本文選題：環(huán)加成反應(yīng) + 季銨鹽��； 參考：《催化學(xué)報(bào)》2017年05期

【摘要】：CO_2是造成溫室效應(yīng)的主要原因,同時(shí)又是地球上儲(chǔ)量最為豐富的可再生C1能源.因此,CO_2資源化受到了廣泛關(guān)注.CO_2與環(huán)氧化物反應(yīng)可合成環(huán)狀碳酸酯,后者廣泛用作極性溶劑、鋰離子電池的電解液和聚碳酸酯中間體等.但是,由于CO_2的化學(xué)惰性,其反應(yīng)需要高活性的催化劑.近年來(lái),堿性金屬、金屬配合物及離子液體等均相催化劑被用于催化CO_2與環(huán)氧化物加成反應(yīng).其中,離子液體具有高熱穩(wěn)定性、低揮發(fā)性和結(jié)構(gòu)可調(diào)性,得到了廣泛研究.季銨鹽、咪唑鹽和季擕鹽等離子液體已經(jīng)被證實(shí)具有較高的催化活性.然而,均相催化劑回收困難,而且產(chǎn)物需要進(jìn)一步純化.將離子液體固載化制備成非均相催化劑,可以實(shí)現(xiàn)簡(jiǎn)單的固/液分離.聚合物、SiO_2、SBA-15、氧化石墨烯和羧甲基纖維素等固載化催化劑已經(jīng)廣泛用于CO_2和環(huán)氧化物的環(huán)加成反應(yīng).雖然非均相催化劑顯示了潛在的優(yōu)勢(shì),但是催化活性較低的問(wèn)題仍然亟待解決,尤其是在較溫和的反應(yīng)條件下.因此,通過(guò)催化劑分子結(jié)構(gòu)設(shè)計(jì)以提高催化性能,成為目前的研究熱點(diǎn).本文提出在催化活性基團(tuán)和載體之間引入長(zhǎng)烷基鏈,增加催化活性位點(diǎn)與反應(yīng)物的接觸面積,同時(shí)引入助催化的羥基,通過(guò)長(zhǎng)鏈與羥基的協(xié)同作用,提高非均相催化劑活性.本文合成了羥基功能化長(zhǎng)柔性鏈季銨化聚苯乙烯微球非均相催化劑([AHTAPC-PS]X,X=Cl,Br,I),用于催化CO_2與環(huán)氧化物的環(huán)加成反應(yīng),并與不含羥基的長(zhǎng)烷基鏈季銨鹽離子液體非均相催化劑([TAPB-PS]Br)及短烷基鏈季銨鹽離子液體非均相催化劑([TMA-PS]X)的催化性能進(jìn)行了對(duì)比.考察了固載后的離子液體烷基鏈長(zhǎng)及側(cè)鏈羥基對(duì)催化性能的影響,并通過(guò)實(shí)驗(yàn)和密度泛函理論計(jì)算研究了催化機(jī)理.紅外光譜、掃描電鏡和能量散射譜結(jié)果充分證明了季銨鹽非均相催化劑的成功合成;熱重測(cè)試表明,此類催化劑具有可以滿足反應(yīng)需求的熱穩(wěn)定性.密度泛函理論計(jì)算結(jié)果顯示,與短烷基鏈非均相催化劑相比,長(zhǎng)烷基鏈非均相催化劑的陰離子負(fù)電性更強(qiáng),同時(shí)羥基與環(huán)氧化合物的氧原子之間存在強(qiáng)的氫鍵作用.羥基形成的氫鍵可以增加環(huán)氧化物的C O鍵長(zhǎng),同時(shí)強(qiáng)負(fù)電的陰離子更加容易攻擊β-碳原子,促進(jìn)環(huán)氧化物開環(huán).另外,長(zhǎng)烷基鏈結(jié)構(gòu)使得鹵素陰離子具有與反應(yīng)物更大的接觸范圍,因此提高了反應(yīng)活性.當(dāng)采用短烷基鏈季銨鹽非均相催化劑時(shí),環(huán)氧丙烷(PO)與CO_2環(huán)加成反應(yīng)生成碳酸丙烯酯(PC)的產(chǎn)率僅為70.9%,而采用長(zhǎng)烷基鏈季銨鹽非均相催化劑時(shí)產(chǎn)率可達(dá)91.4%(135°C,1.5 MPa,3 h),進(jìn)一步加入助催化的羥基,則PC產(chǎn)率可提高到98.5%.此外,含羥基的長(zhǎng)烷基季銨鹽非均相催化劑在溫和條件下也具有較高的催化活性(100°C,1.5 MPa,3 h,PC產(chǎn)率78.4%),該催化劑同時(shí)具有較高的循環(huán)穩(wěn)定性(10次循環(huán)后,PC產(chǎn)率≥96%,選擇性≥99%).綜上所述,該催化劑具有優(yōu)異的綜合性能,展現(xiàn)了良好的工業(yè)應(yīng)用前景.
[Abstract]:CO_2 is the main cause of Greenhouse Effect and the most abundant renewable C1 energy on earth. Therefore, the reaction of CO2 with epoxides has attracted much attention. The latter can be widely used as polar solvent, electrolyte for lithium ion batteries and polycarbonate intermediates. However, due to the chemical inertia of CO_2, its reaction requires highly active catalysts. In recent years, homogeneous catalysts such as basic metals, metal complexes and ionic liquids have been used to catalyze the addition of CO_2 to epoxides. Among them, ionic liquids with high thermal stability, low volatility and structural adjustable, has been widely studied. Quaternary ammonium salts, imidazole salts and quaternary salt-carrying plasma liquids have been proved to have high catalytic activity. However, homogeneous catalyst recovery is difficult and the product needs further purification. Heterogeneous catalysts were prepared by immobilization of ionic liquids to achieve simple solid / liquid separation. The supported catalysts, such as polymer SiO2 / SBA-15, graphene oxide and carboxymethyl cellulose, have been widely used in the cycloaddition reaction of CO_2 and epoxides. Although heterogeneous catalysts show potential advantages, the problem of low catalytic activity still needs to be solved, especially under mild reaction conditions. Therefore, the design of catalyst molecular structure to improve catalytic performance has become a research hotspot. In this paper, a long alkyl chain is introduced between the catalytic active group and the support to increase the contact area between the catalytic active site and the reactant. At the same time, the co-catalytic hydroxyl group is introduced to improve the heterogeneous catalytic activity through the synergistic effect of the long chain and the hydroxyl group. In this paper, hydroxyl functionalized long flexible chain quaternary ammonium polystyrene microsphere heterogeneous catalyst ([AHTAPC-PS] X _ (X _ (1) C _ (1) C _ (1) Br-B) has been synthesized to catalyze the cycloaddition reaction of CO_2 with epoxide. The catalytic properties of the catalyst ([TAPB-PS] Brand [TMA-PS] X) without hydroxyl group were compared with those of the non-hydroxyl chain quaternary ammonium salt ionic liquid heterogeneous catalyst ([TAPB-PS] Br) and the short alkyl chain quaternary ammonium salt ionic liquid heterogeneous catalyst ([TMA-PS] X). The effects of alkyl chain length and side chain hydroxyl groups on the catalytic performance of ionic liquids were investigated, and the catalytic mechanism was studied by means of experiments and density functional theory (DFT). The results of infrared spectra, scanning electron microscopy and energy scattering spectra fully proved the successful synthesis of quaternary ammonium salt heterogeneous catalysts, and the thermogravimetric test showed that these catalysts had the thermal stability which could meet the reaction requirements. The results of density functional theory (DFT) show that the anionic negative charge of the long alkyl chain heterogeneous catalyst is stronger than that of the short alkyl chain heterogeneous catalyst, and there is a strong hydrogen bond between the hydroxyl group and the oxygen atom of the epoxy compound. The hydrogen bond formed by hydroxyl groups can increase the C-O bond length of epoxides, and strongly negative anions can attack 尾 -carbon atoms more easily and promote the ring opening of epoxides. In addition, the long alkyl chain structure makes the halogen anions have a wider contact range with the reactants, thus increasing the reaction activity. When short alkyl chain quaternary ammonium salt was used as heterogeneous catalyst, Propoxypropane oxide reacted with CO_2 cycloaddition to produce propylene carbonate. The yield of propene carbonate was only 70.9, while the yield of long alkyl chain quaternary ammonium salt heterogeneous catalyst could reach 91.4 ~ 135 擄C ~ (1.5) MPa ~ (3) h ~ (-1). The yield of PC could be increased to 98.5% if the hydroxyl group was added further. In addition, the heterogeneous catalyst containing hydroxyl long alkyl quaternary ammonium salt also has high catalytic activity of 100 擄C ~ (-1) 1.5 MPa ~ (3) h ~ (-1) and 78.4% PC yields under mild conditions. The catalyst also has a high cyclic stability of 10 cycles and a PC yield of 鈮，

本文編號(hào)：1988486