Innovation of Green Chemistry for Synthesizing Nanoporous and Microporous Aluminosilicate via Microemulsion Technique

Abstract

This work proposed a novel and straightforward method for synthesizing of nanoporous and microporous aluminosilicate with simple procedure and short process time at room temperature. It was conducted by microemulsion technique using aluminum sulfate hexadecahydrate (Al2(SO4)3.16H2O) and tetraethylorthosilicate (TEOS) as aluminium and silicon sources. Microemulsion or nanoreactor was formed with the use of a straight chain cationic cetyltrimethylammonium bromide (CTAB) surfactant with mixed solvents of butanol, heptane, and water. These microemulsions allowed the aluminosilicate formation to occur at room temperature. 1H NMR data were used to support the alignment of chemical reagents. The suspension sample was purified by washing with 10 wt% ethanol and then evaporated the solvent out to collect a white sample powder of aluminosilicate (as-synthesized product). As-synthesized product was calcined at 550 ºC for 5 hours. The results showed that the purification and collection techniques used were successful and capable of eliminating the carbonaceous residues at 300 ºC. The effect of Si/Al ratio on the formation of aluminosilicate was also studied by varying the ratio of Si/Al at 2/1 and 10/1. The amorphous phases of 2/1 and 10/1 Si/Al were clearly demonstrated by observing an XRD pattern. The surface area of aluminosilicate was increased with increasing Si/Al ratio. The amorphous phase aluminosilcate has Langmuir’s surface area of 394.8 m2/g (Si/Al = 2/1) and 1,217 m2/g (Si/Al = 10/1) with the total pore volume of 0.115 cc/g (Si/Al =2/1) and 0.320 cc/g (Si/Al = 10/1) and average pore diameter of 25 Å (Si/Al = 2/1) and 14 Å (Si/Al=10/1). Furthermore, FT-IR spectra suggested that as-synthesized formations were similar to analcime and ZSM-5 for Si/Al of 2/1 and 10/1, respectively.