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Boosting Benzene Alkylation Conversion with CO2/H2 via a Triple Composite Catalyst
ACS Catalysis ( IF 11.3 ) Pub Date : 2024-07-26 , DOI: 10.1021/acscatal.4c02253 Ruiwen Cao 1 , Tingjun Fu 1 , Yuyu Liu 1 , Weichao Qin 1 , Yuhang Guo 1 , Caiyan Li 1 , Shouying Huang 2 , Zhong Li 1
ACS Catalysis ( IF 11.3 ) Pub Date : 2024-07-26 , DOI: 10.1021/acscatal.4c02253 Ruiwen Cao 1 , Tingjun Fu 1 , Yuyu Liu 1 , Weichao Qin 1 , Yuhang Guo 1 , Caiyan Li 1 , Shouying Huang 2 , Zhong Li 1
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The alkylation of benzene with CO2/H2 to synthesize toluene and xylene is of great significance for alleviating carbon emissions and upgrading light aromatics toward value-added chemicals. However, the alkylation reagent from CO2 hydrogenation showed relatively weak alkylation activity and severe self-reaction, leading to a low alkylation efficiency. Here, a high-performance triple composite catalytic system was constructed by using ZnZrOx oxide, Al2O3 oxide, and H-ZSM-5 zeolite as catalyst components for the alkylation of benzene with CO2/H2 to toluene and xylene. According to the results, CO2 is hydrogenated to methanol on oxygen vacancies, methanol is dehydrated to dimethyl ether (DME) on Lewis acid sites, and benzene is then alkylated with the formed DME to toluene and xylene over the acidic sites of the zeolite. The combined selectivity of toluene and xylene among all hydrocarbons reached 97% at a benzene conversion of 9.7%, surpassing that of most reported traditional catalysts. The methanol dehydration to DME is responsible for the high alkylation activity, providing more alkylation reagents with high activity and suppressing the self-reaction of methanol to light hydrocarbons (C1–C5). More importantly, water is formed by methanol dehydration before the alkylation step and outside the zeolite, thus reducing the competitive adsorption of benzene and water on the acidic sites in the zeolite channel, consequently increasing the conversion of benzene and improving the catalytic stability. The establishment of the triple composite catalytic system in this work opens valuable horizons for enhancing the alkylation of benzene by coupling with CO2 hydrogenation.
中文翻译：
通过三重复合催化剂促进 CO2/H2 苯烷基化转化
苯与CO 2 /H 2烷基化合成甲苯和二甲苯对于减少碳排放、轻芳烃升级为高附加值化学品具有重要意义。然而，CO 2加氢所得烷基化试剂的烷基化活性较弱，自反应严重，导致烷基化效率较低。本文以ZnZrO x氧化物、Al 2 O 3氧化物和H-ZSM-5沸石为催化剂组分构建了高性能三重复合催化体系，用于苯与CO 2 /H 2烷基化制甲苯和二甲苯。结果表明，CO 2在氧空位上加氢为甲醇，甲醇在路易斯酸位上脱水为二甲醚(DME)，然后苯在沸石的酸性位上与形成的DME烷基化为甲苯和二甲苯。所有烃类中甲苯和二甲苯的综合选择性达到97%，苯转化率为9.7%，超过了大多数报道的传统催化剂。甲醇脱水生成二甲醚是烷基化活性较高的原因，提供了更多的高活性烷基化试剂，并抑制了甲醇生成轻质烃（C1-C5）的自反应。更重要的是，在烷基化步骤之前，甲醇在沸石外脱水形成水，从而减少了苯和水在沸石通道酸性位点上的竞争吸附，从而提高了苯的转化率，提高了催化稳定性。 本工作中三重复合催化体系的建立为通过耦合CO 2加氢来增强苯的烷基化开辟了宝贵的前景。
更新日期：2024-07-26
中文翻译：
通过三重复合催化剂促进 CO2/H2 苯烷基化转化
苯与CO 2 /H 2烷基化合成甲苯和二甲苯对于减少碳排放、轻芳烃升级为高附加值化学品具有重要意义。然而，CO 2加氢所得烷基化试剂的烷基化活性较弱，自反应严重，导致烷基化效率较低。本文以ZnZrO x氧化物、Al 2 O 3氧化物和H-ZSM-5沸石为催化剂组分构建了高性能三重复合催化体系，用于苯与CO 2 /H 2烷基化制甲苯和二甲苯。结果表明，CO 2在氧空位上加氢为甲醇，甲醇在路易斯酸位上脱水为二甲醚(DME)，然后苯在沸石的酸性位上与形成的DME烷基化为甲苯和二甲苯。所有烃类中甲苯和二甲苯的综合选择性达到97%，苯转化率为9.7%，超过了大多数报道的传统催化剂。甲醇脱水生成二甲醚是烷基化活性较高的原因，提供了更多的高活性烷基化试剂，并抑制了甲醇生成轻质烃（C1-C5）的自反应。更重要的是，在烷基化步骤之前，甲醇在沸石外脱水形成水，从而减少了苯和水在沸石通道酸性位点上的竞争吸附，从而提高了苯的转化率，提高了催化稳定性。 本工作中三重复合催化体系的建立为通过耦合CO 2加氢来增强苯的烷基化开辟了宝贵的前景。
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