生物质利用新途径:多元醇催化合成可再生燃料和化学品

日益严重的全球性能源和环境问题促使开发利用可再生的生物质资源成为当前研究的一个热点。本文概述了生物质基多元醇合成燃料和化学品来实现生物质转化利用的一些最新进展,特别是集中介绍了甘油和山梨醇等多元醇催化水相重整合成氢气和液体烃等燃料、催化选择氢解和氧化合成高附加值化学品或化学中间体等方面的进展,分析了存在的问题和可能的解决措施以及今后的发展趋势,指出生物质基多元醇将成为今后合成可再生燃料和化学品的新型平台分子。     

生物质利用新途径:多元醇催化合成可再生燃料和化学品

日益严重的全球性能源和环境问题促使开发利用可再生的生物质资源成为当前研究的一个热点.本文概述了生物质基多元醇合成燃料和化学品来实现生物质转化利用的一些最新进展,特别是集中介绍了甘油和山梨醇等多元醇催化水相重整合成氢气和液体烃等燃料、催化选择氢解和氧化合成高附加值化学品或化学中间体等方面的进展,分析了存在的问题和可能的解决措施以及今后的发展趋势,指出生物质基多元醇将成为今后合成可再生燃料和化学品的新型平台分子.     

Aluminum(III) triflate-catalyzed selective oxidation of glycerol to formic acid with hydrogen peroxide

Glycerol is a by-product of biodiesel production and is an important readily available platform chemical. Valorization of glycerol into value-added chemicals has gained immense attention. Herein, we carried out the conversion of glycerol to formic acid and glycolic acid using H₂O₂ as an oxidant and metal (III) triflate-based catalytic systems. Aluminum(III) triflate was found to be the most efficient catalyst for the selective oxidation of glycerol to formic acid. A correlation between the catalytic activity of the metal cations and their hydrolysis constants (K_h) and water exchange rate constants was observed. At 70 °C, a formic acid yield of up to 72% could be attained within 12 h. The catalyst could be recycled at least five times with a high conversion rate, and hence can also be used for the selective oxidation of other biomass platform molecules. Reaction kinetics and ¹H NMR studies showed that the oxidation of glycerol (to formic acid) involved glycerol hydrolysis pathways with glyceric acid and glycolic acid as the main intermediate products. Both the [Al(OH)_x]ⁿ⁺ Lewis acid species and CF₃SO₃H Brønsted acid, which were generated by the in-situ hydrolysis of Al(OTf)₃, were responsible for glycerol conversion. The easy availability, high efficiency, and good recyclability of Al(OTf)₃ render it suitable for the selective oxidation of glycerol to high value-added products.     

复合金属氧化物催化剂用于甘油氧化制丙烯酸的研究进展

随着化石燃料的短缺及其利用所产生的环境问题,可再生生物质资源逐渐成为生产燃料以及化学品的重要来源。近年来,甘油作为生物柴油生产的主要副产物受到了人们的广泛关注,利用其生产高附加值产品以及开发相关的转化技术也成为了国内外学者研究的热点。在诸多转化技术中,甘油选择性氧化制丙烯酸展现出了广阔的发展前景,对该反应尤其是催化剂开展研究具有重要的经济意义和社会意义。文中综述了用于甘油选择性氧化制丙烯酸复合金属氧化物催化剂的研究现状,介绍了当前用于该反应的催化体系类型以及对甘油氧化制丙烯酸催化反应机理的认识,分析并提出了存在的问题以及对未来的展望。     

Gas-chromatographic determination of the degree of conversion of microbiological synthesis products into biodiesel

In the development of promising methods for the production of biodiesel from different raw materials, it was proposed to perform the comparative evaluation of the degree of conversion of the source material and the effectiveness of the heterogeneous catalyst used by the gas-chromatographic determination of the resulting amount of glycerol with the direct injection of a reaction mixture (or end products) into the column without derivatization. A Bruker 430 GS gas chromatograph with a flame-ionization detector and a quartz capillary column in the isothermal regime was used for determining the glycerol formed. The degree of conversion was evaluated in a study of the transesterification of sunflower oil and microalgae lipids with the use of the enzyme catalyst Novozym 435. For comparison, the degree of conversion was determined by HPLC–MS based on the triglyceride content of the reaction mixture.     

Protection Strategies Enable Selective Conversion of Biomass

Selective and economic conversion of lignocellulosic biomass components to bio‐based fuels and chemicals is the major goal of biorefineries, but low yields and selectivity for fuel precursors such as sugars, furanics, and lignin‐derived monomers pose significant disadvantages in process economics. In this Minireview we summarize the existing protection strategies used in biomass chemocatalytic conversion processes and focus the discussions on the mechanisms, challenges, and opportunities of each strategy. We introduce a concept of using analogous methods to manipulate biomass catalytic conversion pathways during the upgrading of carbohydrates to fuels and chemicals. This Minireview may provide new insights into the development of selective biorefining processes from a different perspective, expanding the options for selective conversion of biomass to fuels and chemicals.     

Products and production routes for the catalytic conversion of seed oil into fuel and chemicals: a comprehensive review

With the depletion of fossil resources, there is a need to find alternative resources of fuels and chemicals. The use of renewable feedstock such as those from seed oil processing is one of the best available resources that have come to the fore-front recently. This paper critically analyzes and highlights major factors in the biodiesel industry, such as seeds oil composition, production methods, properties of biodiesel, problems and potential solutions of using vegetable seed oil, the composition, quality and effective utilization of crude glycerol, the catalytic conversion of glycerol into possible fuels and chemicals.     

Ca-Al催化剂上甘油与碳酸二甲酯酯交换合成碳酸甘油酯

生物柴油是一种环保、可再生、使用安全、可替代石化柴油的新型液体燃料,其产量和使用范围正逐年扩大。然而生物柴油生产过程中的主要副产物甘油严重过剩,因此甘油资源化转化和利用已经成为近年研究热点。甘油可以作为一种平台化合物实现向多种高附加值化学品的转化,例如通过催化氢解合成1,2-丙二醇,通过发酵和催化氧化制备二羟基丙酮,通过脱水制备丙烯醛和羟基丙酮,通过酯交换反应生成甘油酯等。其中,以甘油为原料合成的碳酸甘油酯(GC)具有很好的工业应用前景。以碳酸二甲酯(DMC)为原料与甘油进行酯交换合成GC是近年内比较有工业发展潜力的合成路线。前期研究发现,固体碱对该反应具有很好的催化活性,而且随着催化剂碱性增强,甘油转化率明显增加,然而当催化剂(如NaOH, KOH和K2CO3等)碱性过强时,产物选择性明显降低。水滑石类化合物是一种常见的碱性温和的固体催化剂,而且其碱性与结构可以调节,因此我们选择了一种常见水滑石——水铝钙石作为本研究的重点。 本文通过共沉淀法制备了一系列不同Ca/Al比(1–6)的Ca-Al水滑石,并以此作为前驱体制备了新型的固体碱催化剂。 XRD结果表明,当Ca/Al比为1–6时,所有样品都出现了明显的水滑石特征衍射峰,但当铝含量过高时会出现氢氧化铝杂相。 SEM结果发现,当Ca/Al =2–4时,样品中水滑石的结晶度高,有较完整的水滑石晶片, Ca/Al =6的样品中水滑石晶片较小, Ca/Al =1的样品中有明显的无定形氧化铝杂相。 TG-DSC结果表明, Ca/Al =2的样品除了几个与水滑石相关的特征失重峰以外,在786oC还检测到明显的热吸收峰,说明此时钙铝石已经发生分解,生成了单独的Ca12Al14O33晶相和氧化钙,这与SEM结果一致。这些水滑石经焙烧后用于温和条件下催化甘油与DMC酯交换生成GC的反应,发现上述催化剂对该反应具有很高的催化活性和目的产物选择性。当DMC与甘油的摩尔比为3时,70oC反应3 h后,甘油转化率达到93%, GC选择性高于97%。表征结果显示,甘油转化率主要取决于焙烧后Ca-Al催化剂中强碱性中心数量。其中经800oC焙烧后Ca/Al =2的样品中强碱性中心数量最多,因而表现出最高的催化活性。焙烧后催化剂中形成的Ca12Al14O33晶相在多次重复使用后仍可以稳定存在,但是表面CaO易流失,可能会降低催化剂的重复使用活性。     

Glycerol from the tubers of Jerusalem artichoke

The search for alternate sources of chemicals has resulted in a re-evaluation of many carbohydrates for conversion to oxychemicals. Inulin is an example of a carbohydrate receiving an increased amount of attention for use in industrial processes. This polymer is composed almost exclusively of fructofuranose structural units, making it very attractive for conversion into high fructose syrup and ethanol. Inulin can also be oxidized and reduced by a number of methods, and therefore lends itself well as feedstock for the exclusive conversion to glycerol. The advantages of inulin, coupled with a renewable supply, make it a very attractive source for industrial processes.     

催化选择转化多羟基化合物制备高附加值化学品研究进展

对近年来催化转化多羟基化合物制备5-羟甲基糠醛、乙二醇、1,2-丙二醇、1,3-丙二醇等高附加值化学品进行了综述. 分析了果糖、葡萄糖、纤维素等不同结构的碳水化合物制5-羟甲基糠醛存在的挑战, 并对相应的解决方法进行了总结. 对于5-羟甲基糠醛的转化, 我们重点讨论了5-羟甲基糠醛选择性氧化制备2,5-二甲酰基呋喃和2,5-呋喃二甲酸以及它们作为聚合单体的潜在应用. 概述了催化氢解纤维素、糖醇、甘油等多羟基化合物制备乙二醇、1,2-丙二醇、1,3-丙二醇等二元醇的方法, 并对可能的机理进行了讨论. 依据近年来多羟基化合物催化选择性转化制备高附加值化学品的研究现状, 对今后的研究热点进行了展望.     

多相固体催化剂用于甘油氧化制乳酸研究进展

随着新的全球气候协议下的中国双碳行动计划的实施, 开发和利用可再生生物质资源显得极为重要. 甘油作为生物柴油在生产过程中的主要副产物, 将其催化转化成各种高附加值衍生物受到广泛关注, 其中甘油选择性氧化为乳酸具有巨大的应用前景. 近年来, 采用固体催化剂催化氧化甘油制乳酸成为国内外学者研究的热点. 我们综述了固体催化剂用于甘油催化转化制备乳酸的研究现状, 对甘油催化转化为乳酸的反应途径做了分析, 并讨论了影响催化剂活性的因素, 对当前所存在的问题提出建议, 也对未来相关催化剂制备发展进行了展望.     

The Inhibiting Behavior of Glycerol on the Kinetics of Transesterification of Palm Oil

Glycerol, a by-product from transesterification, is well-known as one of the factors inhibiting the reaction. Previous works have mostly shown that the reaction rate slows to a near-steady state and eventually reaches chemical equilibrium. This work aimed to study the inhibiting behavior of glycerol on the transesterification of palm oil. Observation under an LCD digital microscopy showed that glycerol-coated droplets of catalyst-methanol dispersed in the triglyceride phase. This work proposes that glycerol inhibits transesterification by the following mechanism: Droplets of catalyst-methanol disperse into the triglyceride phase; the reaction takes place at an interphase called the reactive zone; methyl ester, the desired product, has low polarity and moves to the triglyceride phase, whereas glycerol, the non-desired product, is more highly polar and accumulates on the droplet surface of catalyst-methanol droplets, inhibiting triglyceride mass transfer and diluting the concentration of the catalyst-methanol. The triglyceride mass transfer coefficient and reaction rate constant were both investigated and expressed as the exponential function.

     

Visible light-induced conversion of biomass-derived chemicals integrated with hydrogen evolution over 2D Ni2P–graphene–TiO2

Research on Chemical Intermediates - Highly selective photocatalytic conversion of biomass-derived chemicals into value-added chemicals and clean hydrogen energy under mild conditions by...     

Mg-Al水滑石催化甘油与碳酸二甲酯的酯交换反应简

报道了温和条件下甘油和碳酸二甲酯在一系列不同Mg/Al比（0.5-6）的Mg-Al水滑石催化下合成碳酸甘油酯（GC）的反应. 发现,Mg-Al水滑石对该反应具有很高的GC选择性,其中Mg/Al=2经400℃处理所得水滑石催化效率最高：70 ℃反应3 h甘油转化率达66.9%时,GC选择性维持在97%以上. 表征结果表明,水滑石样品的比表面积、孔径、结晶度和表面碱性对其催化活性影响很大.     

Polyoxometalates as efficient catalysts for transformations of cellulose into platform chemicals

Efficient utilisation of renewable biomass resources, particularly lignocellulosic biomass, for the production of chemicals and fuels has attracted much attention in recent years. The catalytic conversion of cellulose, the main component of lignocellulosic biomass, selectively into a platform chemical such as glucose, 5-hydroxymethyl furfural (HMF), sorbitol or gluconic acid under mild conditions is the most desirable route. Acid catalysis plays a crucial role in the conversion of cellulose via the cleavage of its glycosidic bonds. Owing to their unique features such as strong acidity, water-tolerance, low corrosiveness and recoverability, polyoxometalates have shown promising performances in transformations of cellulose into platform chemicals both in homogeneous and heterogeneous systems. This article highlights recent studies on polyoxometalates and polyoxometalate-based bifunctional catalysts or catalytic systems for the selective conversions of cellulose and cellobiose, a model molecule of cellulose, into platform chemicals.     

碱性离子液体催化甘油合成1,2-甘油碳酸酯(英)

以离子液体为催化剂,在无溶剂体系中,考察了生物质平台化合物甘油转化1,2-甘油碳酸酯的反应.与酸性离子液体和常用无机碱性催化剂相比,碱性离子液体咪唑基1-丁基-3-甲基咪唑([Bmim]Im)、氢氧化1-丁基-3-甲基咪唑([Bmim]OH)、咪唑基1-烯丙基-3-甲基咪唑([Amim]Im)、氢氧化1-烯丙基-3-甲基咪唑([Amim]OH)在甘油与碳酸二甲酯的酯交换反应中表现出优异的活性.其中,以[Bmim]Im离子液体为催化剂时甘油转化率为98.4%和甘油碳酸酯选择性接近100%.另外,该离子液体可以回收重复利用3次后甘油转化率仍可达92%,甘油碳酸酯选择性可近100%.此碱性离子液体催化方法具有反应结果较好、产物分离简单、条件温和以及环境友好等特点.     

Catalytic performance of acidic ionic liquid-functionalized silica in biodiesel production

Acidic ionic liquid ([BsAIm][OTf]) was immobilized on sulfhydryl-group-modified SiO₂ (MPS-SiO₂) via free radical addition reaction. The [BsAIm][OTf] loading on acidic ionic liquid-functionalized silica ([BsAIm][OTf]/SiO₂) was controlled through tuning the sulfydryl (SH) content of MPS-SiO₂. All the samples were characterized by FT-IR, elemental analysis, N₂ adsorption-desorption measurements and TG-DTA. The catalytic performance of [BsAIm][OTf]/SiO₂ in the esterification of oleic acid and the transesterification of glycerol trioleate for biodiesel production was investigated. The results showed that with the increase of [BsAIm][OTf] loading on SiO₂ the specific surface area and pore volume of [BsAIm][OTf]/SiO₂ decreased, and the pore diameter of [BsAIm][OTf]/SiO₂ narrowed. In the esterificaiton of oleic acid, the oleic acid conversion increased with the increasing [BsAIm][OTf] loading. In the transesterification of glycerol trioleate, with the increasing [BsAIm][OTf] loading the glycerol trioleate conversion decreased and the selectivities to glycerol monooleate and methyl oleate increased.     

Pt/Nb-WOx催化甘油选择氢解制1,3-丙二醇: Nb掺杂抑制WOx的过度还原

随着生物柴油产业的快速发展, 甘油作为副产物大量过剩, 通过甘油氢解制备具有高附加值的丙二醇既符合原子经济的原则, 又具有重要的学术研究意义和应用价值. 其中选择氢解制备1,3-丙二醇, 因其产物在新型聚酯材料合成中的重要应用而备受关注, 被认为是最具工业应用潜力的甘油转化工艺之一. 但是由于反应空间位阻效应和热力学上的限制, 甘油氢解制备1,3-丙二醇仍存在很大的挑战. 目前, 可高选择性制得1,3-丙二醇的催化剂体系主要是铱-铼催化剂和铂-钨催化剂两类; 且反应通常需要较苛刻的压力. 在我们的前期工作中, 单原子/准单原子Pt催化剂(Pt/WOx)成功突破了这一压力壁垒, 实现了在较低(1 MPa)氢气压力下优异的甘油选择氢解制1,3-丙二醇活性; 但是该催化剂的耐压性能较差, 是长期反应后失活的一个主要原因, 且随着氢气压力的进一步升高, Pt/WOx催化剂活性大幅下降. 研究发现, 在高压氢气下, 单原子/准单原子催化剂Pt/WOx中的WOx易被过度还原, 导致催化剂失活, 大大限制了该系列单原子催化剂在涉氢催化反应中的应用. 因此, 通过载体改性设计制备具有良好氢气稳定性的载体, 有可能拓宽催化反应的氢压窗口.一般来讲, 可以通过掺杂来改变载体的电子结构、表面化学性质等, 进而改变催化剂活性、选择性和稳定性. 为了提高单原子/准单原子催化剂(Pt/WOx)在高压氢气中的稳定性, 本文采用原位掺杂法制备了一系列具有不同掺杂量、结构、及物化性质的Nb-WOx载体, 并通过物理吸附, XRD, SEM, HRTEM, Raman, XPS对其进行表征. 结果发现Nb掺杂的介孔WOx仍保持较高的比表面积(~136 m2/g); 且当Nb掺杂量增加至2 wt%时, WOx由一维针状堆积转变为二维片状堆积;至5 wt%时,变为三维球状堆积. 以所得的Nb-WOx为载体, 我们制备了一系列Pt高度分散的Pt/Nb-WOx催化剂, 并考察了其在甘油选择性氢解制备1,3-丙二醇反应中的催化性能. 结果表明, 当H2压力由1 MPa升到5 MPa后, Pt/WOx催化剂上1,3-丙二醇的收率由13.9%急剧下降到8.3%; 但随着Nb掺杂量的增加(>2wt%), 1,3-丙二醇的收率随压力升高并没有明显变化, 说明该催化剂在高压氢气下的过度还原被有效抑制, 反应的最佳氢气压力由1 MPa拓宽到5 MPa. 其中, Nb的最佳掺杂量为2 wt%, 在Pt/2%Nb-WOx催化剂上1 MPa甘油氢解转化率为40.0%, 1,3-丙二醇收率11.9%; 当氢气压力为5 MPa时, 甘油氢解转化率为40.3%, 1,3-丙二醇收率11.1%. 值得一提的是, 虽然Nb的掺杂使WOx的表面酸量增加, 并且表现出了更优的酸催化纤维二糖水解活性, 但是在甘油氢解制备1,3-丙二醇的反应中Pt/Nb-WOx催化剂的性能并没有得到提升反而略有下降, 进一步证实了催化剂本身的表面酸性位并不是催化甘油选择氢解的活性中心, 真正的活性中心很可能是氢气辅助下原位产生的B酸.对WOx载体进行Nb的掺杂改性, 显著提高了单原子/准单原子Pt/WOx催化剂在高压氢气反应条件下的稳定性, 进而在更宽压力范围内实现了甘油氢解制1,3-丙二醇的高效催化转化. 同时, 载体的改性也拓宽了该系列催化剂在其他涉氢反应中的应用范围, 尤其是需要较高氢气压力的反应.     

Catalytic Conversion of Glycerol to Lactic Acid: State of the Art and Prospects

In this review article, recent trends in the catalytic processes for the synthesis of lactic acid from glycerol are systematized. Based on literature data, the mechanisms of glycerol conversion in the presence of bases and the oxidative conversion of glycerol are proposed. Advantages and disadvantages of each method are shown and prospects in the use of highly selective heterogeneous catalytic processes are discussed.     

Calculations of phase equilibria for mixtures of triglycerides,fatty acids,and their esters in lower alcohols

The objects of study were mixtures containing triglycerides and lower alcohols and also the products of the transesterification of triglycerides, glycerol and fatty acid esters. The Redlich-Kwong-Soave equation of state was used as a thermodynamic model for the phase state of the selected mixtures over wide temperature, pressure, and composition ranges. Group methods were applied to determine the critical parameters of pure substances and their acentric factors. The parameters obtained were used to calculate the phase diagrams and critical parameters of mixtures containing triglycerides and lower alcohols and the products of the transesterification of triglycerides, glycerol and fatty acid esters, at various alcohol/oil ratios. The conditions of triglyceride transesterification in various lower alcohols providing the supercritical state of reaction mixtures were selected.