多相無堿催化丙三醇一步合成乳酸酯研究
發(fā)布時(shí)間：2018-08-14 13:11
【摘要】：生物質(zhì)作為一種豐富的可再生資源,可部分替代化石資源。從而減輕化石資源過度消耗帶來的環(huán)境和經(jīng)濟(jì)壓力。由生物質(zhì)轉(zhuǎn)化制備燃料或者化學(xué)品引起眾多研究者的興趣。其中,研究生物質(zhì)轉(zhuǎn)化制備高附加值化學(xué)品備受關(guān)注。乳酸(酯)是一種重要的平臺化合物,具有廣泛用途。丙三醇作為生物柴油的主要副產(chǎn)物,年產(chǎn)量大。研究催化丙三醇轉(zhuǎn)化制備乳酸(酯)具有重大的科學(xué)意義和應(yīng)用價(jià)值。論文設(shè)計(jì)并制備了Au/Sn-USY雙功能催化劑,用于無堿一步催化丙三醇轉(zhuǎn)化制備乳酸酯。研究了催化劑制備條件、反應(yīng)條件等對催化劑結(jié)構(gòu)及催化性能的影響。Au溶膠pH的影響:當(dāng)Au溶膠的pH較低(pH=1)或較高(pH=7)時(shí)均會導(dǎo)致形成較大的Au納米顆粒(10 nm),使催化劑活性降低,pH=3或5時(shí),Au納米顆粒尺寸較小(10 nm)。PVA與Au質(zhì)量比的影響:PVA與Au的質(zhì)量比等于1時(shí),Au顆粒平均尺寸為6.2 nm,PVA的量過低或過高時(shí),將導(dǎo)致Au納米顆粒長大。Sn含量的影響:當(dāng)Sn含量為0 wt%到2 wt%時(shí),Sn主要進(jìn)入分子篩骨架,形成Lewis酸性位;當(dāng)Sn含量超過2 wt%(如3 wt%或4 wt%)時(shí),過量的Sn與脫鋁后介孔周圍的Si-OH作用,形成非骨架Sn。這部分非骨架Sn與Au之間通過相互作用,使Au均勻分散于分子篩的介孔周圍,得到顆粒尺寸較小,且分布均勻的納米Au顆粒。將制備條件優(yōu)化后的催化劑用于目標(biāo)反應(yīng),并對反應(yīng)時(shí)間、反應(yīng)溫度、催化劑量等條件進(jìn)行優(yōu)化,發(fā)現(xiàn)在160 oC條件下,反應(yīng)10 h,乳酸甲酯收率可達(dá)79%,選擇性達(dá)90%。論文進(jìn)一步對低溫條件下催化丙三醇轉(zhuǎn)化制備乳酸酯進(jìn)行了研究,課題組已經(jīng)實(shí)現(xiàn)了1,3-二羥基丙酮(DHA)室溫轉(zhuǎn)化制備乳酸酯,因此,本文重點(diǎn)研究低溫催化丙三醇轉(zhuǎn)化制備DHA。以不同來源的CuO為載體,制備Au/CuO催化劑,在甲醇溶劑中,低溫催化丙三醇轉(zhuǎn)化為DHA。發(fā)現(xiàn)不同來源的CuO載體,形貌及物理化學(xué)性質(zhì)差異較大,對Au的催化氧化性能影響顯著。以醋酸銅熱分解得到的CuO負(fù)載Au后活性較好,50 oC條件下,反應(yīng)4 h,丙三醇轉(zhuǎn)化率可達(dá)55%,DHA收率為33%。實(shí)現(xiàn)了醇溶劑中,低溫催化丙三醇轉(zhuǎn)化為中間產(chǎn)物DHA。
[Abstract]:As a kind of abundant renewable resources, biomass can partly replace fossil resources. Thus reducing the environmental and economic pressure caused by excessive consumption of fossil resources. The production of fuels or chemicals from biomass has attracted interest from many researchers. Among them, graduate student material conversion to produce high added-value chemicals has attracted much attention. Lactic acid (ester) is an important platform compound with a wide range of applications. As the main by-product of biodiesel, glycerol has a large annual output. It is of great scientific significance and application value to study the synthesis of lactic acid (ester) by catalytic conversion of glycerol. In this paper, Au/Sn-USY bifunctional catalyst was designed and prepared, which was used to catalyze the conversion of glycerol to lactate without alkalinity. The preparation conditions of the catalyst were studied. Effects of reaction conditions on Catalytic structure and Catalytic performance. Effects of au sol pH: when au sol pH is lower (pH=1) or higher (pH=7), larger au nanoparticles will be formed (10 nm), can reduce catalyst activity at pH 3 or 5 au). The effect of the mass ratio of PVA to au on the particle size is smaller (10 nm). When the mass ratio of PVA to au is equal to 1, the average size of au particles is 6.2 nm, the amount of PVA is too low or too high. The effect of Sn content on the growth of au nanoparticles: when Sn content is from 0 wt% to 2 wt%, the Sn mainly enters the framework of molecular sieve to form the acidic site of Lewis, and when Sn content exceeds 2 wt% (for example, 3wt% or 4wt%), Excessive Sn acts with Si-OH around mesoporous after dealumination to form non-skeleton SnS. Through the interaction between non-skeleton Sn and au, au particles are dispersed around the mesoporous structure of molecular sieve, and the particles are smaller in size and uniformly distributed. The optimized catalyst was used in the target reaction and the reaction time, reaction temperature and catalyst quantity were optimized. It was found that under the condition of 160oC, the yield of methyl lactate could reach 79% and the selectivity was 90% under the condition of 160oC for 10 h. In this paper, the preparation of lactate by catalytic conversion of glycerol to lactate at low temperature has been studied. The room temperature conversion of 1h3- dihydroxyacetone (DHA) to lactate has been realized. Therefore, this paper focuses on the study of catalyzing the conversion of glycerol at low temperature to prepare lactate. The CuO catalyst was prepared by using CuO from different sources as the carrier. The catalyst was used to catalyze the conversion of glycerol to DHA in methanol solvent at low temperature. It was found that the morphology and physicochemical properties of CuO carriers from different sources varied greatly, which had a significant effect on the catalytic oxidation of au. Under the condition of 50 鈩，
本文編號：2182961
[Abstract]:As a kind of abundant renewable resources, biomass can partly replace fossil resources. Thus reducing the environmental and economic pressure caused by excessive consumption of fossil resources. The production of fuels or chemicals from biomass has attracted interest from many researchers. Among them, graduate student material conversion to produce high added-value chemicals has attracted much attention. Lactic acid (ester) is an important platform compound with a wide range of applications. As the main by-product of biodiesel, glycerol has a large annual output. It is of great scientific significance and application value to study the synthesis of lactic acid (ester) by catalytic conversion of glycerol. In this paper, Au/Sn-USY bifunctional catalyst was designed and prepared, which was used to catalyze the conversion of glycerol to lactate without alkalinity. The preparation conditions of the catalyst were studied. Effects of reaction conditions on Catalytic structure and Catalytic performance. Effects of au sol pH: when au sol pH is lower (pH=1) or higher (pH=7), larger au nanoparticles will be formed (10 nm), can reduce catalyst activity at pH 3 or 5 au). The effect of the mass ratio of PVA to au on the particle size is smaller (10 nm). When the mass ratio of PVA to au is equal to 1, the average size of au particles is 6.2 nm, the amount of PVA is too low or too high. The effect of Sn content on the growth of au nanoparticles: when Sn content is from 0 wt% to 2 wt%, the Sn mainly enters the framework of molecular sieve to form the acidic site of Lewis, and when Sn content exceeds 2 wt% (for example, 3wt% or 4wt%), Excessive Sn acts with Si-OH around mesoporous after dealumination to form non-skeleton SnS. Through the interaction between non-skeleton Sn and au, au particles are dispersed around the mesoporous structure of molecular sieve, and the particles are smaller in size and uniformly distributed. The optimized catalyst was used in the target reaction and the reaction time, reaction temperature and catalyst quantity were optimized. It was found that under the condition of 160oC, the yield of methyl lactate could reach 79% and the selectivity was 90% under the condition of 160oC for 10 h. In this paper, the preparation of lactate by catalytic conversion of glycerol to lactate at low temperature has been studied. The room temperature conversion of 1h3- dihydroxyacetone (DHA) to lactate has been realized. Therefore, this paper focuses on the study of catalyzing the conversion of glycerol at low temperature to prepare lactate. The CuO catalyst was prepared by using CuO from different sources as the carrier. The catalyst was used to catalyze the conversion of glycerol to DHA in methanol solvent at low temperature. It was found that the morphology and physicochemical properties of CuO carriers from different sources varied greatly, which had a significant effect on the catalytic oxidation of au. Under the condition of 50 鈩，
本文編號：2182961
本文鏈接：http://sikaile.net/kejilunwen/huaxue/2182961.html
最近更新
教材專著
