Physical characteristics and utilization of ZSM-5 prepared from rice husk silica and aluminum hydroxide as catalyst for transesterification of Ricinus communis oil

Natural and synthetic zeolites are well-known materials sharing a wide range of applications, such as adsorbents, ion exchange, and catalysts. However, synthetic zeolites are more widely used, due to several limitations of natural zeolites, such as the presence of impurities and diverse compositions. In this study, rice husk silica (97.86% purity) and aluminum hydroxide were utilized for the preparation of ZSM-5, to study the effect of crystallization time on the physical characteristics and catalytic activity in the transesterification of Ricinus communis oil. The raw materials, with molar ratio of SiO₂:0.025Al₂O₃:0.165Na₂O:25H₂O, were subjected to crystallization at 180 °C for 48, 72, 96, and 120 h, completed by 6 h calcination at 600 °C. The formation of ZSM-5 was demonstrated by FTIR, XRD, and SEM techniques, confirmed that the formation of ZSM-5 had taken place at 48 h crystallization, with no significant change with prolonged time. The PSA indicates the existence of two clusters of particles, and the BET confirmed the existence of the zeolites as porous materials, with the sample prepared with crystallization time of 96 h had the largest surface area and smallest pore diameter. This particular sample exhibited the highest activity, resulting in 96% conversion of Ricinus communis oil. (paper)