Highly selective CO2 conversion to valuable aromatics over ZnCr2O4/HZSM-11

• Published in: International journal of hydrogen energy 2024-11, Vol.92, p.779-790
• Main Authors: Hou, Hui, Zhu, Xiaoli, Chen, Guanyi, Yan, Beibei, Cheng, Zhanjun, Yao, Jingang
• Format: Article
• Language: English
• Subjects: Aromatics; Bifunctional catalyst; CO2 conversion; Nano-flake ZSM-11 zeolite; Spinel
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.10.331

CO2 serves as a crucial precursor for synthesizing aromatic, offering a resultful pathway for utilizing non-petroleum carbon sources. Nonetheless, the Anderson-Schulze-Flory (ASF) distribution limits aromatics selectivity, challenging the direct conversion of CO2 into specific aromatic products. Bifunctional catalysts consisting of ZnCr2O4, ZnAl2O4 and ZnIn2O4 spinel with nano-flake ZSM-11 zeolite were constructed and investigated for converting CO2 to valuable aromatics. Remarkably, the selectivity towards aromatics greatly surpasses the constraints of ASF. Under identical reaction conditions, the single pass CO2 conversion of the ZnCr2O4/ZSM-11 increased by 7.2% and 5.2%, while the aromatic selectivity rose by 9.5% and 10.5%, respectively, compared to the ZnAl2O4/ZSM-11 and ZnIn2O4/ZSM-11. Additionally, under optimal conditions (300 °C, 3.5 MPa and a gas hourly space velocity (GHSV) of 1800 mL·gcat−1·h−1), ZnCr2O4/ZSM-11 displayed outstanding aromatic selectivity of 90.5% (without CO) alongside a single pass CO2 conversion of 23.6%. Simultaneously, the synthetic ZSM-11 facilitates the timely diffusion of monocyclic aromatics and the production of C8–C12 monocyclic aromatics, which constitute 97.2% of the total aromatic products, while polycyclic aromatics account for only 0.2%. Even after 100 h, the ZnCr2O4/ZSM-11 catalyst maintained its significant catalytic activity with CO2 conversion and aromatic selectivity at 22.0% and 88.0%, respectively. These results highlight the potential of ZnCr2O4/ZSM-11 for directly converting CO2 to valuable aromatics. [Display omitted] •ZnX2O4 (X = Cr, In, Al) spinels were designed to compare the catalytic properties.•ZnCr2O4/ZSM-11 bifunctional catalyst enables direct CO2 to aromatics conversion.•ZnCr2O4/ZSM-11 achieved 90.5% aromatics selectivity, 23.6% CO2 conversion.•Remarkably, C8–C12 monocyclic aromatics constitute 97.2% of the total aromatic.•Post 100 h, catalyst still gave 22.0% CO2 conversion, 88.0% aromatics selectivity.