Response to Extreme Temperatures of Mesoporous Silica MCM-41: Porous Structure Transformation Simulation and Modification of Gas Adsorption Properties

• DOI: 10.1021/acs.langmuir.6b02814
• Publication Date: 2016-10-17T17:55:32Z
• Authors: Shenli Zhang; Maria Perez-Page; Kelly Guan; Erick Yu; Joseph Tringe; Ricardo H. R. Castro; Roland Faller; Pieter Stroeve
• Keywords: MCM-41

Molecular dynamics (MD) and Monte Carlo (MC) simulations were applied together for the first time to reveal porous structure transformation mechanisms of mesoporous silica MCM-41 subjected temperatures up 2885 K. Silica was experimentally characterized inform models enable prediction changes in gas adsorption/separation properties. MD suggest that pore closure process is activated by a collective diffusion matrix atoms into region, accompanied bond reformation at surface. Degradation kinetically limited, such complete postponed high heating rates. We observe decreased adsorption with increasing temperature heated fixed rates, due structural degradation consistent simulation predictions. Applying Kissinger equation, we find strong correlation between simulated collapse experimental values which implies an activation energy 416 ± 17 kJ/mol closure. MC give selectivity thermally treated MCM-41, N2, Ar, Kr, Xe room within 1–10 000 kPa pressure range. Relative pristine increased surface roughness decreasing size amplifies difference absolute amount differently different adsorbate molecules. In particular, strongly interacting molecules can be enhanced low-pressure region while weakly inhibited. This then results higher binary mixture silica.