Koshti Hardik, Bandyopadhyay Rajib
Department of Chemistry, School of Energy Technology, Pandit Deendayal Energy University, Gandhinagar, Gujarat, 382426, India.
Environ Sci Pollut Res Int. 2025 May;32(22):13159-13171. doi: 10.1007/s11356-023-26777-w. Epub 2023 Apr 3.
In this work, post-synthetic effective acid (HNO) and base (NaOH) etching technique are used to create hierarchical mordenite having different pore structure. The powder X-ray diffraction (P-XRD) technique was used to confirm the crystalline structure of the base-modified and acid-modified mordenite. Field emission-scanning electron microscope (FE-SEM) was employed to confirm the structural morphology of the materials. The modified mordenite was further characterised by inductive coupled plasma-optical emission spectrometry (ICP-OES), N adsorption-desorption isotherms, thermogravimetric analysis (TGA), and acid-base titration, to confirm the structural integrity, presence of active acidic sites, and other vital parameters. The structure was well conserved after the change, as evidenced by the characterisation. The toluene benzylation with benzyl alcohol using hierarchical mordenite and H-mordenite produced mono-benzylated toluene. Comparison between acid treated, base treated, and H-mordenite was done. All samples were catalytically active as proved by the catalytic result in the benzylation reaction. The results show that the base alteration dramatically enhances the mesoporous surface area of H-mordenite. Furthermore, the acid-treated mordenite had the highest benzyl alcohol conversion (75%), but the base-modified mordenite had benzyl alcohol conversion of 73% with the highest mono-benzylated toluene selectivity (61%). The process was further optimised by varying the reaction temperature, duration, and catalyst quantity. Gas chromatography (GC) was used to evaluate the reaction products and gas chromatography-mass spectrometry (GC-MS) was used to confirm them. Introduction of mesoporosity in the microporous mordenite was found to have significant effect on their catalytic activity.
在这项工作中，采用合成后有效的酸（HNO）和碱（NaOH）蚀刻技术来制备具有不同孔结构的分级丝光沸石。利用粉末X射线衍射（P-XRD）技术来确认碱改性和酸改性丝光沸石的晶体结构。采用场发射扫描电子显微镜（FE-SEM）来确认材料的结构形态。通过电感耦合等离子体发射光谱法（ICP-OES）、N吸附-脱附等温线、热重分析（TGA）和酸碱滴定对改性丝光沸石进行进一步表征，以确认其结构完整性、活性酸性位点的存在以及其他重要参数。表征结果表明，改性后结构得到了很好的保留。使用分级丝光沸石和H-丝光沸石将甲苯与苯甲醇进行苄基化反应生成单苄基化甲苯。对酸处理、碱处理和H-丝光沸石进行了比较。苄基化反应的催化结果证明所有样品都具有催化活性。结果表明，碱改性显著提高了H-丝光沸石的介孔表面积。此外，酸处理的丝光沸石具有最高的苯甲醇转化率（75%），但碱改性的丝光沸石苯甲醇转化率为73%，单苄基化甲苯选择性最高（61%）。通过改变反应温度、持续时间和催化剂用量对该过程进行了进一步优化。使用气相色谱（GC）评估反应产物，并使用气相色谱-质谱联用仪（GC-MS）进行确认。发现在微孔丝光沸石中引入介孔对其催化活性有显著影响。
