混合氧化物脫硝催化劑制備基礎(chǔ)研究
發(fā)布時(shí)間：2018-12-13 19:38
【摘要】：目前在國內(nèi)外多種煙氣脫硝方法中SCR法是最成熟的煙氣脫硝技術(shù)。然而對于這一技術(shù)，我國起步較晚，特別是在其核心技術(shù)催化劑的制備上還沒有自主知識產(chǎn)權(quán)，因此要更為成熟的運(yùn)用SCR技術(shù)，我國必須自主研發(fā)SCR脫硝催化劑。催化劑作為SCR技術(shù)的核心，在我國具有廣闊的市場需求，且其在SCR脫硝系統(tǒng)中的投資占到總投資的1/3，而現(xiàn)行的商業(yè)催化劑價(jià)格較高，，這會直接導(dǎo)致脫硝技術(shù)成本的增加。因此，本課題選擇了某價(jià)格低廉的工業(yè)副產(chǎn)品混合氧化物(以下簡稱M)為主要原料進(jìn)行SCR-氨法脫硝催化劑的實(shí)驗(yàn)室制備研究工作，即在對M表面性質(zhì)進(jìn)行分析和研究的基礎(chǔ)上，考察了粘結(jié)劑對該混合氧化物成型性能的影響，為實(shí)現(xiàn)混合氧化物脫硝催化劑的成型奠定基礎(chǔ)。 本文利用XRF、XRD、金相顯微鏡等表征手段對混合氧化物的物化性質(zhì)進(jìn)行了研究，并結(jié)合抗壓強(qiáng)度、BET比表面積、NH_3-TPD等表征方法考察了有機(jī)粘結(jié)劑（聚乙烯醇、甲基纖維素和聚丙烯酰胺）、無機(jī)粘結(jié)劑（氧化鋁、皂土）及有機(jī)-無機(jī)混合粘結(jié)劑對混合氧化物成型性能的影響。 結(jié)果表明原混合氧化物比表面積為1.485m~2/g，其比表面積較小，不利于活性成分的負(fù)載，需在后續(xù)研究中考慮其比表面積對制備催化劑活性的影響。綜合各實(shí)驗(yàn)數(shù)據(jù)，選定在后續(xù)實(shí)驗(yàn)中所用混合氧化物的條件：以干法球磨45min （1800r/min）、篩分大于80目的混合氧化物為主要原料。通過各粘結(jié)劑成型混合氧化物的過程可知，有機(jī)粘結(jié)劑對混合氧化物成型時(shí)，漿料流動性較好，采用造粒機(jī)壓片、制丸等過程更易實(shí)施，其中以MC更甚，在選用混合粘結(jié)劑對混合氧化物成型時(shí)，也以有機(jī)粘結(jié)劑的成型特點(diǎn)占主導(dǎo)作用。僅以有機(jī)粘結(jié)劑對混合氧化物成型時(shí)，得到的成型氧化物抗壓強(qiáng)度均不高，而以無機(jī)粘結(jié)劑成型得到的成型氧化物抗壓強(qiáng)度較高，皂土最高抗壓強(qiáng)度達(dá)到1.846MPa，與單獨(dú)使用有機(jī)粘結(jié)劑成型相比，無機(jī)粘結(jié)劑的添加可使抗壓強(qiáng)度有顯著提高。采用有機(jī)粘結(jié)劑對混合氧化物成型時(shí)，成型氧化物BET比表面積與粘結(jié)劑分子量大小有關(guān)，分子量太大，在焙燒過程中會產(chǎn)生大量氣體形成大量氣孔，引起其孔結(jié)構(gòu)塌陷，進(jìn)而導(dǎo)致成型物比表面積有所下降。選用無機(jī)粘結(jié)劑成型時(shí)比表面積較大，與僅用有機(jī)粘結(jié)劑成型相比，混合粘結(jié)劑成型得到的成型氧化物BET比表面積有明顯提高。通過幾組粘結(jié)劑對混合氧化物成型得到的最佳抗壓強(qiáng)度的成型物比表面積與抗壓強(qiáng)度對比說明，該混合氧化物成型得到的成型物的抗壓強(qiáng)度與比表面積之間不存在明顯的正相關(guān)關(guān)系。粘結(jié)劑對混合氧化物成型得到的成型氧化物對氨氣的吸附性質(zhì)相似，NH_3吸附量和表面酸量均不大，成型氧化物對NH_3的吸附量和表面酸性與其抗壓強(qiáng)度間沒有明顯的正相關(guān)關(guān)系。
[Abstract]:At present, SCR method is the most mature technology of flue gas denitrification among many flue gas denitrification methods at home and abroad. However, for this technology, China started late, especially in the preparation of its core technology catalyst has not yet independent intellectual property rights, so in order to more mature use of SCR technology, our country must independently develop SCR denitrification catalyst. As the core of SCR technology, catalyst has broad market demand in China, and its investment in SCR denitrification system accounts for 1 / 3 of the total investment. However, the current commercial catalyst price is relatively high, which will directly lead to the increase of denitrification technology cost. Therefore, a low cost industrial by-product mixed oxide (M) was selected as the main raw material for the preparation of SCR- ammonia denitrification catalyst. On the basis of the analysis and study of the surface properties of M, the influence of binder on the molding performance of the mixed oxide was investigated, which laid a foundation for the formation of mixed oxide denitrification catalyst. In this paper, the physicochemical properties of mixed oxides were studied by means of XRF,XRD, metallographic microscope. The organic binder (polyvinyl alcohol) was investigated by means of compressive strength, specific surface area of BET and NH_3-TPD. Effects of methyl cellulose and polyacrylamide), inorganic binder (alumina, bentonite) and organic-inorganic binder on the molding properties of mixed oxides. The results show that the specific surface area of the mixed oxide is 1.485 mm2 / g, which is small, which is not conducive to the loading of the active component. The effect of the specific surface area on the activity of the catalyst should be considered in the follow-up study. According to the experimental data, the conditions of mixed oxides used in subsequent experiments were selected: dry milling 45min (1800r/min), sieving more than 80 objects mixed oxides as the main raw material. Through the process of forming mixed oxides with various binders, it can be seen that when organic binders are used to form mixed oxides, the fluidity of slurry is better, and the process of pelletizing, such as pelletizer, pelletizing, etc., is easier to carry out, especially MC. When mixed binder is used to form mixed oxide, the forming characteristics of organic binder also play a leading role. When mixed oxides were molded only with organic binder, the compressive strength of formed oxides was not high, but that of inorganic binder was higher, and the highest compressive strength of bentonite was 1.846 MPA. Compared with using organic binder alone, the addition of inorganic binder can significantly improve the compressive strength. When the mixed oxide is molded with organic binder, the specific surface area of the formed oxide BET is related to the molecular weight of the binder, and the molecular weight is too large. A large amount of gas will form a large number of pores during the roasting process, which will cause the pore structure to collapse. In turn, the specific surface area of the molded material is decreased. The specific surface area of inorganic binder is larger than that of only organic binder, and the specific surface area of oxide BET formed by mixed binder is obviously improved. The comparison of the specific surface area and compressive strength of the best compressive strength obtained by several groups of binders on the mixed oxides shows that, There is no obvious positive correlation between the compressive strength and the specific surface area. The adsorptive properties of the molded oxides formed by binder on mixed oxides are similar to those of ammonia, and the amount of NH_3 adsorbed and the amount of surface acid are not large. There was no significant positive correlation between the adsorption amount and surface acidity of NH_3 and the compressive strength of the formed oxides.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：X701
本文編號：2377102
[Abstract]:At present, SCR method is the most mature technology of flue gas denitrification among many flue gas denitrification methods at home and abroad. However, for this technology, China started late, especially in the preparation of its core technology catalyst has not yet independent intellectual property rights, so in order to more mature use of SCR technology, our country must independently develop SCR denitrification catalyst. As the core of SCR technology, catalyst has broad market demand in China, and its investment in SCR denitrification system accounts for 1 / 3 of the total investment. However, the current commercial catalyst price is relatively high, which will directly lead to the increase of denitrification technology cost. Therefore, a low cost industrial by-product mixed oxide (M) was selected as the main raw material for the preparation of SCR- ammonia denitrification catalyst. On the basis of the analysis and study of the surface properties of M, the influence of binder on the molding performance of the mixed oxide was investigated, which laid a foundation for the formation of mixed oxide denitrification catalyst. In this paper, the physicochemical properties of mixed oxides were studied by means of XRF,XRD, metallographic microscope. The organic binder (polyvinyl alcohol) was investigated by means of compressive strength, specific surface area of BET and NH_3-TPD. Effects of methyl cellulose and polyacrylamide), inorganic binder (alumina, bentonite) and organic-inorganic binder on the molding properties of mixed oxides. The results show that the specific surface area of the mixed oxide is 1.485 mm2 / g, which is small, which is not conducive to the loading of the active component. The effect of the specific surface area on the activity of the catalyst should be considered in the follow-up study. According to the experimental data, the conditions of mixed oxides used in subsequent experiments were selected: dry milling 45min (1800r/min), sieving more than 80 objects mixed oxides as the main raw material. Through the process of forming mixed oxides with various binders, it can be seen that when organic binders are used to form mixed oxides, the fluidity of slurry is better, and the process of pelletizing, such as pelletizer, pelletizing, etc., is easier to carry out, especially MC. When mixed binder is used to form mixed oxide, the forming characteristics of organic binder also play a leading role. When mixed oxides were molded only with organic binder, the compressive strength of formed oxides was not high, but that of inorganic binder was higher, and the highest compressive strength of bentonite was 1.846 MPA. Compared with using organic binder alone, the addition of inorganic binder can significantly improve the compressive strength. When the mixed oxide is molded with organic binder, the specific surface area of the formed oxide BET is related to the molecular weight of the binder, and the molecular weight is too large. A large amount of gas will form a large number of pores during the roasting process, which will cause the pore structure to collapse. In turn, the specific surface area of the molded material is decreased. The specific surface area of inorganic binder is larger than that of only organic binder, and the specific surface area of oxide BET formed by mixed binder is obviously improved. The comparison of the specific surface area and compressive strength of the best compressive strength obtained by several groups of binders on the mixed oxides shows that, There is no obvious positive correlation between the compressive strength and the specific surface area. The adsorptive properties of the molded oxides formed by binder on mixed oxides are similar to those of ammonia, and the amount of NH_3 adsorbed and the amount of surface acid are not large. There was no significant positive correlation between the adsorption amount and surface acidity of NH_3 and the compressive strength of the formed oxides.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：X701
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