Synthesis of X-type zeolite from dealuminated kaolin by reaction with sulfuric acid at high temperature

X-type zeolite was synthesized from kaolin previously dealuminated through reaction with sulfuric acid at high temperature to raise its SiO2/Al2O3 ratio. All of the steps in the synthesis of X-type zeolite from dealuminated kaolin were studied. Parameters analyzed included temperature, time, stirring speed, and composition ratios. The optimum values for the variables were the following: In the gel formation step, temperature was 60 degrees C, time was 1 h, and stirring speed was 450 rpm. In the aging step, temperature was 20 degrees C and time was 12 h. In the crystallization step, temperature was 80 degrees C, time was 24 h, and stirring speed was 0 rpm. The optimum molar ratios were SiO2/Al2O3 = 3.2, (Na2O + K2O)/SiO2 = 1, H2O/(Na2O + K2O) = 30, and K2O/(Na2O + K2O) = 0.1. Some significant differences from other works were observed, particularly in the aging and crystallization steps. These variations in the synthesis process might be caused by changes in the kaolin structure occurring during dealumination with sulfuric acid.