Production of Biocrude from Biomass using Supercritical Water

CBET-0828269R。GuptaBiomass是全球第四大能源，可以填补石油枯竭造成的燃料供应缺口。生物质的液化是生物质资源化利用的关键步骤。一旦形成液体，生物原油就可以利用石化行业已经完善/优化的成熟的管道运输、精炼和化学工艺。例如，生物原油可以加氢生产汽油，也可以重整生产氢气。使用亚临界和超临界水(高于374PoPC和220巴)进行液化是有利的，因为它可以在不干燥的情况下利用生物质。超临界水由于其特殊的性质(如非极性、高扩散性和低粘度)，可以溶解包括生物质在内的有机物。高反应速率允许设计紧凑型反应器，需要的典型反应时间不到一分钟。纤维素、木质素和半纤维素的快速解聚导致各自单体和低聚物的形成。这个过程，也被称为热液液化，是这个项目的主题。在此过程中，有机材料的氧含量从40wt%降至10-15wt%之间，氧以CoB2B和HB2BO的形式离开。半纤维素和纤维素生成的环状分子(例如葡萄糖、呋喃和低聚糖)以及木质素生成的芳香族环状分子(例如苯酚)可被加氢以产生类似于汽油的燃料，汽油近似为环己烷、甲苯和异辛烷的混合物。此外，生物粗品也可以在超临界水中进行重整，以产生高压HB2B和高压COB2B(准备进行封存)。该项目的智力优势在于对所涉及的各个步骤进行了基础性研究，包括解聚、水解、氧化、脱水和脱羧基，从而可以进行合理的反应器/工艺设计。将使用一种新的反应器结构，该结构利用生物质中半纤维素、纤维素和木质素组分的解聚动力学的差异。使用廉价的碱催化剂(如KB2BCOB3B、NaB2BCOB3B、KOH)可以降低反应温度和缩短反应时间。该项目将利用超临界抗溶剂的概念(注：碱性盐由于低介电性而不溶于超临界水)来原位生产催化剂纳米颗粒，其新生成的高表面有望具有高度催化作用。对本研究感兴趣的生物质包括半纤维素、纤维素、木质素、秋刀草、玉米秸秆和南方松树。研究各种工艺参数对整体能效的影响。该项目的更广泛影响是利用生物质来满足关键的燃料供应需求。在这个项目中，生物原油将被加氢生产汽油，并进行重整以生产氢气。如果成功，该结果将为传统运输使用的液体燃料和未来燃料电池汽车的氢气开辟一种新的解决方案。生物质衍生的液体或气态燃料有潜力提供具有成本效益和可持续的能源供应，同时实现温室气体减排目标。对研究生和本科生(包括少数族裔学生)的培训将有助于将技术转移到美国行业，增强其竞争力。此外，与K-12教师的互动将有助于将可持续燃料的概念带入他们的课堂。该项目的成功完成可能会对美国农业、林产品和纸浆行业的盈利能力产生影响。

CBET-0828269R. GuptaBiomass, the fourth largest energy source worldwide, can fill in gaps in fuel supply created by the depletion of petroleum. A key step in the utilization of biomass is its liquefaction to biocrude. Once in liquid form, biocrude can utilize well established pipeline transportation, refining and chemical processes that have been perfected/optimized by the petrochemical industry. For example, biocrude can be hydrogenated to produce gasoline or reformed to produce hydrogen. The use of sub- and supercritical water (above 374 PoPC and 220 bar) for liquefaction is advantageous as it can utilize biomass without drying. Due to its special characteristics (e.g., non-polar nature, high diffusivity, and low viscosity), supercritical water can solubilize organic compounds including biomass. The high reaction rates allow for the design of a compact reactor, needing typical reaction times of less than a minute. Rapid depolymerization of cellulose, lignin, and hemicelluloses results in the formation of the respective monomers and oligomers. This process, also termed as hydrothermal liquefaction, is the subject of this project. During this process, the oxygen content of the organic material is reduced from 40 wt% to between 10-15 wt%, with oxygen leaving as COB2B and HB2BO. The resulting cyclic molecules (e.g., glucose, furans, and oligosaccharides) from hemicelluloses and cellulose, and aromatic cyclic molecules (e.g, phenols) from lignin can be hydrogenated to produce fuel similar to gasoline which is an approximate mixture of cyclohexane, toluene, and iso-octane. Also the biocrude can be reformed in supercritical water itself to produce high pressure HB2B and high pressure COB2B (ready for sequestration). Intellectual merit of the project is in the fundamental study of the various steps involved including depolymerization, hydrolysis, oxidation, dehydration, and decarboxylation so that rational reactor/process design can be done. A novel reactor configuration is to be used that makes use of the differences in the de-polymerization kinetics of hemicelluloses, cellulose, and lignin components of the biomass. The reaction temperature and time can be reduced by the use of inexpensive alkali catalysts (e.g., KB2BCOB3B, NaB2BCOB3B, KOH). This project will utilize the concept of supercritical antisolvent (note: alkali salts are insoluble in supercritical water due to low dielectric) to in-situ produce catalyst nanoparticles whose newly generated high surface is expected to be highly catalytic. Biomass of interest for this study includes hemicelluloses, cellulose, lignin, switch grass, corn stover, and southern pine. Impact of various process parameters on the overall energy efficiency will be studied. Broader impact of the project is in the utilization of biomass to address critical fuel supply needs. In this project itself, the biocrude will be hydrogenated to produce gasoline, and reformed to produce hydrogen. If successful, the results can open up a novel solution to the liquid fuels for conventional transportation use and hydrogen for future fuel cell cars. Biomass derived liquid or gaseous fuels have potential to provide a cost-effective and sustainable supply of energy, while meeting the greenhouse gas reduction targets. The training of the graduate and undergraduate students (including minority students) will help transfer technology to the US industry enhancing its competitiveness. In addition, interaction with K-12 teachers will help bring the concepts of sustainable fuel to their classrooms. The successful completion of this project could have an impact on the profitability of farming, forest product, and pulp industries in the United States.