CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science & Technology of China , Hefei, 230026, China.
Chem Rev. 2017 May 10;117(9):6367-6398. doi: 10.1021/acs.chemrev.6b00647. Epub 2017 Mar 24.
Biomass is increasingly perceived as a renewable resource rather than as an organic solid waste today, as it can be converted to various chemicals, biofuels, and solid biochar using modern processes. In the past few years, pyrolysis has attracted growing interest as a promising versatile platform to convert biomass into valuable resources. However, an efficient and selective conversion process is still difficult to be realized due to the complex nature of biomass, which usually makes the products complicated. Furthermore, various contaminants and inorganic elements (e.g., heavy metals, nitrogen, phosphorus, sulfur, and chlorine) embodied in biomass may be transferred into pyrolysis products or released into the environment, arousing environmental pollution concerns. Understanding their behaviors in biomass pyrolysis is essential to optimizing the pyrolysis process for efficient resource recovery and less environmental pollution. However, there is no comprehensive review so far about the fates of chemical elements in biomass during its pyrolysis. Here, we provide a critical review about the fates of main chemical elements (C, H, O, N, P, Cl, S, and metals) in biomass during its pyrolysis. We overview the research advances about the emission, transformation, and distribution of elements in biomass pyrolysis, discuss the present challenges for resource-oriented conversion and pollution abatement, highlight the importance and significance of understanding the fate of elements during pyrolysis, and outlook the future development directions for process control. The review provides useful information for developing sustainable biomass pyrolysis processes with an improved efficiency and selectivity as well as minimized environmental impacts, and encourages more research efforts from the scientific communities of chemistry, the environment, and energy.
如今，生物质被越来越多地视为可再生资源，而不是有机固体废物，因为它可以通过现代工艺转化为各种化学品、生物燃料和固体生物炭。在过去的几年中，热解作为一种有前途的多功能平台，将生物质转化为有价值的资源，引起了越来越多的关注。然而，由于生物质的复杂性，通常会使产物变得复杂，因此仍然难以实现高效和选择性的转化过程。此外，生物质中固有的各种污染物和无机元素（例如重金属、氮、磷、硫和氯）可能会转移到热解产物中或释放到环境中，引起环境污染问题。了解它们在生物质热解中的行为对于优化热解过程以实现高效资源回收和减少环境污染至关重要。然而，目前还没有关于生物质热解过程中化学元素命运的全面综述。在这里，我们对生物质热解过程中主要化学元素（C、H、O、N、P、Cl、S 和金属）的命运进行了批判性的回顾。我们综述了元素在生物质热解中排放、转化和分布的研究进展，讨论了资源转化和减排的当前挑战，强调了理解热解过程中元素命运的重要性和意义，并展望了未来的发展方向，以实现过程控制。该综述为开发具有提高效率和选择性以及最小化环境影响的可持续生物质热解工艺提供了有用的信息，并鼓励化学、环境和能源领域的科学界做出更多的研究努力。
