本文選題：微晶纖維素 + 水熱還原　； 參考：《遼寧科技大學(xué)》2017年碩士論文

【摘要】：基于超細(xì)粉體的小尺寸效應(yīng)、量子尺寸效應(yīng)、表面效應(yīng)和宏觀量子隧道效應(yīng)等優(yōu)異特性,超細(xì)銅粉可用作替代MLCC貴金屬內(nèi)電極的理想材料,在制作導(dǎo)電涂料、高級潤滑油添加劑、催化劑及納米銅材料方面也具有廣泛的應(yīng)用前景。目前制備超細(xì)銅粉的工藝方法主要有氣相沉積法、機械化合法、電解法及液相還原法等,這些制備方法在產(chǎn)品純度和顆粒度、生產(chǎn)成本、還原效率及環(huán)保等方面都各自存在著難以克服的缺點。因此,本研究提出了高壓水熱還原法制備超細(xì)銅粉的工藝思路,在高壓反應(yīng)釜內(nèi),以微晶纖維素作為還原劑,水熱還原氧化銅粉制備球形超細(xì)銅粉。高壓水熱還原工藝對環(huán)境無污染,所得產(chǎn)品純度高,粒徑小,粒度分布窄而均勻。本文探討了纖維素水熱還原氧化銅的反應(yīng)機制;利用XRD、SEM、激光顆粒分布測量儀等分析測試手段研究了反應(yīng)溫度、反應(yīng)時間、還原劑用量、催化劑用量、液固比和攪拌速度對產(chǎn)物銅粉的純度、物相組成、微觀結(jié)構(gòu)及粒度分布的影響,并對氧化銅的高壓水熱還原過程進(jìn)行動力學(xué)分析,得出如下結(jié)論:(1)微晶纖維素在堿性溶液中可分解為低級羧酸、醛酮類產(chǎn)物,并進(jìn)一步水解并放出H·形成還原性的水熱介質(zhì),在水熱介質(zhì)中按CuO→Cu2O→Cu進(jìn)程逐級還原。(2)在反應(yīng)溫度為220℃、反應(yīng)時間為2h,微晶纖維素、CuO和NaOH質(zhì)量比為6:5:5,液固比為4:1,轉(zhuǎn)速為300r/min時,可制得純度為99%以上的高純銅粉。(3)水熱還原過程的動力學(xué)研究表明,微晶纖維素水熱還原CuO反應(yīng)的表觀活化能E=65.996kJ/mol,反應(yīng)過程的速率限制環(huán)節(jié)受化學(xué)反應(yīng)控制。(4)原料及產(chǎn)物的微觀形貌表明,CuO顆粒粒徑為4.28×10-6m,呈多邊形晶型結(jié)構(gòu);隨著水熱還原過程的進(jìn)行,逐漸在CuO晶體表面形成球形的Cu顆粒。(5)還原溫度升高,顆粒粒徑顯著減小,顆粒粒度趨于均勻且分布變窄。當(dāng)反應(yīng)溫度為215~230℃時,Cu顆粒平均粒徑為2.3~2.4×10-7m。
[Abstract]:Based on the excellent properties of ultrafine powder, such as small size effect, quantum size effect, surface effect and macroscopic quantum tunneling effect, ultrafine copper powder can be used as an ideal material to replace MLCC noble metal internal electrode in making conductive coatings.High-grade lubricating oil additives, catalysts and nano-copper materials also have a wide range of applications.At present, the main methods of preparing ultrafine copper powder are vapor deposition, mechanization, electrolysis and liquid phase reduction, etc. These preparation methods are used in product purity and particle size, production cost, etc.Reduction efficiency and environmental protection have their own shortcomings which are difficult to overcome.Therefore, in this study, the technological idea of preparing ultrafine copper powder by high pressure hydrothermal reduction method was put forward. In the autoclave, the spherical ultrafine copper powder was prepared by hydrothermal reduction of copper oxide powder with microcrystalline cellulose as reducing agent.The high pressure hydrothermal reduction process has no pollution to the environment. The product is of high purity, small particle size and narrow and uniform particle size distribution.In this paper, the mechanism of hydrothermal reduction of copper oxide with cellulose was discussed, and the reaction temperature, reaction time, amount of reductant, amount of catalyst, and so on were studied by means of XRDX SEM and laser particle distribution analyzer.The effects of liquid-solid ratio and stirring speed on the purity, phase composition, microstructure and particle size distribution of copper powder were studied.It is concluded that microcrystalline cellulose can be decomposed into lower carboxylic acids, aldehydes and ketones in alkaline solution, and further hydrolyzed and released to form a reductive hydrothermal medium.When the reaction temperature is 220 鈩，

本文編號：1742844