Surface Acidity of Sulfuric Acid Activated Maredan Clay Catalysts with Boehm Titration Method and Pyridine Adsorption-FTIR

Abstract

The acid or base of the solid surface is a very interesting aspect at the structure of surface and important in the field of ion exchange and heterogeneous catalysts. The use of clay as a heterogeneous catalyst is due to its acidity. In this paper, the acidity of heterogeneous catalysts Maredan clay activated by sulfuric acid was examined by the Boehm titration and adsorption pyridine method. In this study, Maredan clay was activated with several variation concentration of sulfuric acid (0.5, 1, 2 and 3 M) by impregnation method. The mixture was refluxed at 80°C for 3 hours, washed with double deionised water, dried and calcined at 500 °C for 3 hours. The results showed that activation of Maredan clay by sulfuric acid produced the total acid amount of 0.6483 mmol/g catalyst by using Boehm titration method and 1.1137 mmol/g catalyst by using pyridine vapor adsorption method. FTIR analysis of the spectra of pyridine adsorption was seen that the acid site of the Maredan clay catalyst activated by sulfuric acid dominant was Lewis acid site, with wave numbers at 1449.57; 1490.07; 1573.98 and 1616.42 cm−1.