Abstract:

First,the meso-porous adsorbent SiO₂-TiO₂ was synthesized via the sol-gel method. Next,its structure and morphology are characterized by using N2 adsorption and desorption isotherms and by means of TEM so as to reveal the influence of the titanium content in the titanium-doped silica gel on the silica gel structure. Then,the water vapor adsorption and regeneration properties of the adsorbent SiO₂-TiO₂ are investigated by using a dynamic water vapor sorption analyzer ( DVSA) ,and the desorption activation energy of water molecules on absorbent was also estimated by a temperature programmed desorption ( TPD) test. Finally,the Frenkel-Halsey-Hill ( FHH) model is used to analyze the surface roughness and pore size distribution of the adsorbent. The experimental results show that,with the decrease of the titanium-to-silicon molar ratio,the specific surface area of the adsorbent increases with a narrower pore size distribution and a smaller average pore size,and the desorption activation energy of water molecules on absorbent decreases,and that,the adsorbent SiO₂-TiO₂ is of a lower regeneration temperature,and its water vapor adsorption capacity is greater than that of MCM-41 silica under a low relative humidity of less than 30%.

Key words: meso-porous adsorbent, silica, titanium-doped, sol-gel method, adsorption isotherms, temperature programmed desorption, adsorbent regeneration