Integrated furfural production as a renewable fuel and chemical platform from lignocellulosic biomass

Furfural is a natural precursor to furan‐based chemicals and has the potential to become a major renewable platform chemical for the production of biochemicals and biofuels. However, current industrial furfural production relies on relatively old and inefficient strategies that have hindered its capacity, and low production yields have strongly diminished its competitiveness with petroleum‐based alternatives in the global market. This mini‐review provides a critical analysis of past and current progress to enhance furfural production from lignocellulosic biomass. First, important chemical and fuel products derived from the catalytic conversion of furfural are outlined. We then discuss the importance of developing integrated production strategies to co‐produce furfural with other valuable chemicals. Furfural formation and loss chemistries are explored to understand effective methods to improve furfural yields from pentosans. Finally, selected relevant commercial and academic technologies that promise to improve lignocellulosic furfural production are discussed. © 2013 Society of Chemical Industry     

木质纤维素衍生平台化学品制备液态烷烃的研究进展

液态烷烃C₅₊是汽油、柴油、航空燃油等当前社会的运输燃料的主要成分。本文综述了利用木质纤维素衍生平台化学品制备液体燃料的研究进展,着重总结了生物质衍生平台化学品通过碳链增长得到长链含氧化合物,然后经过加氢脱氧（HDO）得到C₇₊液体烷烃的技术研究进展。木质纤维素衍生平台化学品包括山梨醇、糠醛、5-羟甲基糠醛（HMF）、环戊酮、甲基呋喃、酚类、丙酮、丁醇、乙醇、乙酰丙酸、γ-戊内酯等。其中,糠醛、5-羟甲基糠醛和环戊酮在碱性催化剂作用下能与其他羰基化合物发生羟醛缩合反应实现碳链增长;甲基呋喃、苯类及苯酚类衍生物可以在强酸催化作用下通过烷基化/羟烷基化反应实现碳链增长;丙酮能与乙醇、丁醇发生α-烷基化反应实现碳链增长;乙酰丙酸可以转化为戊酸、丁烯或当归内酯,再分别通过酮基化反应、烯烃齐聚反应和加成反应实现碳链增长。诸多利用生物质衍生物化学品制备长链烷烃的路径中,利用5-羟甲基糠醛和甲基呋喃制备长链烷烃的技术路线存在路径过长、原料不易获取的问题;利用环戊酮和苯酚类物质能够得到高密度长链环烷烃,是一条有竞争力的路线;糠醛和乙酰丙酸易于从生物质中大规模制取,且利用糠醛和乙酰丙酸制备长链烷烃的反应路径短,较易实现工业应用。     

Ionic Liquids in Biomass Processing

The ionic liquids have emerged as new solvents and catalysts for processing biomass to value added chemicals and fuels. This review will present the recent developments in applications of ionic liquids in lignocellulosic biomass pretreatments, depolymerization, biodiesel synthesis, dehydration of carbohydrates to renewable feedstock chemicals as well as further transformations of biomass derived feedstocks such as furfural, 5‐hydroxymethylfurfural and levulinic acid to value added chemicals. In addition, the recycling of ionic liquids used in biomass processing is also discussed in the review.     

糠醛、糠醇和糠酸为电子给体在Pt/TiO2上光催化制氢

糠醛、糠醇和糠酸在TiO2表面吸附符合Langmuir吸附模型,吸附常数分别为9.43×102、3.88×102和1.48×103L/mol。与纯水体系相比,4.00×10-3mol/L糠醛、糠醇和糠酸作电子给体时,10h光照Pt/TiO2光解水制氢效率分别提高了33.8、260和444。光照5h,糠醛、糠醇和糠酸分别降解了10.0,16.3和48.5,COD(化学需氧量)平均去除率分别为10.0、18.0和28.4mg/L.h。溶液pH对放氢有影响,糠醛和糠酸弱酸性条件下放氢效果好,而糠醇弱碱性条件下放氢效果好。通过对降解产物分析,探讨了污染物降解的可能反应机理。     

Aluminiumchlorid‐katalysierter Organosolv‐Aufschluss von Buchenholz

The Organosolv pulping is a process to separate lignocellulosic biomass into its components cellulose, hemicellulose and lignin. Usually this process is catalyzed by Brønsted acids. In this work the Brønsted acid is replaced by the Lewis acid aluminum chloride. Much less aluminum chloride is needed to achieve similar pulp properties like high cellulose recovery, high hemicellulose and lignin removal. Also aluminum chloride catalyzes the degradation of xylose to the important basic chemicals furfural and lactic acid.     

润滑油精制装置中的防腐与防焦研究

阐明了润滑油精制装置中的糠醛腐蚀及生焦机理。根据工艺流程的特点，采用注入有机胺类缓蚀剂等措施，可破坏糠醛、糠酸和水的共沸，阻止糠酸从糠醛回收塔返回装置系统，结果使全装置酸值下降，同时使全装置的腐蚀及焦生成量减少，装置开工周期从一年延长至两年半。     

Effects of Different Oil Sources and Residues on Biomass and Metabolite Production by Yarrowia lipolytica YB 423-12

Yarrowia lipolytica is known to have the ability to assimilate hydrophobic substrates like triglycerides, fats, and oils, and to produce single-cell oils, lipases, and organic acids. The aim of the present study was to investigate the effects of different oil sources (borage, canola, sesame, Echium, and trout oils) and oil industry residues (olive pomace oil, hazelnut oil press cake, and sunflower seed oil cake) on the growth, lipid accumulation, and lipase and citric acid production by Y. lipolytica YB 423-12. The maximum biomass and lipid accumulation were observed with linseed oil. Among the tested oil sources and oil industry residues, hazelnut oil press cake was the best medium for lipase production. The Y. lipolytica YB 423-12 strain produced 12.32 ± 1.54 U/mL (lipase activity) of lipase on hazelnut oil press cake medium supplemented with glucose. The best substrate for citric acid production was found to be borage oil, with an output of 5.34 ± 0.94 g/L. The biotechnological production of valuable metabolites such as single-cell oil, lipase, and citric acid could be achieved by using these wastes and low-cost substrates with this strain. Furthermore, the cost of the bio-process could also be significantly reduced by the utilization of various low-cost raw materials, residues, wastes, and renewable resources as substrates for this yeast.     

木质纤维素制备5-羟甲基糠醛的催化过程强化

5-羟甲基糠醛(HMF)是一种链接可再生生物质资源与燃料化合物及化学中间体的重要新型平台化合物。文中对高温(180—200℃)条件下,金属氯化物为催化剂,离子液体[BMIM]Cl为溶剂,木质纤维素(相思木木屑)为原料快速制备HMF和糠醛的反应过程进行了研究。通过对反应温度、原料用量、盐酸(HCl)添加量、催化剂种类及用量等因素进行考察,优化了反应条件。研究结果表明:与文献报道的低温下纤维素降解反应相比,高温条件可使木质纤维素为原料制备HMF的反应过程得到强化。在所考察的金属氯化物催化剂中,CrCl3.6H2O的催化效果最优,其中以CrCl3.6H2O为催化剂,200℃下反应4 min时产物HMF及糠醛的收率分别可达55.0%和22.9%。该高温反应过程反应快速、产物收率高,无需木质纤维素原料的预处理操作,为工业上简单快速制备HMF提供了一种可行方法。     

Electrochemical investigations of the oxidation-reduction of furfural in aqueous medium: Application to electrosynthesis

The present study concerns the electrochemical properties of furfural in aqueous medium on noble (Au and Pt) and non-noble (Pb, Cu and Ni) metal electrodes. The anodic and cathodic reactions are investigated by cyclic voltammetry on Au, Pt and Ni electrodes and during prolonged electrolyses on Pt, Pb and Cu in order to find the optimum conditions for a paired electrosynthesis. Anodic reactions are controlled by diffusion in the range of the stability of the solvent (water). Beside these limits, the gas evolution competes with the conversion of furfural. The best conditions for preparative electrooxidation (Ni anode, 0.5 M NaOH, j=0.8 mA cm⁻¹) gave furoic acid in a 80% yield and furfuryl alcohol was obtained by electroreduction in a 55% yield on Cu cathodes at pH 10 and 30 mA cm⁻².     

Validated Growth Rate-Dependent Regulation of Lipid Metabolism in Yarrowia lipolytica

Given the strong potential of Yarrowia lipolytica to produce lipids for use as renewable fuels and oleochemicals, it is important to gain in-depth understanding of the molecular mechanism underlying its lipid accumulation. As cellular growth rate affects biomass lipid content, we performed a comparative proteomic analysis of Y. lipolytica grown in nitrogen-limited chemostat cultures at different dilution rates. After confirming the correlation between growth rate and lipid accumulation, we were able to identify various cellular functions and biological mechanisms involved in oleaginousness. Inspection of significantly up- and downregulated proteins revealed nonintuitive processes associated with lipid accumulation in this yeast. This included proteins related to endoplasmic reticulum (ER) stress, ER–plasma membrane tether proteins, and arginase. Genetic engineering of selected targets validated that some genes indeed affected lipid accumulation. They were able to increase lipid content and were complementary to other genetic engineering strategies to optimize lipid yield.     

Citric acid,biomass and cellular lipid production by Yarrowia lipolytica strains cultivated on olive mill wastewater‐based media

BACKGROUND: Olive mill wastewaters (OMWs) are an important residue and several physico‐chemical and/or biotechnological methods have been proposed for their treatment. RESULTS: The ability of three Yarrowia lipolytica strains to grow on and convert glucose‐enriched OMWs into added‐value compounds in carbon‐ and nitrogen‐limited shake‐flask cultures was assessed. Remarkable decolorization (up to 63%) and non‐negligible removal of phenolic compounds (up to 34%, w/w) occurred. In nitrogen‐limited cultures, the accumulation of cellular lipids was favored by OMW addition into the medium. In contrast, although remarkable quantities of citric acid (Cit) were produced in control experiments (cultures without OMW addition), in which Cit up to 18.9 g L^?1 was produced with yield of Cit synthesized per sugar consumed ～0.73 g g^?1), adaptation of cultures to media supplemented with OMWs reduced the final Cit quantity and conversion yield values achieved. In OMW‐based media, the highest concentration of citric acid produced was 18.1 g L^?1, with conversion yield ～0.51 g g^?1. In carbon‐limited cultures, despite the presence of inhibitory compounds in the medium (e.g. phenols), biomass production was enhanced with the addition of OMWs. The highest biomass concentration achieved was 12.7 g L^?1, with biomass conversion yield per sugar consumed ～0.45 g g^?1. Fatty acid analysis of cellular lipid produced demonstrated that adaptation of all strains in OMW‐based media favored the synthesis of cellular lipids that contained increased concentrations of cellular oleic acid. CONCLUSIONS: The Y. lipolytica strains tested can be regarded as possible candidates for simultaneous OMWs remediation and production of added‐value compounds. Copyright © 2011 Society of Chemical Industry     

Application of a New Engineered Strain of Yarrowia lipolytica for Effective Production of Calcium Ketoglutarate Dietary Supplements

The present study aimed to develop a technology for the production of dietary supplements based on yeast biomass and α-ketoglutaric acid (KGA), produced by a new transformant of Yarrowia lipolytica with improved KGA biosynthesis ability, as well to verify the usefulness of the obtained products for food and feed purposes. Transformants of Y. lipolytica were constructed to overexpress genes encoding glycerol kinase, methylcitrate synthase and mitochondrial organic acid transporter. The strains were compared in terms of growth ability in glycerol- and oil-based media as well as their suitability for KGA biosynthesis in mixed glycerol–oil medium. The impact of different C:N:P ratios on KGA production by selected strain was also evaluated. Application of the strain that overexpressed all three genes in the culture with a C:N:P ratio of 87:5:1 allowed us to obtain 53.1 g/L of KGA with productivity of 0.35 g/Lh and yield of 0.53 g/g. Finally, the possibility of obtaining three different products with desired nutritional and health-beneficial characteristics was demonstrated: (1) calcium α-ketoglutarate (CaKGA) with purity of 89.9% obtained by precipitation of KGA with CaCO₃, (2) yeast biomass with very good nutritional properties, (3) fixed biomass-CaKGA preparation containing 87.2 μg/g of kynurenic acid, which increases the health-promoting value of the product.     

农业废弃物转化成能源及高附加值化学品的研究进展

在简单介绍农业废弃生物质主要组分及含量的基础上,概述了当前农业废弃生物质主要组分纤维素、半纤维素及木质素转化为乙醇、丙酮等生物能源以及糠醛、呋喃等高附加值化学品的国内外研究进展,并分析其在研究中存在的问题及未来发展方向。     

The Role of Hexokinase and Hexose Transporters in Preferential Use of Glucose over Fructose and Downstream Metabolic Pathways in the Yeast Yarrowia lipolytica

The development of efficient bioprocesses requires inexpensive and renewable substrates. Molasses, a by-product of the sugar industry, contains mostly sucrose, a disaccharide composed of glucose and fructose, both easily absorbed by microorganisms. Yarrowia lipolytica, a platform for the production of various chemicals, can be engineered for sucrose utilization by heterologous invertase expression, yet the problem of preferential use of glucose over fructose remains, as fructose consumption begins only after glucose depletion what significantly extends the bioprocesses. We investigated the role of hexose transporters and hexokinase (native and fructophilic) in this preference. Analysis of growth profiles and kinetics of monosaccharide utilization has proven that the glucose preference in Y. lipolytica depends primarily on the affinity of native hexokinase for glucose. Interestingly, combined overexpression of either hexokinase with hexose transporters significantly accelerated citric acid biosynthesis and enhanced pentose phosphate pathway leading to secretion of polyols (31.5 g/L vs. no polyols in the control strain). So far, polyol biosynthesis was efficient in glycerol-containing media. Moreover, overexpression of fructophilic hexokinase in combination with hexose transporters not only shortened this process to 48 h (84 h for the medium with glycerol) but also allowed to obtain 23% more polyols (40 g/L) compared to the glycerol medium (32.5 g/L).     

非酶催化转化半纤维素生成能源及高附加值化学品

利用非酶工艺将半纤维素转化成能源及高附加值化学品具有技术上和经济上的可行性。本文详细介绍通过水热法、微波辅助法、离子液体以及复合型固体催化剂将半纤维素催化转化成乙醇、丁二醇等能源以及糠醛、酸、呋喃类高附加值化学品的国内外研究进展。非酶催化工艺克服传统酶催化反应条件苛刻、酶成本高等缺点,但对反应设备要求高,反应机理不明确,反应选择性低。因此,深入研究反应机理、改善反应条件成为今后研究方向。     

香料糠酸甲酯的新法合成与表征

从糠醛出发 ,由制备的糠酸和甲醇反应 ,在盐酸催化下 ,合成了香料糠酸甲酯 ,并用IR、1HNMR、GC等进行了表征 ;探讨了包括高纯度糠酸的制备在内的反应影响因素 ,在醇酸物质的量之比为 5∶1、催化剂体积占甲醇体积 13.0 %、反应时间 3h的最佳工艺条件下 ,酯化收率为81 0 % ,收率比硫酸法、某些固体超强酸法高     

Pyrolysis kinetics of forestry residues from the Portuguese Central Inland Region

The pyrolysis behaviour and kinetics of forest shrub wastes (Cytisus multiflorus, Spartium junceum, Acacia dealbata and Pterospartum tridentatum) from the Portuguese Central Inland Region have been studied in a thermobalance, as a previous step for their valorization by pyrolysis in order to obtain fuels and chemicals within the framework of the BioREFINA-Ter project. The kinetic model consists of a multi-component mechanism that describes the volatile formation involving three independent and parallel reaction networks corresponding to the decomposition of the three main biomass pseudo-components: hemicellulose, cellulose and lignin. The thermogravimetric curves and kinetic parameters have been compared with those obtained for other materials, and the chemical features of the biomasses have been determined. Although the samples are highly heterogeneous because of their bark and leaf content, the degradation of these shrubby biomasses is similar to other lignocellulosic materials, evidencing that their valorization by pyrolysis is feasible.     

Elevating Phospholipids Production Yarrowia lipolytica from Crude Glycerol

Phospholipids (PLs) are a class of lipids with many proven biological functions. They are commonly used in lipid replacement therapy to enrich cell membranes damaged in chronic neurodegenerative diseases, cancer, or aging processes. Due to their amphipathic nature, PLs have been widely used in food, cosmetic, and pharmaceutical products as natural emulsifiers and components of liposomes. In Yarrowia lipolytica, PLs are synthesized through a similar pathway like in higher eukaryotes. However, PL biosynthesis in this yeast is still poorly understood. The key intermediate in this pathway is phosphatidic acid, which in Y. lipolytica is mostly directed to the production of triacylglycerols and, in a lower amount, to PL. This study aimed to deliver a strain with improved PL production, with a particular emphasis on increased biosynthesis of phosphatidylcholine (PC). Several genetic modifications were performed: overexpression of genes from PL biosynthesis pathways as well as the deletion of genes responsible for PL degradation. The best performing strain (overexpressing CDP-diacylglycerol synthase (CDS) and phospholipid methyltransferase (OPI3)) reached 360% of PL improvement compared to the wild-type strain in glucose-based medium. With the substitution of glucose by glycerol, a preferred carbon source by Y. lipolytica, an almost 280% improvement of PL was obtained by transformant overexpressing CDS, OPI3, diacylglycerol kinase (DGK1), and glycerol kinase (GUT1) in comparison to the wild-type strain. To further increase the amount of PL, the optimization of culture conditions, followed by the upscaling to a 2 L bioreactor, were performed. Crude glycerol, being a cheap and renewable substrate, was used to reduce the costs of PL production. In this process 653.7 mg/L of PL, including 352.6 mg/L of PC, was obtained. This study proved that Y. lipolytica is an excellent potential producer of phospholipids, especially from waste substrates.     

New methods for the one-pot processing of polysaccharide components (cellulose and hemicelluloses) of lignocellulose biomass into valuable products. Part 2: Biotechnological approaches to the conversion of polysaccharides and monosaccharides into the valuable industrial chemicals

Part 2 of the review discusses modern processes for biotechnological conversion of lignocellulosic biomass into the valuable chemicals. It also recognizes the new approaches toward the development of more efficient enzymes for the depolymerization of biomass and the properties of the microorganisms employed in the fermentation of the biomass-derived sugars. Various biotechnological approaches to the fermentation of the depolymerized biomass products are described, including SHF, SSF, NSSF, SSFF, SSCF, and CBP. It is demonstrated that that the main tendencies for development of the new technologies for biotechnological biomass processing are the application of genetic engineering, synthetic biology and reduction of the number of processing steps. Application of one-pot processing of lignocellulosic biomass is promising for development of the new and efficient manufacturing technologies for production of valuable chemicals.