木质纤维素生物质预处理低成本离子液体
Summary
The pretreatment of lignocellulosic biomass with protic low-cost ionic liquids is shown, resulting in a delignified cellulose-rich pulp and a purified lignin. The pulp gives rise to high glucose yields after enzymatic saccharification.
Abstract
A number of ionic liquids (ILs) with economically attractive production costs have recently received growing interest as media for the delignification of a variety of lignocellulosic feedstocks. Here we demonstrate the use of these low-cost protic ILs in the deconstruction of lignocellulosic biomass (Ionosolv pretreatment), yielding cellulose and a purified lignin. In the most generic process, the protic ionic liquid is synthesized by accurate combination of aqueous acid and amine base. The water content is adjusted subsequently. For the delignification, the biomass is placed into a vessel with IL solution at elevated temperatures to dissolve the lignin and hemicellulose, leaving a cellulose-rich pulp ready for saccharification (hydrolysis to fermentable sugars). The lignin is later precipitated from the IL by the addition of water and recovered as a solid. The removal of the added water regenerates the ionic liquid, which can be reused multiple times. This protocol is useful to investigate the significant potential of protic ILs for use in commercial biomass pretreatment/lignin fractionation for producing biofuels or renewable chemicals and materials.
Introduction
会议人类的能源需求是可持续的，我们的文明所面临的最大挑战之一。能源消耗预计在未来50年内翻番，投入更大的压力对化石燃料资源1通过广泛的化石燃料的使用大气中温室气体（GHG）的建设问题尤其严重，因为二氧化碳从燃烧产生化石燃料的负责人为温室效应50％。2因此，可再生能源和碳中和技术的大规模应用是满足子孙后代的增加能量和物质需要是必不可少的。1，3
植物生物量是最通用的可再生资源，因为它可以被用来生产热，电以及基于碳的化学物质，材料和燃料。在其他生物质类型的木质纤维素生物质的主要优势是高收益的PE其丰富，潜力土地，往往高得多的二氧化碳排放量储蓄R一侧，其中包括在土壤中碳的高保持4,5利用生物质的其它优点还包括当地的可用性，低资本要求将生物质转化为能量，而水土流失防治。8
木质纤维素原料的主要生产国是林业产业和农业部门以及市政废物管理。6木质纤维素生产有潜力扩大，用脑子来限制森林砍伐和避免了更换粮食作物和潜在污染物的释放。7可再生的生物质成为液体运输燃料和化学品的一个可行的普遍来源，它的处理必须成为与化石燃料转化技术在经济上有竞争力。9,10实现这方面的一个关键是要提高产率和生物量衍生的中间体的质量，同时降低成本。</ P>
木素纤维素含有糖，可通过催化和微生物的转化被转化为燃料和化学品的比例很高。11这些糖是存在于木质纤维素中聚合形式如纤维素和半纤维素。它们可以被水解成葡萄糖和其它糖单体，然后用于生产生物乙醇和其它生物衍生的化学品和溶剂。12
为了访问纤维素糖，生物质的预处理是通过物理，化学，或结合的方法必要的。4预处理可以说是在木质纤维素生物质的物价稳定措施中最昂贵的步骤。因此，研究改进预处理工艺势在必行。
各种预处理技术是可用的。特别感兴趣的是那些分开纤维素（fractionative预处理）的木质素。木质素，在第三主要组分木素纤维素，水解剂以纤维素和半纤维素的访问限制，并降低每吨原料的糖产率。11，如果它是在合适的质量分离的分离木质素可以用作额外的生物精炼中间体13之一fractionative过程是硫酸盐方法，该方法为纸/纤维素生产中最常用的预处理。在硫酸盐法制浆，木片在高压下放入氢氧化钠和硫化钠和加热的混合物中在约170℃的高温下进行。14的碱性反应通过经由亲核打破聚合物下降到短的片段除去半纤维素和木质素和碱催化，并且通过经由酚羟基/醇基团的去质子化的木质素片段溶解。另一种常见的脱木素工艺是有机溶剂法的过程，也片段并溶解木质素和半纤维素。而不是使用碱性aqueo我们的解决方案，如乙醇和乙酸的有机溶剂中在高温下从5-30巴160-200℃，和压力之间的范围内使用。有机溶剂预处理拥有卡夫一些优势制浆，因为它产生较少的空气和水的污染。15这两个过程都具备一定的经济挑战，如果用于生产化学品和燃料，而不是纤维素。16 Ionosolv预处理采用离子液体，这是盐的具有低于100℃熔点和，作为其强大库仑相互作用，非常低的蒸汽压的结果。17这消除在预处理过程的空气污染，并能处理在大气压或接近大气压。
而在费力，多步合成中创建最离子液体，质子离子液体可以在从大宗化学品的一步骤的过程，这使得它们更便宜来合成据估计，一些离子液体可以在批量规模生产要每公斤1.24 $价格这与普通的有机溶剂如丙酮和甲苯18中，在相对 较低的温度和压力下操作的过程中回收和再利用这些定制离子液体的能力使得这个更无害的替代和经济上有吸引力的候选对于生物精炼。
该详细视频协议演示了Ionosolv过程的木质纤维素生物质和富含纤维素的纸浆的最终酶糖化，以及高纯度的无异味的木质素的回收的脱木素实验室规模的版本。19
Protocol
Representative Results
Discussion
对于这里提出的木质纤维素生物质的分馏技术产生一个富含纤维素的纸浆和木质素。大多数的半纤维素的溶解到离子液体和水解，但不恢复。如果半纤维素糖是需要的话，前Ionosolv脱木素半纤维素预萃取步骤可能是必要的。它迄今不可能完全关闭质量平衡为生物量，因为它不可能识别和量化在离子液体中液中发现的所有降解产物，特别是那些从木质素而产生。关于回收和质量平衡的详细研究正在?…
Offenlegungen
The authors have nothing to disclose.
Acknowledgements
作者承认格兰瑟姆研究所气候变化与环境，气候KIC和自然科学研究理事会（EP / K038648 / 1和EP / K014676 / 1）资金和皮埃尔·布维尔为松预处理提供实验数据。
Materials
| IL synthesis | ||||
| Round bottom flask, with standard ground joint 24/29 NS, 1000 ml | Lenz | 3 0024 70 | VWR product code 271-1309 | |
| 250mL Addition Funnel, Graduated, 29/26 Joint Size, 0-4mm PTFE Valve | GPE | CG-1714-16 | ||
| Dish-shaped dewar flask, SCH 31 CAL | KGW-Isotherm | 1197 | ||
| Volumetric flask, 200 ml | VWR | 612-3745 | ||
| Cork rings, pasteur pipettes and teet, wash bottle with deionised water, large magentic stir bar | ||||
| Biomass size reduction | ||||
| Heavy Duty Cutting Mill SM2000 | Retsch | Discontinued | Replaced with Cutting Mill SM 200 (20.728.0001) | |
| Bottom sieves (10 mesh square holes, for particle size <2 mm) | Retsch | 03.647.0318 | Part of cutting mill | |
| Analytical Sieve Shaker AS 200 | Retsch | 30.018.0001 | Part of sieving machine | |
| Test Sieve 200 mm Ø x 50 mm height ISO 3310/1 (180 µm) | Retsch | 60.131.000180 | Part of sieving machine | |
| Test Sieve 200 mm Ø x 50 mm height ISO 3310/1 (850 µm) | Retsch | 60.131.000850 | Part of sieving machine | |
| Collecting pan, stainless steel, 200 mm Ø, height 50 mm | Retsch | 69.720.0050 | Part of sieving machine | |
| Rotary evaporator: | ||||
| Rotary evaporator (Rotavapor R-210) | Buchi | Discontinued | Replaced with Rotavapor R-300 | |
| Water bath (Heating bath B-491) | Buchi | 48201 | Part of rotary evaporator | |
| Recirculator | Julabo | F25 | Part of rotary evaporator | |
| Vacuum pump (MPC 101 Z) | Ilmvac GmbH | 412522 | Part of rotary evaporator | |
| Vacuum controller (Vacuum Control Box VCB 521) | Ilmvac GmbH | 600053 | Part of rotary evaporator | |
| Parallel evaporator: | ||||
| StarFish Base Plate 135mm (for Radleys & IKA) | Radleys | RR95010 | Part of parallel evaporator | |
| Monoblock for 5 x 250ml Flasks | Radleys | RR95130 | Part of parallel evaporator | |
| Telescopic 5-way Clamp with Velcro | Radleys | RR95400 | Part of parallel evaporator | |
| Gas/Vacuum Manifold with connectors | Radleys | RR95510 | Part of parallel evaporator | |
| 650mm Rod | Radleys | RR95665 | Part of parallel evaporator | |
| Quick Release Male, R/A Barbed 6.4mm + Shut-off (3.2mm ID) | Radleys | RR95520 | Part of parallel evaporator | |
| Stirrer/hot plate | Radleys | RR98072 | Part of soxhlet extractor | |
| Temperature controller | Radleys | RR98073 | Part of soxhlet extractor | |
| Elliptical Stirring Bar 15mm Rare Earth | Radleys | RR98097 | Part of parallel evaporator | |
| Vacuum cold trap, plastic coated, PTFE stopcock | Chemglass | CG-4519-01 | Part of parallel evaporator | |
| Vacuum pump (MPC 101 Z) | Ilmvac GmbH | 412522 | Part of parallel evaporator | |
| Tygon tubing E-3603, 6,40 mm (internal) 12,80 mm (external) | Saint-Gobain/VWR | 228-1292 | Part of parallel evaporator | |
| Parallel Soxhlet extractor: | ||||
| StarFish Base Plate 135mm (for Radleys & IKA) | Radleys | RR95010 | Part of soxhlet extractor | |
| Monoblock for 5 x 250ml Flasks | Radleys | RR95130 | Part of soxhlet extractor | |
| Telescopic 5-way Clamp with Velcro | Radleys | RR95400 | Part of soxhlet extractor | |
| Telescopic 5-way Clamp with Silicone Strap and Long Handle | Radleys | RR95410 | Part of soxhlet extractor | |
| Water Manifold with connectors | Radleys | RR95500 | Part of soxhlet extractor | |
| 650mm Rod | Radleys | RR95665 | Part of soxhlet extractor | |
| Quick Release Male, R/A Barbed 6.4mm + Shut-off (3.2mm ID) | Radleys | RR95520 | Part of soxhlet extractor | |
| Coil condensers with standard ground joints 29/32 NS | Lenz | 5.2503.04 | Part of soxhlet extractor | |
| Extractor Soxhlet 40mL borosilicate glass 29/32 socket 24/29 cone | Quickfit | EX5/43 | Part of soxhlet extractor | |
| Stirrer/hot plate | Radleys | RR98072 | Part of soxhlet extractor | |
| Temperature controller | Radleys | RR98073 | Part of soxhlet extractor | |
| Recirculator | Grant | LTC1 | Part of soxhlet extractor | |
| Cellulose extraction thimble | Whatman | 2280-228 | ||
| Tweezers | Excelta | 20A-S-SE | ||
| Vacuum drying oven: | ||||
| Vacuum drying oven | Binder | VD 23 | Part of vacuum oven | |
| Dewar vessel 2L 100x290mm with handle | KGW-Isotherm | 10613 | Part of vacuum oven | |
| Vacuum Trap | GPE | CG-4532-01 | Part of vacuum oven | |
| Other equipment: | ||||
| Analytical balance | A&D | GH-252 | accuracy to ± 0.1 mg | |
| Volumetric Karl Fischer titrator | Mettler Toledo | V20 | ||
| 10 mL disposable pipette | Corning Inc | Costar 4101 10 mL Stripette | ||
| Eppendorf Research plus pipette, variable volume, volume 100-1000 μL | Eppendorf | 3120000062 | ||
| Desiccator | Jencons | JENC250-028BOM | ||
| Ace pressure tube bushing type, Front seal, volume 15 mL | Ace Glass | 8648-04 | ||
| Ace O-rings, silicone, 2.6 mm, I.D. 9.2 mm | Ace Glass | 7855216 | O-ring for pressure tube | |
| Vortex shaker | VWR International | 444-1378 (UK) | ||
| Fan-assisted convection oven | ThermoScientific | HeraTherm OMH60 | ||
| Oven glove (Crusader Flex) | Ansel Edmont | 42-325 | ||
| 250 mL Round bottom flask single neck ground joint 24/29 (Pyrex) | Quickfit | FR250/3S | ||
| Rotaflo stopcock adapter with cone 24/29 | Rotaflo England | MF11/2/SC | ||
| 50 mL Falcon tube | Heraeus/Kendro | HERA 76002844 | ||
| Centrifuge (Mega Star 3.0) | VWR | 521-1751 | ||
| Reagents: | ||||
| Ethanol absolute | VWR | 20820.464 | ||
| Triethylamine | Sigma-Aldrich | T0886 | ||
| Sulfuric acid 5 mol/l (10N) AVS TITRINORM volumetric solution Safe-break bottle 2,5L | VWR | 191665V | ||
| Purified water (15 MΩ ressitance) | Elga | CENTRA R200 | ||
| Lignocellulosic biomass: | ||||
| Miscanthus X gigantheus | ||||
| Pinus sylvestris |
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