本文選題：燃料電池 + 催化劑��； 參考：《武漢大學(xué)》2010年博士論文

【摘要】： 燃料電池具有高效、清潔等優(yōu)點,被認為是未來的備選能源之一。以氫為燃料的質(zhì)子交換膜燃料電池(PEMFC)已經(jīng)達到相當(dāng)高的技術(shù)水平,但氫氣儲運的困難和安全問題成為其商品化的主要障礙。研究者們在企圖解決這一問題的同時,開始尋求新的燃料,直接甲醇燃料電池(DMFC)和直接甲酸燃料電池(DFAFC)成為研究的熱點。Pt/C、PtRu/C和Pd/C是上述三種燃料電池最常用的催化劑。無論何種燃料電池,都需要適于規(guī)模生產(chǎn)的高效電催化劑的制備方法。 本論文工作對最適合批量生產(chǎn)的浸漬法進行較全面的研究,探究控制催化劑品質(zhì)的關(guān)鍵,最終獲得了高分散的PtRu/C、Pt/C和Pd/C催化劑,并對其物理化學(xué)性質(zhì)及相關(guān)電催化進行了研究。主要的工作內(nèi)容與結(jié)論如下： 1、高分散、高載量PtRu/C催化劑的浸漬法制備及表征 發(fā)展了一種簡單的易實現(xiàn)規(guī)模化制備的催化劑合成方法,整個過程由“浸漬-干燥-氫氣還原”三個步驟構(gòu)成,無需過濾洗滌。即便采用含Cl-前驅(qū)體,也可獲得分散度很高的金屬載量為60wt%的PtRu/C催化劑。TEM分析表明,所制60wt%PtRu/C的金屬粒徑為1.5±0.5nm；通過EDAX, XRD, XPS和TGA/DTA等分析發(fā)現(xiàn),制備的PtRu/C催化劑中含PtRu合金與非晶態(tài)RuOxHy。電催化研究表明,所制PtRu/C對甲醇氧化具有優(yōu)越的性能,可能與催化劑中含非晶態(tài)RuOxHy有關(guān)。 2、PtRu/C催化劑的熱重分析 熱重分析(TGA)是文獻中用于指認PtRu催化劑中RuOxHy組分的常用實驗方法,通常將150-600℃下的催化劑失重歸結(jié)為RuOxHy的失水。我們通過TG-FTIR聯(lián)用分析發(fā)現(xiàn),在上述溫度區(qū)間催化劑失重的主要產(chǎn)物是C02,沒有發(fā)現(xiàn)可以檢測的H2O。因此此溫度范圍內(nèi)催化劑的失重應(yīng)該歸因于碳載體在PtRu催化下的氧化,而且氧的來源主要是催化劑中Pt表面的氧與氧化釕中的氧。此研究對PtRu/C催化劑的熱重行為產(chǎn)生了不同于文獻的認識,TGA并非分析PtRu/C催化劑中非合金釕組分的有效方法。 3、高分散Pt/C催化劑的浸漬法制備 對Pt/C催化劑浸漬法制備過程中的關(guān)鍵實驗參數(shù)進行探究,發(fā)現(xiàn)獲得高分散Pt/C催化劑的關(guān)鍵因素包括：(1)采用大比表面積的載體有利于獲得小粒徑的Pt/C。(2)熱浸漬和超聲結(jié)合攪拌是我們的方法與傳統(tǒng)浸漬法的重要區(qū)別,也是獲得高分散Pt/C的關(guān)鍵。(3)氫氣還原的溫度須控制在80-150℃之間,過高的還原溫度導(dǎo)致Pt粒徑增大。(4)浸漬后凝膠態(tài)的含水量對Pt粒徑有影響,水碳質(zhì)量比在5-20范圍內(nèi),催化劑的粒徑為2.5nm左右。 4、Pd/C催化劑的浸漬法制備 以PdCl2為前體,采用浸漬法制備Pd/C催化劑很難獲得高的分散度。研究發(fā)現(xiàn),Cl-的存在和還原氣體的種類是影響Pd/C粒徑的兩大因素。采用Pd(NO3)2為前體,并以Ar+H2混合氣或CO代替純氫氣作為還原劑,可以顯著提高Pd/C催化劑的分散度。優(yōu)化條件下制得的20wt%Pd/C的Pd粒徑為3.5nm,10wt%Pd/C的Pd粒徑為2.7nm。 5、Pd/C催化劑的電催化粒度效應(yīng)研究 對粒徑分別為2.7、3.5、4.7、6.1、8.1nm的Pd/C催化劑進行氫氧化、氧還原、甲酸氧化等反應(yīng)的粒度效應(yīng)研究。結(jié)果表明,Pd粒徑越小,催化劑與氧原子結(jié)合力越強,氧還原反應(yīng)動力電流密度隨著粒徑增大而提高。對于氫氧化反應(yīng),隨著粒徑增加,反應(yīng)交換電流密度增大；4.7nm Pd/C的氫氧化交換電流密度為0.21mAcm-2,約為Pt的百分之一。對于甲酸氧化反應(yīng),4.7nm的Pd/C催化劑具有最高的質(zhì)量比活性和面積比活性。
[Abstract]:Fuel cells have the advantages of high efficiency and cleanliness, which are considered to be one of the future alternative energy sources. Proton exchange membrane fuel cells (PEMFC) with hydrogen as fuel have reached a high level of technology, but the difficulties and safety problems of hydrogen storage and transportation have become the main obstacle to its commercialization. In search of new fuel, direct methanol fuel cell (DMFC) and direct formic acid fuel cell (DFAFC) have become the hot.Pt/C of the research. PtRu/C and Pd/C are the most commonly used catalysts for these three fuel cells. All kinds of fuel cells need a preparation method suitable for large-scale production of high-efficiency electrocatalytic agents.
In this paper, the most suitable impregnation method for mass production is studied in a more comprehensive way. The key to control the quality of the catalyst is studied. The highly dispersed PtRu/C, Pt/C and Pd/C catalysts are finally obtained. The physical and chemical properties and related electrocatalysis are studied. The main work internal capacity and conclusion are as follows:
1. Preparation and characterization of highly dispersed and highly loaded PtRu/C catalyst by impregnation method
A simple and easy to realize synthesis method of catalyst is developed. The whole process is composed of three steps of "impregnation - drying - hydrogen reduction". No filtration is needed. Even using Cl- precursor, a PtRu/C catalytic agent with high dispersive metal load of 60wt% can also be obtained. The analysis of 60wt%PtRu/C metal The particle size is 1.5 + 0.5nm. Through the analysis of EDAX, XRD, XPS and TGA/DTA, it is found that the electrocatalysis of PtRu alloy and amorphous RuOxHy. in the prepared PtRu/C catalyst shows that the prepared PtRu/C has superior performance to methanol oxidation and may be related to amorphous RuOxHy in the catalyst.
Thermo gravimetric analysis of 2, PtRu/C catalyst
Thermogravimetric analysis (TGA) is a common experimental method used in the identification of RuOxHy components in PtRu catalysts in the literature. Usually, the weight loss of catalyst at 150-600 C is attributed to RuOxHy's loss of water. Through TG-FTIR combined analysis, we found that the main product of the weight loss of the catalyst at the above temperature range is C02, and the detected H2O. is not found so this temperature is found. The weight loss of the catalyst in the range should be attributed to the oxidation of the carbon carrier under the catalysis of PtRu, and the source of oxygen is mainly the oxygen on the Pt surface in the catalyst and the oxygen in the ruthenium oxide. This study is different from the literature on the thermogravimetric behavior of the PtRu/C catalyst. TGA is not an effective method for the analysis of the unalloyed ruthenium components in the PtRu/C catalyst.
3, preparation of highly dispersed Pt/C catalyst by impregnation method
The key experimental parameters in the preparation process of Pt/C catalyst impregnation method are explored, and the key factors for obtaining highly dispersed Pt/C catalysts include: (1) the important difference between our method and the traditional impregnation method is the important difference between our square method and the traditional impregnation method by using the carrier of large specific surface area to obtain the small particle size Pt/C. (2) and the ultrasonic combined agitation. The key to dispersing Pt/C. (3) the temperature of hydrogen reduction must be controlled at 80-150 degrees C, and the high reduction temperature leads to the increase of the particle size of the Pt. (4) the water content of the gelation state after impregnation has an effect on the particle size of Pt, and the water carbon mass ratio is within the range of 5-20, and the particle size of the catalyst is about 2.5nm.
4, preparation of Pd/C catalyst by impregnation method
It is difficult to obtain high dispersion by using PdCl2 as precursor to prepare Pd/C catalyst by impregnation. It is found that the existence of Cl- and the type of reducing gas are two factors affecting the particle size of Pd/C. Using Pd (NO3) 2 as the precursor and using Ar+H2 mixture or CO instead of pure hydrogen as a reductant, the dispersion of the Pd/C catalyst can be significantly improved. The diameter of Pd prepared by 20wt%Pd/C is 3.5Nm, and the diameter of 10wt%Pd/C Pd is 2.7nm..
Study on the effect of 5, Pd/C catalyst on the particle size of electrocatalysis
The particle size effect of hydrogen oxidation, oxygen reduction, formic acid oxidation, and so on. The results show that the smaller the Pd particle size, the stronger the binding force of the catalyst with oxygen atoms, the increase of the kinetic current density of the oxygen reduction reaction with the increase of the particle size. For the hydrogen oxidation reaction, the reaction with the particle size increases. The exchange current density increases; the hydrogen peroxide exchange current density of 4.7nm Pd/C is 0.21mAcm-2, about one percent of Pt. For the oxidation of formic acid, the Pd/C catalyst of 4.7nm has the highest mass ratio activity and area specific activity.

【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2010
【分類號】：TM911.4

【參考文獻】

相關(guān)期刊論文 前6條

1 魏子棟，，郭鶴桐，唐致遠;氧在Pt－Fe－Co／C合金催化劑上的還原[J];催化學(xué)報;1995年02期

2 黃成德,韓佐青,李曉婷,陳延禧;PEMFC用Pt/C電催化劑的制備[J];電源技術(shù);2000年04期

3 劉建國,衣寶廉,魏昭彬;直接甲醇燃料電池的原理、進展和主要技術(shù)問題[J];電源技術(shù);2001年05期

4 成青;;熱重分析技術(shù)及其在高分子材料領(lǐng)域的應(yīng)用[J];廣東化工;2008年12期

5 江紅;馮蘭英;朱紅;郭志軍;張新衛(wèi);;摻雜Fe元素對Pd/C催化劑性能的影響[J];無機材料學(xué)報;2008年04期

6 干林;杜鴻達;李寶華;康飛宇;;載體炭與Pt催化劑之間的相互作用及其引起的尺寸效應(yīng)(英文)[J];新型炭材料;2010年01期

相關(guān)博士學(xué)位論文 前1條

1 唐道平;堿性聚合物電解質(zhì)燃料電池陽極Ni基催化劑研究[D];武漢大學(xué);2009年

相關(guān)碩士學(xué)位論文 前3條

1 劉衛(wèi)鋒;Pt/C及合金催化劑的研制[D];中國科學(xué)院研究生院（大連化學(xué)物理研究所）;2002年

2 黃俊杰;羰基簇合物途徑制備直接甲醇燃料電池陽極催化劑的研究[D];南京師范大學(xué);2004年

3 王明涌;碳納米管基直接醇類燃料電池電極研究[D];湖南大學(xué);2005年

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