本文選題：氧化鋁工藝　切入點(diǎn)：堿溶碳分法　出處：《北京化工大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：堿溶碳分法氧化鋁生產(chǎn)工藝是一種突破傳統(tǒng)拜耳法的高效新工藝,其關(guān)鍵技術(shù)是膜電解碳酸鈉溶液獲得碳酸氫鈉和氫氧化鈉�，F(xiàn)有膜電解碳酸鈉技術(shù)采用析氫陰極和析氧陽極,槽壓為2.5-2.6 V,電耗高達(dá)1800～1900 kWh/t Al2O3,為大幅度降低電耗,本課題組提出以氫陽極替代析氧陽極,并且將陰極產(chǎn)生的氫氣導(dǎo)入陽極,形成氫循環(huán)利用的節(jié)能電解技術(shù)方案。其中,研究出一種高性能的氫陽極催化劑是高效節(jié)電的氫循環(huán)電解的關(guān)鍵所在。本文研究設(shè)計(jì)了一類以NiCu合金為核,Pd為殼層的碳載NiCu@Pd納米核殼結(jié)構(gòu)的氫陽極催化劑。采用熱還原法制備NiCu/C,通過乙二醇還原的方法在NiCu合金上負(fù)載Pd合成NiCu@Pd/C催化劑。主要考察NiCu合金的含量,Ni/Cu的比例,Pd的載量以及制備過程對(duì)催化劑形貌、納米結(jié)構(gòu)、微觀組分的影響機(jī)制,以及對(duì)催化劑電催化氫氣氧化動(dòng)力學(xué),抗中毒能力,壽命等的影響規(guī)律。XRD分析表明NiCu合金的含量,Ni/Cu的比例,Pd的載量均對(duì)外層Pd原子的晶格間距有著顯著的影響。TEM圖像表明Ni1Cu4@Pd/C催化劑的粒徑為6.8±1.2 nm,且粒徑分布均勻。電化學(xué)測(cè)試表明NiCu@Pd/C催化劑的氫氧化性能受到晶格間距和電子效應(yīng)的共同影響。綜合考慮,NiCu合金含量為20%,前驅(qū)體Ni/Cu比例為1：4,Pd的載量為10%時(shí),該催化劑顯示出了最優(yōu)的氫氧化性能。相比于載量為20%的Pd/C的催化劑,該催化劑不僅在氫氧化性能方面大大優(yōu)于20%Pd/C,同時(shí)其抗甲醇中毒能力也超過20% Pd/C。這主要是因?yàn)橛捎趦?nèi)核NiCu金屬與貴金屬之間的相互作用,導(dǎo)致貴金屬晶格間距的收縮。這樣的配位效應(yīng)使得貴金屬d軌道重疊增加,d能帶中心下降。另外,NiCu與貴金屬Pd之間相互作用使得貴金屬上的d軌道電子云密度降低。貴金屬Pd的d能帶中心的下降和d軌道電子云密度降低使得其與中間產(chǎn)物(COads)的作用大大降低,避免了活性位的中毒。將上述Ni1Cu4@Pd/C為催化劑的的氣體擴(kuò)散氫陽極,在應(yīng)用于氫陽極電解碳酸鈉的電解時(shí)展現(xiàn)出了非常的低的槽壓和突出的節(jié)能優(yōu)勢(shì)。在10 mA·cm-2的電流密度下,槽壓僅僅為0.44 V。在100 mA·cm-2的電流密度下,相比于Pd/C氫陽極電解1.38 V的槽壓和傳統(tǒng)電解2.53 V的槽壓,Ni1Cu4@Pd/C氫陽極電解碳酸鈉的槽壓可降低至1.09 V,相當(dāng)于電解電耗約800 kWh/t Al2O3,相比常規(guī)電解節(jié)電57%,具有顯著的節(jié)電節(jié)能意義。
[Abstract]:The alkali soluble carbon process for alumina production is a breakthrough in the traditional new efficient process with Bayer method, the key technology is membrane electrolytic solution of sodium carbonate to obtain sodium bicarbonate and sodium hydroxide. The existing membrane electrolysis of sodium carbonate by hydrogen evolution and oxygen evolution anode, tank pressure is 2.5-2.6 V, power consumption of up to 1800~1900 kWh/t for Al2O3 greatly reduce the power consumption, the research group proposed to replace the hydrogen anode anode, and the hydrogen into the anode and cathode of the formation of the program, energy recycling hydrogen electrolysis technology. The research of a high performance hydrogen anode catalyst is high efficiency electrolytic hydrogen cycle is the key. This paper studies the design a class of NiCu alloy as anode catalyst for hydrogen nuclei, Pd shell carbon nano NiCu@Pd core-shell structure. The preparation of NiCu/C by thermal reduction method, Pd method by ethylene glycol reduction of negative in NiCu alloy The NiCu@Pd/C content of catalyst. Mainly on the NiCu alloy, the ratio of Ni/Cu, Pd load and the preparation process of the catalyst morphology, nano structure, the influence mechanism of micro components, as well as the catalyst electrocatalytic hydrogen oxidation kinetics, anti poisoning ability,.XRD influence life analysis showed that the content of NiCu alloy, Ni/Cu the proportion of the Pd load are outer layer Pd atoms with lattice spacing of.TEM images are significantly affected that of Ni1Cu4@Pd/C catalyst particle size of 6.8 + 1.2 nm, and homogeneous particle size distribution. The electrochemical test shows that hydrogen oxidation performance of NiCu@Pd/C catalyst is influenced by lattice spacing and electron effect. Considering NiCu alloy the content is 20%, the precursor Ni/Cu ratio of 1:4, the Pd load is 10%, the catalyst showed hydrogen oxidation. Compared to the optimal performance of the load of 20% Pd/C catalyst, the catalyst not only Much better than the hydrogen oxidation performance of 20%Pd/C, and its anti methanol poisoning capacity than 20% Pd/C. this is mainly because the interaction between the kernel NiCu metal and precious metals, precious metals lead to contraction of the lattice spacing. Such coordination effect makes the noble metal d orbitals overlap, d band center also decreased. And the interaction between NiCu and noble metal Pd makes d orbital electron cloud density on the precious metals decreased. Noble metal Pd d band center declined and d orbital electron density lower with the intermediate product (COads) greatly reduced the effect of the active sites, to avoid poisoning. The Ni1Cu4@Pd/C catalyst for gas the diffusion of hydrogen in the anode used in hydrogen anode electrolysis of sodium carbonate showed a very low pressure trough and prominent energy-saving advantages. At a current density of 10 mA - cm-2, the tank pressure is only 0.44 V. at 100 m The current density of A - cm-2, the tank pressure and the traditional electrolysis groove of 2.53 V compared to 1.38 V Pd/C hydrogen anode voltage, anode electrolytic hydrogen Ni1Cu4@Pd/C sodium carbonate cell voltage can be decreased to 1.09 V, equivalent to the electrolytic power consumption of about 800 kWh/t Al2O3, compared with conventional electrolytic power saving of 57% has significant energy saving.

【學(xué)位授予單位】：北京化工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TQ133.1;O643.36

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

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本文編號(hào)：1558798