ZSM-5颗粒间烃类的接力和反馈转化对甲醇芳构化过程中产物选择性和结焦的影响,ACS Catalysis

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ZSM-5颗粒间烃类的接力和反馈转化对甲醇芳构化过程中产物选择性和结焦的影响
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-07-05 , DOI: 10.1021/acscatal.3c01332
Liangliang Zhang ₁ , Tingjun Fu ₁ , Yating Han ₁ , Ran Wang ₁ , Zhong Li ₁

Affiliation

烃类分子在酸性硅铝分子筛上的催化转化是石油化工和煤化工工业的核心。通过配置具有不同酸性质的沸石，可以精细控制催化剂颗粒之间的反应过程，以实现催化稳定性和产物选择性，但具体细节仍然无法确定。本文以不同酸构型的混合ZSM-5为催化平台，以甲醇制芳烃为模型反应，研究颗粒间的相互催化行为。发现ZSM-5颗粒之间发生了明显的烃中间体多重反应。_{由具有低 SiO 2} /Al的无锌 ZSM-5 生产的典型 C ₃ –C _5烃₂ O ₃比例可以在相邻的Zn60颗粒上芳构化。虽然由于返回芳烃的二次转化促进了无锌ZSM-5颗粒的外部积炭，但在外部强酸位点上增强了脱烷基反应，从而显着提高了轻芳烃选择性。降低SiO ₂ /Al ₂ O ₃无Zn ZSM-5与120的比例可以显着促进重芳烃脱烷基化，并由于足够的外部强酸位点而抑制外部焦炭沉积。这种混合催化剂的寿命比之前报道的烯烃-芳烃双催化体系延长了近3倍，重芳烃选择性降低了30%。该工作有助于阐明酸性分子筛催化剂在烃类转化反应中的催化行为，并为通过配置不同分子筛催化剂来提高催化性能提供有效途径。

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Relay and Feedback Conversion Effect of Hydrocarbons between ZSM-5 Grains on Product Selectivity and Coke Formation during Methanol Aromatization

The catalytic conversion of hydrocarbon molecules over an acidic silica-aluminum molecular sieve is the core of the petrochemical and coal chemical industry. Finely controlling the reaction process between catalyst grains for catalytic stability and product selectivity can be achieved by configuring zeolites with different acid properties, but the details continue to be indefinable. Herein, mixed ZSM-5 with different acid configurations was used as the catalytic platform to study the inter-catalytic behavior of the grains using methanol to aromatics as the model reaction. It was found that the obvious multiple reactions of hydrocarbon intermediates occurred between ZSM-5 grains. The typical C₃–C₅ hydrocarbons produced from Zn-free ZSM-5 with a low SiO₂/Al₂O₃ ratio could be aromatized on adjacent Zn60 grains. Although the external coke deposition of Zn-free ZSM-5 grains was promoted due to the secondary conversion of returned aromatics, the dealkylation reaction was enhanced on external strong acid sites, which significantly increased the light aromatic selectivity. Decreasing the SiO₂/Al₂O₃ ratio of Zn-free ZSM-5 to 120 could significantly promote the heavy aromatic de-alkylation and inhibited external coke deposition due to the sufficient external strong acid sites. The lifetime of such a mixed catalyst was prolonged nearly 3 times than that of the previously reported olefin-aromatic doubled catalytic system, and the heavy aromatic selectivity was reduced by 30%. This work helps to clarify the catalytic behavior of acidic molecular sieve catalysts in the hydrocarbon conversion reaction and provides an effective path to improve the catalytic performance by configurating different molecular sieve catalysts.

更新日期：2023-07-05

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