Nitrogen Adsorption Study of MCM-41 Molecular Sieves Synthesized Using Hydrothermal Restructuring
Source: Adsorption, Volume 6, Number 1, January 2000 , pp. 47-51(5)
Nitrogen desorption scanning hysteresis loops (DSHLs) for large-pore MCM-41 silicas (pore diameter from 4.0 to 6.5 nm) are reported for the first time. DSHLs for MCM-41 were compared with those of conventional mesoporous silicas and no appreciable differences were found, although hysteresis loops and DSHLs for the latter were usually broader. Since desorption behavior of conventional porous silicas is appreciably influenced by pore connectivity, the observed similarity in hysteresis behavior suggests single-pore blocking effects for MCM-41 due to variation of pore diameter along its nonintersecting channels. It was also shown that the steepness of nitrogen desorption branches at relative pressures close to 0.4 often results from proximity of the lower pressure limit of adsorption-desorption irreversibility and consequently it is not justified to consider it as an indication of narrow pore size distribution. Thus, application of desorption data in calculations of pore size distributions may be grossly misleading.
Document Type: Regular paper
Affiliations: 1: Department of Chemistry, Kent State University, Kent, Ohio 44242, USA 2: Department of Chemistry, Kent State University, Kent, Ohio 44242, USA. Jaroniec@scorpio.kent.edu 3: Department of Chemical Engineering and CERPIC, UniversitéLaval, Ste-Foy, QC, Canada, G1K 7P4
Publication date: 2000-01-01