應(yīng)用及再生具有重要的意義。本論文主要以V2O5-MoO3/TiO2催化劑為研究對象,考察了Pr、La和Ce摻雜以及堿金屬元素Cs和Rb,N族元素Bi和Sb修飾對釩鈦催化劑性能的影響。探究了其催化反應(yīng)機理,并采用TG-MS研究了NH4HSO4在Ce摻雜釩鈦催化劑上的分解規(guī)律。主要研究結(jié)果如下：(1)利用溶膠-凝膠法和浸漬法制備了Pr、La和Ce摻雜的V2O5/TiO2和V2O5-MoO3/TiO2催化劑,并考察其NH3-SCR性能,實驗結(jié)果表明：摻雜稀土元素Ce(與Pr和La相比)明顯提高V2O5/TiO2催化劑的NH3-SCR活性；Pr摻雜的V2O5-MoO3/TiO2催化劑在220～400℃范圍內(nèi)具有良好的脫硝效率、N2選擇性和較強的抗SO2和H2O性能；La摻雜和Ce摻雜,均可以提高V2O5-MoO3/TiO2催化劑的NH3-SCR反應(yīng)活性,并且La和Ce的最佳摻雜量分別為4 wt%和10wt%。摻雜稀土元素(主要分析討論了Pr和La)可以提高V2O5-MoO3/TiO2催化劑的比表面積、表面化學(xué)吸附氧物種濃度、橋式硝酸鹽物種和Br(?)nsted酸位數(shù)量,從而促進了催化劑上NH3-SCR反應(yīng)的進行。(2)采用浸漬法添加Pr對工業(yè)TiO2進行改性,制備了不同Pr摻雜量和V負載量的V2O5-MoO3/TiO2催化劑,實驗結(jié)果表明：摻雜少量Pr可以提高3V6MoTi催化劑在低溫(100～180℃)及高溫(300～400℃)區(qū)間的NH3-SCR反應(yīng)活性,其中Pr最佳摻雜量為1 wt%,在180℃時,IM-3V6MolPrTi催化劑上NO轉(zhuǎn)化率達到了93%。隨著V2O5負載量(0.3～3 wt%)的增加,V2O5-MoO3/l wt%Pr6O11-TiO2催化劑的活性隨之提高。(3)采用浸漬法將Cs、Rb、Bi和Sb金屬元素添加到釩鈦催化劑中,并考察其NH3-SCR性能,活性結(jié)果表明：當添加少量Cs2O和Rb2O時,對3V6MoTi催化劑上NH3-SCR反應(yīng)活性影響不大,但是隨著Cs20和Rb2O負載量的增加,催化活性也隨之降低；當催化劑中添加Sb2O5時,3V6MoTi催化劑在低溫區(qū)的NH3-SCR反應(yīng)活性降低,而在高溫(350℃)的活性提高；當Bi205的負載量為0.1～0.5 wt%時,可以提高3V6MoTi催化劑的催化活性,但是隨著Bi205的負載量的繼續(xù)增加,催化活性也隨之降低。(4)采用TG-MS考察了NH4HSO4在V2O5-MoO3/CeO2-TiO2催化劑上的分解規(guī)律,研究發(fā)現(xiàn)：在200℃前催化劑上部分NH4HSO4受熱分解生成NH3和H20,而S02吸附在催化劑表面,樣品表面部分S02在415℃左右脫附,并且當Ce02摻雜量的增加至10 wt%時,在高溫區(qū)SO2的信號峰溫度降低,出現(xiàn)在720℃附近。因此,摻雜Ce可以促進V2O5-MoO3/TiO2催化劑上的NH4HSO4分解,降低其分解溫度。反應(yīng)過程如下：
[Abstract]:Nitrogen oxide (NOx) is one of the main pollutants in the atmosphere. Currently, the mainstream technology to control NOx emission is selective catalytic reduction (SCR) technology, in which the catalyst is the core and the commonly used SCR catalyst is V2O5-WO3 (MoO3) /TiO2 system. In engineering application, the catalytic activity gradually decreases after the SCR catalyst has been running for a period of time, but it is not in power. Industry, due to the low operating temperature of the catalyst, the catalyst surface will produce ammonium hydrogen sulfate, attach to the surface of the catalyst, plug the active site of the catalyst, and reduce the activity of the catalyst. At the same time, the alkali metal in the fly ash or the flue gas and the arsenic are also the source of the reduction of the activity of the catalyst. Therefore, the study of different metal impurities on the vanadium and titanium catalyst NH3-SCR The effect of the activity and the decomposition law of NH4HSO4 on the catalyst have important significance for the engineering application and regeneration of the catalyst. This paper is mainly based on the V2O5-MoO3/TiO2 catalyst as the research object. The effects of Pr, La and Ce doping, the alkali metal elements Cs and Rb, the Bi and Sb modification of the N elements on the performance of the vanadium and titanium catalysts are investigated. The reaction mechanism was studied and the decomposition rules of NH4HSO4 on Ce Doped Vanadium and titanium catalysts were studied by TG-MS. The main results were as follows: (1) the V2O5/TiO2 and V2O5-MoO3/TiO2 catalysts doped with Pr, La and Ce were prepared by sol-gel method and impregnation method, and their NH3-SCR properties were investigated. The experimental results showed that doped rare earth elements Ce (Pr and La) The NH3-SCR activity of V2O5/TiO2 catalyst was obviously improved, and the V2O5-MoO3/TiO2 Catalyst Doped with Pr had good denitrification efficiency in the range of 220~400 C, N2 selectivity and strong resistance to SO2 and H2O; La doping and Ce doping could increase the NH3-SCR reaction activity of V2O5-MoO3/TiO2 catalyst, and the best doping amount of La and impurities could be obtained. 4 wt% and 10wt%. doped rare earth elements (mainly analysis and discussion of Pr and La) can improve the specific surface area of the V2O5-MoO3/TiO2 catalyst, the surface chemical adsorption oxygen species concentration, the bridge type nitrate species and the Br (?) nsted Acid Number, thus promoting the NH3-SCR reaction on the catalyst. (2) adding Pr to the industrial TiO2 with the impregnation method. The V2O5-MoO3/TiO2 catalyst with different Pr doping amount and V load was prepared. The experimental results showed that doping a small amount of Pr could improve the NH3-SCR reactivity of 3V6MoTi catalyst at low temperature (100~180 C) and high temperature (300~400 C), of which the optimum doping amount of Pr was 1 wt%, and the NO conversion rate on IM-3V6MolPrTi catalyst reached to 180. The activity of V2O5-MoO3/l wt%Pr6O11-TiO2 catalyst was increased with the increase of V2O5 load (0.3 ~ 3 wt%). (3) Cs, Rb, Bi and Sb metals were added to the vanadium and titanium catalyst by impregnation, and the properties of NH3-SCR were investigated. The activity results showed that when a small amount of Cs2O and Rb2O were added, the reaction activity on the catalyst was found. However, the catalytic activity decreased with the increase of the load of Cs20 and Rb2O. When Sb2O5 was added to the catalyst, the NH3-SCR reaction activity of 3V6MoTi catalyst decreased at low temperature and the activity at high temperature (350 C) increased. When the load of Bi205 was 0.1 to 0.5 wt%, the catalytic activity of 3V6MoTi catalyst could be improved, but the catalytic activity of 3V6MoTi catalyst could be improved. With the increasing of the load of Bi205, the catalytic activity also decreased. (4) the decomposition rule of NH4HSO4 on V2O5-MoO3/CeO2-TiO2 catalyst was investigated by TG-MS. It was found that the partial NH4HSO4 was decomposed into NH3 and H20 on the catalyst before 200 c, and S02 adsorbed on the surface of the catalyst, and the S02 at the sample surface was around 415. Desorption, and when the amount of Ce02 doping increases to 10 wt%, the signal peak temperature of SO2 in high temperature zone decreases, and occurs near 720 C. Therefore, doping Ce can promote NH4HSO4 decomposition on V2O5-MoO3/TiO2 catalyst and reduce the decomposition temperature. The reaction process is as follows:
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X701;O643.36
本文編號：2159681
[Abstract]:Nitrogen oxide (NOx) is one of the main pollutants in the atmosphere. Currently, the mainstream technology to control NOx emission is selective catalytic reduction (SCR) technology, in which the catalyst is the core and the commonly used SCR catalyst is V2O5-WO3 (MoO3) /TiO2 system. In engineering application, the catalytic activity gradually decreases after the SCR catalyst has been running for a period of time, but it is not in power. Industry, due to the low operating temperature of the catalyst, the catalyst surface will produce ammonium hydrogen sulfate, attach to the surface of the catalyst, plug the active site of the catalyst, and reduce the activity of the catalyst. At the same time, the alkali metal in the fly ash or the flue gas and the arsenic are also the source of the reduction of the activity of the catalyst. Therefore, the study of different metal impurities on the vanadium and titanium catalyst NH3-SCR The effect of the activity and the decomposition law of NH4HSO4 on the catalyst have important significance for the engineering application and regeneration of the catalyst. This paper is mainly based on the V2O5-MoO3/TiO2 catalyst as the research object. The effects of Pr, La and Ce doping, the alkali metal elements Cs and Rb, the Bi and Sb modification of the N elements on the performance of the vanadium and titanium catalysts are investigated. The reaction mechanism was studied and the decomposition rules of NH4HSO4 on Ce Doped Vanadium and titanium catalysts were studied by TG-MS. The main results were as follows: (1) the V2O5/TiO2 and V2O5-MoO3/TiO2 catalysts doped with Pr, La and Ce were prepared by sol-gel method and impregnation method, and their NH3-SCR properties were investigated. The experimental results showed that doped rare earth elements Ce (Pr and La) The NH3-SCR activity of V2O5/TiO2 catalyst was obviously improved, and the V2O5-MoO3/TiO2 Catalyst Doped with Pr had good denitrification efficiency in the range of 220~400 C, N2 selectivity and strong resistance to SO2 and H2O; La doping and Ce doping could increase the NH3-SCR reaction activity of V2O5-MoO3/TiO2 catalyst, and the best doping amount of La and impurities could be obtained. 4 wt% and 10wt%. doped rare earth elements (mainly analysis and discussion of Pr and La) can improve the specific surface area of the V2O5-MoO3/TiO2 catalyst, the surface chemical adsorption oxygen species concentration, the bridge type nitrate species and the Br (?) nsted Acid Number, thus promoting the NH3-SCR reaction on the catalyst. (2) adding Pr to the industrial TiO2 with the impregnation method. The V2O5-MoO3/TiO2 catalyst with different Pr doping amount and V load was prepared. The experimental results showed that doping a small amount of Pr could improve the NH3-SCR reactivity of 3V6MoTi catalyst at low temperature (100~180 C) and high temperature (300~400 C), of which the optimum doping amount of Pr was 1 wt%, and the NO conversion rate on IM-3V6MolPrTi catalyst reached to 180. The activity of V2O5-MoO3/l wt%Pr6O11-TiO2 catalyst was increased with the increase of V2O5 load (0.3 ~ 3 wt%). (3) Cs, Rb, Bi and Sb metals were added to the vanadium and titanium catalyst by impregnation, and the properties of NH3-SCR were investigated. The activity results showed that when a small amount of Cs2O and Rb2O were added, the reaction activity on the catalyst was found. However, the catalytic activity decreased with the increase of the load of Cs20 and Rb2O. When Sb2O5 was added to the catalyst, the NH3-SCR reaction activity of 3V6MoTi catalyst decreased at low temperature and the activity at high temperature (350 C) increased. When the load of Bi205 was 0.1 to 0.5 wt%, the catalytic activity of 3V6MoTi catalyst could be improved, but the catalytic activity of 3V6MoTi catalyst could be improved. With the increasing of the load of Bi205, the catalytic activity also decreased. (4) the decomposition rule of NH4HSO4 on V2O5-MoO3/CeO2-TiO2 catalyst was investigated by TG-MS. It was found that the partial NH4HSO4 was decomposed into NH3 and H20 on the catalyst before 200 c, and S02 adsorbed on the surface of the catalyst, and the S02 at the sample surface was around 415. Desorption, and when the amount of Ce02 doping increases to 10 wt%, the signal peak temperature of SO2 in high temperature zone decreases, and occurs near 720 C. Therefore, doping Ce can promote NH4HSO4 decomposition on V2O5-MoO3/TiO2 catalyst and reduce the decomposition temperature. The reaction process is as follows:
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：X701;O643.36
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