介孔復合金屬氧化物三維結(jié)構(gòu)的構(gòu)筑與雙金屬納米顆粒的限域調(diào)控制備及應用
發(fā)布時間：2018-09-19 06:13
【摘要】：介孔復合金屬氧化物材料(2-50 nm)由于其大的比表面、靈活可調(diào)的孔徑與組成,以及在催化、能量轉(zhuǎn)換及生物技術(shù)方面的應用潛力,越來越引起人們的廣泛關(guān)注。但是由于本身有機模板劑的尺寸限制,目前合成的孔徑都在16nm以下。而在催化反應中,反應物和產(chǎn)物的傳輸效率直接影響最后的催化性能,所以孔徑上的難突破極大的限制了它們在大分子催化中的應用。另一方面,催化劑一般是由活性位點和載體兩大部分組成,金屬納米顆粒是活性位點的重要組成部分,而雙金屬納米顆粒所表現(xiàn)出的協(xié)同作用有著比單金屬更好的催化表現(xiàn),所以,人們越來越多致力于研究雙金屬納米顆粒的設(shè)計合成。目前,絕大多數(shù)的雙金屬顆粒是通過溶液相方法得到,這些顆粒在高溫苛刻催化環(huán)境下易發(fā)生燒結(jié)長大,直接導致催化活性的下降甚至喪失,所以,如何制備高溫穩(wěn)定的雙金屬是這一領(lǐng)域的一大難點。更重要的是,催化領(lǐng)域研究的最終目標是能夠根據(jù)催化反應所需要的空間結(jié)構(gòu)設(shè)計并控制合成出具有所需構(gòu)架的雙金屬顆粒,這樣就可以省去大量盲目嘗試的時間,各取所需,使合成更具有目的性和方向性。本論文致力于解決如上問題,即大孔介孔復合金屬氧化物的合成與雙金屬納米顆粒的可控合成,分為六章。第一章是課題相關(guān)文獻綜述,對所做工作的歷史背景、最新進展及后期展望做了大體的概括；第二章介紹實驗過程中用到的主要試劑、儀器設(shè)備、表征方法及催化反應條件；第三章介紹三維大孔介孔復合金屬氧化物的普適性合成及催化應用；第四章介紹三維介孔限域空間內(nèi)復合雙金屬納米顆粒的合成及應用；第五章介紹調(diào)變初始納米金尺寸實現(xiàn)金鎳復合雙金屬的結(jié)構(gòu)控制合成及其應用；第六章是總結(jié)與展望。論文得到的結(jié)論主要有以下幾點：我們借助本身具有三維開放孔道的介孔氧化硅EP-FDU-12為骨架,將金屬氧化物前驅(qū)體通過AcHE溶劑揮發(fā)的方法涂覆在其內(nèi)表面,然后通過焙燒后處理得到結(jié)構(gòu)復制的三維大孔介孔復合金屬氧化物。此法成功的關(guān)鍵因素有兩點：一是EP-FDU-12的開放孔道結(jié)構(gòu)可以有效防止涂覆過程中金屬氧化物前驅(qū)體單獨聚集而引起的相分離現(xiàn)象,二是在AcHE體系中形成的非常穩(wěn)定的金屬氧化物前驅(qū)體納米顆粒。通過一系列表征,證實EP-Al2O3, EP-TiO2, EP-ZrO2,二元EP-Cu-TiO2及三元EP-K-Cu-TiO2等都可以通過此法成功合成,并且涂層的厚度可以通過改變前驅(qū)體初始加入量靈活調(diào)控；將所得到的EP-Al2O3材料用于在強酸或中強B酸位點上進行的大分子傅-克烷基化反應中,并以純EP-FDU-12和部分涂覆部分相分離的Al2O3@EP-FDU-12-100℃(1/9)為對比樣品,發(fā)現(xiàn)EP-Al2O3催化活性比后兩者都高出很多,說明此反應不僅需要酸性位點的存在,而且需要三維開放的孔道結(jié)構(gòu)促進過程中物質(zhì)的順利傳輸,EP-Al2O3正是將兩個必不可少的條件集為一身,從而得到非�？捎^的催化活性；將其用作載體負載PdNPs用于VOC正已烷的催化氧化中,也得到了高于對比樣品的催化活性。為了得到高溫條件下依然穩(wěn)定的雙金屬納米顆粒,我們采取了一種新的合成策略。將兩種金屬組分(Au,Pd或Ni,Pd等)直接負載到一種載體孔內(nèi)進行高溫焙燒,通過后續(xù)系列材料表征,證實這種高溫冶煉合成雙金屬合金的方法是非常可行的。并且在我們所采用的EP-FDU-12限域空間內(nèi),得到的合金顆粒非常均,尺寸大都在5 nm左右,有效的防止了高溫催化下顆粒發(fā)生聚集長大的問題。在Au-Pd體系中,不同的Au-Pd摩爾比可以有效控制Pd的抗氧化能力,O2-TPO證實當Au與Pd的摩爾比為1時,對于Pd的抗氧化溫度提高了50℃之多,為330℃左右(純Pd約260℃)。而后我們將所合成的Au-Pd體系用于Pd0為活性位的正已烷催化氧化中,證實了我們所得到的Au-Pd在富氧環(huán)境下,依然可以穩(wěn)定絕大部分Pd0存在,從而很好的保持了高的催化活性；通過調(diào)變AuNPs的初始尺寸,并在相同的EP-FDU-12限域空間內(nèi),實現(xiàn)金鎳復合雙金屬的結(jié)構(gòu)控制合成,通過XRD,XPS等表征手段得到了初步結(jié)果,并且在苯甲醇的氣相選擇性氧化反應中得到了彼此不同的催化活性,間接證實AuNPs的不同初始尺寸可以影響與NiNPs在焙燒過程中的相互作用,此工作還在繼續(xù)研究中。
[Abstract]:Mesoporous composite metal oxides (2-50 nm) have attracted more and more attention due to their large specific surface area, flexible and adjustable pore size and composition, as well as their potential applications in catalysis, energy conversion and biotechnology. However, due to the size limitation of their organic templates, the pore sizes are all below 16 nm. The transport efficiency of reactants and products has a direct impact on the final catalytic performance of the reactions, so the difficulty in breaking through the pore size limits their application in macromolecular catalysis. The synergistic effect of nanoparticles is better than that of single metal, so more and more people are devoting themselves to the design and synthesis of bimetallic nanoparticles. Therefore, how to prepare high temperature stable bimetallic particles is a major difficulty in this field. More importantly, the ultimate goal of catalytic research is to be able to control the synthesis of bimetallic particles with the required framework according to the space structure of catalytic reaction. This paper is devoted to solve the above problems, namely, the synthesis of macroporous mesoporous composite metal oxides and the controllable synthesis of bimetallic nanoparticles, which can be divided into six chapters. Chapter 1 is a literature review of the subject, the historical background of the work done, the latest progress and the future. In the second chapter, the main reagents, apparatus, characterization methods and catalytic reaction conditions used in the experiment are introduced; in the third chapter, the universality of synthesis and catalytic application of three-dimensional macroporous mesoporous composite metal oxides are introduced; in the fourth chapter, the suitability of composite bimetallic nanoparticles in three-dimensional mesoporous confined space is introduced. In the fifth chapter, the structure-controlled synthesis of gold-nickel composite bimetals by adjusting the initial size of gold nanoparticles and its application are introduced; in the sixth chapter, the summary and prospect are given. Three-dimensional macroporous mesoporous composite metal oxides were prepared by evaporation of AcHE solvent and then calcination. The key factors for the success of this method are as follows: 1. The open-channel structure of EP-FDU-12 can effectively prevent the aggregation of metal oxide precursors during the coating process. Phase separation, and the formation of very stable metal oxide precursor nanoparticles in AcHE system. Through a series of characterization, it is confirmed that EP-Al2O3, EP-TiO2, EP-ZrO2, binary EP-Cu-TiO2 and ternary EP-K-Cu-TiO2 can be successfully synthesized by this method, and the coating thickness can be flexibly changed by the initial addition of precursor. The obtained EP-Al2O3 material was used in the macromolecular Fourier-Crafts alkylation reaction at strong acid or moderate B acid sites, and compared with pure EP-FDU-12 and partially coated Al2O3@EP-FDU-12-100 C(1/9) samples, it was found that the catalytic activity of EP-Al2O3 was much higher than that of the latter two, indicating that the reaction needed not only acid. EP-Al2O3 is used as a carrier to support PdNPs in the catalytic oxidation of VOC n-hexane, and the catalytic activity of EP-Al2O3 is higher than that of the control sample. Activity. In order to obtain stable bimetallic nanoparticles at high temperature, we adopted a new synthetic strategy. Two metal components (Au, Pd or Ni, Pd, etc.) were directly loaded into a carrier pore for high-temperature roasting. The subsequent characterization of a series of materials confirmed that this method of high-temperature metallurgical synthesis of bimetallic alloys is very feasible. OK. And in the EP-FDU-12 confinement space we used, the alloy particles are very uniform, most of them are about 5 nm in size, which effectively prevents the agglomeration and growth of particles under high temperature catalysis. In the Au-Pd system, different Au-Pd molar ratio can effectively control the oxidation resistance of Pd, O2-TPO confirmed when the molar ratio of Au to Pd. For Pd, the antioxidant temperature increased by 50 C to about 330 C (pure Pd about 260 C). Then we applied the synthesized Au-Pd system to the catalytic oxidation of n-hexane with Pd0 as the active site, which confirmed that most of the Pd0 could still be stable in the oxygen-enriched environment, thus maintaining the high catalytic activity. By changing the initial size of AuNPs and in the same EP-FDU-12 confinement space, the structure-controlled synthesis of Au-Ni composite bimetals was realized. The preliminary results were obtained by XRD, XPS and other characterization methods, and the catalytic activities of AuNPs were different from each other in the gas-phase selective oxidation of benzyl alcohol. The initial size can affect the interaction between NiNPs and calcination. This work is still under study.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB383.1
[Abstract]:Mesoporous composite metal oxides (2-50 nm) have attracted more and more attention due to their large specific surface area, flexible and adjustable pore size and composition, as well as their potential applications in catalysis, energy conversion and biotechnology. However, due to the size limitation of their organic templates, the pore sizes are all below 16 nm. The transport efficiency of reactants and products has a direct impact on the final catalytic performance of the reactions, so the difficulty in breaking through the pore size limits their application in macromolecular catalysis. The synergistic effect of nanoparticles is better than that of single metal, so more and more people are devoting themselves to the design and synthesis of bimetallic nanoparticles. Therefore, how to prepare high temperature stable bimetallic particles is a major difficulty in this field. More importantly, the ultimate goal of catalytic research is to be able to control the synthesis of bimetallic particles with the required framework according to the space structure of catalytic reaction. This paper is devoted to solve the above problems, namely, the synthesis of macroporous mesoporous composite metal oxides and the controllable synthesis of bimetallic nanoparticles, which can be divided into six chapters. Chapter 1 is a literature review of the subject, the historical background of the work done, the latest progress and the future. In the second chapter, the main reagents, apparatus, characterization methods and catalytic reaction conditions used in the experiment are introduced; in the third chapter, the universality of synthesis and catalytic application of three-dimensional macroporous mesoporous composite metal oxides are introduced; in the fourth chapter, the suitability of composite bimetallic nanoparticles in three-dimensional mesoporous confined space is introduced. In the fifth chapter, the structure-controlled synthesis of gold-nickel composite bimetals by adjusting the initial size of gold nanoparticles and its application are introduced; in the sixth chapter, the summary and prospect are given. Three-dimensional macroporous mesoporous composite metal oxides were prepared by evaporation of AcHE solvent and then calcination. The key factors for the success of this method are as follows: 1. The open-channel structure of EP-FDU-12 can effectively prevent the aggregation of metal oxide precursors during the coating process. Phase separation, and the formation of very stable metal oxide precursor nanoparticles in AcHE system. Through a series of characterization, it is confirmed that EP-Al2O3, EP-TiO2, EP-ZrO2, binary EP-Cu-TiO2 and ternary EP-K-Cu-TiO2 can be successfully synthesized by this method, and the coating thickness can be flexibly changed by the initial addition of precursor. The obtained EP-Al2O3 material was used in the macromolecular Fourier-Crafts alkylation reaction at strong acid or moderate B acid sites, and compared with pure EP-FDU-12 and partially coated Al2O3@EP-FDU-12-100 C(1/9) samples, it was found that the catalytic activity of EP-Al2O3 was much higher than that of the latter two, indicating that the reaction needed not only acid. EP-Al2O3 is used as a carrier to support PdNPs in the catalytic oxidation of VOC n-hexane, and the catalytic activity of EP-Al2O3 is higher than that of the control sample. Activity. In order to obtain stable bimetallic nanoparticles at high temperature, we adopted a new synthetic strategy. Two metal components (Au, Pd or Ni, Pd, etc.) were directly loaded into a carrier pore for high-temperature roasting. The subsequent characterization of a series of materials confirmed that this method of high-temperature metallurgical synthesis of bimetallic alloys is very feasible. OK. And in the EP-FDU-12 confinement space we used, the alloy particles are very uniform, most of them are about 5 nm in size, which effectively prevents the agglomeration and growth of particles under high temperature catalysis. In the Au-Pd system, different Au-Pd molar ratio can effectively control the oxidation resistance of Pd, O2-TPO confirmed when the molar ratio of Au to Pd. For Pd, the antioxidant temperature increased by 50 C to about 330 C (pure Pd about 260 C). Then we applied the synthesized Au-Pd system to the catalytic oxidation of n-hexane with Pd0 as the active site, which confirmed that most of the Pd0 could still be stable in the oxygen-enriched environment, thus maintaining the high catalytic activity. By changing the initial size of AuNPs and in the same EP-FDU-12 confinement space, the structure-controlled synthesis of Au-Ni composite bimetals was realized. The preliminary results were obtained by XRD, XPS and other characterization methods, and the catalytic activities of AuNPs were different from each other in the gas-phase selective oxidation of benzyl alcohol. The initial size can affect the interaction between NiNPs and calcination. This work is still under study.
【學位授予單位】：浙江大學
【學位級別】：博士
【學位授予年份】：2015
【分類號】：TB383.1
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