本文選題：紫菜 + 分級多孔炭　； 參考：《北京化工大學(xué)》2017年碩士論文

【摘要】：多孔炭材料具有比表面積高、孔隙發(fā)達(dá)、導(dǎo)電導(dǎo)熱性能好等特點,被廣泛應(yīng)用于能量轉(zhuǎn)化與儲存、工業(yè)催化、氣體吸附和分離等領(lǐng)域。近年來發(fā)展的具有微孔-介孔-大孔三維貫通的分級多孔炭材料,可以大幅度地提高反應(yīng)物/生成物的傳質(zhì),進(jìn)而促進(jìn)電化學(xué)反應(yīng)過程,因而在氧還原反應(yīng)中具有良好的應(yīng)用前景。生物質(zhì)材料富含碳、氮、磷等元素,可再生、來源廣泛,是制備分級多孔炭的理想前驅(qū)體,本文采用廉價易得的紅藻類植物---紫菜為前驅(qū)體,通過對炭化和活化工藝條件的調(diào)控,制備出系列分級多孔炭材料,揭示了紫菜的成碳機制。在此基礎(chǔ)之上,開展了紫菜炭作為氧還原反應(yīng)催化劑載體的應(yīng)用研究。本論文的主要創(chuàng)新工作如下:一、以紫菜為前驅(qū)體,通過預(yù)碳化、碳化活化制備了高比表面積且具有微孔-介孔-大孔三維連通的蜂窩狀孔道結(jié)構(gòu)的氮摻雜分級多孔炭材料。研究表明,紫菜中富含的蛋白質(zhì)和多糖是主要的碳、氮前驅(qū)體,紫菜中所含的無機鹽可作為天然模板在活化過程中進(jìn)一步調(diào)控孔道結(jié)構(gòu)。當(dāng)預(yù)碳化物與活化劑質(zhì)量比為2,碳化活化溫度為900℃時,制備的分級多孔炭比表面積最高(2152.5 m2g-1),孔容為1.03 cm3 g-1,孔結(jié)構(gòu)以微孔為主(占比91.6 %),氮含量為1.8 at.%。二、以制備的紫菜基多孔炭為載體,通過吸附以及低溫?zé)崽幚矸稚⒌姆椒?負(fù)載具有高活性Fe(Ⅱ)-N4中心的酞菁鐵分子,制得紫菜基多孔炭負(fù)載酞菁鐵的分子級鐵、氮共摻雜分級多孔炭催化劑。同時考察了炭載體、酞菁鐵負(fù)載量等對催化劑性能的影響,發(fā)現(xiàn)紫菜基多孔炭的分級多孔結(jié)構(gòu)和表面氮摻雜結(jié)構(gòu),有利于提高酞菁鐵分子的負(fù)載量,同時增強酞菁鐵分子和載體之間的相互作用,從而提高其氧還原催化性能。電化學(xué)測試表明,400 ℃熱解制備的分子級催化劑氧還原半波電位為0.88 Vvs. RHE,比商業(yè)化Pt/C高40 mV,電子轉(zhuǎn)移數(shù)為4,為理想的4電子反應(yīng)。該催化劑經(jīng)3000圈循環(huán)穩(wěn)定性測試后,半波電位僅負(fù)移6 mV,具有優(yōu)于商業(yè)化Pt/C的電化學(xué)穩(wěn)定性。三、根據(jù)微孔結(jié)構(gòu)和表面摻雜結(jié)構(gòu)對原子級活性中心的約束作用,進(jìn)一步采用血晶素為天然鐵/氮源,紫菜基多孔炭為載體,通過吸附以及高溫?zé)峤膺�原的方法,將原始血晶素中低催化活性的Cl-Fe(Ⅲ)-N4結(jié)構(gòu),在800 ℃時熱解還原成與炭載體緊密相連的高活性原子級Fe-NxCy催化中心,同時該催化劑表現(xiàn)出鐵原子高度均勻分散的特點。通過電化學(xué)測試表明,該原子級催化劑的半波電位達(dá)到0.87 V vs. RHE,高于Pt/C 30 mV,動力學(xué)電流密度(Jk@ 0.88 V vs.RHE)高達(dá)4.1mA cm-2,同時具有顯著優(yōu)于Pt/C的穩(wěn)定性和抗甲醇毒化能力。由于血晶素中有機相的高溫?zé)峤馓炕?該原子型催化劑中的鐵原子和炭載體緊密相連,相比與之前的分子型催化劑,表現(xiàn)出更強的催化穩(wěn)定性(3000圈穩(wěn)定性實驗后半波電位僅負(fù)移1 mV)。
[Abstract]:Porous carbon materials have been widely used in energy conversion and storage, industrial catalysis, gas adsorption and separation due to their high specific surface area, well developed pores and good conductivity and thermal conductivity. Recently developed porous carbon materials with microporous mesoporous and macroporous three dimensional permeation can greatly improve the mass transfer of reactants / products and thus promote the electrochemical reaction process. Therefore, it has a good application prospect in oxygen reduction reaction. Biomass materials are rich in carbon, nitrogen, phosphorus and other elements. They can be regenerated and come from a wide range of sources. They are ideal precursors for the preparation of graded porous carbon. In this paper, the cheap and easily available red-algae -porphyra was used as the precursor. A series of graded porous carbon materials were prepared by controlling the carbonization and activation conditions, which revealed the carbonation mechanism of porphyra yezoensis. On this basis, the application of porphyra charcoal as catalyst carrier for oxygen reduction reaction was studied. The main innovative work of this thesis is as follows: 1. The nitrogen-doped porous carbon materials with high specific surface area and three dimensional connectivity of microporous mesoporous and macroporous channels were prepared by carbonization and carbonization with porphyra yezoensis as precursor. The results showed that the protein and polysaccharide rich in porphyra were the main precursors of carbon and nitrogen. The inorganic salts contained in the porphyra could be used as natural templates to further regulate the pore structure in the process of activation. When the mass ratio of precarbide to activator is 2 and the activation temperature of carbonation is 900 鈩，

本文編號：1854223