EAGER: Determining pyrolysis kinetics through time-resolved measurements of condensed phase reactions

该项目探索了生物质在缺氧条件下快速加热分解的化学过程，这一过程被称为快速热解，产生气体、液体和固体。生物质快速热解产生的液体有望生产先进的生物燃料和生物基化学品，类似于从石油中生产的传统汽油和柴油燃料。了解快速热解过程中发生的化学反应并测量其速率对于设计未来将生物质转化为燃料和化学品的生物精炼厂非常重要。该项目将探索新的实验技术，用于探测固体生物质在几秒钟内迅速加热到高温后发生的反应。通过跟踪各种分解产物的浓度随时间的变化，可以确定重要热解反应的速率。本研究的目的是通过凝聚相反应的时间分辨测量来测量生物质快速热解的化学动力学。热解是大多数热化学过程的基础，包括燃烧、气化、快速热解甚至溶剂液化。在这些技术中，快速热解在过去几年中因其从木质纤维素生物质中生产先进生物燃料和生物基化学品的前景而受到相当大的关注。热解的反应机理自20世纪50年代以来一直在研究，但在确定与组成木质纤维素生物质的生物聚合物解聚相关的基本反应速率方面只取得了有限的进展。没有这些反应的速率系数和活化能，很难从第一性原理准确地建模和设计热解反应器。以前的大多数热解动力学研究都测量了经过相对缓慢加热的样品的重量损失，这对固体生物质中发生的基本反应的信息很少。本研究将展示两种由爱荷华州立大学开发的用于研究凝聚相基本化学反应的可控热解持续时间(CPD) -猝灭反应器的实用性。第一个，能够研究在几秒钟内发生的反应，将用于研究小寡糖的解压缩，形成无水单糖左旋葡聚糖。第二个，能够研究更快的反应，将用于研究纤维素裂解成低聚糖的早期解聚过程。这些装置也将用于研究半纤维素和木质素的解聚。

1630404-BrownThis project explores the chemical processes responsible for the decomposition of biomass when it is rapidly heated in the absence of oxygen, a process known as fast pyrolysis, to produce gases, liquids, and solids. The liquids from fast pyrolysis from biomass show promise for the production of advanced biofuels and biobased chemicals that resemble conventional gasoline and diesel fuels produced from petroleum. Understanding the chemical reactions that occur during fast pyrolysis and measuring their rates are important for designing future biorefineries that would convert biomass into fuels and chemicals. This project will explore new experimental techniques for probing reactions that occur in solid biomass after it has been rapidly heated to high temperatures in a matter of seconds. By tracking the change in concentration of various decomposition products with time, rates of important pyrolysis reactions can be determined. The goal of this research is to measure the chemical kinetics of biomass fast pyrolysis through time-resolved measurements of condensed phase reactions. Pyrolysis is the basis for most thermochemical processes including combustion, gasification, fast pyrolysis, and even solvent liquefaction. Among these technologies, fast pyrolysis has gained considerable attention in the last few years for its prospects to produce advanced biofuels and biobased chemicals from lignocellulosic biomass. The reaction mechanisms of pyrolysis have been studied since the 1950s, but only modest progress has been made in determining elementary reaction rates associated with the depolymerization of the biopolymers that make up lignocellulosic biomass. Without rate coefficients and activation energies for these reactions, it is difficult to accurately model and design pyrolysis reactors from first principles. Most previous studies of pyrolysis kinetics have measured weight loss of samples undergoing relatively slow heating, which yields little information about elementary reactions occurring in solid biomass. This research will demonstrate the utility of two versions of Controlled Pyrolysis Duration (CPD) - Quench reactors developed at Iowa State University for studying condensed phase elementary chemical reactions. The first, capable of investigating reactions that occur on the order of a few seconds, will be used to study unzipping of small oligosaccharides to form the anhydro-monosaccharide levoglucosan. The second, capable of investigating much faster reactions, will be used to study cracking of cellulose to oligosaccharides early in the depolymerization process. These apparatus will also be employed to study depolymerization of hemicellulose and lignin.