發(fā)布時(shí)間：2018-04-18 18:23

  本文選題：選擇性催化還原(SCR) + 釩鈦基催化劑　； 參考：《北京工業(yè)大學(xué)》2016年碩士論文

【摘要】：氮氧化物(NO_x)是大氣主要污染物之一,對(duì)環(huán)境和人類健康都造成了嚴(yán)重的危害。選擇性催化還原(SCR)技術(shù)具有脫除NO_x效率高(90%)和運(yùn)行穩(wěn)定等優(yōu)點(diǎn)而成為世界脫硝市場(chǎng)的主流技術(shù),其常用的SCR催化劑是V_2O_5-WO_3(MoO_3)/TiO_2體系。在這一催化劑體系中,TiO_2載體起著的重要的作用,因?yàn)樗�不僅具有優(yōu)異的抗硫性能,而且具有良好的分散釩的能力。研究表明不同形貌或高暴露特殊晶面的TiO_2可能會(huì)導(dǎo)致其物理化學(xué)性質(zhì)發(fā)生顯著變化,如表面能、表面酸性,以及其與活性組分的相互作用等。具有特定形貌和表面結(jié)構(gòu)的TiO_2在光催化和染料敏化太陽(yáng)能電池等領(lǐng)域的應(yīng)用已多有報(bào)道,并顯示出獨(dú)特的性質(zhì)。然而,人們對(duì)TiO_2載體形貌對(duì)鈦基SCR催化劑活性影響方面的認(rèn)識(shí)還很有限。本論文在對(duì)比了工業(yè)TiO_2粉體性能的基礎(chǔ)上,著重研究了TiO_2載體形貌對(duì)V_2O_5/TiO_2催化劑活性的影響。得到主要研究結(jié)果如下:1)比較了四種工業(yè)TiO_2粉體的性能的差異。以四種工業(yè)TiO_2作為載體,采用浸漬法制備相應(yīng)的V_2O_5-MoO_3/TiO_2催化劑。通過(guò)SCR活性評(píng)價(jià),發(fā)現(xiàn)具有圓形小球規(guī)整形貌的TiO_2-J載體所制備的催化劑具有更好的NO轉(zhuǎn)化率。BET結(jié)果顯示,TiO_2-J載體負(fù)載釩活性組分后,比表面積明顯提高,而其他載體負(fù)載釩后,比表面積均呈下降趨勢(shì)。從TPR和TPD結(jié)果發(fā)現(xiàn),以TiO_2-J為載體的催化劑比其他催化劑具有更高的還原性和更多的酸性位。因此證明,TiO_2-J有良好的物理化學(xué)性質(zhì)是可以提高催化劑SCR活性并拓寬反應(yīng)溫度窗口的良好載體。2)討論了不同形貌載體TiO_2的可控制備方法。采用水熱法,通過(guò)調(diào)節(jié)水合肼的濃度,得到具有規(guī)整八面體形貌的TiO_2,記作TiO_2-O,其主要暴露{101}晶面。通過(guò)添加HF封端劑,制備出扁平片狀形貌的TiO_2,記作TiO_2-S,其主要暴露高能{001}晶面。3)考察了載體形貌對(duì)V_2O_5/TiO_2催化劑脫硝活性的影響。以TiO_2-O、TiO_2-S和商業(yè)TiO_2 P25為載體,由浸漬法制備了三個(gè)3 wt%V_2O_5/TiO_2催化劑�；钚栽u(píng)價(jià)結(jié)果顯示,負(fù)載在TiO_2-S上的V_2O_5/TiO_2-S催化劑,其NH_3-SCR催化活性最高。通過(guò)SEM、TEM、BET、H_2-TPR、Raman、NH_3-TPD、DRIFT、XPS等手段對(duì)所制備的催化劑進(jìn)行物化性質(zhì)表征。發(fā)現(xiàn)具有特殊結(jié)構(gòu)的高能{001}晶面為主導(dǎo)晶面的TiO_2-S載體與活性組分之間存在較強(qiáng)相互作用,使釩物種在TiO_2表面良好地分散。進(jìn)而造成V_2O_5/TiO_2-S催化劑具有較高的還原性和更多化學(xué)吸附氧,這可能是其具有良好NH_3-SCR反應(yīng)活性的主要原因。
[Abstract]:Nitrogen oxide (NOX) is one of the main atmospheric pollutants, which has caused serious harm to the environment and human health.Selective catalytic reduction (NO_x) technology has the advantages of high NO_x removal efficiency and stable operation, and has become the mainstream technology in the world denitrification market. The commonly used SCR catalyst is the V_2O_5-WO_3(MoO_3)/TiO_2 system.TiO-2 support plays an important role in this catalyst system, because it not only has excellent sulfur resistance, but also has a good ability to disperse vanadium.It is shown that the physical and chemical properties of TiO_2 with different morphology or high exposure to special crystal surfaces may cause significant changes, such as surface energy, surface acidity, and interaction with active components.The applications of TiO_2 with specific morphology and surface structure in photocatalysis and dye sensitized solar cells have been widely reported and have shown unique properties.However, the effect of TiO_2 support morphology on the activity of titanium based SCR catalyst is still limited.On the basis of comparing the properties of industrial TiO_2 powders, the effect of the morphology of TiO_2 support on the activity of V_2O_5/TiO_2 catalysts was studied in this paper.The main results are as follows: 1: 1) the properties of four kinds of industrial TiO_2 powders are compared.Four kinds of industrial TiO_2 were used as carriers to prepare corresponding V_2O_5-MoO_3/TiO_2 catalysts by impregnation method.Through the SCR activity evaluation, it was found that the catalyst prepared by the TiO_2-J support with circular spheroid shape had better no conversion. The results showed that the specific surface area of the catalyst prepared by loading vanadium active component on TiO2-J support was obviously increased, while that of other supports supported on vanadium was obviously increased.The specific surface area showed a decreasing trend.The results of TPR and TPD show that the catalysts supported on TiO_2-J have higher reductivity and more acidic sites than other catalysts.Therefore, it is proved that TiO2-J has good physical and chemical properties, which can improve the SCR activity of catalyst and widen the reaction temperature window. 2) the controllable preparation methods of TiO_2 with different morphologies are discussed.By adjusting the concentration of hydrazine hydrate, the TIO _ 2 with regular octahedron morphology was obtained by hydrothermal method. The TIO _ 2-O was recorded as TIO _ 2-O, and the {101} crystal plane was mainly exposed.The effect of support morphology on the denitrification activity of V_2O_5/TiO_2 catalyst was investigated by adding HF capping agent to prepare TIO _ 2 with flat flake morphology, which was recorded as TIO _ 2-S, which was mainly exposed to high energy {001} crystal face. 3) the effect of support morphology on the denitrification activity of V_2O_5/TiO_2 catalyst was investigated.Three 3 wt%V_2O_5/TiO_2 catalysts were prepared by impregnation with TiO2-OO2-S and commercial TiO_2 P25 as supports.The results of activity evaluation showed that the V_2O_5/TiO_2-S catalyst supported on TiO_2-S had the highest NH_3-SCR catalytic activity.The physicochemical properties of the prepared catalysts were characterized by SEMMOTEMBETH H2-TPRN Ramanji NH3-TPDD DRIFTXPS and so on.It is found that there is a strong interaction between the active component and the TiO_2-S carrier with special structure on the {001} crystal plane, which makes the vanadium species dispersed well on the surface of TiO_2.Therefore, the V_2O_5/TiO_2-S catalyst has higher reductivity and more chemisorbed oxygen, which may be the main reason for its good NH_3-SCR reaction activity.
【學(xué)位授予單位】：北京工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：O643.36

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