Ball‐Milling Preparation of Bimodal Mesoporous Silica from MCM‐48 for Application in CO ₂ Capture

This study presents a novel method for preparing bimodal mesoporous silica (BMS) by ball milling presynthesized MCM‐48 under controlled conditions. Structural analyses confirm that prolonged milling, particularly at 700 rpm for 9 h, induces particle reagglomeration and generates a hierarchical pore system of small mesopores and larger transport pores while partially preserving the original ordered framework. Nitrogen adsorption–desorption, X‐ray diffraction, and electron microscopy show that the resulting BMS achieves the highest total pore volume (2.78 cm 3 g −1 ) under the examined conditions. Amine functionalization reveals that the hierarchical pore structure alleviates steric hindrance and pore plugging compared to that of pristine MCM‐48, leading to higher CO 2 uptake and faster kinetics. In particular, 3‐(2‐aminoethylamino)propyltrimethoxysilane (AEAP)‐modified BMS exhibits a favorable balance between adsorption capacity and amine utilization efficiency. Moreover, the reduced gap between the short‐term (30 min) and maximum adsorption amounts indicates improved diffusion. Cyclic adsorption–desorption confirms the structural stability and reusability of the material. These findings demonstrate that ball milling provides a simple and scalable route for producing BMS with superior textural properties, offering a promising platform for the development of efficient and durable CO 2 adsorbents.