生物质基糠醛和5-羟甲基糠醛加氢转化研究进展

近年来,利用生物质基平台化合物转化制备各种燃料及高值化学品引起研究人员的广泛关注.5-羟甲基糠醛(HMF)和糠醛(FFR)作为一类重要的生物质衍生平台化合物,分子结构中醛基和呋喃环等官能团赋予其独特的化学性质.本综述针对HMF和FFR在氢气、低碳醇、甲酸和硅烷等不同氢源中的催化加氢反应研究现状进行了阐述,对加氢转化过程...     

葡萄糖制备5-羟甲基糠醛

5-羟甲基糠醛(HMF)作为一种重要且多用途的生物质基平台化合物,可被转化为多种高附加值化学品,如乙酰丙酸、2,5-二甲基呋喃、2,5-呋喃二甲酸、2,5-呋喃二甲醇、γ-戊内酯、5-氨基乙酰丙酸等,而这些化学品可进一步作为化石燃料替代品、燃料添加剂或作为聚合物单体或医药产品等进行应用。葡萄糖是由纤维素水解大量得到的六碳单糖,由葡萄糖制备HMF是生物质资源最大化利用的有效途径之一。本文通过对近几年HMF制备方法的概述,分别由催化剂、反应体系两方面进行分类总结葡萄糖基碳水化合物制备HMF的研究进展,并对其各个反应过程的催化活性、反应体系稳定性和应用前景进行了总结归纳。随后论述了用于HMF制备的多种溶剂体系(诸如单相体系、双相体系、离子液体和低共熔溶剂体系)。最后,结合目前葡萄糖制备HMF过程中存在的问题,对未来工作的研究重点进行了展望,以期为相关研究者提供参考。     

氧化钽及钽钨复合氧化物固体酸催化己糖脱水制备5-羟甲基糠醛以及非等计量比的甲酸和乙酰丙酸（英文）

5-羟甲基糠醛(HMF)是最具应用前景的平台化合物之一, HMF制备的研究越来越成为热点,并且已经取得了令人瞩目的研究成果.尽管如此,在现阶段利用固体酸催化剂催化碳水化合物制备HMF的研究仍然面临许多挑战,以葡萄糖为原料制备HMF时产物选择性普遍较低.因此,合成制备高活性催化糖类化合物脱水制HMF的固体酸催化剂,并且研究固体酸催化剂表面酸性质比如酸密度、酸强度以及Br?nsted/Lewis酸比值等对糖类化合物制HMF反应中各反应产物选择性的影响,对新型高效催化剂的开发设计具有重要意义.本文通过溶剂挥发自组装法合成了一系列介孔Ta及Ta-W氧化物固体酸催化剂,并用于催化果糖和葡萄糖脱水制备5-羟甲基糠醛.以三甲基膦(TMP)为探针分子,利用31P固体核磁共振谱技术表征催化剂表面酸性质,考察复合金属氧化物固体酸催化剂酸量、酸强度以及酸类型对催化果糖和葡萄糖制备HMF反应性能的影响,为高效催化剂的设计提供一定的理论指导.另外,我们还通过引入2-丁醇构建有机溶剂/水体系,考察有机溶剂对葡萄糖脱水制HMF反应中所用催化剂活性和产物选择性的影响.31P固体核磁共振技术表征样品的酸性质发现,随着W...     

木质纤维素催化转化制备能源平台化合物

可再生生物质资源的能源化利用能有效缓解能源短缺和环境恶化的双重压力。木质纤维素类生物质原料通过催化转化途径可以转化成为用途广泛的平台化合物,如呋喃类化合物、多元醇和有机酸及其酯类衍生物等。以这些平台化合物为原料,通过基元反应的转化可以制备高附加值的生物质基液体燃料。基于上述背景,本文概述了国内外木质纤维素通过不同催化转化途径制备各种新能源平台化合物的研究进展。目前木质纤维素制备新能源平台化合物的可行途径主要包括液体酸催化、固体酸催化、离子液体催化和多功能材料催化。在介绍这些催化途径的同时,重点讨论了所使用的催化剂,分析了仍然存在的问题和可能的解决措施,同时对今后该领域的研究前景进行了展望。     

油脂和木质纤维素催化转化制备生物液体燃料

世界范围能源短缺和环境恶化的双重压力促使可再生生物质资源的能源化利用成为当前研究的一个重要方向。生物质种类多样,但考虑到粮食安全等因素,其中油脂和木质纤维素适合替代化石资源用于制备液体燃料。本文概述了油脂和木质纤维素通过不同催化转化途径制备液体燃料的一些研究进展。油脂可以通过催化热裂解、加氢和酯交换方法制备生物液体燃料,而木质纤维素制备液体燃料的可行途径包括气化-费托合成、液化-精炼和经历平台化合物的选择性合成。在介绍这些催化途径的同时,特别讨论了其中所使用的催化剂和工艺等方面的研究进展,分析了存在的问题和可能的解决措施,以期能为生物质能源化利用的研究提供参考。     

光催化/光电催化5-羟甲基糠醛的研究进展

储量丰富的生物质作为一种可再生的有机资源,可通过化学反应转化为高附加值的化学品或燃料,有助于降低对化石能源的依赖. 5-羟甲基糠醛(5-hydroxymethylfurfural, HMF)是一种关键的生物质平台分子,其含有醛基、羟甲基和呋喃环,具有优越的化学性能,可通过氧化、加氢、开环水解、醚化和聚合等化学反应转化为一系列高价值的衍生物,可应用于医药、材料、化工、生物燃料等领域.近年来,光催化作为一种经济有效的绿色化学方法不仅克服了传统热催化的缺点,还应用于生物质转化.本文系统地综述了近年来光催化/光电催化HMF的研究进展.同时,本文重点关注了光催化氧化过程中活性物种对HMF选择性的影响和用HMF氧化取代动力学迟缓的水氧化以促进光解水产氢.最后,还对未来的研究方向进行了展望,包括探索多步骤反应策略以提高2,5-呋喃二羧酸(FDCA)的产率,深入研究光催化HMF氧化反应动力学和催化活性位点以全面理解HMF的光催化氧化机制,以及优化光催化剂实现高效选择性的HMF转化,为可持续能源、生物质转化和液体生物燃料领域提供新的创新解决方案.     

5-羟甲基糠醛加氢制备1-羟基-2,5-己二酮的研究进展

生物质基平台化合物5-羟甲基糠醛的转化研究是近年来的研究热点之一,1-羟基-2,5-己二酮是一种具有广泛应用前景的化合物.由5-羟甲基糠醛加氢制备1-羟基-2,5-己二酮是一种重要的合成策略,具有绿色、原子经济性高等优势,取得了一些重要的研究进展.从非均相催化和均相催化两方面对1-羟基-2,5-己二酮的制备进行了综述,讨论了催化体系的优劣和催化机理的研究.     

碳纳米管负载钯基催化剂催化氧化2,5-呋喃二甲醇合成2,5-呋喃二甲酸

为积极应对化石能源枯竭和生态环境日益严峻等问题,可再生生物质资源的深度开发并进一步替代传统能源或石化原料被广泛认可.利用高效催化技术将生物质资源转化为高附加值的平台化合物,有望衍生出大量具备新颖结构与功能的绿色化学品.2,5-呋喃二甲酸(FDCA)作为重要的生物质基平台化合物之一,具有巨大的市场应用价值,其中因其与化石基对苯二甲酸(PTA)有着极其相似的化学结构,以FDCA替代PTA作为合成单体制备大宗聚合物备受关注.以5-羟甲基糠醛(HMF)为原料,采用多相催化体系(主要是贵金属催化剂)选择氧化制备FDCA是目前广泛采用的方法.但“HMF路线”面临一些基础性的难题,如HMF熔点较低,需低温存储,增加了实际应用中的运输成本;HMF在碱性溶液中易降解,导致反应过程中碳平衡损失;HMF结构中含有的不对称的羟基和醛基官能团在氧化反应中会发生竞争反应,致使反应副产物较多;此外,碱性反应介质中通常会得到醛基优先氧化的中间体5-羟甲基-2-呋喃甲酸(HMFCA),但由于HMFCA结构中羧基官能团的存在使得羟基进一步氧化较为困难,通常需要增加碱浓度、提升温度或压力,使反应条件变得苛刻.因此,寻求新的原料替代HMF,实现温和条件下高效合成FDCA具有重要意义.本文采用改性后的碳纳米管负载Pd催化剂(Pd/o-CNT),从具有独特对称结构的2,5-二羟甲基呋喃(BHMF)出发,提出一种新颖、高效催化合成FDCA的“BHMF路线”.反应在60°C常压下进行,BHMF在20 min内即可完全转化,60 min后FDCA的产率最高可达93.0%,优于相同条件下HMF为原料时的性能(FDCA产率仅为35.7%).相比于未作处理的碳纳米管负载钯催化剂(Pd/CNT),Pd/o-CNT催化剂具有更高含量的氢化钯(PdH_x)物种,显著促进了FDCA产率的提升.Pd/o-CNT在循环使用10次后,BHMF仍能完全转化,FDCA产率维持在75%.稳定性下降可能与活性物种流失、团聚及价态变化有关.基于对照试验,本文提出了可能的反应路径,即BHMF主要是通过2,5-二甲酰基呋喃和5-甲酰基-2-呋喃甲酸作为过程中间体,有效转化为FDCA,从而规避并减少生成HMF和活性较低的HMFCA.本文通过以新原料BHMF作底物,实现了高效制备生物基平台化合物FDCA,为生物质的产业化应用提供了新的研究思路.     

负载离子液体的生物质炭磺酸催化水解纤维素

纤维素是生物质的主要成分,其水解产物作为平台化合物在能源化工方面具有广泛的用途.绿色、低成本、高效的转化纤维素为平台化合物是目前研究的热点.本文报道了以生物质玉米秸秆、花生壳、核桃壳为原料经700℃碳化150℃磺化后得到生物质炭磺酸,将得到的生物质炭磺酸进行离子液体的负载得到离子液体功能化的生物质炭磺酸催化剂,探讨了时间和温度对制备的催化剂水解纤维素后总还原糖产率的影响,与负载前的生物质炭磺酸进行了对比.结果表明,150℃反应28 h三种催化剂均得到良好的总还原糖产率,相对于生物质炭磺酸总还原糖产率分别提升了13. 9%、16. 4%和14. 7%.循环使用四次后,催化剂依然保持着良好的催化活性.     

由果糖催化合成5-羟甲基糠醛的研究进展

5-羟甲基糠醛(HMF)是一种具有重要应用价值的原材料和中间体,以果糖脱水合成HMF具有实现生物质转化利用的重大意义。本文综述了近三年来果糖制备HMF过程的两大关键因素:催化剂和反应介质的重要进展。固体酸(特别是杂多酸及其盐)、离子液体(ILs)中添加卤化物或ILs作为催化剂是近几年来研究的热点,固体酸的优点是可多次重复使用且易于分离,而ILs中果糖的降解条件较温和,副反应较少。目前,用于果糖转化HMF的反应溶剂优、缺点并存。最后对该反应存在的问题和今后的研究进行了总结和展望。     

Recent Progress in Metal-Catalyzed Selective Oxidation of 5-Hydroxymethylfurfural into Furan-Based Value-Added Chemicals

5-hydroxymethylfurfural (HMF), one of the most significant biomass-derived renewable resources, has been widely utilized to create furan-based value-added chemicals such as 2,5-diformylfuran (DFF), 5-hydroxymethyl-2-furancarboxylic acid (HMFCA), 5-formyl-2-furancarboxylic acid (FFCA), and 2,5-furan dicarboxylic acid (FDCA). Indeed, DFF, HMFCA and FFCA are key intermediate products during the oxidation of HMF to FDCA. Herein, this review aims to demonstrate the recent advances in metal-catalyzed oxidation of HMF into FDCA via two different reaction routes (HMF-DFF-FFCA-FDCA and HMF-HMFCA-FFCA-FDCA). All the four furan-based compounds are comprehensively discussed by the selective oxidation of HMF. Additionally, various metal catalysts, reaction conditions, and reaction mechanisms used to obtain the four different products are systematically reviewed. It is anticipated that this review will provide related researchers with new perspectives and speed up the development of this field.     

碱性条件下Ru/C催化5-羟甲基糠醛选择氧化反应

以活性炭负载金属钌(Ru/C)为催化剂,在碱性水溶液中研究了5-羟甲基糠醛(HMF)选择氧化反应.与MgO,Ca(OH)₂和NaOH相比,加入具有合适碱强度的镁铝水滑石有利于生成5-甲酰基-2-呋喃甲酸(FFCA)或2,5-呋喃二甲酸(FDCA).X射线光电子能谱实验表明金属态的钌是活性催化中心.同位素示踪结果则表明水而非氧气提供了5-甲酰基-2-呋喃甲酸及2,5-呋喃二甲酸等羧酸产物的氧源.根据这些结果,并结合HMF和2,5-呋喃二甲醛氧化的动力学研究,我们提出HMF选择性氧化制备FFCA遵循Langmuir-Hinshelwood反应机理.其中,HMF在金属Ru表面饱和解离吸附,在解离吸附的氧原子的协助下发生β-脱氢生成2,5-呋喃二甲醛(DFF)吸附物种.该DFF物种进一步发生水合与氧化形成FFCA产物.     

Enzyme‐Catalyzed Oxidation of 5‐Hydroxymethylfurfural to Furan‐2,5‐dicarboxylic Acid

Furan‐2,5‐dicarboxylic acid (FDCA) is a biobased platform chemical for the production of polymers. In the past few years, numerous multistep chemical routes have been reported on the synthesis of FDCA by oxidation of 5‐hydroxymethylfurfural (HMF). Recently we identified an FAD‐dependent enzyme which is active towards HMF and related compounds. This oxidase has the remarkable capability of oxidizing [5‐(hydroxymethyl)furan‐2‐yl]methanol to FDCA, a reaction involving four consecutive oxidations. The oxidase can produce FDCA from HMF with high yield at ambient temperature and pressure. Examination of the underlying mechanism shows that the oxidase acts on alcohol groups only and depends on the hydration of aldehydes for the oxidation reaction required to form FDCA.     

Catalytic Synthesis of 2,5‐Furandicarboxylic Acid from Concentrated 2,5‐Diformylfuran Mediated by N‐hydroxyimides under Mild Conditions

Producing polyester monomer 2,5‐furandicarboxylic acid (FDCA) from biomass as an alternative to fossil‐derived terephthalic acid has drawn much attention from both academy and industry. In this work, an efficient FDCA synthesis was proposed from 10.6 wt % 2,5‐diformylfuran (DFF) in acetic acid using a combined catalytic system of Co/Mn acetate and N‐hydroxyimides. The intermediate product of 5‐formyl‐2‐furandicarboxylic acid (FFCA) possesses the least reactive formyl group. N‐hydroxysuccinimide was found to be superior to N‐hydroxyphthalimide in catalyzing the oxidation of the formyl group in FFCA intermediate, affording a near 95 % yield of FDCA under mild conditions of 100 °C. Trace maleic anhydride was detected as by‐product, which mainly came from the oxidative cleavage of DFF via furfural, furoic acid and 5‐acetoxyl‐2(5H)‐furanone as intermediates.     

One-pot,one-step,catalytic synthesis of 2,5-diformylfuran from fructose

MIL-101, a chromium-based metal-organic framework, is known for its very large pore size, large surface area and good stability. However, application of this material in catalysis is still limited. In this paper, a simple and practical catalytic method for the preparation 2,5-diformylfuran (DFF) directly from fructose was investigated. 5% Pd-V(3: 2)@MIL-101 was evaluated as a potential and effective catalyst for the direct oxidation of fructose. The amount of the catalyst, reaction time and temperature had a large effect on the reaction. At the optimized reaction conditions, when the reaction was conducted at 140°C for 600 min, 1 atm oxygen pressure, the yield of DFF reached 34%, fructose conversion was up to 100%. In our system, the main side products were 5-formyl-2-furancarboxylic acid (FFCA) and 2,5-furandicarboxylic acid (FDCA), which are the products of deep oxidation of DFF. This simple and effective catalytic system may be valuable to facilitate energy-efficient conversion of fructose into biofuels and platform chemicals.     

Selective Synthesis of 2,5‐Diformylfuran by Sustainable 4‐acetamido‐TEMPO/Halogen‐Mediated Electrooxidation of 5‐Hydroxymethylfurfural

A new method was developed for the selective gram‐scale synthesis of 2,5‐diformylfuran (DFF), which is an important chemical with a high application potential, via oxidation of biomass‐derived 5‐hydroxylmethylfurfural (HMF) catalyzed by 4‐acetylamino‐2,2,6,6‐tetramethylpiperidine‐1‐oxyl (4‐AcNH‐TEMPO) in a two‐phase system consisting of a methylene chloride and aqueous solution containing sodium hydrogen carbonate and potassium iodide. The key feature of this method is the generation of the I₂ (co‐)oxidant by anodic oxidation of iodide anions during pulse electrolysis. In addition, the electrolyte can be successfully recycled five times while maintaining a 62–65 % yield of DFF. This novel method provides a sustainable pathway for waste‐free production of DFF without the use of metal catalysts and expensive oxidants. An advantage of electrooxidation is utilized in the preparation of demanding chemical.     

Electrocatalytic Oxidation of 5‐(Hydroxymethyl)furfural Using High‐Surface‐Area Nickel Boride

The electrochemical oxidation of the biorefinery product 5‐(hydroxymethyl)furfural (HMF) to 2,5‐furandicarboxylic acid (FDCA), an important platform chemical for the polymer industry, is receiving increasing interest. FDCA‐based polymers such as polyethylene 2,5‐furandicarboxylate (PEF) are sustainable candidates for replacing polyethylene terephthalate (PET). Herein, we report the highly efficient electrocatalytic oxidation of HMF to FDCA, using Ni foam modified with high‐surface‐area nickel boride (Ni_xB) as the electrode. Constant potential electrolysis in combination with HPLC revealed a high faradaic efficiency of close to 100 % towards the production of FDCA with a yield of 98.5 %. Operando electrochemistry coupled to ATR‐IR spectroscopy indicated that HMF is oxidized preferentially via 5‐hydroxymethyl‐2‐furancarboxylic acid rather than via 2,5‐diformylfuran, which is in agreement with HPLC results. This study not only reports a low‐cost active electrocatalyst material for the electrochemical oxidation of HMF to FDCA, but additionally provides insight into the reaction pathway.     

5-Hydroxymethylfurfural: A key intermediate for efficient biomass conversion

Biomass has been widely accepted as a "zero-emission" energy carrier to take place fossil fuels, while its catalytic conversion is still limited by low efficiency of carbon atoms. Biomass conversion via 5-hydroxymethylfurfural(HMF) as a platform chemical is highly attractive because almost all carbon atoms could be retained in the downstream chemicals under mild reaction conditions. Here we summarize recent fundamental researches and industrial progresses on all involved processes including biomass degradation to hexoses, HMF formation, hydrogenation and oxidation of HMF.     

Functionalized expanded corn starch-anchored Cu(I): An efficient and recyclable catalyst for oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran

The development of new strategies for the synthesis of biomass-based non-precious metal heterogeneous catalysts has recently received great interest from chemists because of the advantages of these catalytic systems being sustainable, low cost and green. An expanded corn starch-supported CuBr catalyst (ECS-SB-CuBr) has been successfully prepared and well characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, powder X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy/energy-dispersive X-ray spectroscopy. Further, ECS-SB-CuBr was used as a heterogeneous catalyst for the selective oxidation of 5-hydroxymethylfurfural (HMF) into 2,5-diformylfuran (DFF) and a full HMF conversion is obtained with 98% DFF yield in acetonitrile under ambient pressure of dioxygen at 50°C. The catalyst also showed good reusability, could be easily recovered through filtration and washing and was reused in at least six consecutive runs with virtually no loss of catalytic performance.