Pyrolysis of Lignin for Bio-oil under CO2 Laser Irradiation in the "Wall-Less" reactor

生物质代表木质素的能源生产是一个有吸引力的选择，因为它提供了更高的生物油产量和减少炭的形成。在本提案中，将开发一种新的工艺，将木质素转化为更高质量的生物油和化学品，几乎没有二次焦效应，基于一种被称为红外激光驱动的均匀热解或IR-LPHP的方法。PI是该方法多样化的专家，该方法允许在红外CO2激光照射下在均匀的“无壁”条件下进行热解实验。这种方法的主要优点是，所有的化学过程只发生在一个小的“热区”，实际上在反应堆壁的冷条件下。CO2激光在气相中对喷雾技术产生的木质素分散颗粒进行快速热解，随后对许多产品进行快速淬火，这些产品将扩散出“热区”，避免进一步的二次过程（降解，裂解或与其他分子的缩合）。这种方法被认为可以提高液体产品（生物油）的产量。在相同的激光照射功率下，在特定的“无壁”条件下，由于加热速率、温度和停留时间的不同，在木质素的IR-LPHP下预计会产生明显不同的产品。在获得高产量生物油和减少炭形成的途径上，炭和反应器壁对整个过程的有害非均相影响从未被阐明。本课题的新颖之处在于利用闪蒸红外LPHP技术在最小炭气相相互作用下，在“无壁”反应器中获得更高质量的生物油。这种特殊的反应器设计允许采用前瞻性的探索性研究，期望分解木质素？S大分子结构，但保持了芳香族的基本分子性质。本文首次利用低温基质分离（LTMI）电子顺磁共振（EPR）技术对木质素在无壁反应器条件下气相热解过程中形成的中间自由基进行了直接鉴定。与布法罗大学团队合作，评估关键气相反应的动力学参数，将基于CHEMKIN - 4 Pro燃烧动力学包建立木质素热解的全局伪一级集总动力学模型，以预测芳香族所需化合物形成的最佳途径。因此，该项目代表了潜在的变革性研究，因为它将提供一种独特的、非标准的方法，以高产量生产更多高质量（升级）的生物油，并将生物油转化为替代运输燃料和重要化学品。PI提出的假设是基于利用激光热解在“无壁”反应器中的优势，在各种生物质热解工艺中具有很大的应用潜力。从像木质素这样结构复杂多样的材料中高效地提取大量芳烃是一项具有挑战性的工作，但由于生物油的几种环境优势（请注意，生物油可以通过多种方式——物理、化学和催化——升级为生物燃料），作为一种清洁燃料，与化石燃料相比，它对社会有益。CO2/GHG（温室气体）中性，无硫氧化物排放（因为植物生物质中含有少量的硫），与燃气轮机中的柴油相比，NOx排放量降低50%以上。该项目将促进对在“无壁”反应器条件下形成生物油的新途径的理解；因此，在生物质转化、生物燃料和生物能源等领域将有广泛的应用。开发的反应动力学全局模型将有助于了解木质素热转化为高质量生物油产品的效率，既可以作为能源又可以作为化工生产的原料，并且可以包括在纤维素、半纤维素热解以及煤炭工业的类似模型中。实际上，任何形式的生物质都可以考虑用于IR-LPHP应用。因此，满足生产高质量生物油要求的新方法可能在经济上具有竞争力，可以在许多应用中使用生物油代替燃料油、柴油，包括锅炉、炉子、发动机和发电涡轮机。

The energy production from a biomass representative lignin is an attractive option given that the higher bio-oil yields and decreased char formation are provided. In this proposal a novel process will be developed to convert lignin into the more high-quality bio-oil and chemicals with virtually no secondary char effect based on a method known as Infrared Laser Powered Homogeneous Pyrolysis or IR-LPHP. The PI is an expert in diversification of this method, which allows performing the pyrolysis experiments strongly in homogeneous, "wall-less" conditions under irradiation of IR CO2 laser. The principal advantage of this method is that all chemical processes occur only in a small "hot zone" practically at cold conditions of the reactor walls.The CO2 laser flash pyrolyses the lignin dispersed particles generated by a spray technique in gas phase, followed by a rapid quenching of many products which will diffuse out of the "hot zone" avoiding further secondary processes (degradation, cleavage, or condensation with other molecules). Such an approach is strongly believed to upgrade the liquid product (bio-oil) yields. Markedly different products are expected to be produced under the IR-LPHP of lignin due to the diverse heating rates, temperature, and residence times in the specific "wall-less" condition at the same power of laser irradiation.On the way to obtain higher yields bio-oil and decrease the char formation, the detrimental heterogeneous influence of the char and reactor walls on the total process has never been elucidated. The novelty of this project is to obtain more high-quality bio-oil in a "wall-less" reactor using the advantages of the flash IR LPHP technique at minimized char - gas phase interaction. This special reactor design allows employing a perspective exploratory research expecting break up lignin?s macromolecular structure, but maintaining the aromatic nature of the building block molecules. For the first time the intermediate radicals formed in the gas-phase lignin pyrolysis in the "wall-less" reactor conditions, will be identified directly using Low Temperature Matrix Isolation (LTMI) Electron Paramagnetic Resonance (EPR) technique. Collaboration with the University at Buffalo team to evaluate kinetic parameters of the key gas-phase reactions will lead to a global, pseudo-first order lumped kinetic model for lignin pyrolysis based on the CHEMKIN - 4 Pro Combustion kinetic package to predict the optimal pathways for formation of aromatic desired compounds. Therefore, this project represents potentially transformative research because it will offer a unique, non-standard approach for producing more high-quality (upgraded) bio-oil at its high yield with the perspective of transformation of bio-oil into alternative transportation fuel and the important chemicals.The hypothesis put forward by the PI lies on the idea that utilizing the advantages of laser pyrolysis in "wall-less" reactor would have a great potential for application to various biomass pyrolysis processes. Bringing high-volume aromatics efficiently from a material as structurally complex and diverse as lignin becomes a challenging but beneficial for society due to the several environmental advantages of the bio-oil (note that the bio-oil can be upgraded to the bio-fuel in a number of ways - physically, chemically and catalytically) over fossil fuels as a clean fuel as well: CO2/GHG (greenhouse gas) neutral, no SOx emissions (because the plant biomass contains insignificant amounts of sulfur), more than 50% lower NOx emissions than diesel oil in a gas turbine. This project will advance understanding of the new pathways for formation of bio-oil in "wall-less" reactor conditions; therefore, will have broad applications across biomass conversion, biofuels and bioenergy. Developed reaction-kinetic global model will help to understand the efficiency of thermal conversion of lignin into high-quality bio-oil product used both as an energy source and a feedstock for chemical production and can be included in similar models for cellulose, hemicellulose pyrolysis as well in coal industry. Virtually any form of the biomass can be considered for IR-LPHP application. Therefore, the new methodologies satisfying requirements for producing high-quality bio-oils may be economically competitive in using bio-oils as substitute for fuel oil, diesel in many applications, including boilers, furnaces, engines, and turbines for electricity generation.