EFFECT OF K2SO4 TO THE PORE PROPERTIES OF PRODUCTS IN THE SYNTHESIS OF MESOPOROUS SILICATES MCM-41

Abstract

Researchs about the effects of K2SO4 to the pore properties of the products in the synthesis of mesoporous silicates MCM-41 has been done. MCM-41 was synthesized by hydrothermal treatment of the mixture containing : 9.31 of sodium silicate solution, 8.67 g of cetyltrimetylammoniumbromide (CTMAB) and 29 g of distilled water (molar ratio of 8 Na2SiO3 : CTMAB : NaOH : 400H2O). The hydrothermal treatment was carried out at 100 oC in a teflon-lined stainless steel autoclave heated in the oven for 36 h. The solid phase was filtered, washed with distilled water, and dried in the oven at 100 oC for 2 h. The surfactant CTMAB was removed by calcinations at 550 oC for 10 h with heating rate of 2 ºC/min. The as-synthesized MCM-41 was characterized by using FTIR spectroscopy and X-ray diffraction, while calcined-MCM-41 was characterized by using FTIR spectroscopy, X-ray diffraction; and N2 physisorption methods. The same procedure was carried out, with the addition of 17.4 g of K2SO4 and 21.6 ml of distilled water to obstain the molar composition of the gel of: 8Na2SiO3 : CTMAB : NaOH: 400H2O : 2 K2SO4. The results showed that the addition of K2SO4 increased the crystalinity. MCM-41 prepared with K2SO4 has a higher specific surface area of 972.812 m2 g-1 compared to the MCM-41 prepared without K2SO4 (i.e., 946.607 m2 g-1), higher mean pore diameter of 3.714 nm compared to the MCM-41 prepared without K2SO4 (i.e. 3.357 nm), and thicker pore walls of 0.830 nm compared to the MCM-41 prepared without K2SO4 (i.e. 1.176 nm).

Key words : MCM-41, K2SO4, pore properties