In the present work, two kinds of porous silicas (PS-C16 Two kinds of the porous silicas with uniform and cylindrical and PS-C18) were synthesized from the calcined Na 4 SiO 4 pores were prepared from calcined Na 4 SiO 4 and cationic surfacand the cationic surfactant of [C 16 H 33 N(CH 3 ) 3 ]Cl or tants ([C 16 H 33 N(CH 3 ) 3 ]Cl and [C 18 H 37 N(CH 3 ) 3 ]Br). In this pa-[C 18 H 37 N(CH 3 ) 3 ]Br. It has been found that the porous siliper, we call these porous silicas PS-C16 and PS-C18. PS-C16 was cas synthesized by the present method have a porous texture calcined in vacuo at 873-1273 K in order to prepare a series of similar to MCM-41 or FSM-16. Besides PS-C16 and PSporous silicas having different pore sizes. All nitrogen adsorption C18, we prepared a series of porous silicas with different isotherms for a series of the porous silicas show no hysteresis in pore sizes (cf. Table 1).
the adsorption and desorption branches. The nitrogen adsorption
The purpose of the present work is (1) to prepare a series isotherms were analyzed by the t method, and the pore surface area (S p ), the pore volume (V p ), and the core volume (V c ) were of the porous silica adsorbents with known porous texture determined. The pore radius (r p ), the core radius (r c ), and the (cf. Table 1), ( 2) to measure the nitrogen adsorption isoadsorbed thickness on the pore wall (t pore ) were computed from therms for the prepared adsorbents (cf. Figs. 3, 4, and9), the measured values of S p , V p , and V c . We can determine the and (3) to analyze the nitrogen isotherms by the t method relationship between the Polanyi adsorption potential and the core (22)(23)(24)(25)6,and 10). As a result, the pore size radius in the range of r c Å 0.6-1.2 nm. On the basis of the present (r p ), the core size (r c ), and the adsorbed thickness on the data, we propose a new method of calculating the pore size distripore wall (t pore ) were determined for a series of adsorbents bution in the range of r p Å 1-2 nm. ᭧ 1997 Academic Press having different pore sizes (cf. Table 2). The data given in