| ZnCr2O4/ZSM-5@Silicalite-1优化CO2一步法加氢制芳烃反应选择性 | |
| ZnCr2O4/ZSM-5@Silicalite-1 to optimize the selectivity of one-step hydrogenation of CO2 to aromatics | |
| 摘要: 本研究采用外延生长方法制备出核壳结构分子筛ZSM-5@Silicalite-1。相关表征结果显示，惰性Silicalite-1壳层均匀包覆在ZSM-5的外表面，调控了分子筛酸性质，特别是降低了外表面酸性，有利于改善芳烃分布。将ZSM-5@Silicalite-1与Zn-Cr氧化物耦合应用于二氧化碳加氢制芳烃的反应，轻质芳烃（苯、甲苯、二甲苯）在总芳烃中的占比从ZnCr2O4/ZSM-5耦合体系的14.8%显著提高到33.5%。此外，Silicalite-1壳层的疏水性还可有效抑制逆水煤气变换副反应，降低CO的选择性。在优化的壳层厚度下，ZnCr2O4/ZSM-5@Silicalite-1耦合体系的芳烃时空收率较ZnCr2O4/ZSM-5体系提高了22%。 | |
| 关键词: 二氧化碳 芳烃 耦合催化 反应路径 核壳结构分子筛 | |
| 基金项目: 国家自然科学基金（No.22293025，U22B6011）和上海市自然科学基金（No.20ZR1455500）资助 | |
| Abstract: The CO2 hydrogenation reaction over the oxide-zeolite bifunctional catalyst yields a mixture of BTX (benzene, toluene, and xylene), C9, and C10+ aromatic products, among which BTX is of the highest commercial value. To improve the distribution of the aromatic products and promote the production of BTX, the core-shell structured zeolite ZSM-5@Silicalite-1 was prepared by the epitaxial growth method in this work. According to the characterization results of powder X-ray diffraction (PXRD), N2 adsorption-desorption, temperature-programmed desorption of NH3 (NH3-TPD), scanning electron microscope (SEM), transmission electron microscopy (TEM), and pyridine adsorption Fourier transform infrared spectroscopy (Py-IR), the inert Silicalite-1 shell is uniformly coated on the external surface of the ZSM-5 core, therefore changes its acidic properties especially reduces the external acidity, which contributes to improving the aromatic distribution. When applied in the one-step CO2-to-aromatic reaction, the combination of ZSM-5@Silicalite-1 and Zn-Cr oxide resulted in a CO2 conversion of 21.9% and aromatics selectivity of 79.3% under the conditions of VH2/VCO2=3.0, 1 200 mL·g-1·h-1, 320 ℃, and 4.0 MPa, and it gave a 33.5% of light aromatics in the overall aromatics, which was higher than 14.8% over the ZnCr2O4/ZSM-5 system. Additionally, in the one-step CO2-to-aromatic reaction system, the by-products of CO and H2O are generated from the side reaction of reverse water-gas shift (RWGS). Due to the higher hydrophobicity of Silicalite-1 than ZSM-5, H2O is enriched at the interface between the oxide and core-shell zeolite, which can shift the reaction equilibrium of RWGS, thus inhibiting the generation of CO. As a result, the CO selectivity was significantly reduced at high space velocities compared with the unmodified oxide-zeolite system. At an optimal shell thickness, the ZnCr2O4/ZSM-5@Silicalite-1 bifunctional catalyst obtained a space-time yield of aromatics of 2.4 mmol·g-1·h-1 at 8 400 mL·g-1·h-1, which was 22% higher compared with ZnCr2O4/ZSM-5. | |
| Keywords: carbon dioxide aromatics bifunctional catalysis reaction path core-shell zeolite | |
| 投稿时间：2023-04-13 修订日期：2023-11-02 | |
| 摘要点击次数: 3573 | |
| 全文下载次数: 736 | |
| 张保连,刘畅,刘苏,周海波,苏俊杰,王仰东,毛东森.ZnCr2O4/ZSM-5@Silicalite-1优化CO2一步法加氢制芳烃反应选择性[J].无机化学学报,2023,39(12):2339-2348. | |
| 查看全文 查看/发表评论 下载PDF阅读器 | |
| Support information: | |
|
| |
|
| |
|
| |