Zeolite LTA synthesis: Optimising synthesis conditions by using the modified sequential simplex method

Abstract

This paper presents research concerning the simultaneous effect of the most influential synthesis variables in the preparation of Zeolite LTA. The simplex method was used for ascertaining optimal synthesis conditions, where the relative crystallinity (regarding a commercial sample) of synthesised zeolite was defined as response function. Crystallinity was measured by X-ray diffraction. Optimum conditions were found after 24 trials, giving 95.4% relative crystallinity and Na2O/SiO2=2.58, SiO2/Al2O3=1.45 and H2O/Na2O=46.92 molar ratios; 11.7 h crystal growth time, 6.1 h crystallisation time (reaction) and 78°C reaction temperature were found to be optimal synthesis conditions. A computer programme for simulating a zeolite phase diagram was designed to verify whether the molar ratios indicated by the optimisation algorithm were leading to the desired zeolite type. The results were compared to those in previous work where the fixed factor method was used.