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。     

生物质平台分子γ-戊内酯的研究进展

生物质是自然界存量丰富的可再生资源.随着化石资源的日渐枯竭,由生物质制备燃料和化学品引起人们关注.把生物质转化为燃料和化学品通常经过生物质平台分子步骤.在众多生物质平台分子中,γ-戊内酯(GVL)具有广泛的用途,有关γ-戊内酯的合成和转化的研究成为一个热点课题.由木质纤维素制备GVL已经开发出多种催化体系,将GVL转化为燃料、化学品以及高分子材料也有大量文献报道.着重从不同的原料、催化体系归纳GVL的合成路线和方法,为探索高效、经济、绿色、可持续的GVL合成途径提供思路,并对GVL的高效转化的研究加以总结,为发展新的转化技术,拓展应用范围提供参考.     

生物质转化合成新能源化学品乙酰丙酸酯

生物质是唯一可替代化石资源获取液态燃料和化学品的可再生资源,近年来由生物质转化合成乙酰丙酸酯引起了研究者们越来越广泛的关注。乙酰丙酸酯是一类重要的化学中间体和新能源化学品,具有高的反应特性和广泛的工业应用价值。目前开发的从生物质资源出发转化合成乙酰丙酸酯的潜在合成途径可概括为4种:直接酸催化醇解法、经乙酰丙酸酯化、经5-氯甲基糠醛醇解和经糠醇醇解。本文分别介绍了这4种转化合成途径的化学反应过程及最新研究进展,从反应合成工艺、催化体系、经济可行性等方面评述了各自的特点与发展趋势,并分析了目前工业规模转化生物质合成乙酰丙酸酯仍面临的一些科学难点。最后,对今后该领域的研究前景进行了展望。     

生物质水热催化制备重要含氧化学品研究进展

作为唯一可再生、 分布广泛的绿色含碳资源, 生物质的高值化利用尤其是制备高品质含氧化学品日益引起研究者的广泛关注, 其中生物质水热催化制备重要含氧化学品是当前的一个重要研究方向. 本文对生物质经水热催化加氢、 脱水和水解制备多元醇、 5-羟甲基糠醛和乳酸的研究进展进行了系统总结和评述, 分析了催化剂的作用机制和产物生成机理, 并对生物质水热催化的研究前景进行了展望.     

光电解水制氢耦合生物质醇/醛氧化的研究进展

生物质醇/醛是一类重要的生物基平台化合物, 通过催化氧化重整可将其进一步转化为高值含氧化学品或燃料. 太阳能驱动的光电催化技术是实现生物质醇/醛氧化最为绿色高效的途径之一. 与传统光电解水制氢相比, 利用生物质醇/醛氧化来替代阳极析氧过程不仅可以提高阳极产物的附加值, 同时可以提升太阳能到氢能的转化效率. 因此, 光电解水制氢耦合生物质醇/醛氧化对绿氢提效降本和高值化学品合成具有重要意义. 本文综合评述了光电解水制氢耦合生物质醇/醛的氧化反应机理, 总结了目前光电催化技术在生物质醇/醛氧化方面的研究进展, 最后对该领域所面临的机遇和挑战进行了展望.     

生物质热化学转化制备生物燃料及化学品

生物质是环境友好的可再生能源.近年来相关研究不断升温,文献报道量激增.本文在现有文献综述及近期报道的基础上,从利用热化学方法由生物质获得燃料油及化学品的角度对各方案进行了归纳、适当补充及简要述评,重点介绍了生物油催化裂解精制、水相重整制备烷烃、超临界水/水热制备化学品3个领域.     

生物质平台化合物电催化制备高值燃料与化学品研究进展

生物质是一类丰富的可再生碳基资源, 有望代替传统化石资源生产燃料和化学品, 受到了广泛关注和研究. 近年来, 电催化作为一种绿色高效的转化策略, 成为生物质催化转化的重要研究方向之一, 具有巨大的应用前景. 本文总结了生物质平台化合物电催化制备高附加值燃料与化学品的研究进展, 根据反应类型重点介绍了电催化氧化、 还原和偶联反应, 对催化反应过程和机理进行了阐述, 并对电催化生物炼制的前景进行了展望.     

生物质热化学转化制备生物燃料及化学品

生物质是环境友好的可再生能源。近年来相关研究不断升温,文献报道量激增。本文在现有文献综述及近期报道的基础上,从利用热化学方法由生物质获得燃料油及化学品的角度对各方案进行了归纳、适当补充及简要述评,重点介绍了生物油催化裂解精制、水相重整制备烷烃、超临界水/水热制备化学品3个领域。     

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。     

呋喃类平台化合物催化转化成可再生化学品和燃料

正随着石油资源的相对贫乏和环境问题的加剧,寻求新的能源和途径来代替传统的化石资源越来越受到人们的关注.生物质在地球上含量丰富、分布广泛、价格较低廉且能够很好的实现碳循环,作为一种可持续和可再生资源,在取代传统的石油产品方面具有很大的潜力,能很好满足社会对燃料和化学品的需求,从而实现由不可再生的石油资源向可再生的生物能源的过渡.植物类生物质的主要成分是碳水化合物即纤维素和木质素,在一定条件下可     

用于生物质水相加氢多相负载型金属催化剂的稳定策略

生物质是天然的可再生能源和资源,具有来源广泛、储量丰富、价格低廉的优点以及可转化为高附加值化学品的多功能性,因此作为传统化石能源替代材料受到广泛关注和研究.将生物质通过催化转化为平台化合物再进一步利用是生物质利用的重要途径,其中催化加氢是常用的反应之一.由于绝大多数生物质平台化合物分子中都含氧元素,其加氢过程中会不可避免的产生水,同时水作为绿色环保,价廉易得的溶剂,可以溶解绝大多数生物质平台化合物,因此选择水做溶剂具有重要意义.负载型纳米金属催化剂(如Au、Rh、Pt、Pd、Ru、Cu和Co等)在生物质水相加氢反应中具有广泛的应用,但其在水相反应条件下(通常为高温、高压、强酸性等苛刻条件)容易在反应过程中发生纳米金属粒子的团聚、流失以及载体的坍塌、结构转变等引起失活.因此,发展可以在水相体系中稳定的金属多相催化剂对生物质资源化利用非常必要.本文首先综述了溶剂水对反应的影响以及负载型金属催化剂在水相体系中的失活类型与机理,内容包括:(1)溶剂水对催化剂及催化加氢反应的积极作用,包含提高转化率和影响产物选择性;(2)溶剂水引起催化剂失活的原因,如引起金属纳米粒子发生团聚、氧化、流失以及载体发生溶解、坍塌、结构转变等.从负载型金属催化剂的失活机理入手,分别从提高金属纳米粒子的稳定性和载体的稳定性两个方向综述了提高负载型金属催化剂稳定性的普适性策略,内容包括:(1)通过界面限域策略增强金属-载体相互作用的方式提高金属纳米粒子在载体上的稳定性,包括有机基团配位、杂原子配位、镶嵌法等;(2)通过空间限域策略将金属纳米颗粒封装的方式提高金属纳米粒子的稳定性,包括利用一维的空心管状材料、二维的超薄材料以及三位的空心球(笼)材料等;(3)通过提高载体(主要为氧化物载体)的稳定性以提高催化剂整体稳定性,包括对载体进行修饰、包覆、杂化等方式.本工作所综述的提高生物质水相加氢金属催化剂稳定性的策略为高稳定性催化剂的设计指出了方向.     

Recent advances in paired electrolysis of biomass-derived compounds toward cogeneration of value-added chemicals and fuels

Pairing the electrocatalytic hydrogenation reaction with different anodic reactions driven by renewable electricity offers a greener way for producing value-added chemicals and fuels. In particular, replacing the sluggish water oxidation with a biomass-based upgrading reaction can reduce the overall energy cost, thus allowing for the simultaneous generation of high-value products at both electrodes. This mini-review summarized the recent progress in paired electrolysis of biomass-derived compounds, particularly the furanic chemicals. Some perspectives and outlooks were proposed for further improvements in this research area.     

Organocatalytic Upgrading of Biomass Derived Building Blocks

The depletion of finite primary fossil fuels we are facing makes necessary a deep metamorphosis in fundamental parts of the chemical industry. A progressive transition from petro-based starting materials toward renewable biomass-derived sources will have to take place in the synthesis of added-value chemicals, important for our everyday life, such as pharmaceuticals, polymers, agrochemicals etc. Moreover, greener processes, carried out under friendlier reaction conditions, must be designed to address current concerns about the climate change and the resulting pressing need to reduce the environmental footprint of chemical processes. To this end, organocatalysis could offer a valuable opportunity for upgrading biomass-derived platform molecules in line with the principles of Green Chemistry. This review presents some of recent and remarkable advancements in this emerging area. Organocatalysis has proven to be an efficient tool to transform low value bio-based renewable platform building blocks into new high value bio-based chemicals, with potential applications as synthetic intermediates, innovative materials and pharmaceutically active compounds.     

Differentiation of O-H and C-H bond scission mechanisms of ethylene glycol on Pt and Ni/Pt using theory and isotopic labeling experiments

Understanding and controlling bond-breaking sequences of oxygenates on transition metal catalysts can greatly impact the utilization of biomass feedstocks for fuels and chemicals. The decomposition of ethylene glycol, as the simplest representative of biomass-derived polyols, was studied via density functional theory (DFT) calculations to identify the differences in reaction pathways between Pt and the more active Ni/Pt bimetallic catalyst. Comparison of the computed transition states indicated three potentially feasible paths from ethylene glycol to C1 oxygenated adsorbates on Pt. While not important on Pt, the pathway to 1,2-dioxyethylene (OCH(2)CH(2)O) is favored energetically on the Ni/Pt catalyst. Temperature-programmed desorption (TPD) experiments were conducted with deuterated ethylene glycols for comparison with DFT results. These experiments confirmed that decomposition of ethylene glycol on Pt proceeds via initial O-H bond cleavage, followed by C-H and the second O-H bond cleavages, whereas on the Ni/Pt surface, both O-H bonds are cleaved initially. The results are consistent with vibrational spectra and indicate that tuning of the catalyst surface can selectively control bond breaking. Finally, the significant mechanistic differences in decomposition of polyols compared to that of monoalcohols and hydrocarbons serve to identify general trends in bond scission sequences.     

Molybdenum-Catalyzed Deoxygenation Coupling of Lignin-Derived Alcohols for Functionalized Bibenzyl Chemicals

With the growing demand for sustainability and reducing CO₂ footprint, lignocellulosic biomass has attracted much attention as a renewable, carbon-neutral and low-cost feedstock for the production of chemicals and fuels. To realize efficient utilization of biomass resource, it is essential to selectively alter the high degree of oxygen functionality of biomass-derivates. Herein, we introduced a novel procedure to transform renewable lignin-derived alcohols to various functionalized bibenzyl chemicals. This strategy relied on a short deoxygenation coupling pathway with economical molybdenum catalyst. A well-designed H-donor experiment was performed to investigate the mechanism of this Mo-catalyzed process. It was proven that benzyl carbon-radical was the most possible intermediate to form the bibenzyl products. It was also discovered that the para methoxy and phenolic hydroxyl groups could stabilize the corresponding radical intermediates and then facilitate to selectively obtain bibenzyl products. Our research provides a promising application to produce functionalized aromatics from biomass-derived materials.     

Integrated production of ethanol fuel and protein from Coastal Bermudagrass

The herbaceous crops that may provide fermentable carbohydrates for production of fuels and chemicals also contain 10–20% protein. Protein coproduction with biomass-derived fuels and chemicals has important advantages: (1) food and fuel production can be integrated, and (2) protein is a high-value product that may significantly improve overall process economics. We report the results of an integrated approach to producing protein and fermentable sugars from one herbaceous species, Coastal Bermudagrass (CBG). The ammonia fiber explosion (AFEX) process makes possible over 90% conversion of cellulose and hemicellulose to simple sugars (about 650 mg reducing sugars/g dry CBG) at 5 IU cellulase/g vs < 20% conversion for untreated CBG. The AFEX treatment also improves protein extraction from CBG; over 80% protein recovery is possible from AFEX-treated CBG vs about 30% recovery from untreated CBG.     

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.