氧化亞銅可控合成及其暴露晶面對CO-PROX催化性能影響的研究
發(fā)布時間：2018-11-28 07:20
【摘要】：氫能作為新世紀(jì)一種清潔、高效的戰(zhàn)略能源,有望代替?zhèn)鹘y(tǒng)化石燃料以緩解當(dāng)今能源危機(jī)。氫能的理想轉(zhuǎn)化裝置—燃料電池的研發(fā)和利用促進(jìn)了氫能的發(fā)展,其中最具應(yīng)用前景的為質(zhì)子交換膜燃料電池。經(jīng)處理后的重整氣仍含有少量的CO會導(dǎo)致Pt電極中毒,因此CO的含量必須降到10 ppm以下。CO優(yōu)先氧化被認(rèn)為是消除CO最簡便有效的方法之一。銅鈰體系是CO-PROX領(lǐng)域中最具潛力的催化劑,具有較高的經(jīng)濟(jì)價值和研究意義。本論文系統(tǒng)研究了以不同形貌的氧化亞銅為載體負(fù)載氧化鈰用于CO-PROX的催化性能,初步探討了催化劑應(yīng)用于CO-PROX體系的反應(yīng)機(jī)理、關(guān)鍵銅物種及失活原因。同時考察了催化劑界面性質(zhì)以及氧化亞銅載體對催化劑催化性能的影響。采用SEM、TEM、XRD、N2吸附-脫附、H2-TPR、in situ FTIR、XPS表征手段對銅鈰催化劑的物相結(jié)構(gòu)與性能進(jìn)行了測試分析。具體研究內(nèi)容如下：1.采用液相還原法合成星狀Cu20載體,通過浸漬法制備了一系列CeO2/CuxO催化劑并應(yīng)用于CO-PROX體系,研究發(fā)現(xiàn)CeO2/CuxO催化劑具有較好的CO-PROX的催化活性。CO-PROX反應(yīng)發(fā)生在銅鈰的接觸界面處；CO化學(xué)吸附的中心位點(diǎn)是界面處被還原的Cu+物種；反應(yīng)過程中催化劑表面吸附的碳酸鹽、碳酸氫鹽物種會引起催化劑失活。2.以浸漬法在星狀Cu20載體上負(fù)載不同量的Ce02制得一系列CeO2/CuxO催化劑,通過表征手段和CO-PROX反應(yīng)測試考察了CeO2含量對催化劑界面性質(zhì)及其催化性能影響。研究發(fā)現(xiàn),催化劑中CeO2的含量不同,其界面組成和性質(zhì)有較大的差異。催化劑中大顆粒的CeO2會形成更長的界面接觸周邊長從而具有更多的活性位。而存在的小顆粒CuO易被還原成Cu+,促進(jìn)了CeO2對CO的還原。3.采用液相還原法制備出暴露不同晶面的CCe2O載體,采用沉積沉淀法制備出一系列CeO2/CuxO催化劑。研究發(fā)現(xiàn),立方體、六面體、多莢狀和多面體的Cu2O主要暴露(100)、(110)、(111)和(311)晶面,高晶面指數(shù)的CeO2具有較大的懸鍵密度和較高的表觀活化能,負(fù)載CeO2后表現(xiàn)出良好的CO催化劑活性。載體的暴露晶面對催化劑的織構(gòu)性能和催化性能有較大的影響。
[Abstract]:Hydrogen energy, as a clean and efficient strategic energy source in the new century, is expected to replace traditional fossil fuels in order to alleviate the current energy crisis. The development and utilization of hydrogen energy is promoted by the research and utilization of fuel cell, the most promising of which is proton exchange membrane fuel cell (PEMFC). A small amount of CO in the treated reforming gas can lead to Pt electrode poisoning, so the content of CO must be reduced to less than 10 ppm. The preferential oxidation of CO is considered to be one of the most convenient and effective methods to eliminate CO. The copper-cerium system is the most potential catalyst in the field of CO-PROX, which has high economic value and research significance. In this paper, the catalytic properties of cerium oxide supported on different morphologies of cuprous oxide for CO-PROX were systematically studied. The reaction mechanism, key copper species and deactivation reasons of the catalysts applied to CO-PROX system were discussed. The interfacial properties of the catalyst and the effect of cuprous oxide support on the catalytic performance of the catalyst were also investigated. The phase structure and properties of copper-cerium catalyst were characterized by SEM,TEM,XRD,N2 adsorption desorption and H 2-TPRN situ FTIR,XPS characterization. The specific research contents are as follows: 1. The stellate Cu20 carrier was synthesized by liquid phase reduction method. A series of CeO2/CuxO catalysts were prepared by impregnation method and applied to CO-PROX system. It is found that CeO2/CuxO catalyst has better catalytic activity of CO-PROX. CO-PROX reaction takes place at the contact interface of Cu and ce. The central site of CO chemisorption is the reduced Cu species at the interface, and the carbonate species adsorbed on the surface of the catalyst during the reaction will cause the deactivation of the catalyst. 2. A series of CeO2/CuxO catalysts were prepared by impregnating different amounts of Ce02 on stellate Cu20 support. The effects of CeO2 content on the interfacial properties and catalytic properties of the catalysts were investigated by means of characterization and CO-PROX reaction tests. It was found that the interfacial composition and properties of the catalyst varied with the content of CeO2. The CeO2 of the large particles in the catalyst will form longer interface contact length and thus have more active sites. However, the existing small particle CuO was easily reduced to Cu, which promoted the reduction of CO by CeO2. CCe2O carriers exposed to different crystal planes were prepared by liquid phase reduction method and a series of CeO2/CuxO catalysts were prepared by deposition precipitation method. It is found that the Cu2O of cube, hexahedron, polypods and polyhedrons are mainly exposed to (100), (110), (111) and (311) faces. The CeO2 with high crystal face index has higher hanging bond density and higher apparent activation energy. After loading CeO2, the catalyst activity of CO was good. The texture and catalytic performance of the catalyst were greatly affected by the exposed crystal of the support.
【學(xué)位授予單位】：內(nèi)蒙古大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ116.2;TQ426
[Abstract]:Hydrogen energy, as a clean and efficient strategic energy source in the new century, is expected to replace traditional fossil fuels in order to alleviate the current energy crisis. The development and utilization of hydrogen energy is promoted by the research and utilization of fuel cell, the most promising of which is proton exchange membrane fuel cell (PEMFC). A small amount of CO in the treated reforming gas can lead to Pt electrode poisoning, so the content of CO must be reduced to less than 10 ppm. The preferential oxidation of CO is considered to be one of the most convenient and effective methods to eliminate CO. The copper-cerium system is the most potential catalyst in the field of CO-PROX, which has high economic value and research significance. In this paper, the catalytic properties of cerium oxide supported on different morphologies of cuprous oxide for CO-PROX were systematically studied. The reaction mechanism, key copper species and deactivation reasons of the catalysts applied to CO-PROX system were discussed. The interfacial properties of the catalyst and the effect of cuprous oxide support on the catalytic performance of the catalyst were also investigated. The phase structure and properties of copper-cerium catalyst were characterized by SEM,TEM,XRD,N2 adsorption desorption and H 2-TPRN situ FTIR,XPS characterization. The specific research contents are as follows: 1. The stellate Cu20 carrier was synthesized by liquid phase reduction method. A series of CeO2/CuxO catalysts were prepared by impregnation method and applied to CO-PROX system. It is found that CeO2/CuxO catalyst has better catalytic activity of CO-PROX. CO-PROX reaction takes place at the contact interface of Cu and ce. The central site of CO chemisorption is the reduced Cu species at the interface, and the carbonate species adsorbed on the surface of the catalyst during the reaction will cause the deactivation of the catalyst. 2. A series of CeO2/CuxO catalysts were prepared by impregnating different amounts of Ce02 on stellate Cu20 support. The effects of CeO2 content on the interfacial properties and catalytic properties of the catalysts were investigated by means of characterization and CO-PROX reaction tests. It was found that the interfacial composition and properties of the catalyst varied with the content of CeO2. The CeO2 of the large particles in the catalyst will form longer interface contact length and thus have more active sites. However, the existing small particle CuO was easily reduced to Cu, which promoted the reduction of CO by CeO2. CCe2O carriers exposed to different crystal planes were prepared by liquid phase reduction method and a series of CeO2/CuxO catalysts were prepared by deposition precipitation method. It is found that the Cu2O of cube, hexahedron, polypods and polyhedrons are mainly exposed to (100), (110), (111) and (311) faces. The CeO2 with high crystal face index has higher hanging bond density and higher apparent activation energy. After loading CeO2, the catalyst activity of CO was good. The texture and catalytic performance of the catalyst were greatly affected by the exposed crystal of the support.
【學(xué)位授予單位】：內(nèi)蒙古大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TQ116.2;TQ426
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