負(fù)載型金屬納米顆粒的光化學(xué)沉積可控合成及催化應(yīng)用
發(fā)布時間：2018-07-29 07:45
【摘要】：隨著納米化學(xué)的發(fā)展,金屬納米顆粒受到越來越多的關(guān)注。特別是負(fù)載在多孔材料中的多金屬納米材料,在工業(yè)催化方面有很大的發(fā)展前景。但在其實(shí)際應(yīng)用中,納米顆粒的組成調(diào)控和熱穩(wěn)定性是困擾研究者的兩大難題。很多合成方法無法對單個多金屬顆粒的組成和尺寸進(jìn)行精確調(diào)控,并且在后續(xù)的熱處理過程中容易出現(xiàn)相分離和燒結(jié)等現(xiàn)象。針對上述情況,本文提出了簡單和普適的原位光化學(xué)沉積合成策略,制備一系列負(fù)載型金屬納米顆粒。該方法采用多種金屬前驅(qū)體的一步共同光沉積,在介孔限域空間內(nèi)制備高分散、高活性和高熱穩(wěn)定性的多金屬納米顆粒。一方面,通過調(diào)控金屬前驅(qū)體的濃度,可精確控制單個納米顆粒的組成。另一方面,通過焙燒下的金屬合金化過程,可制得小尺寸、抗燒結(jié)的均一合金納米顆粒。我們考察了多金屬納米顆粒在光催化產(chǎn)氫、高溫催化氧化等方面的應(yīng)用,并在納米合金相圖的研究中得到了初步結(jié)果。主要研究內(nèi)容如下：1)基于原位光化學(xué)沉積法,在介孔Ti02中均勻負(fù)載Cu納米顆粒�？疾霤u前驅(qū)體濃度和顆粒尺寸的關(guān)系。以甲醛溶液紫外光下的重整產(chǎn)氫作為探針反應(yīng),考察Cu-Ti02在光催化中的催化效果和作用機(jī)理。我們的研究表明低濃度的Cu前驅(qū)體可得到小尺寸的Cu納米顆粒,更有利于光催化的進(jìn)行。2)以三維籠狀超大介孔TiO2為載體,采用光沉積法合成負(fù)載型Au/Pt/Pd單金屬納米顆粒。通過調(diào)控焙燒溫度,考察Pt納米顆粒的尺寸與溫度的關(guān)系。另外,通過調(diào)控金屬前驅(qū)體濃度,考察金屬負(fù)載量和正己烷催化燃燒性能的關(guān)系。我們發(fā)現(xiàn)籠狀介孔孔道的超大比表面積和有序限域結(jié)構(gòu)有效增強(qiáng)了納米顆粒的熱穩(wěn)定性,繼而提高其催化性能。3)根據(jù)一步光合成的策略,將多種金屬前驅(qū)體共同沉積到超大介孔YiO2的籠狀孔道內(nèi),制得負(fù)載型雙金屬納米顆粒(AuPt/AuPd/PtPd)。以AuPt為例,考察了低溫焙燒下納米顆粒的尺寸、組成和結(jié)構(gòu)變化。AuPt顆粒高度分散在介孔孔道中,并在空氣焙燒下由核殼結(jié)構(gòu)變?yōu)閱蜗嗪辖鸾Y(jié)構(gòu)。由于多金屬間的協(xié)同作用,AuPt合金具有更好的催化燃燒性能。4)深入研究AuPtPd三金屬納米顆粒,考察其在高溫空氣焙燒下的尺寸、組成和結(jié)構(gòu)變化。得益于原位共沉積過程,我們能夠精確調(diào)控單個納米顆粒中三種組分的含量。更重要的是,AuPtPd三金屬體系具有超高溫穩(wěn)定性和抗氧化性。與單金屬和雙金屬相比,三金屬納米顆粒在高溫(700-900。C)焙燒下具有均勻的合金結(jié)構(gòu),并保持很高的金屬Pd比例。納米顆粒的三金屬組成和介孔載體的限域空間對于其上述性質(zhì)起到了關(guān)鍵作用。在正己烷催化燃燒反應(yīng)中,AuPtPd催化劑也表現(xiàn)出穩(wěn)定的催化性能。5)以AuPtPd體系為例,研究三金屬材料的高溫納米合金相圖。從實(shí)驗(yàn)數(shù)據(jù)的角度,展現(xiàn)納米顆粒在800℃下的相變過程。對于不同組成的AuPtPd納米顆粒,其XRD峰位置、峰型以及EDS所得的元素分布均有不同。我們首次繪制出AuPtPd納米材料在800℃下的不混溶區(qū)等溫線,并發(fā)現(xiàn)納米尺度的合金相圖不僅與尺寸效應(yīng)有關(guān),還受到組成效應(yīng)的影響。通過相圖中不同組成樣品的正己烷催化燃燒性能,初步考察了納米相圖對于催化的指導(dǎo)作用。
[Abstract]:With the development of nanosochemistry, metal nanoparticles have attracted more and more attention. Especially the multi metal nanomaterials loaded in porous materials have great prospects in industrial catalysis. But in their practical applications, the composition and regulation and thermal stability of nanoparticles are the two difficult problems that perplex researchers. The composition and size of single polymetallic particles can not be regulated accurately, and phase separation and sintering are easy to occur during the subsequent heat treatment. In this paper, a simple and universal in situ photochemical deposition strategy is proposed to prepare a series of negative metal nanoparticles. This method uses a variety of metals. One step of the precursor's common photo deposition is to prepare polymetallic nanoparticles with high dispersion, high activity and high thermal stability in the mesoporous limit space. On the one hand, the composition of single nanoparticles can be controlled accurately by controlling the concentration of metal precursors. On the other hand, small size and anti sintering can be made by the metal alloying process under calcination. We investigated the application of polymetallic nanoparticles in the photocatalytic hydrogen production and high temperature catalytic oxidation and obtained the preliminary results in the study of the nanoscale phase diagram. The main contents are as follows: 1) Cu nanoparticles were uniformly loaded in mesoporous Ti02 based on in situ photochemical deposition. The precursor of Cu was investigated. The relationship between concentration and particle size. The catalytic effect and mechanism of Cu-Ti02 in photocatalytic catalysis are investigated by reformed hydrogen production under Formaldehyde Solution ultraviolet light as a probe. Our research shows that low concentration of Cu precursor can obtain small size Cu nanoparticles, and is more conducive to the photochemical.2) with three-dimensional cage like mesoporous TiO2 Supported Au/Pt/Pd single metal nanoparticles were synthesized by light deposition. The relationship between the size of Pt nanoparticles and the temperature was investigated by controlling the calcination temperature. In addition, the relationship between the metal load and the catalytic combustion performance of n-hexane was investigated by regulating the concentration of metal precursors. The ordered domain structure effectively enhanced the thermal stability of the nanoparticles and improved its catalytic performance.3). Based on the one step light synthesis strategy, a variety of metal precursors were deposited into the cage like channel of the super large mesoporous YiO2, and the AuPt/AuPd/ PtPd was prepared. The AuPt was used as an example to investigate the nanoscale particles under low temperature. The size, composition and structure change of.AuPt particles are highly dispersed in the mesoporous channel, and the core shell structure becomes single-phase alloy structure under the air roasting. Because of the synergistic effect of multi metal, AuPt alloy has better catalytic combustion performance.4) to study AuPtPd three metal nanoparticles and investigate its size under high temperature air roasting. The composition and structure change. Thanks to the in-situ co deposition process, we can accurately regulate the content of three components in a single nanoparticle. More importantly, the AuPtPd three metal system has super high temperature stability and oxidation resistance. Compared with the single metal and bimetallic, three metal nanoparticles have a uniform alloy under high temperature (700-900.C) roasting. Structure, and maintain a high proportion of metal Pd. The three metal composition of the nanoparticles and the confinement space of the mesoporous carrier play a key role in the above properties. In the catalytic combustion reaction of n-hexane, the AuPtPd catalyst also shows a stable catalytic performance.5), as an example of the AuPtPd system, to study the high temperature nanoscale phase diagram of the metal material. From the angle of experimental data, the phase transition process of nano particles at 800 C is shown. For different AuPtPd nanoparticles, the XRD peak position, peak type and EDS distribution are different. We first draw the isotherm of the immiscible region at 800 C at 800 C, and find that the nanoscale alloy phase diagram is not only the same as that of the nanoscale. The effect of the size effect is also influenced by the composition effect. Through the catalytic combustion performance of n-hexane of different composition samples in the phase diagram, the guiding role of nano phase diagram to catalysis is preliminarily investigated.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TB383.1;O643.36
[Abstract]:With the development of nanosochemistry, metal nanoparticles have attracted more and more attention. Especially the multi metal nanomaterials loaded in porous materials have great prospects in industrial catalysis. But in their practical applications, the composition and regulation and thermal stability of nanoparticles are the two difficult problems that perplex researchers. The composition and size of single polymetallic particles can not be regulated accurately, and phase separation and sintering are easy to occur during the subsequent heat treatment. In this paper, a simple and universal in situ photochemical deposition strategy is proposed to prepare a series of negative metal nanoparticles. This method uses a variety of metals. One step of the precursor's common photo deposition is to prepare polymetallic nanoparticles with high dispersion, high activity and high thermal stability in the mesoporous limit space. On the one hand, the composition of single nanoparticles can be controlled accurately by controlling the concentration of metal precursors. On the other hand, small size and anti sintering can be made by the metal alloying process under calcination. We investigated the application of polymetallic nanoparticles in the photocatalytic hydrogen production and high temperature catalytic oxidation and obtained the preliminary results in the study of the nanoscale phase diagram. The main contents are as follows: 1) Cu nanoparticles were uniformly loaded in mesoporous Ti02 based on in situ photochemical deposition. The precursor of Cu was investigated. The relationship between concentration and particle size. The catalytic effect and mechanism of Cu-Ti02 in photocatalytic catalysis are investigated by reformed hydrogen production under Formaldehyde Solution ultraviolet light as a probe. Our research shows that low concentration of Cu precursor can obtain small size Cu nanoparticles, and is more conducive to the photochemical.2) with three-dimensional cage like mesoporous TiO2 Supported Au/Pt/Pd single metal nanoparticles were synthesized by light deposition. The relationship between the size of Pt nanoparticles and the temperature was investigated by controlling the calcination temperature. In addition, the relationship between the metal load and the catalytic combustion performance of n-hexane was investigated by regulating the concentration of metal precursors. The ordered domain structure effectively enhanced the thermal stability of the nanoparticles and improved its catalytic performance.3). Based on the one step light synthesis strategy, a variety of metal precursors were deposited into the cage like channel of the super large mesoporous YiO2, and the AuPt/AuPd/ PtPd was prepared. The AuPt was used as an example to investigate the nanoscale particles under low temperature. The size, composition and structure change of.AuPt particles are highly dispersed in the mesoporous channel, and the core shell structure becomes single-phase alloy structure under the air roasting. Because of the synergistic effect of multi metal, AuPt alloy has better catalytic combustion performance.4) to study AuPtPd three metal nanoparticles and investigate its size under high temperature air roasting. The composition and structure change. Thanks to the in-situ co deposition process, we can accurately regulate the content of three components in a single nanoparticle. More importantly, the AuPtPd three metal system has super high temperature stability and oxidation resistance. Compared with the single metal and bimetallic, three metal nanoparticles have a uniform alloy under high temperature (700-900.C) roasting. Structure, and maintain a high proportion of metal Pd. The three metal composition of the nanoparticles and the confinement space of the mesoporous carrier play a key role in the above properties. In the catalytic combustion reaction of n-hexane, the AuPtPd catalyst also shows a stable catalytic performance.5), as an example of the AuPtPd system, to study the high temperature nanoscale phase diagram of the metal material. From the angle of experimental data, the phase transition process of nano particles at 800 C is shown. For different AuPtPd nanoparticles, the XRD peak position, peak type and EDS distribution are different. We first draw the isotherm of the immiscible region at 800 C at 800 C, and find that the nanoscale alloy phase diagram is not only the same as that of the nanoscale. The effect of the size effect is also influenced by the composition effect. Through the catalytic combustion performance of n-hexane of different composition samples in the phase diagram, the guiding role of nano phase diagram to catalysis is preliminarily investigated.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2015
【分類號】：TB383.1;O643.36
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1 杜松濤,熊貴光;復(fù)合金屬納米顆粒多孔硅的光學(xué)非線性特性[J];武漢大學(xué)學(xué)報(理學(xué)版);2003年05期
2 何武強(qiáng),何寶林,陳益賢,廖小娟,劉漢范;溶劑穩(wěn)定的鈀金屬納米顆粒的制備[J];中南民族大學(xué)學(xué)報(自然科學(xué)版);2004年04期
3 杜天倫;楊修春;黃文e，
本文編號：2151996
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