Synthesis of aluminophosphate xerogels by non-hydrolytic sol–gel condensation of EtAlCl2 with trialkylphosphates
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We have investigated the preparation of high-surface-area mesoporous aluminophosphates by non-hydrolytic sol–gel method based on reactions of EtAlCl2 with trialkylesters of phosphoric acid (OP(OR)3, R = Me, Et, iPr, nBu, in dry organic solvents. The condensations proceed by alkylchloride elimination. Various reaction and calcination conditions were examined. Porosity is obtained after calcination by removal of organic residual groups. This thermal processing at 300 °C of as-synthesized precursor gels leads to amorphous aluminophosphate xerogels with surface areas of 400–500 m2 g–1 provided by small mesopores (2–8 nm). Changes in the coordination environment of aluminium from six- to four-coordinate are evidenced by shift of 27Al MAS NMR resonances.
Dichloroethylalane reacts with trialkylphosphates by alkylchloride elimination.
Aluminophosphate gels are obtained from the non-hydrolytic sol-gel technique.
Thermal processing at 300 °C leads to amorphous xerogels with surface areas of 400–500 m2 g–1.
Porosity is composed of small mesopores (2–8 nm).
Templating with Pluronic P123 significantly improves pore size distribution.
KeywordsMesoporous xerogels Aluminium phosphate Non-hydrolytic synthesis Sol–gel processing Alkylhalide elimination mechanism
This research has been financially supported by the Ministry of Education, Youth and Sports of the Czech Republic under the project Mobility FRANCE 7AMB17FR050 and CEITEC 2020 (LQ1601). ZM thanks to Postdoc II CZ.1.07/2.3.00/30.0037 for financial assistance. Authors thank to L. Simonikova and Dr. K. Novotny for ICP-OES analyses, T. Samoril for TEM analyses, Dr. P. Roupcova for XRD and Dr. P. Bezdicka for HT XRD measurements and M. Babiak for the single-crystal X-ray diffraction analyses. CIISB research infrastructure project LM2015043 funded by the MEYS CR is gratefully acknowledged for the financial support of the measurements at the CEITEC MU CF X-ray Diffraction and Bio-SAXS, the CF Cryo-electron Microscopy and Tomography.
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Conflict of interest
The authors declare that they have no conflict of interest.
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