Unraveling the role of Zn species in catalyst deactivation and coke formation over Zn/ HZSM ‐5 during LDPE pyrolysis

IF 4.4 3区工程技术 Q2 ENGINEERING, CHEMICAL

AIChE Journal Pub Date : 2026-09-25 DOI:10.1002/aic.70667

Hao Liu, Xuanshen Shen, Yixian Zhao, Yu Wang, Ruibin Yuan, Ning Deng, Jian Wang, Liangyuan Jia

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引用次数: 0

Abstract

Zn/HZSM‐5 enables selective LDPE pyrolysis to monocyclic aromatics with minimal light olefins, yet suffers from rapid coke‐induced deactivation. This study clarifies the dynamic evolution of Zn species governing this process. Isolated Zn sites drive deep dehydrogenation, generating acetylene and diene intermediates that accelerate polycyclic aromatic hydrocarbons (PAHs, coke precursors) formation. Crucially, oxygenated additives in LDPE degrade over acid sites to form intermediates that lower the energy barrier for PAH condensation, further exacerbating coking. Coke distribution is spatially heterogeneous: external surfaces accumulate long‐chain alkenes and oxygenates, while micropores foster condensed aromatics via sequential HACA and MAC mechanisms. Progressive coking encapsulates and sinters active [ZnOH] + into inert ZnO, triggering a switch from Zn‐driven aromatization to Brønsted acid‐dominated cracking. These findings reveal an intrinsic trade‐off where sites enabling high selectivity simultaneously dictate rapid deactivation, guiding the design of robust catalysts for plastic upcycling.

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揭示Zn在LDPE热解过程中Zn/ HZSM - 5催化剂失活和焦炭生成中的作用

Zn/HZSM‐5可以选择性地将LDPE热解为单环芳烃，并含有最少的轻烯烃，但会受到焦炭引起的快速失活的影响。本研究阐明了控制这一过程的Zn物种的动态演化。孤立的Zn位点驱动深度脱氢，生成乙炔和二烯中间体，加速多环芳烃（PAHs，焦炭前体）的形成。至关重要的是，LDPE中的含氧添加剂在酸位点上降解，形成中间体，降低多环芳烃缩聚的能垒，进一步加剧焦化。焦炭的分布在空间上是不均匀的：外表面积聚长链烯烃和氧化物，而微孔通过连续的HACA和MAC机制促进凝聚芳烃。渐进式焦化将活性[ZnOH] +包封并烧结成惰性ZnO，触发从Zn驱动的芳构化到Brønsted酸主导的裂化的转换。这些发现揭示了一种内在的权衡，即能够实现高选择性的位点同时决定了快速失活，从而指导了塑料升级回收的强大催化剂的设计。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

AIChE Journal 工程技术-工程：化工

CiteScore

7.10

自引率

10.80%

发文量

411

审稿时长

3.6 months

期刊介绍： The AIChE Journal is the premier research monthly in chemical engineering and related fields. This peer-reviewed and broad-based journal reports on the most important and latest technological advances in core areas of chemical engineering as well as in other relevant engineering disciplines. To keep abreast with the progressive outlook of the profession, the Journal has been expanding the scope of its editorial contents to include such fast developing areas as biotechnology, electrochemical engineering, and environmental engineering. The AIChE Journal is indeed the global communications vehicle for the world-renowned researchers to exchange top-notch research findings with one another. Subscribing to the AIChE Journal is like having immediate access to nine topical journals in the field. Articles are categorized according to the following topical areas: Biomolecular Engineering, Bioengineering, Biochemicals, Biofuels, and Food Inorganic Materials: Synthesis and Processing Particle Technology and Fluidization Process Systems Engineering Reaction Engineering, Kinetics and Catalysis Separations: Materials, Devices and Processes Soft Materials: Synthesis, Processing and Products Thermodynamics and Molecular-Scale Phenomena Transport Phenomena and Fluid Mechanics.