Base-acid tandem catalytic upgrading of coal pyrolysis volatiles: The effects of alkaline earth oxides and modified HZSM-5 zeolites

IF 5.8 2区化学 Q1 CHEMISTRY, ANALYTICAL

Journal of Analytical and Applied Pyrolysis Pub Date : 2024-10-01 DOI:10.1016/j.jaap.2024.106804

Li Zhang , Hang Yang , Qinglong Tan , Jiehan Zhang , Jinze Dai , Zhaohui Chen

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Abstract

Catalytic upgrading of coal pyrolysis volatiles is a promising technology to bolster the production of value-added chemicals from coal. To optimize product distribution and mitigate catalyst deactivation, this work investigated tandem catalysts combining the upper alkaline earth oxides (CaO or MgO) with the lower modified HZSM-5 (mesopore creation and Ga loading). The pre-cracking of volatiles over CaO or MgO lowered the average molecule size of tar components. The diffusion properties and aromatization of these pre-cracking-derived intermediates were improved, facilitating the secondary upgrading over HZSM-5-based catalysts, promoting the formation of aromatics. The experimental results showed that tandem CaO-HZSM-5 catalysts presented better synergy to improve the tar components as compared to MgO-HZSM-5, considering the formation of aromatics in tar. In this context, the mesopore and metal Ga were introduced into HZSM-5 to further upgrade the tar quality. The mesoporous structure for HZSM-5-meso and Ga/HZSM-5-meso promoted the conversion of aliphatic hydrocarbons into aromatics. Simultaneous introduction of mesopores and Ga synergistically increased the aromatic content in tar to 41.6 % and reduced the carbon deposition to 0.88 wt%. In summary, this work elucidated the mechanism of tandem CaO-modified HZSM-5 catalysis for the upgrading of volatiles from coal pyrolysis.

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煤热解挥发物的碱-酸串联催化升级：碱土氧化物和改性 HZSM-5 沸石的影响

煤热解挥发物的催化升级是一项前景广阔的技术，可促进煤炭增值化学品的生产。为了优化产品分布并减轻催化剂失活，本研究对上层碱土氧化物（CaO 或 MgO）与下层改性 HZSM-5 （中孔创建和镓负载）相结合的串联催化剂进行了研究。挥发物在 CaO 或 MgO 上的预裂解降低了焦油成分的平均分子尺寸。这些预裂解衍生的中间产物的扩散特性和芳香化得到了改善，从而促进了基于 HZSM-5 催化剂的二次升级，促进了芳烃的形成。实验结果表明，考虑到焦油中芳烃的形成，与 MgO-HZSM-5 相比，串联 CaO-HZSM-5 催化剂在改善焦油组分方面具有更好的协同作用。在此背景下，HZSM-5 中引入了介孔和金属镓，以进一步提高焦油质量。HZSM-5-meso 和 Ga/HZSM-5-meso 的介孔结构促进了脂肪烃向芳烃的转化。同时引入介孔和 Ga 能协同将焦油中的芳烃含量提高到 41.6%，并将碳沉积降低到 0.88 wt%。总之，这项工作阐明了串联 CaO 改性 HZSM-5 催化煤热解挥发物升级的机理。

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来源期刊

Journal of Analytical and Applied Pyrolysis 化学-分析化学

CiteScore

9.10

自引率

11.70%

发文量

340

审稿时长

44 days

期刊介绍： The Journal of Analytical and Applied Pyrolysis (JAAP) is devoted to the publication of papers dealing with innovative applications of pyrolysis processes, the characterization of products related to pyrolysis reactions, and investigations of reaction mechanism. To be considered by JAAP, a manuscript should present significant progress in these topics. The novelty must be satisfactorily argued in the cover letter. A manuscript with a cover letter to the editor not addressing the novelty is likely to be rejected without review.