Biomass Group, Nanjing Agricultural University, PO Box 68, 40 Dianjiangtai Road, Nanjing 210031

Coproduction of Furfural and Easily Hydrolyzable Residue from Sugar Cane Bagasse

In order to develop a process for the simultaneous production of furfural and easily hydrolyzable cellulose, the degradation of sugar cane bagasse in a single aqueous system and in a 2-methyltetrahydrofuran (MTHF)/aqueous AlCl₃ biphasic system was studied.

Biomass group successfully produced furfural and easily hydrolyzable residue from sugar cane bagasse. In single aqueous system, the influence of acid species (FeCl₃, HCl, and AlCl₃) on furfural production and cellulose degradation was investigated at 150 °C. FeCl₃ and HCl promoted furfural production from hemicellulose but with severe cellulose degradation. AlCl₃ decreased cellulose degradation with considerable furfural yield and high glucan content in solid residues. The role of NaCl in furfural production and cellulose decomposition was also investigated in the single aqueous system using different acids as catalysts. Addition of NaCl significantly promoted furfural yield but also accelerated cellulose decomposition when FeCl₃ or HCl was used as catalyst. In the AlCl₃-catalyzed system, NaCl had less influence on residue yield and its composition, although NaCl also promoted furfural production. The influence of MTHF on furfural yield, residue composition, and enzymatic hydrolysis of residue was also studied. Under the best conditions (0.45 g of bagasse, 9 mL of MTHF, 9 mL of water, 0.1 M AlCl₃, 150 °C, 45 min, and 10 wt % NaCl), 58.6% furfural was obtained while more than 90% of cellulose remained in the residue. The organic phase was separated from the aqueous phase directly by decantation. After reuse of organic phase for 3 cycles, 11.5 g/L furfural was obtained. The catalyst-containing aqueous phase could be reused directly after decantation of the organic phase without loss of activity. The obtained residue was easy to hydrolyze and produced 89.3% glucose yield after 96-h enzymatic hydrolysis at low cellulase loading (30 FPU of cellulase/g-glucan).

The study was published:

XK Li, Zhen Fang*, et al., Coproduction of Furfural and Easily Hydrolyzable Residue from Sugar Cane Bagasse in the MTHF/Aqueous Biphasic System: Influence of Acid Species, NaCl Addition, and MTHF, ACS Sustainable Chemistry & Engineering, 4, 5804−5813 (2016).

Furfural (58.6% yield) and cellulose-enriched residue (>90% glucan recovered) are coproduced with 89.3% glucose yield in a MTHF/aqueous AlCl₃ system.

从甘蔗渣中生产糠醛和易水解残渣

为了开发生产糠醛和容易水解纤维素的生产工艺，对甘蔗渣在单一水相体系和 2-甲基四氢呋喃 (MTHF)/ AlCl₃水溶液双相体系进行了研究。生物能源组成功地从甘蔗渣中生产糠醛和易水解残渣。

在单一水相体系和 150 °C条件下，对酸的种类（FeCl₃、 HCl 和 AlCl₃）生产糠醛和纤维素降解的影响进行了研究。FeCl₃和HCl 促进半纤维素生产糠醛，而严重地引起纤维素的降解。AlCl₃可减少降解植物纤维素，并产生相当数量的糠醛产量和高含量的葡聚糖的固体残留物。使用不同的酸作为催化剂，在单一水相体系中考察了 NaCl 在糠醛生产和纤维素分解中的作用。当用FeCl₃ 或盐酸作为催化剂时，添加NaCl 有力地促进糠醛产量，但也加速了纤维素分解。在 AlCl₃ 催化体系中，NaCl对残留物产量和其组成影响较小，尽管NaCl 也促进了糠醛生产。MTHF对糠醛产量、 残留物的组成及其酶水解进行了研究。在最佳条件下(0.45 g蔗渣，9 毫升 MTHF，9 毫升的水、 0.1 M AlCl₃、 150 °C、 45 分钟和 10 wt % NaCl)，可获得58.6%的糠醛和超过 90%的纤维素留存在残渣中。有机相可从水相直接分层而得到并循环利用。有机相循环3次后，可得到 11.5 g/L 糠醛。有机相分离后，包含催化剂的水相没有失去活性，可以直接重复使用。

所得的残渣很容易水解， 96 h酶水解后，葡萄糖产率为 89.3% (30 FPU纤维素酶/g-葡聚糖)。

该研究发表于︰

XK Li, Zhen Fang*, et al., Coproduction of Furfural and Easily Hydrolyzable Residue from Sugar Cane Bagasse in the MTHF/Aqueous Biphasic System: Influence of Acid Species, NaCl Addition, and MTHF, ACS Sustainable Chemistry & Engineering, 4, 5804−5813 (2016).

Efficient valorization of biomass to biofuels with bifunctional solid catalytic materials

Catalytic transformation of biomass sources into biofuels and value-added chemicals generally involves multi-step reaction processes, as well as difficulty in product separation and purification. In recent years, bifunctional catalytic materials have been demonstrated to be capable of catalyzing various domino/cascade- and tandem/sequential-type reactions in a single pot, thus realizing the direct and highly efficient conversion of upstream biomass molecules to target compounds.

Dr. Hu Li, a postdoctoral student, supervised by Profs. Song Yang (Guizhou university), RL Smith (Tohoku university, Japan) and Zhen Fang reviewed a series of bifunctional materials being used in one-pot multiple transformations of biomass into biofuels and related chemicals. Emphasis is placed on the assessment of the bifunctionality of catalytic materials, including Bronsted-Lewis acid, acid-base, and metal particles–acid or base bifunctional catalysts with some discussion being on combined catalytic systems with electrochemical, chemoenzymatic and photochemical methods. Plausible reaction mechanisms for key pathways are shown. Meanwhile, relevant auxiliaries to boost catalytic activity and product selectivity, such as reaction media, heating modes and morphological properties of the catalytic materials are analyzed. Use of appropriate bifunctional catalytic materials provides many opportunities for design of highly efficient reaction systems and simplified processing to produce biofuels and chemicals from lignocellulosic biomass.

The study was published:

H Li, Zhen Fang*, RL Smith Jr., S Yang, Efficient Valorization of Biomass to Biofuels with Bifunctional Solid Catalytic Materials, Progress in Energy and Combustion Science, 55: 98-194 (2016).

The paper is in “Altmetrics – Top Rated Articles”

——————————————————————–

双功能固体材料催化生物质高值转化为生物燃料

 生物质资源催化转化为液体燃料和高附加值化学品通常会经历多步反应历程，且往往涉及产物难分离、纯化等问题。近年来，双功能催化材料被证实能“一锅法”催化多种串联或级联反应，实现生物质上游分子直接、高效地催化转化为目标化合物。

生物能源组博士后李虎在杨松教授（贵州大学），RL Smith教授（日本东北大学）和方真教授的指导下，综述了一系列双功能催化材料在一锅、多步催化生物质转化为生物燃料和相关化学品中的应用情况，并重点考察了固体材料的双功能活性位点（包括Bronsted-Lewis酸位点、酸-碱位点、金属-酸或碱位点等）在催化反应过程中对产物种类、选择性、产率等的调控作用。同时，也简要探讨了电化学、化学-酶、光化学等方法在协同催化生物质转化为高附加值小分子中的研究近况。针对上述催化体系，提出了可能的反应机理，并分析了反应介质、加热方式、固体材料的形貌结构等对催化性能的影响。最后，本论文展望了双功能固体材料在高效催化木质纤维素转化为特定目标产物、以及在简化或便利催化过程中潜在的研究空间和发展前景。

详情可见：

H Li, Zhen Fang*, RL Smith Jr., S Yang, Efficient Valorization of Biomass to Biofuels with Bifunctional Solid Catalytic Materials, Progress in Energy and Combustion Science, 55: 98-194 (2016).

该论文进入：”Altmetrics – Top Rated Articles”

有机电解液预处理北美白松用于水解生产生物质和生产乙醇

软木是自然界中一类对预处理和酶促水解具有强顽拗性的生物质。这大大限制了其作为纤维素乙醇工业原料的潜力。田霄飞博士在加拿大Western大学Lars Rehmann副教授, Chunbao Charles Xu教授和方真教授的指导下，使用了有机电解液的溶剂体系对的北美白松为代表的软木进行了预处理、水解和乙醇发酵的研究工作。本研究探讨了影响生物质溶解和预处理效力的关键因素。随着有机电解液种离子液体的摩尔比的上升，生物质中的结晶纤维素I结构的结晶度发生了有规律的降低，生物质碎片化和纤丝化程度明显上升，生物质表面木质素成分的分布发生了明显了改变。同时，纤维素，半纤维素和酸不溶型木质素成分的含量没有明显的改变。对预处理后的生物质进行酶促水解，24小时的快速水解率和120小时的最终水解率分别提高了460%和500%。水解液中没有对发酵过程有抑制的产物存在。经过含有离子液体摩尔比为0.9的有机电解液预处理后，乙醇的最终产率达到了11.04克／100克原料。

相关工作已经发表，请参考：

Xiaofei Tian, Lars Rehmann, Chunbao Charles Xu, and Zhen Fang. Pretreatment of Eastern White Pine (Pinus strobes L.) for Enzymatic Hydrolysis and Ethanol Production by Organic Electrolyte Solutions. ACS Sustainable Chemistry & Engineering 2016 4 (5), 2822-2829

DOI: 10.1021/acssuschemeng.6b00328

—————————————————————————

Pretreatment of Eastern White Pine (Pinus strobes L.) for Enzymatic Hydrolysis and Ethanol Production by Organic Electrolyte Solutions

 Dr Xiaofei Tian, supervised by Dr. Lars Rehmann, Prof. Chunbao Charles Xu and Professor Zhen FANG, developed and applied organic electrolyte solution (OES) in pre-treating of eastern white pine (EWP) that was acting as one of the most recalcitrant woody biomass for a subsequent enzymatic hydrolysis and bioethanol production. The influence of various crucial parameters that govern the dissolution and further pretreatment process were examined. A gradual reduction of the crystallinity of cellulose I, fragmentation and fibrillation, as well as lignin redistribution occurred with an increase of χ_[AMIM]Cl (molar portion of [AMIM]Cl) from 0.1 to 0.9; whereas the content of the cellulose, acid insoluble lignin as well as hemicellulose composition did not change. The efficiency of glucose released from EWP through rapid enzymatic hydrolysis (24 h hydrolysis yield) and the final hydrolysis yield (120 h hydrolysis yield) were improved remarkably by up to 460% and 500% after OES pretreatment. No negative effect of OES pretreatment on downstream ethanol fermentation was observed, and the highest ethanol productivity was 11.04 g ethanol/100 g EWP (when χ_[AMIM]Cl = 0.9).

More detailed information is available by referring this work as below.

Xiaofei Tian, Lars Rehmann, Chunbao Charles Xu, and Zhen Fang. Pretreatment of Eastern White Pine (Pinus strobes L.) for Enzymatic Hydrolysis and Ethanol Production by Organic Electrolyte Solutions. ACS Sustainable Chemistry & Engineering 2016 4 (5), 2822-2829

DOI: 10.1021/acssuschemeng.6b00328

响应面优化丁酸梭菌培养基并用于发酵热带植物废弃物水解液制备氢气

氢气作为一种清洁和可再生能源，生物制氢技术与其他制氢方法相比，具有无污染、成本低、可再生等优点，因此，生物制氢技术的研究受到广泛关注。

生物能源组研究人员，通过响应面优化丁酸梭菌的发酵培养基，并运用发酵热带植物废弃物水解液制备氢气。此项工作表明，当丁酸梭菌的发酵培养基为（g/L）：15.66 葡萄糖, 6.04 酵母粉, 4 蛋白胨, 3 K2HPO4, 3 KH2PO4, 0.05 L-cysteine, 0.05 MgSO4·7H2O, 0.1 MnSO4·H2O 和0.3 FeSO4·7H2O时氢气产率可达到最优值（2.02 mol H2 /mol葡萄糖）。甘蔗渣和小桐子果壳作为热带生物质废弃物经过两步稀酸水解后得到可用于发酵的还原糖。在最优培养基条件下，分别以甘蔗渣和小桐子果壳水解液代替葡萄糖作为碳源，丁酸梭菌的氢气产率达到2.06 mol H2 /mol总还原糖（甘蔗渣）和1.95 mol H2 /mol总还原糖（小桐子果壳）。其中氢气含量为49.7–64.34%。该研究为丁酸梭菌制备氢气的研究提供了一个较优的培养基组分，此外为进一步利用生物质废弃物制备氢气的研究提供了有效的方法。

详情可见：
D Jiang, Zhen Fang*, SX Chin, XF Tian, Biohydrogen Production from Hydrolysates of Jatropha Hulls and Sugarcane Bagasse with Clostridium Butyrium, Scientific Reports, 6:27205 (2016).

Biohydrogen Production from Hydrolysates of Selected Tropical Biomass Wastes with Clostridium Butyricum

Hydrogen can serve as a clean and renewable energy resource. In comparison with of existing methods of hydrogen production, biohydrogen (or biological hydrogen) production technology possesses advantages, such as pollution-free, lower cost, and renewable.
Biomass group successfully optimized the fermentation medium of Clostridium Butyricum by response surface methodology, and produced hydrogen from hydrolyzates of selected tropical biomass wastes under the optimal condition.
In their work, highest H2 yield of 2.02 mol H2/mol-glucose was achieved, while the composition of medium was (g/L): 15.66 glucose, 6.04 yeast extract, 4 tryptone, 3 K2HPO4, 3 KH2PO4, 0.05 L-cysteine, 0.05 MgSO4·7H2O, 0.1 MnSO4·H2O and 0.3 FeSO4·7H2O. Sugarcane bagasse and Jatropha hulls were selected as typical tropical biomass wastes to produce sugars via a two-step acid hydrolysis for hydrogen production. Under the optimized fermentation conditions, H2 yield (mol H2/mol-total reducing sugar) was 2.15 for glucose, 2.06 for bagasse hydrolysate and 1.95 for Jatropha hulls hydrolysate in a 3L fermenter for 24 h at 35 °C, with H2 purity of 49.7–64.34%. The results provide useful information and basic data for practical use of tropical plant wastes to produce hydrogen.

The study was published:
D Jiang, Zhen Fang*, SX Chin, XF Tian, Biohydrogen Production from Hydrolysates of Jatropha Hulls and Sugarcane Bagasse with Clostridium Butyrium, Scientific Reports, 6:27205 (2016).

(a) Response surface plot and (b) corresponding contour of the mutual effects of glucose and yeast extract on H₂ yield (24 h bottle fermentation at 35 °C with 130 rpm shaking).

固体酸和碱催化剂的合成及用以生产生物柴油和氢气

最近，生物能源组通过溶剂热炭法、 热解和磺化木质素从脱碱木质素中合成碳基固体酸。木质素在亚临界和超临界乙醇中碳化，提供了良好的表面性能，丰富的官能团 (2.81 和 1.35 mmol[H⁺]/g)，可为随后的磺化反应，合成高稳定、高活性的催化剂生产生物柴油。合成的催化剂，酸含量高 (> 5.05 mmol[H⁺]/g)，在80 摄氏度下，从油酸酯化反应生产生物柴油，产率 > 95%，催化剂可以循环3-5次。用该催化剂，从高酸值的小桐子油和混合的大豆油中，也成功合成高收率生物柴油（> 90%）。

同时，一种新型磁性碳基镍和硅酸钠催化剂 (Na₂SiO₃@Ni/C)也合成并用于共生产生物柴油和氢气，该方法是先将Ni(OH)₂沉淀于竹粉上，再热解和加载Na₂SiO₃。Na₂SiO₃@Ni/C 具有高碱值 (3.18 mmol/g) 和磁性 （15.7 Am²/kg），并且很稳定， 可使用4次并保持生物柴油产量 > 93%，催化剂有高的回收率（85.3%，循环5次后）。用在生产生物柴油失活的 Na₂SiO₃@Ni/C催化剂，水热气化粗甘油，气化率可达80.1 mol %并可生产82.7 mol %纯度的氢气。

结果发表在Green Chemistry和Applied Catalysis B: Environmental上。

 ———————————————————–

Synthesis of Solid Carbonaceous Acids and Base for Green Production of Biodiesel

Recently, biomass group synthesized carbonaceous acids from dealkaline lignin via solvothermal carbonization, pyrolysis and sulfonation. Carbonization of lignin in sub- and super-critical ethanol provided good surface properties with abundant functional groups (2.81 and 1.35 mmol [H⁺]/g) for the subsequent sulfonation to result in high active and stable catalysts for biodiesel production. The synthesized catalysts had high acid content (> 5.05 mmol[H⁺]/g), with biodiesel yield > 95% from the esterification of oleic acid at 80 ◦C and can be recycled 3-5 times. High biodiesel yield > 90% was obtained from Jatropha and blended soybean oils with high acid values.

A novel magnetic carbon-based nickel and sodium silicate catalyst (Na₂SiO₃@Ni/C) was also prepared by the precipitation of Ni(OH)₂ on bamboo powders, pyrolysis and the loading of Na₂SiO₃, and was used in the co-production of biodiesel and hydrogen. Na₂SiO₃@Ni/C has high basic content (3.18 mmol/g) and magnetism (15.7 Am²/kg), and is stable for 4 cycles with biodiesel yield > 93% and high recovery rate of 85.3% after 5 cycles. With the deactivated Na₂SiO₃@Ni/C, 80.1 mol% of crude glycerol gasification rate are achieved with 82.7 mol% H₂.

The results were published:

• (1)F Zhang, Xue-Hua Wu, Min Yao, Zhen Fang*, YT Wang, Production of Biodiesel and Hydrogen from Plant Oil Catalyzed by Magnetic Carbon-Supported Nickel and Sodium Silicate, Green Chemistry, 18, 3302-3314 (2016).
• (2)M Huang, J Luo, Zhen Fang*, H Li, Biodiesel Production Catalyzed by Highly Acidic Carbonaceous Catalysts Synthesized via Carbonizing Lignin in Sub- and Super-critical Ethanol, Applied Catalysis B: Environmental, 190, 103–114 (2016).

Production of biodiesel from plant oil catalyzed by magnetic Na₂SiO₃@Ni/C catalyst, and H₂ by the deactivated catalyst from by-product glycerol.