鈀納米粒子的制備及催化硝基苯加氫反應(yīng)研究
發(fā)布時(shí)間：2019-01-13 09:09
【摘要】：本論文從環(huán)境友好和高效催化的目的出發(fā),以聚乙烯醇(PVA)為穩(wěn)定劑,探究了水相PVA-Pd納米催化劑催化硝基苯加氫制備苯胺。在水相中,采用氫氣還原法制備了PVA-Pd納米催化劑,Pd納米粒子的平均粒徑為3.2 nm。在較佳工藝條件下:底物與催化劑摩爾比(S/C)1:500、溫度45°C、H_2壓力2 MPa、反應(yīng)時(shí)間3 h,硝基苯的轉(zhuǎn)化率為99.30%,苯胺的選擇性為100%。催化劑重復(fù)使用4次后,硝基苯的轉(zhuǎn)化率仍在90%以上。以三嵌段共聚物P123(PEO20-PPO70-PEO20)為穩(wěn)定劑,探究了水相P123-Pd納米催化劑催化硝基苯加氫制備苯胺。在水相中,采用氫氣還原法制備了P123-Pd納米催化劑,Pd納米粒子的平均粒徑為2.5 nm。在較佳工藝條件下:底物與催化劑摩爾比(S/C)1:500、溫度60°C、H_2壓力3 MPa、反應(yīng)時(shí)間1 h,硝基苯的轉(zhuǎn)化率為99.40%,苯胺的選擇性為100%。催化劑重復(fù)使用5次,活性和選擇性均無(wú)明顯變化�；陔x子液體的靜電位阻雙重穩(wěn)定作用,探究了聚醚十八胺離子液體-Pd納米催化劑催化硝基苯加氫制備苯胺�？疾炝穗x子液體的聚合度、烷基鏈和陰離子對(duì)Pd納米粒子尺寸及形貌的影響。在較佳工藝條件下:底物與催化劑摩爾比(S/C)1:2000、70°C、H_2壓力2 MPa、反應(yīng)時(shí)間3 h,硝基苯的轉(zhuǎn)化率為96.05%,苯胺的選擇性為100%,催化劑循環(huán)使用6次后,催化性能無(wú)明顯變化。上述工作涵蓋了制備金屬Pd納米粒子的聚合物穩(wěn)定法和離子液體穩(wěn)定法。采用透射電鏡(TEM)、共聚焦激光掃描顯微鏡(CLSM)、X射線(xiàn)衍射(XRD)等技術(shù)對(duì)Pd納米催化劑進(jìn)行了表征。三種穩(wěn)定劑與Pd納米粒子之間發(fā)生物理和化學(xué)吸附作用,包裹Pd納米粒子后,形成了局部的微環(huán)境。這種微環(huán)境在增溶底物、促進(jìn)底物與催化劑接觸等方面發(fā)揮了巨大的作用。因此三種催化體系都體現(xiàn)出催化活性高、選擇性好等優(yōu)點(diǎn),具有良好的重復(fù)使用性。以水或離子液體為反應(yīng)介質(zhì),無(wú)論催化劑的制備還是硝基苯的加氫反應(yīng)都在溫和及環(huán)境友好的條件下進(jìn)行。此外,產(chǎn)物與催化劑易分離。該研究為硝基苯催化加氫制備苯胺提供了有效方法,也為其它芳香硝基化合物的催化加氫提供借鑒。
[Abstract]:In this paper, the hydrogenation of nitrobenzene to aniline was studied by using polyvinyl alcohol (PVA) as stabilizer in aqueous PVA-Pd nanometer catalyst for the purpose of environmental friendly and efficient catalysis. PVA-Pd nanoparticles were prepared by hydrogen reduction method in aqueous phase. The average particle size of Pd nanoparticles was 3.2 nm.. Under the optimum conditions, the molar ratio of substrate to catalyst (S / C) 1: 500, temperature 45 擄C, pressure 2 MPa, reaction time 3 h, the conversion of nitrobenzene was 99.30 and the selectivity of aniline was 100. The conversion of nitrobenzene was still over 90% after the catalyst was reused for 4 times. Using triblock copolymer P123 (PEO20-PPO70-PEO20) as stabilizer, the hydrogenation of nitrobenzene to aniline over aqueous phase P123-Pd nano-catalyst was studied. P123-Pd nanocatalysts were prepared by hydrogen reduction method in aqueous phase. The average particle size of Pd nanoparticles was 2.5 nm.. Under the optimum conditions, the molar ratio of substrate to catalyst (S / C) 1: 500, temperature 60 擄C, pressure 3 MPa, reaction time 1 h, the conversion of nitrobenzene was 99.40 and the selectivity of aniline was 100. When the catalyst was reused for 5 times, there was no significant change in activity and selectivity. Based on the double stability of electrostatic steric hindrance of ionic liquids, the hydrogenation of nitrobenzene to aniline over polyether octadecylamine ionic liquid-Pd nanometer catalyst was investigated. The effects of ionic liquid polymerization degree, alkyl chain and anions on the size and morphology of Pd nanoparticles were investigated. Under the optimum conditions, the molar ratio of substrate to catalyst (S / C) is 1: 2000.70 擄C / C, and the reaction time is 3 h at 2 MPa,. The conversion rate of nitrobenzene is 96.05 and the selectivity of aniline is 100. After the catalyst is recycled for 6 times, the conversion rate of nitrobenzene is 96.05 and the selectivity of aniline is 100. There was no obvious change in catalytic activity. The above work includes polymer stabilization method and ionic liquid stabilization method to prepare metal Pd nanoparticles. Pd nanocatalysts were characterized by transmission electron microscope (TEM),) confocal laser scanning microscope (CLSM), X) (XRD) and other techniques. The physical and chemical adsorption between the three stabilizers and Pd nanoparticles resulted in the formation of a local microenvironment after encapsulating the Pd nanoparticles. This microenvironment plays an important role in solubilizing substrates and promoting the contact between substrates and catalysts. Therefore, the three catalytic systems have the advantages of high catalytic activity, good selectivity and good reusability. Using water or ionic liquid as the reaction medium, both the preparation of catalyst and the hydrogenation of nitrobenzene were carried out under mild and environmentally friendly conditions. In addition, the product is easily separated from the catalyst. This study provides an effective method for the hydrogenation of nitrobenzene to aniline, and also provides a reference for the hydrogenation of other aromatic nitro compounds.
【學(xué)位授予單位】：青島科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：O643.36
[Abstract]:In this paper, the hydrogenation of nitrobenzene to aniline was studied by using polyvinyl alcohol (PVA) as stabilizer in aqueous PVA-Pd nanometer catalyst for the purpose of environmental friendly and efficient catalysis. PVA-Pd nanoparticles were prepared by hydrogen reduction method in aqueous phase. The average particle size of Pd nanoparticles was 3.2 nm.. Under the optimum conditions, the molar ratio of substrate to catalyst (S / C) 1: 500, temperature 45 擄C, pressure 2 MPa, reaction time 3 h, the conversion of nitrobenzene was 99.30 and the selectivity of aniline was 100. The conversion of nitrobenzene was still over 90% after the catalyst was reused for 4 times. Using triblock copolymer P123 (PEO20-PPO70-PEO20) as stabilizer, the hydrogenation of nitrobenzene to aniline over aqueous phase P123-Pd nano-catalyst was studied. P123-Pd nanocatalysts were prepared by hydrogen reduction method in aqueous phase. The average particle size of Pd nanoparticles was 2.5 nm.. Under the optimum conditions, the molar ratio of substrate to catalyst (S / C) 1: 500, temperature 60 擄C, pressure 3 MPa, reaction time 1 h, the conversion of nitrobenzene was 99.40 and the selectivity of aniline was 100. When the catalyst was reused for 5 times, there was no significant change in activity and selectivity. Based on the double stability of electrostatic steric hindrance of ionic liquids, the hydrogenation of nitrobenzene to aniline over polyether octadecylamine ionic liquid-Pd nanometer catalyst was investigated. The effects of ionic liquid polymerization degree, alkyl chain and anions on the size and morphology of Pd nanoparticles were investigated. Under the optimum conditions, the molar ratio of substrate to catalyst (S / C) is 1: 2000.70 擄C / C, and the reaction time is 3 h at 2 MPa,. The conversion rate of nitrobenzene is 96.05 and the selectivity of aniline is 100. After the catalyst is recycled for 6 times, the conversion rate of nitrobenzene is 96.05 and the selectivity of aniline is 100. There was no obvious change in catalytic activity. The above work includes polymer stabilization method and ionic liquid stabilization method to prepare metal Pd nanoparticles. Pd nanocatalysts were characterized by transmission electron microscope (TEM),) confocal laser scanning microscope (CLSM), X) (XRD) and other techniques. The physical and chemical adsorption between the three stabilizers and Pd nanoparticles resulted in the formation of a local microenvironment after encapsulating the Pd nanoparticles. This microenvironment plays an important role in solubilizing substrates and promoting the contact between substrates and catalysts. Therefore, the three catalytic systems have the advantages of high catalytic activity, good selectivity and good reusability. Using water or ionic liquid as the reaction medium, both the preparation of catalyst and the hydrogenation of nitrobenzene were carried out under mild and environmentally friendly conditions. In addition, the product is easily separated from the catalyst. This study provides an effective method for the hydrogenation of nitrobenzene to aniline, and also provides a reference for the hydrogenation of other aromatic nitro compounds.
【學(xué)位授予單位】：青島科技大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：O643.36
【參考文獻(xiàn)】
相關(guān)期刊論文 前10條
1 王韶霞;呂永康;;液相硝基苯加氫N(xiāo)i-Zr-B非晶態(tài)合金催化劑制備及結(jié)構(gòu)表征[J];化工新型材料;2014年06期
2 黃穎娟;周曉燕;李在均;顧志國(guó);王光麗;;陰離子表面活性劑作為添加劑種子生長(zhǎng)法制備尺寸可調(diào)的單分散金納米棒[J];無(wú)機(jī)化學(xué)學(xué)報(bào);2013年06期
3 尹華杰;楊繼萍;;陽(yáng)離子表面活性劑作用下制備一維納米結(jié)構(gòu)聚苯胺[J];高等學(xué)�；瘜W(xué)學(xué)報(bào);2011年11期
4 魏s，
本文編號(hào)：2408302
本文鏈接：http://sikaile.net/kejilunwen/huaxue/2408302.html
最近更新
教材專(zhuān)著
