Characterization of titania/silica gel by means of low-pressure nitrogen adsorption

Adsorbents synthesized by grafting of titania onto mesoporous silica gel su rfaces at different temperatures were studied by means of nitrogen adsorpti on-desorption and water desorption. The pore size distribution f(R-p) of ti tania/silica gel depends on the titania concentration (C-TiO2) and the temp erature of titania synthesis. Nonuniformity of TiO2 phase is maximal at a l ow C-TiO2 value (3.2 wt.% anatase deposited at 473 K), and two peaks of the fractal dimension distribution f(D) are observed at such a concentration o f titania, but at larger C-TiO2 values, only one f(D) peak is seen. More or dered filling of pores and adsorption sites by nitrogen, reflecting in the shape of adsorption energy distributions f(E) at different pressures of ads orbate, is observed for adsorbent with titania (rutile + anatase) grafted o n silica gel at a higher temperature (673 K). (C) 2000 Academic Press.