Pore size distributions of the parent RH-MCM-41 and silylated samples are displayed in Fig. 4. Their BET surface
and average pore size diameters are tabulated in Table 1. After silylation of RH-MCM-41, the BET surface area, and effective pore size had been reduced from *900 to 500 m2/g, and from proximity of 2.9–2.2 nm, respectively. The pore size was related to the molecular size of silylating agents. Because the PTCS molecule size is larger than other silylating agents, it reduced average pore size of material more than the TMCS and DMCS did. Micropores were also observed in the pore size distribution of some silylated RH-MCM-41, as described before.