本文選題：六價(jià)鉻　切入點(diǎn)：Pd　出處：《武漢紡織大學(xué)》2017年碩士論文　論文類型：學(xué)位論文

【摘要】：六價(jià)鉻(Cr(VI))是常見的水污染源之一,具有高環(huán)境毒性及致癌性;而三價(jià)鉻(Cr(III))低毒且可轉(zhuǎn)為氫氧化鉻沉淀,易從水體中分離。在合適的催化條件下,利用甲酸將Cr(VI)還原為Cr(III)是處理鉻污染的有效方法之一。本論文通過液相法合成了兩種炭負(fù)載的納米金屬催化劑,探索了其將Cr(VI)還原轉(zhuǎn)化為Cr(III)的催化活性和催化機(jī)理。首先,以水合肼為還原劑、采用一步水熱還原法制備了氮摻雜石墨烯(NG)負(fù)載的CuPd納米合金(PdCu/NG),并利用XRD、HRTEM、EDX、ICP-OES和XPS等手段對(duì)材料的物相、結(jié)構(gòu)、組成和表面化學(xué)態(tài)等進(jìn)行了詳細(xì)表征。結(jié)果表明,NG表面上負(fù)載的納米金屬為均相的PdCu合金(而非常見的Cu和Pd兩相混合物),金屬的負(fù)載量為35 wt.%,平均粒徑為4.7 nm。該P(yáng)dCu/NG催化劑對(duì)甲酸還原Cr(VI)具有優(yōu)異的催化活性,催化反應(yīng)速率高達(dá)0.406 min-1,活化能低至34.9 kJ/mol。優(yōu)異的催化活性來源于金屬-載體強(qiáng)相互作用(SMSI)效應(yīng),以及PdCu金屬間的協(xié)同效應(yīng)。相比于常見的貴金屬催化劑(如Pd、Pt等),所合成的PdCu/NG具有價(jià)格低廉、活性更高等優(yōu)點(diǎn)。其次,將金屬有機(jī)框架化合物ZIF-8炭化后得到的ZC作為載體,水合肼為還原劑,合成了ZC負(fù)載的NiPd雙金屬納米催化劑(NiPd/ZC)。并利用XRD、HRTEM、EDX、ICP-OES和XPS等手段對(duì)其進(jìn)行了表征。研究發(fā)現(xiàn),炭化后的載體保持著多孔炭骨架空間結(jié)構(gòu),NiPd雙金屬納米顆粒均勻地負(fù)載在ZC介孔內(nèi)。ZC上負(fù)載的納米金屬為雙相Ni Pd納米粒子。在催化還原Cr(VI)的實(shí)驗(yàn)中,NiPd/ZC雙金屬催化劑的催化活性明顯優(yōu)于單金屬納米催化劑。其催化速率高達(dá)0.396 min-1,活化能低至28.7 kJ/mol。經(jīng)過五次循環(huán)使用后,催化劑的催化活性只降低了2.7%。相比較PdCu/NG催化劑,ZC具有更大的比表面積和獨(dú)特的空間框架結(jié)構(gòu),使得金屬粒子的附著位點(diǎn)增多,催化穩(wěn)定性更好。磁性Ni粒子的引入,讓催化劑的回收再使用變的更加方便。最后,總結(jié)全文并展望了課題未來研究方向。
[Abstract]:Hexavalent chromium (Cr) is one of the most common sources of water pollution, with high environmental toxicity and carcinogenicity, while the trivalent chromium (Cr) is low toxic and can be converted to chromium hydroxide precipitation, which is easily separated from water. In this paper, two kinds of carbon supported nanometallic catalysts were synthesized by liquid phase method, and their catalytic activity and catalytic mechanism were explored. Using hydrazine hydrate as reducing agent, a nitrogen-doped graphene (NGN) supported CuPd nanoalloy PdCu / NGN was prepared by a one-step hydrothermal reduction method. The phase and structure of the material were analyzed by means of XRDX HRTEMU EDXICP-OES and XPS. The composition and surface chemical state were characterized in detail. The results show that the nanometallic loaded on the surface of NG is a homogeneous PdCu alloy (not a common Cu and PD two-phase mixture). The metal loading amount is 35wt. and the average particle size is 4.7 nm. The PdCu/NG catalyst has excellent catalytic activity for the reduction of CrVI by formic acid. The catalytic reaction rate is as high as 0.406 min-1, and the activation energy is as low as 34.9 kJ / mol. The excellent catalytic activity comes from the strong metal-carrier interaction (SMSI) effect. Compared with the common noble metal catalysts (such as PD Pt etc.), the synthesized PdCu/NG has the advantages of low cost and higher activity. Secondly, the ZC obtained from the carbonization of the organometallic framework compound ZIF-8 is used as the carrier. The ZC-supported NiPd bimetallic catalyst, NiPD / ZCX, was synthesized by hydrazine hydrate as a reductant. It was characterized by XRDD-HRTEMN EDX ICP-OES and XPS. The carbonized carrier maintained the porous carbon skeleton space structure and the nanometallic particles loaded uniformly on ZC mesoporous. ZC were biphasic NiPd nanoparticles. In the experiment of catalytic reduction of CrVI, NiPd / ZC bimetallic catalyst was used. The catalytic activity of the catalyst is obviously better than that of the monometallic nanometer catalyst. The catalytic rate is up to 0.396 min-1, and the activation energy is as low as 28.7 KJ / mol. Compared with the PdCu/NG catalyst ZC has a larger specific surface area and a unique spatial frame structure, which makes the metal particles have more adhesion sites and better catalytic stability. It is more convenient to recycle and reuse the catalyst. Finally, the paper summarizes the whole paper and looks forward to the future research direction.
【學(xué)位授予單位】：武漢紡織大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：X52;O643.36

【參考文獻(xiàn)】

相關(guān)期刊論文 前6條

1 魏英祥;涂偉霞;;膨脹石墨負(fù)載鈀納米顆粒催化六價(jià)鉻還原反應(yīng)[J];高等學(xué)校化學(xué)學(xué)報(bào);2014年11期

2 郭小惠;李勇;劉琪英;申文杰;;微波輔助的多元醇法合成CoNi納米材料(英文)[J];催化學(xué)報(bào);2012年04期

3 趙穎華;金程;李登新;;膨脹石墨對(duì)廢水中鉻的吸附研究[J];環(huán)境科學(xué)與技術(shù);2012年04期

4 熊道陵;李英;鐘洪鳴;馬智敏;李金輝;武巖鵬;羅序燕;;鉻回收技術(shù)及其研究進(jìn)展[J];有色金屬科學(xué)與工程;2011年05期

5 裘凱棟;黎維彬;;水溶液中六價(jià)鉻在碳納米管上的吸附[J];物理化學(xué)學(xué)報(bào);2006年12期

6 段碧林;曾令可;劉艷春;劉平安;稅安澤;;微波輔助加熱技術(shù)在無機(jī)材料中的應(yīng)用[J];陶瓷學(xué)報(bào);2006年01期

，

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