Synthesis and characterization of mesoporous aluminosilicate molecular sieve from K-feldspar

Abstract

Mesoporous aluminosilicate molecular sieves have been synthesized using K-feldspar, a natural ore rich in silicon and aluminum sources, as starting material. In this method, the mixture of K-feldspar and K 2CO 3 with mass ratio of 2:3 was first calcined at 880 °C for 1.2 h. The calcined materials were then dissolved in water together with cetyltrimethylammonium bromide as structure-directing agent, resulting in mesoporous molecular sieves after heating the solution at 130 °C for 60 h. Scanning electron microscopy and transmission electron microscopy observations indicated that the resulting materials were spherical particles with size of about 100 nm. The mesoporous structure of the as-synthesized materials was confirmed by low angle X-ray diffraction and nitrogen sorption analysis. The BET surface area of the as-prepared material after calcined at 550 °C was 507 m 2 g −1 and the pore volume was 0.854 cm 3 g −1. 27Al MAS NMR analysis showed that nearly all of aluminium is incorporated into the framework of the mesoporous material with 4-coordinated state. The acidity of the product was analyzed by FTIR spectroscopy of pyridine-adsorbed product. The product was treated in water at 100 °C for 360 h, and its mesoporous structure was still intact, suggesting its high hydrothermal stability.