本文選題：Pd-Ni雙金屬催化劑 + 沉積條件�。� 參考：《昆明理工大學(xué)》2017年碩士論文

【摘要】：Pd-Ni雙金屬催化劑普遍應(yīng)用于化工、食品和環(huán)保等領(lǐng)域,目前主要制備方法是浸漬法,但該法制備的催化劑存在分散度不高、活性金屬利用率低及脫氯效果不理想等問題。本文采用超聲波-化學(xué)沉淀法制備不同載體的Pd-Ni雙金屬催化劑。研究了沉積、焙燒及還原過程的最佳工藝條件,采用激光粒度分析議、X射線衍射儀、差熱分析議、透射電子顯微鏡和N2吸附-脫附儀等對催化劑成分、物相和性能進(jìn)行表征,同時(shí)研究了催化劑用于漂白紫膠催化加氫脫氯性能。結(jié)果表明:以γ-Al2O3為載體的Pd-Ni雙金屬催化劑的最佳沉積條件為pH12、鈀鎳質(zhì)量比1:1、攪拌時(shí)間2h、溶液溫度40 ℃、分散劑質(zhì)量3%、攪拌速率500 r/min、超聲時(shí)間5 min和超聲強(qiáng)度60%(720 W),在此條件下,粒度分布集中,催化劑顆粒尺寸從14.07 μm降低至5.07 μm,有效的降低了顆粒間團(tuán)聚效應(yīng);以Si02為載體的Pd-Ni雙金屬催化劑的最佳沉積條件為pH11.5、鈀鎳質(zhì)量比1:1、溶液溫度35 ℃、攪拌時(shí)間1h、分散劑質(zhì)量4%、攪拌速率500 r/min、超聲時(shí)間7min和超聲強(qiáng)度20%(240W);以γ-A1203-Si02為載體的Pd-Ni雙金屬催化劑的最佳沉積條件為pH11.5、鈀鎳質(zhì)量比1:1、載體質(zhì)量比1:1、攪拌時(shí)間1 h、溶液溫度30 ℃、分散劑質(zhì)量3%、攪拌速率500 r/min、超聲時(shí)間7 min和超聲強(qiáng)度40%(480 W),且發(fā)現(xiàn)沉積時(shí)間、超聲時(shí)間和超聲強(qiáng)度對催化劑粒徑及粒度分布影響較為顯著。通過差熱差重和XRD分析確定的催化劑焙燒還原條件:(1)載體y-A1203:焙燒溫度600 ℃、焙燒時(shí)間2h,還原溫度500 ℃、還原時(shí)間2h;(2)載體Si02:焙燒溫度600 ℃、焙燒時(shí)間2.5 h,還原溫度500 ℃、還原時(shí)間2h;(3)載體γ-Al203-SiO2:焙燒溫度550 ℃、焙燒時(shí)間2.5h,還原溫度500 ℃、還原時(shí)間2h。三種Pd-Ni雙金屬催化劑還原后均存在少量NiO物相,Pd物相結(jié)晶度較好,發(fā)現(xiàn)物相特征峰均向右偏移,認(rèn)為產(chǎn)生Pd-Ni合金。催化劑用于紫膠加氫脫氯的研究表明:在液固比7:1、催化劑8 g/L、氫氣流量0.1 L/min、反應(yīng)溫度90 ℃、反應(yīng)時(shí)間4h、攪拌速率300 r/min條件下:(1)Pd-Ni/γ-Al203催化劑脫氯后紫膠中氯含量為0.43%;(2)Pd-Ni/SiO2催化劑脫氯后紫膠中氯含量為0.48%;(3)Pd-Ni/γ-Al203-Si02催化劑脫氯后紫膠中氯含量為0.38%。發(fā)現(xiàn)Pd-Ni/γ-Al203-SiO2雙金屬催化劑具有更高的脫氯效果。此外,三種雙金屬催化劑脫氯后紫膠中氯含量均符合歐美標(biāo)準(zhǔn),同時(shí)達(dá)到國內(nèi)食品、醫(yī)藥行業(yè)要求。
[Abstract]:Pd-Ni bimetallic catalysts are widely used in chemical, food and environmental protection fields. At present, the main preparation method is impregnation method. However, the catalyst prepared by this method has some problems such as low dispersion, low utilization rate of active metals and unsatisfactory dechlorination effect. In this paper, Pd-Ni bimetallic catalysts with different supports were prepared by ultrasonic-chemical precipitation method. The optimum process conditions of deposition, roasting and reduction were studied. The composition, phase and properties of the catalyst were characterized by laser particle size analysis, differential thermal analysis, transmission electron microscope and N2 adsorption-desorption apparatus. The catalytic hydrogenation dechlorination of bleached lac was also studied. The results show that the optimum deposition conditions of Pd-Ni bimetallic catalyst supported on 緯 -Al _ 2O _ 3 are pH 12, mass ratio of palladium and nickel 1: 1, stirring time 2 h, solution temperature 40 鈩，

本文編號：1806523