| Abstract
| - Mesoporous CrSBA-15 materials with different nSi/nCr ratios have been synthesized, for the first time,using Pluronic P123 as a structure-directing agent by simply adjusting the molar ratio of water tohydrochloric acid (nH2O/nHCl). The effect of the nature of Cr-ion source on the synthesis of CrSBA-15has been investigated using different chromium-ion sources: chromium(III) nitrate, chromium(III) chloride,and chromium(III) sulfate. To investigate the effect of structural and textural properties with a higher Crincorporation, CrSBA-15 has also been synthesized with various nSi/nCr ratios and synthesis temperatures.The synthesized CrSBA-15 materials have been characterized by ICP-AES, XRD, N2 adsorption, ESR,TEM, and FE-SEM. ICP-AES results show that chromium(III) nitrate nonohydrate is found to be a goodCr-ion source for the synthesis of mesoporous CrSBA-15 material, with a nSi/nCr ratio up to 9.1 successfullyprepared by changing the nSi/nCr ratio in the synthesis gel at a nH2O/nHCl of 295. For all calcined CrSBA-15 materials, XRD reflection peaks shift to lower angle with increasing Cr-content, resulting in the increaseof the unit cell parameter. By increasing the crystallization temperature from 373 to 403 K, nitrogenadsorption measurement shows that the pore diameter of CrSBA-15 can be tuned from 89.4 to 94.7 Å,with an increase of pore volume from 1.10 to 1.20 cm3/g accompanied by the concomitant decrease ofsurface area from 987 to 797 m2/g and the decrease of pore wall thickness from 38 to 36.7 Å. ESRmeasurements show the amount of Cr-ions incorporated, as well as the location and coordination ofCr-ion on SBA-15 silica walls. TEM and FE-SEM images show the uniform pore diameter and ropelikehexagonal mesoporous structure of CrSBA-15. Furthermore, the hydrothermal stability of CrSBA-15samples has also been investigated, with hexagonal CrSBA-15(8) having better hydrothermal stabilitythan CrSBA-15(50).
- Mesoporous CrSBA-15 materials have been successfully synthesized using the acidic hydrothermal method, with the amount of Cr species incorporated into SBA-15 prepared under a nH2O/nHCl ratio of 295 being much higher than that prepared under other nH2O/nHCl ratios. CrSBA-15(8) prepared using a nSi/nCr ratio of 8 has greater hydrothermal stability than do other CrSBA-15 materials.
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