Preparation of thermostable silica-pillared layered niobic acids with different interlayer distance, surface area and pore size

By varying the concentration of APS aqueous solution, reaction time and tem perature, a series of silica-pillared layered niobic: acids with different interlayer distances, surface areas, pore sizes and thermostability were su ccessfully prepared. It was shown that increasing the concentration of APS aqueous solution under a certain level(from 2. 1% to 10%) led to the format ion of silica-pillared layered niobic acids with a gradually increased inte rlayer distance, surface area and silica pillar density, and therefore a gr adually decreased pore size, but the same thermostability. On the other han d, reducing reaction time from 3 days to 1 day caused the decrease of the i nterlayer distance, surface area and thermostability, but the increase of p ore size due to lower pillar density. Furthermore, the reaction at room tem perature gave rise to the silica-pillared layered,niobic acid with a smalle r interlayer distance and pore size, a slightly larger specific surface are a and a lower thermostability.