甘油催化氧化合成二羟基丙酮研究进展

对甘油选择性催化氧化转化为二羟基丙酮的研究进行综述,介绍了负载型催化剂在不同条件下对产物选择性和反应物转化率的影响,以及催化剂的作用机理。阐述了甘油催化氧化存在的问题以及发展前景。从均相到非均相催化,从单金属到双金属负载催化,从金属到非金属催化,甘油氧化反应的研究不断在完善。研究发现用Bi改性的Pt负载催化剂可以有效地将甘油选择性催化氧化为二羟基丙酮,在最优条件下,可获得较高的甘油转化率和二羟基丙酮选择性,但催化剂稳定性较差,有待进一步提高。杂多酸催化剂以及非金属催化剂也存在稳定性差的问题。指出改善催化剂的稳定性将是未来研究的主要方向。     

电、光和光电催化甘油选择性氧化合成二羟基丙酮的研究进展

甘油，作为生物柴油生产过程中的主要副产物，能够通过不同的催化过程转化为高附加值产品。由电、光和光电驱动的甘油选择性氧化合成被广泛应用于化妆品和医药等行业的二羟基丙酮(DHA)是很有前景的反应途径之一。对近年来在电、光和光电催化甘油选择性氧化合成DHA领域的研究进展进行综述，重点集中在高活性和高选择性催化剂的开发方面。同时对电、光和光电催化甘油选择性氧化合成DHA面临的挑战和发展前景进行展望。     

炭载Pt基催化剂上甘油氧化反应路径的探究

结合透射电镜(TEM)和X射线光电子能谱(XPS)等表征技术,比较研究了碳纳米管(CNTs)负载的单金属Pt和双金属Pt-Sb催化剂的结构及其非碱性条件下催化甘油氧化反应的性能与路径。结果表明:Sb的引入对催化剂的粒径以及Pt电子性质的影响较小,但Sb可能选择性沉积在Pt原子表面形成空间位阻,控制甘油的转化向有利于其仲羟基氧化的方向进行,从而改变了反应的选择性和路径。Pt/CNTs催化剂主要选择性氧化甘油的伯羟基生成甘油醛(GLyD)和甘油酸(GLYA),GLYA再进一步氧化生成羟基丙酮酸(HPYA)和亚酒石酸(TA);Pt-Sb/CNTs催化剂则优先氧化甘油的仲羟基生成二羟基丙酮(DHA),DHA进一步氧化生成HPYA;两种反应路径下生成的HPYA和TA最终都会氧化断键生成乙醇酸(GLYCA)等产物。     

甘油催化氧化制备二羟基丙酮的研究

阐述了采用不同方法合成了一系列的贵金属Pt单金属及多金属催化剂,研究了它们对甘油选择性催化氧化反应的催化性质。当反应温度为55℃,反应时间为8 h时,催化剂9%Pt-5%Bi/C双金属催化剂可以有效地将甘油选择性催化氧化成二羟基丙酮。     

甘油催化氧化制备二羟基丙酮的研究

阐述了采用不同方法合成了一系列的贵金属Pt单金属及多金属催化剂,研究了它们对甘油选择性催化氧化反应的催化性质。当反应温度为55℃,反应时间为8 h时,催化剂9%Pt-5%Bi/C双金属催化剂可以有效地将甘油选择性催化氧化成二羟基丙酮。     

生物转化生产二羟基丙酮的研究进展

介绍了二羟基丙酮的用途及生物转化甘油生产二羟基丙酮的代谢途径和机理,综述了近年来国外生物转化生产二羟基丙酮的进展,并对二羟基丙酮的应用前景进行了展望.     

1,2-丙二醇空气选择氧化合成α-羟基丙酮和丙酮醛

采用电解银催化剂,选择催化氧化1,2-丙二醇联产α-羟基丙酮和丙酮醛。研究了反应条件对产物组成的影响。实验结果表明,以电解银催化氧化1,2-丙二醇可以同时得到α-羟基丙酮和丙酮醛,当温度为360℃,氧醇比为0.25,液时空速为8.73h-1时,单程转化率36%,它们的选择性之和接近100%。氧醇比是选择性氧化合成α-羟基丙酮和丙酮醛的关键因素。     

贵金属液相非均相催化氧化甘油制备二羟基丙酮的研究进展

阐述了化学法中以分子氧为氧化剂,负载型贵金属催化剂液相非均相催化氧化甘油制备二羟基丙酮(DHA)过程的研究进展。叙述了多种贵金属催化剂催化氧化甘油制备DHA的效果及其反应过程中的影响因素。最后对负载型贵金属液相非均相催化氧化甘油制备DHA的研究过程进行展望。     

贵金属液相非均相催化氧化甘油制备二羟基丙酮的研究进展

阐述了化学法中以分子氧为氧化剂,负载型贵金属催化剂液相非均相催化氧化甘油制备二羟基丙酮(DHA)过程的研究进展。叙述了多种贵金属催化剂催化氧化甘油制备DHA的效果及其反应过程中的影响因素。最后对负载型贵金属液相非均相催化氧化甘油制备DHA的研究过程进行展望。     

生物质甘油催化转化为羟基丙酮

探索了生物质甘油在铜铬催化剂作用下催化转化为羟基丙酮的反应条件,采用乙醇为溶剂,考察了甘油浓度、催化剂用量和反应温度等因素的影响。较优反应条件:反应温度240℃,采用连续滴样的进样方式,甘油浓度80%,未还原的铜铬催化剂[n(Cu)∶n(Cr)=1]用量为原料质量的2.5%,甘油转化率和羟基丙酮选择性分别达到95.4%和89.9%。     

Quantification of Mixtures of C2 and C3 Hydroxy Acids and Products of Glycerol Oxidation by High-Performance Liquid Chromatography and Quantitative 13C NMR

The aim of this study was to develop an improved general method for detecting and quantifying mixtures of hydroxy acids and other products of glycerol oxidation in aqueous media, to prevent the confusions that can occur due to similarities and interactions between these compounds depending on media conditions. Standard potential products of glycerol oxidation—glycerol, glyceraldehyde, dihydroxyacetone, glyceric acid, lactic acid, glycolic acid, glyoxylic acid, oxalic acid, tartronic acid, and mesoxalic acid—were analyzed by high-performance liquid chromatography (HPLC) and quantitative ¹³C nuclear magnetic resonance (NMR), in mixtures of known composition. The results obtained were concordant with the known compositions tested. HPLC was more accurate than quantitative ¹³C NMR for simple mixtures, but ¹³C NMR was required for complex mixtures containing dihydroxyacetone and glycerol, oxalic acid and mesoxalic acid, or glyoxylic acid and tartronic acid, pairs of compounds not well separated or detected by HPLC. As proof-of-concept, an unknown mixture generated by glycerol oxidation was analyzed by HPLC and quantitative ¹³C NMR. The results obtained were concordant and allowed accurate determination of the composition of the sample, which contained mesoxalic acid as the major product, with oxalic acid, tartronic acid, and glyceric acid as by-products.     

炭载体对Pt-C复合物非碱性条件下催化甘油氧化性能的影响

采用等量浸渍法制备了具有相似平均粒径的活性炭（AC）和碳纳米管（CNTs）负载的Pt催化剂,并比较研究了非碱性条件下两种催化剂催化甘油氧化反应的性能。结果表明,炭载体对Pt-C复合物催化甘油氧化反应的活性、选择性和稳定性有重要影响。相对于Pt/CNTs催化剂,Pt/AC催化剂中Pt 4f结合能较低,导致其表面氧的覆盖度相对较高,因而抑制了甘油的吸附,降低了甘油氧化反应的初始活性;Pt/AC催化剂会促进甘油醛进一步氧化成甘油酸以及C₃产物的氧化断键;Pt/AC催化剂失活的主要原因是氧中毒和中间产物的吸附,而Pt/CNTs催化剂的失活主要是由于甘油酸的吸附堵塞Pt表面的活性位造成的。     

生物柴油副产物粗甘油催化氧化脱水制备丙烯酸

用生物柴油副产物粗甘油催化氧化脱水制丙烯酸,该过程耦合了甘油脱水制丙烯醛和丙烯醛选择性氧化制备丙烯酸两步反应。结果表明,在甘油脱水反应中,使用Cs3PW12O40, P-ZSM-5和Co0.5H2PO4/SiO2等固体酸催化剂,可得到较高的丙烯醛收率(最高86.9%)。利用上述催化剂和MoVW基氧化催化剂,在脱水/氧化双催化剂床层构型反应器中,以甘油为原料合成丙烯酸的收率达50%~80%,直接加入粗甘油可获得相似的丙烯酸收率。     

Oxidation of glycerol with hydrogen peroxide using silicalite and aluminophosphate catalysts

The oxidation of glycerol using a range of metal‐containing silicalite and aluminophosphate catalysts is described and discussed. Variation in reaction conditions (extent of conversion, temperature, glycerol/hydrogen peroxide ratio) or catalyst (silicalite containing Ti, V, Fe or AlPO‐5 containing Cr, V, Mn, Co) did not lead to the formation of partial oxidation products of glycerol. Formic acid and a mono‐formate ester of glycerol were observed to be the major products together with a complex mixture of acetals. Increasing the pore size of the catalyst was investigated for Ti‐containing materials and it was found that increasing the pore size from ca. 0.5 nm for TS‐1 to 15 nm for a titania–silica co‐gel significantly increased the formation of partial oxidation products of glycerol, namely glyceraldehyde, dihydroxyacetone and glyceric acid. This revised version was published online in July 2006 with corrections to the Cover Date.     

Bimetallic Pt―Cu catalysts for glycerol oxidation with oxygen in a base-free aqueous solution

A series of carbon supported bimetallic Pt―Cu catalysts were prepared and used for glycerol oxidation with oxygen in a base-free aqueous solution. It was found that bimetallic Pt―Cu/C was more active than monometallic Pt/C towards selective oxidation of glycerol to glyceric acid. The selectivity of free glyceric acid reached 70.8% at an 86.2% conversion of glycerol over 5Pt―Cu/C. Highly dispersed bimetallic Pt―Cu nanoparticles with small particle size in dominant alloyed phase of PtCu₃ were confirmed by XRD and TEM in the bimetallic Pt―Cu/C catalyst, which is proposed to contribute to the improved performance.     

Promotional effect of hydroxyl on the aqueous phase oxidation of carbon monoxide and glycerol over supported Au catalysts

Gold particles supported on carbon and titania were explored as catalysts for oxidation of CO or glycerol by O₂ at room temperature in liquid-phase water. Although Au/carbon catalysts were not active for vapor phase CO oxidation at room temperature, a turnover frequency of 5 s⁻¹ could be achieved with comparable CO concentration in aqueous solution containing 1 M NaOH. The turnover frequency on Au/carbon was a strong function of pH, decreasing by about a factor of 50 when the pH decreased from 14 to 0.3. Evidently, a catalytic oxidation route that was not available in the vapor phase is enabled by operation in the liquid water at high pH. Since Au/titania is active for vapor phase CO oxidation, the role of water, and therefore hydroxyl concentration, is not as significant as that for Au/carbon. Hydrogen peroxide is also produced during CO oxidation over Au in liquid water and increasing the hydroxyl concentration enhances its formation rate. For glycerol oxidation to glyceric acid (C₃) and glycolic acid (C₂) with O₂ (1–10 atm) at 308–333 K over supported Au particles, high pH is required for catalysis to occur. Similar to CO oxidation in liquid water, H₂O₂ is also produced during glycerol oxidation at high pH. The formation of the C-C cleavage product glycolic acid is attributed to peroxide in the reaction.     

Optimization of a Colorimetric Test Method for Quantifying Glycerol in Aqueous Solution

Many analytical methods for glycerol involve chemical techniques or instrumentation that may be unavailable to small biodiesel processors or have potential interactions with other components in the glycerol phase. This work presents an analytical method based on periodate oxidation of glycerol to formaldehyde, which is then quantified using a modification of the Nash test required to remove excess periodate. The method provides a linear calibration over the range of diluted glycerol concentrations from 0.02 to 0.25 mM and is limited at high concentrations by the formation of precipitate during the Nash test. There are no observed interferences from the formic acid coproduct of the glycerol oxidation or from potential contaminants in the crude glycerol, which includes methanol and sodium. Several disaccharides and starch, both as individual solutes or in glycerol solutions, gave no response under the conditions of the described method.     

Effects of Reaction Parameters in Catalysis of Glycerol Oxidation by Citrate-Stabilized Gold Nanoparticles

Abstract  

This work describes a catalytic oxidation of glycerol using citrate-stabilized gold nanoparticles (citrate-AuNPs) having a mean diameter of 22 ± 3 nm. A careful product analysis was performed by mean of high-performance liquid chromatography, liquid chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy. Effects of reaction temperature, oxygen pressure, catalyst and reactant concentration, and NaOH/glycerol molar ratio on glycerol conversion, and product yields were investigated. The glycerol conversion and glyceric acid yield were optimum when the oxidation was performed using 0.6 M glycerol and NaOH at 80 °C under 3 bar of O₂ pressure in the presence of 50 ppm citrate-AuNPs catalyst for 3 h.     

Efficient Conversion of Glycerol into High Value-Added Chemicals by Partial Oxidation

Glycerol can be effectively converted to glyceric acid, a high value-added pharmaceutical raw material, through its partial oxidation over an Au/Al₂O₃ catalyst under strongly basic conditions. The factors important for the highly selective production of glyceric acid were investigated experimentally. It was clarified that NaOH was involved in the glycerol activation step to a glycerol alkoxide intermediate (2, 3-dihydroxypropoxide) in the liquid phase, then glyceric acid was formed by OOH species derived from O₂ on an Au catalyst in the partial oxidation step. We have newly discovered the concerted effect of NaOH and O₂ in different reaction steps.