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  本文選題：摻雜型Pd催化劑 + 負(fù)載型Pd催化劑　； 參考：《北京工業(yè)大學(xué)》2015年碩士論文

【摘要】：三效催化劑是控制汽車尾氣排放污染物的有效手段,貴金屬Pt、Rh和Pd是其活性組分。隨著汽車保有量的逐年增加,貴金屬需求量越來越大,導(dǎo)致其價(jià)格不斷攀升。同時,即將實(shí)施的國V汽車排放標(biāo)準(zhǔn)要求尾氣排放達(dá)標(biāo)里程數(shù)從10萬公里增加到了16萬公里,催化劑需要具有更好的耐久性。因此,在保證催化劑三效催化活性的前提下,如何減少貴金屬用量和提高三效催化劑的高溫?zé)岱�(wěn)定性和耐久性是目前三效催化劑產(chǎn)業(yè)面臨的難題。本論文針對以上兩個難題,在前期研究基礎(chǔ)之上,制備了不同結(jié)構(gòu)的貴金屬摻雜型Pd基催化劑,采用SEM、TEM、XRD、H2-TPR、UV-Raman、XPS等多種技術(shù)對所得催化劑的物化性能進(jìn)行了表征,評價(jià)了其三效催化活性,并對其熱穩(wěn)定性進(jìn)行了研究。主要研究內(nèi)容和結(jié)果如下:(1)采用膠體晶體模板法制備了系列不同Pd含量的三維有序大孔(3DOM)Ce0.7-xZr0.3PdxO2(x=0,0.01,0.02,0.05,0.07,0.1)催化劑,所得樣品具有規(guī)整的三維有序大孔結(jié)構(gòu)。Pd的摻雜量存在一個閾值,當(dāng)x≤0.05時,樣品為立方螢石結(jié)構(gòu),沒有檢測到Pd物種的存在,然而當(dāng)x≥0.07時,則檢測到痕量的PdO。當(dāng)x=0.05時,樣品表現(xiàn)出最佳的低溫還原性能和三效催化活性,CO、HC和NO在3DOM Ce0.65Zr0.3Pd0.05O2上的完全轉(zhuǎn)化溫度(T90)分別為153、223和216°C,其活性和3DOM Ce0.6Zr0.3Pd0.1O2的三效催化活性相當(dāng)。(2)為了考察摻雜型催化劑3DOM Ce0.65Zr0.3Pd0.05O2的熱穩(wěn)定性,采用浸漬法制備了Pd含量相同的負(fù)載型催化劑3.42 wt%Pd/3DOM Ce0.7Zr0.3O2作為對比催化劑,對兩種不同類型的Pd基催化劑的三效催化活性及水熱穩(wěn)定性進(jìn)行了對比研究。結(jié)果表明,無論摻雜型還是負(fù)載型催化劑,Pd的引入都未破壞規(guī)整的三維有序大孔結(jié)構(gòu)。無論是新鮮樣品還是老化樣品,負(fù)載型Pd基催化劑具有更好的三效催化活性,但是對HC和NO轉(zhuǎn)化,摻雜型Pd基催化劑老化前后的?T50和?T90均小于負(fù)載型Pd基催化劑,即摻雜型Pd基催化劑具有更好的高溫?zé)岱�(wěn)定性,這是由于Pd物種進(jìn)入CeO2晶格形成-Pd-O-Ce-鏈接,抑制了Pd物種的自由遷移所致。(3)為了考察孔結(jié)構(gòu)對三效催化活性的影響,分別采用軟硬雙模板法、膠體晶體模板法和溶膠凝膠法制備了具有介孔孔壁的三維有序大孔3DOM-meso Ce0.65Zr0.3Pd0.05O2、3DOM Ce0.65Zr0.3Pd0.05O2和無孔Ce0.65Zr0.3Pd0.05O2催化劑,并對它們的物化性能、三效催化活性和熱穩(wěn)定性進(jìn)行了對比研究。結(jié)果表明3DOM-meso Ce0.65Zr0.3Pd0.05O2催化劑具有最佳的三效催化活性和高溫?zé)岱�(wěn)定性,CO、HC和NO在220°C之前可以完全轉(zhuǎn)化,老化后CO和NO的完全轉(zhuǎn)化溫度僅僅提高了40°C左右。(4)為了進(jìn)一步提高摻雜型Pd基催化劑的三效催化活性,又調(diào)整了鈰鋯比,采用溶膠凝膠法制備了系列納米Ce0.5-x/2Zr0.5-x/2PdxO2,并對Pd的最佳摻雜量進(jìn)行了研究。結(jié)果表明,所得樣品為粒徑約10 nm的納米粒子。Pd的摻雜量和三效催化活性之間不存在線性關(guān)系,其中,對于x=0.01的樣品,其三效催化活性和x=0.08的樣品的活性相當(dāng),對CO、HC和NO的T90分別為156、223和196°C,然而,Ce0.495Zr0.495Pd0.01O2中貴金屬Pd的用量僅為Ce0.46Zr0.46Pd0.08O2樣品中Pd含量的20%,大大降低了貴金屬用量,為貴金屬減量提供了數(shù)據(jù)支持。
[Abstract]:The three effect catalyst is an effective means to control the exhaust emission of automobile exhaust. The Pt, Rh and Pd of precious metals are its active components. With the increasing of the car's insured quantity, the demand for precious metals is increasing, which leads to the rising price. At the same time, the emission standard of the national V vehicle that will be implemented is required to increase the mileage of the tail gas from 100 thousand kilometers. At 160 thousand km, the catalyst needs better durability. Therefore, how to reduce the amount of precious metals and improve the thermal stability and durability of the three effect catalyst is a difficult problem for the three effect catalyst industry on the premise of ensuring the catalytic activity of the catalyst in the three effect. This paper is based on the above two difficult problems in the previous research basis. On the other hand, the Pd based catalysts with different structures were prepared. The physical and chemical properties of the catalysts were characterized by SEM, TEM, XRD, H2-TPR, UV-Raman, XPS and so on. The three effect catalytic activity was evaluated and their thermal stability was studied. The main contents and results are as follows: (1) the colloidal crystal template method is used. A series of three dimensional ordered macroporous (3DOM) Ce0.7-xZr0.3PdxO2 (x=0,0.01,0.02,0.05,0.07,0.1) catalysts with different Pd content are prepared. The sample has a regular three-dimensional ordered macroporous structure.Pd doped with a threshold. When x < 0.05, the sample is a cubic fluorite structure, and the existence of Pd species is not detected. However, when x is more than 0.07, then the number of Pd species is not detected. When the trace PdO. was detected as x=0.05, the sample showed the best low temperature reduction and three effect catalytic activity. The total conversion temperature (T90) of CO, HC and NO on 3DOM Ce0.65Zr0.3Pd0.05O2 was 153223 and 216 degrees C, respectively, and the activity of the 3DOM Ce0.6Zr0.3Pd0.1O2 was equal to that of the 3DOM Ce0.6Zr0.3Pd0.1O2. (2) in order to investigate the doped catalyst 3DOM The thermal stability of 0.3Pd0.05O2 was made by impregnation, and 3.42 wt%Pd/3DOM Ce0.7Zr0.3O2 with the same Pd content was prepared as the contrast catalyst. The three effect catalytic activity and the hydrothermal stability of the two different types of Pd based catalysts were compared. The results showed that the doping type or the load type catalyst and the introduction of Pd were introduced. None of the regular three-dimensional ordered macroporous structures. Both fresh and aging samples, the supported Pd based catalysts have better three catalytic activity. But for the conversion of HC and NO, the T50 and T90 of the doped Pd based catalysts are less than those of the loaded Pd based catalysts, that is, the doping type Pd based catalysts have better heat heat. Stability, which is due to the Pd species entering the CeO2 lattice to form the -Pd-O-Ce- link and inhibit the free migration of the Pd species. (3) in order to investigate the effect of the pore structure on the three effective catalytic activity, the soft and hard double die plate method, the colloidal crystal template method and the sol-gel method were used to prepare the three-dimensional ordered macroporous 3DOM-meso Ce0.65Zr0 with the mesoporous pore wall. .3Pd0.05O2,3DOM Ce0.65Zr0.3Pd0.05O2 and non porous Ce0.65Zr0.3Pd0.05O2 catalysts were used to compare their physical and chemical properties, three effect catalytic activity and thermal stability. The results show that 3DOM-meso Ce0.65Zr0.3Pd0.05O2 catalyst has the best three effect catalytic activity and high temperature thermal stability. CO, HC and NO can be complete before 220 degrees C. After aging, the complete conversion temperature of CO and NO was only about 40 C. (4) in order to further improve the three effect catalytic activity of the doped Pd based catalyst and adjust the ratio of cerium to zirconium, a series of nano Ce0.5-x/2Zr0.5-x/2PdxO2 was prepared by sol-gel method, and the best doping amount of Pd was studied. The results showed that the sample was obtained. There is no linear relationship between the doping amount and the three effect catalytic activity of nanoparticles with a particle size of about 10 nm, and for the samples of x=0.01, the activity of the three effect catalytic activity is equal to the activity of the sample of x=0.08, and the T90 of CO, HC and NO is 156223 and 196 degrees C respectively. However, the Pd amount of noble metals in Ce0.495Zr0.495Pd0.01O2 is only Ce0.46Zr0.46Pd0.08O. 2 the Pd content of the sample is 20%, which greatly reduces the amount of precious metals and provides data support for the reduction of precious metals.
【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】：O643.36;X734.2

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