本文選題：鉑銅合金 + 雙金屬催化劑��； 參考：《催化學(xué)報(bào)》2017年07期

【摘要】：Pt是一類高效、穩(wěn)定的催化劑,但Pt資源短缺且價(jià)格昂貴,限制了其廣泛商業(yè)化應(yīng)用.合金化可以使Pt的用量大為減少,且往往能顯著提高其催化性能,因而廣泛應(yīng)用于多相催化和電催化.其中PtCu合金是一類很有前景的催化劑,Cu資源豐富、價(jià)格低廉,不僅降低了成本,而且由于合金效應(yīng)提高了催化劑的活性和穩(wěn)定性.由于合金的粒徑、形狀、組成及結(jié)構(gòu)是影響其催化性能的重要因素,目前研究大多關(guān)注這些特征的可控合成.然而,大多工業(yè)金屬催化劑都是負(fù)載于氧化物上以提高催化性能,合金納米粒子的形貌以及表面組成因與載體作用而發(fā)生改變,也就是所謂的載體效應(yīng).這體現(xiàn)在金屬/氧化物界面處,能夠促進(jìn)金屬粒子分散、改變其形貌甚至化學(xué)態(tài)、進(jìn)而改變其催化性能,其中最具代表性的金屬-載體強(qiáng)相互作用.因此,研究不同氧化物載體上合金催化劑的分散度、表面組成、化學(xué)態(tài),特別是不同氣氛的影響,對(duì)明確影響催化劑性能的關(guān)鍵控制因素非常重要.但是由于多相催化劑的復(fù)雜性,且表面靈敏的測試手段很少,目前相關(guān)報(bào)道還不多.近年發(fā)展起來的高靈敏度低能離子散射譜(HS-LEIS)是表面層靈敏的測試技術(shù),可以測定最表面層的組成和含量.本文采用溶劑熱共還原法成功制備了均一單相、粒徑分布較窄的PtCu_x合金納米顆粒,并運(yùn)用浸漬法將其負(fù)載在TiO_2載體上,以保證載體上納米粒子組成的均一性.應(yīng)用準(zhǔn)原位X-射線光電子能譜(XPS)和高HS-LEIS對(duì)負(fù)載的PtCu合金納米催化劑在不同條件處理后的表面組成和化學(xué)狀態(tài)進(jìn)行表征,發(fā)現(xiàn)催化劑的表面組成、分布、形貌和化學(xué)狀態(tài)顯著受到載體和處理?xiàng)l件的影響,同時(shí)得到負(fù)載和未負(fù)載的催化劑表面組成與體相組成關(guān)系的相圖.結(jié)果表明,PtCux/TiO_2催化劑在連續(xù)氧化過程中,Cu被氧化并較好在載體表面鋪展,Pt-Cu合金狀態(tài)被破壞,Pt可能主要形成單一金屬的納米粒子,并在界面處形成Pt~(δ+).在連續(xù)還原過程中,部分被還原的Cu,與Pt形成富Pt合金粒子.催化劑表面層主要是Cu,Pt很少,與體相組成有很大差別,說明載體對(duì)Cu的分散起到重要作用.
[Abstract]:Pt is a kind of efficient and stable catalyst, but the shortage of Pt resources and the high price limit its wide commercial application. The amount of Pt can be greatly reduced by alloying, and the catalytic performance of Pt can be greatly improved, so it is widely used in heterogeneous catalysis and electrocatalysis. Among them, PtCu alloy is a promising catalyst with rich resources and low price, which not only reduces the cost, but also improves the activity and stability of the catalyst because of the alloy effect. As the particle size, shape, composition and structure of alloys are important factors affecting their catalytic performance, many studies have focused on the controllable synthesis of these characteristics. However, most industrial metal catalysts are supported on oxides to improve their catalytic performance. The morphology and surface composition of alloy nanoparticles are changed by interaction with the support, which is the so-called carrier effect. This is reflected in the metal / oxide interface, which can promote the dispersion of metal particles, change the morphology and even the chemical state of metal particles, and then change their catalytic performance, among which the most representative metal-carrier strongly interacts. Therefore, it is very important to study the influence of the dispersity, surface composition, chemical state, especially the different atmosphere of the alloy catalysts on different oxide supports to determine the key control factors that affect the performance of the catalysts. However, due to the complexity of heterogeneous catalysts and the lack of surface sensitive testing methods, there are few reports. The high sensitivity and low energy ion scattering spectroscopy developed in recent years is a sensitive measurement technique for the surface layer, which can be used to determine the composition and content of the most surface layer. The surface composition and chemical state of the supported PtCu alloy nanocatalysts were characterized by in situ X-ray photoelectron spectroscopy (XPS) and high HS-LEIS. The surface composition and distribution of the catalysts were found. The morphology and chemical state of the catalyst were significantly affected by the carrier and the treatment conditions, and the phase diagrams of the relationship between the surface composition and bulk phase composition of the supported and unloaded catalysts were obtained. In the continuous reduction process, partial reduction of Cu and Pt forms Pt rich alloy particles. The surface layer of the catalyst is mainly Cu-Pt, which is very different from the bulk phase composition, which indicates that the support plays an important role in the dispersion of Cu.
【作者單位】： 廈門大學(xué)化學(xué)化工學(xué)院固體表面物理化學(xué)國家重點(diǎn)實(shí)驗(yàn)室醇醚酯化工清潔生產(chǎn)國家工程實(shí)驗(yàn)室;
【基金】：supported by the National Basic Research Program of China(973 Program,2013CB933102) the National Natural Science Foundation of China(21273178,21573180,91545204) Xiamen-Zhuoyue Biomass Energy Co.Ltd~~
【分類號(hào)】：O643.36

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