A comparative study of drying techniques on the morphology of porous silica gels synthesized via sol-gel process

WANG Li-jiu, XuHaiXun, ZHAO Shan-yu

Institute of Building Materials,School of Civil and Hydraulic Engineering,Dalian University of Technology,Dalian 116024,China



Abstract:

The effect of drying techniques on the microstructure,morphology and pore structure of porous silica gels was studied in the paper.The gels were prepared by using sol-gel process and different drying routes:freeze-drying (FD),low pressure drying (LPD),high temperature drying (HTD) and chemical modification & ambient drying (CMD) techniques.Observation under pore distribution and structural properties showed that CMD technique leads to homogenous mesoporous silica material with specific surface area of 745 m2/g,and the average pore size around 20 nm,while LPD and HTD result in loosely packed particles with non-isotropic aggregation pattern.The specific surface areas of LPD and HTD samples are 419 and 513 m2/g respectively,and the pore size distribution of the samples are observed distributing widely in range of 10-100 nm.Freeze drying method is a new but prospective way to prepare mesoporous silica.The specific area of FD sample is around 500 m2/g.By the comparison for the properties of the gels,this paper wants to induce a further interest in finding a proper method to synthesize the porous silica gels for low price use.

Key words:  sol-gel  porous silica materials  drying techniques  N2 gas adsorption  pore structure

DOI：10.11916/j.issn.1005-9113.2011.04.015

Clc Number:TU58

Fund: