Liu B, Slocombe D R, Wang J, Aldawsari A, Gonzalez-Cortes S, Arden J, Kuznetsov V L, AlMegren H, AlKinany M, Xiao T, Edwards P P
KACST - Oxford Petrochemical Research Centre (KOPRC), Inorganic Chemistry Laboratory, Department of Chemistry, University of Oxford, Oxford, OX1 3QR, UK.
School of Engineering, Cardiff University, Queen's Buildings, The Parade, Cardiff, CF24 3AA, UK.
Nat Commun. 2017 Sep 11;8(1):514. doi: 10.1038/s41467-017-00602-8.
Coking leads to the deactivation of solid acid catalyst. This phenomenon is a ubiquitous problem in the modern petrochemical and energy transformation industries. Here, we show a method based on microwave cavity perturbation analysis for an effective examination of both the amount and the chemical composition of cokes formed over acid zeolite catalysts. The employed microwave cavity can rapidly and non-intrusively measure the catalytically coked zeolites with sample full body penetration. The overall coke amount is reflected by the obtained dielectric loss (ε″) value, where different coke compositions lead to dramatically different absorption efficiencies (ε″/cokes' wt%). The deeper-dehydrogenated coke compounds (e.g., polyaromatics) lead to an apparently higher ε″/wt% value thus can be effectively separated from lightly coked compounds. The measurement is based on the nature of coke formation during catalytic reactions, from saturated status (e.g., aliphatic) to graphitized status (e.g., polyaromatics), with more delocalized electrons obtained for enhanced Maxwell-Wagner polarization.Catalyst deactivation by coke deposition is a major drawback in industrial processes. Here, the authors show a non-intrusive microwave cavity perturbation technique as a powerful tool to determine the nature and extent of coke accumulation in industrially-relevant zeolite catalysts.
结焦会导致固体酸催化剂失活。这种现象在现代石化和能源转化行业中是一个普遍存在的问题。在此，我们展示了一种基于微波腔扰动分析的方法，用于有效检测在酸性沸石催化剂上形成的焦炭的数量和化学成分。所采用的微波腔可以快速且非侵入性地对催化结焦的沸石进行全身穿透测量。总的焦炭量由获得的介电损耗（ε″）值反映，其中不同的焦炭成分导致显著不同的吸收效率（ε″/焦炭重量%）。深度脱氢的焦炭化合物（如多环芳烃）导致明显更高的ε″/重量%值，因此可以有效地与轻度结焦的化合物分离。该测量基于催化反应过程中焦炭形成的性质，从饱和状态（如脂肪族）到石墨化状态（如多环芳烃），随着获得更多离域电子以增强麦克斯韦 - 瓦格纳极化。焦炭沉积导致的催化剂失活是工业过程中的一个主要缺点。在此，作者展示了一种非侵入性的微波腔扰动技术，作为确定工业相关沸石催化剂中焦炭积累的性质和程度的有力工具。
