本文選題：溫敏性 + 高分子��； 參考：《浙江理工大學(xué)》2017年碩士論文

【摘要】：金屬納米粒子由于其特殊的晶體結(jié)構(gòu)和表面性質(zhì)常常被應(yīng)用于催化領(lǐng)域,但由于其極高的表面活性和比表面積,金屬納米粒子之間會(huì)發(fā)生聚集而使其催化活性降低甚至失去催化活性,因此需要將金屬納米粒子負(fù)載到一定的載體上,以分散和穩(wěn)定金屬納米粒子,提高其利用率。目前常用的無(wú)機(jī)載體主要有活性炭、石墨烯、碳納米管、Al2O3、SiO2等,也有一些有機(jī)載體(如樹脂),由于這些載體通常是不溶于反應(yīng)液的,因此將以這些載體負(fù)載的催化劑稱為非均相催化劑。非均相催化劑在回收利用方面很方便,也有將催化劑固定在催化劑床上,但其催化效果往往并不高。相反的,以某些能溶于反應(yīng)液的載體(如超支化聚乙烯亞胺)負(fù)載金屬納米粒子,可以制成均相催化劑。均相催化劑的催化效率很高,但其回收困難。溫敏高分子是一類能夠隨溫度變化發(fā)生性質(zhì)極大轉(zhuǎn)變的高分子。其具有一轉(zhuǎn)變溫度,當(dāng)環(huán)境溫度低于其轉(zhuǎn)變溫度時(shí),溫敏高分子呈親水性,能溶于水中形成均相體系;當(dāng)環(huán)境溫度高于其轉(zhuǎn)變溫度時(shí),溫敏高分子呈疏水性,從水中析出形成非均相體系。因此若使用溫敏高分子作為金屬納米粒子的載體就可以結(jié)合均相催化劑和非均相催化劑的優(yōu)點(diǎn)。不僅如此,由于溫敏高分子載體的結(jié)構(gòu)會(huì)隨溫度的變化而變化,因此可以通過(guò)控制反應(yīng)溫度來(lái)控制催化反應(yīng)的速率,當(dāng)溫敏高分子負(fù)載催化劑從體系中析出,甚至可以使催化反應(yīng)停止,這樣便實(shí)現(xiàn)了催化反應(yīng)的“開”、“關(guān)”控制。另一方面,傳統(tǒng)的催化反應(yīng)通常是在有機(jī)溶劑中進(jìn)行的,而由于在溫敏高分子中同時(shí)存在疏水基團(tuán)和親水基團(tuán),當(dāng)以溫敏高分子為載體的金屬納米粒子催化劑進(jìn)入催化反應(yīng)體系,一些疏水性的底物會(huì)在溫敏高分子的疏水區(qū)域發(fā)生聚集,提高了局部底物濃度,催化反應(yīng)速率增快,因此使用溫敏高分子負(fù)載催化劑可以在水相中進(jìn)行催化反應(yīng)。這樣便在保證了催化反應(yīng)速率的前提下,避免了大量有機(jī)溶劑的使用,符合“綠色化學(xué)”的理念。本文擬利用溫敏高分子隨溫度變化會(huì)發(fā)生親疏水性轉(zhuǎn)變的溫敏性能,制備出以溫敏高分子為載體的高效的易分離的負(fù)載金屬Pd催化劑;另一方面,試圖通過(guò)控制溫度來(lái)調(diào)節(jié)催化劑的催化活性,以制備出一類可控催化劑,并希望建立溫敏高分子載體結(jié)構(gòu)與催化劑催化活性之間的初步關(guān)系。本文以不同分子量的寡聚乙二醇甲醚甲基丙烯酸酯為溫敏高分子單體、以4-乙烯基吡啶為配位單體制備了一系類高效可回收的體型溫敏高分子負(fù)載Pd催化及和線型溫敏高分子負(fù)載Pd催化劑。通過(guò)FTIR、NMR、XRD、DSC、TG、TEM等現(xiàn)代分析方法表征了溫敏高分子載體及其負(fù)載Pd催化劑的結(jié)構(gòu),發(fā)現(xiàn)得到了Pd粒子尺寸為6-10 nm的體型溫敏高分子負(fù)載Pd催化劑和Pd粒子尺寸為3.5 nm左右的線型溫敏高分子負(fù)載Pd催化劑。以對(duì)硝基苯酚的催化還原為模型反應(yīng)研究了不同結(jié)構(gòu)溫敏高分子負(fù)載Pd催化劑的催化反應(yīng)動(dòng)力學(xué),分析了溫敏高分子負(fù)載Pd催化劑的溫敏催化效果以及溫敏高分子載體結(jié)構(gòu)對(duì)其催化效果的影響。最后,為了拓展溫敏高分子載體的結(jié)構(gòu)和應(yīng)用領(lǐng)域,本文還制備和表征了以三苯基膦為配體的溫敏高分子負(fù)載Pd催化劑,并研究了該催化劑對(duì)Suzuki-Miyaura反應(yīng)的催化效果。研究發(fā)現(xiàn),體型溫敏高分子負(fù)載Pd納米粒子催化劑和線型溫敏高分子負(fù)載Pd納米粒子催化劑均能有效地催化還原4-硝基苯酚為4-氨基苯酚,并且具有溫敏催化效果——轉(zhuǎn)變溫度以下是催化反應(yīng)速率快,轉(zhuǎn)變溫度以上時(shí),催化反應(yīng)速率慢,甚至實(shí)現(xiàn)了反應(yīng)“開關(guān)”的控制。載體結(jié)構(gòu)對(duì)催化劑效果影響頗大,線型溫敏高分子負(fù)載Pd催化劑的催化效率是體型溫敏高分子負(fù)載Pd催化劑的催化效率的1000多倍。線型溫敏高分子對(duì)Pd納米粒子的分散效果更好,能得到尺寸更小,單分散性更好的Pd納米粒子。溫敏高分子催化劑在循環(huán)使用8次后,仍能保持90%以上的轉(zhuǎn)化率,重復(fù)使用性能良好。
[Abstract]:Metal nanoparticles are often used in the field of catalysis because of their special crystal structure and surface properties. However, because of their high surface activity and specific surface area, the metal nanoparticles will accumulate to reduce their catalytic activity and even lose the catalytic activity. Therefore, the metal nanoparticles need to be loaded on a certain carrier. The use of active carbon, Shi Moxi, carbon nanotubes, Al2O3, SiO2, as well as some organic carriers (such as resin), are commonly used in the dispersion and stabilization of metal nanoparticles. As these carriers are usually insoluble in the reaction liquid, the catalysts supported by these carriers are called heterogeneous catalysts. The catalyst is easy to recycle and immobilizing the catalyst on the catalyst bed, but its catalytic effect is often not high. On the contrary, a homogeneous catalyst can be made by loading metal nanoparticles (such as hyperbranched polyethyleneimine) with some carriers (such as hyperbranched polyethyleneimine). The catalytic efficiency of the homogeneous catalyst is very high, but the recovery is difficult. It is difficult. Thermosensitive polymer is a kind of polymer which can change greatly with temperature change. It has a transition temperature. When the environment temperature is lower than its transition temperature, the temperature sensitive polymer is hydrophilic and can dissolve in water to form a homogeneous system. When the temperature of the environment is higher than the temperature, the thermo sensitive polymer is hydrophobic and form in the water. Therefore, if the temperature sensitive polymer is used as the carrier of the metal nanoparticles, the advantages of homogeneous and heterogeneous catalysts can be combined. Not only that, because the structure of the temperature sensitive polymer carrier varies with the temperature, so the reaction rate can be controlled by controlling the reaction temperature, as Wen Min. The polymer supported catalyst can be precipitated from the system and even can stop the catalytic reaction. In this way, the "open" and "close" control of the catalytic reaction is realized. On the other hand, the traditional catalytic reaction is usually carried out in the organic solvent, and the hydrophobic group and hydrophilic group in the thermosensitive polymer are used as the thermosensitive polymer. Some hydrophobic substrates will accumulate in the hydrophobic region of the thermosensitive polymer, which improves the concentration of the substrate and the reaction rate increases rapidly. Therefore, the catalytic reaction can be carried out in the water phase by using a thermosensitive polymer supported catalyst. This ensures the catalytic reaction. On the premise of the rate, the use of a large number of organic solvents is avoided and the concept of "green chemistry" is in line with the concept of "green chemistry". In this paper, the temperature sensitive properties of thermosensitive polymers with the change of hydrophobicity will occur with the temperature change. A highly efficient and easily separated load metal Pd catalyst with a thermosensitive polymer is prepared. On the other hand, the temperature sensitive polymer is tried to control the temperature. Degree to regulate the catalytic activity of the catalyst to prepare a kind of controllable catalyst, and hope to establish a preliminary relationship between the structure of the temperature sensitive polymer carrier and the catalytic activity of the catalyst. In this paper, the oligoethylene glycol methyl ether methacrylate with different molecular weight was used as the thermosensitive polymer monomer and 4- vinyl pyridine was used as the coordination monomer. A highly efficient and recoverable type thermosensitive polymer supported Pd catalyst and a linear thermosensitive polymer loaded Pd catalyst. The structure of a thermosensitive polymer carrier and its loaded Pd catalyst was characterized by modern analytical methods such as FTIR, NMR, XRD, DSC, TG, TEM and other modern analytical methods. The Pd particle scale was found to be a 6-10 nm type thermosensitive polymer loaded Pd catalyst. The linear thermosensitive polymer supported Pd catalyst with Pd particle size of about 3.5 nm was used. The catalytic reaction kinetics of different structure thermosensitive polymer supported Pd catalysts was studied with the catalytic reduction of p-nitrophenol as a model reaction. The Wen Mincui effect of the thermosensitive polymer supported Pd catalyst and the temperature sensitive polymer carrier structure were analyzed. Finally, in order to expand the structure and application field of the temperature sensitive polymer carrier, the thermosensitive polymer supported Pd catalyst with three phenyl phosphine as the ligand was prepared and characterized, and the catalytic effect of the catalyst on the Suzuki-Miyaura reaction was studied. The catalyst and linear thermosensitive polymer supported Pd nanoparticle catalyst can effectively catalyze the reduction of 4- nitrophenol to 4- aminophenol, and have a temperature sensitive catalytic effect. The catalytic reaction rate is fast below the transition temperature, and the reaction rate is slow when the transition temperature is above, and even the reaction "switch" control is realized. Carrier structure is the same. The effect of catalyst effect is considerable, the catalytic efficiency of the linear thermosensitive polymer supported Pd catalyst is more than 1000 times the catalytic efficiency of the type thermosensitive polymer loaded Pd catalyst. The dispersion effect of the linear thermosensitive polymer on Pd nanoparticles is better, and the Pd nanoparticles with smaller size and better monodispersity can be obtained. After 8 cycles, it can still maintain more than 90% conversion rate and good reuse performance.
【學(xué)位授予單位】：浙江理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：O643.36

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