Zhao Qiyuan, Savoie Brett M
Davidson School of Chemical Engineering, Purdue University, West Lafayette, IN 47906.
Proc Natl Acad Sci U S A. 2023 Aug 22;120(34):e2305884120. doi: 10.1073/pnas.2305884120. Epub 2023 Aug 14.
Resolving the reaction networks associated with biomass pyrolysis is central to understanding product selectivity and aiding catalyst design to produce more valuable products. However, even the pyrolysis network of relatively simple [Formula: see text]-D-glucose remains unresolved due to its significant complexity in terms of the depth of the network and the number of major products. Here, a transition-state-guided reaction exploration has been performed that provides complete pathways to most significant experimental pyrolysis products of [Formula: see text]-D-glucose. The resulting reaction network involves over 31,000 reactions and transition states computed at the semiempirical quantum chemistry level and approximately 7,000 kinetically relevant reactions and transition states characterized with density function theory, comprising the largest reaction network reported for biomass pyrolysis. The exploration was conducted using graph-based rules to explore the reactivities of intermediates and an adaption of the Dijkstra algorithm to identify kinetically relevant intermediates. This simple exploration policy surprisingly (re)identified pathways to most major experimental pyrolysis products, many intermediates proposed by previous computational studies, and also identified new low-barrier reaction mechanisms that resolve outstanding discrepancies between reaction pathways and yields in isotope labeling experiments. This network also provides explanatory pathways for the high yield of hydroxymethylfurfural and the reaction pathway that contributes most to the formation of hydroxyacetaldehyde during glucose pyrolysis. Due to the limited domain knowledge required to generate this network, this approach should also be transferable to other complex reaction network prediction problems in biomass pyrolysis.
解析与生物质热解相关的反应网络对于理解产物选择性以及辅助催化剂设计以生产更有价值的产物至关重要。然而，即使是相对简单的β-D-葡萄糖的热解网络，由于其在网络深度和主要产物数量方面的显著复杂性，仍然没有得到解决。在此，进行了一种过渡态引导的反应探索，该探索为β-D-葡萄糖的最重要实验热解产物提供了完整的途径。由此产生的反应网络涉及在半经验量子化学水平计算的超过31000个反应和过渡态，以及用密度泛函理论表征的大约7000个动力学相关反应和过渡态，构成了报道的最大的生物质热解反应网络。该探索使用基于图的规则来探索中间体的反应性，并采用Dijkstra算法的一种变体来识别动力学相关的中间体。这种简单的探索策略出人意料地（重新）确定了通往大多数主要实验热解产物的途径、许多先前计算研究提出的中间体，还确定了新的低势垒反应机制，解决了同位素标记实验中反应途径和产率之间的突出差异。该网络还为羟甲基糠醛的高产率以及葡萄糖热解过程中对羟基乙醛形成贡献最大的反应途径提供了解释性途径。由于生成此网络所需的领域知识有限，这种方法也应该能够转移到生物质热解中其他复杂的反应网络预测问题上。
