Transformation of silica SBA-15 to zeolite beta for craking of plastic waste and plastic-drived crude oil

A novel method for the synthesis of nanoparticle zeolite beta beta was performed by transformation of SBA-15 in the presence of tetraehtylammonium hydroxide and aluminum isopropoxide under autogenous pressure at a constant temperature of 135℃. The effects of various parameters such as transformation periods, TEAOH/SiO₂ ratio and SBA-15/AIP ratio on the properties of the zeolite product were studied. The zeolite samples were characterized by XRD, SEM, ²⁷ AI-MAS-NMR, nitrogen adsorption, NH₃-TPD and XRF techniques. With a TEAOH/SiO₂ ratio of 0.39, SBA-15 is completely decomposed to α-quartz and gradually to the zeolite beta with the maximum crystallinity within a period of 24 h. However, the zeolite is obtained at the highest yield of 42.4 % after transformation for 48 h. Most samples containing zeolite beta have the particle sizes ranging from 116 to 147 nm depending on the transformation period. but the crystallite size and BET specific surface area are not significantly affected. By varying TEAOH/SiO₂ ration from 0.10 to 0.39, the TEAOH/SiO₂ ratio of 0.26 is found to give the highest yield of zeolite beta up to 71.8% with larger average particle size of 215 nm. The zeolite beta samples obtained were tested for their catalytic activities in the cracking of PP.HDPE waste and PP-derived crude oil in a batch reactor under various conditions. The nanoparticle zeolite beta is found very active up to 95.8 % conversion in cracking of PP waste. The plastic conversions and the yields of products fractions obviously depend on the reaction temperatures, the SBA-15/AIP rations and the plastic to catalyst rations. The product selectivity is affected by those factors. The gas products obtained by PP and HDPE cracking are mainly propene. i-butane and C₅ while those from catalytic cracking of PP-derived crude oil are propene. n-butane, i-butane and C₅ . The liquid products obtained by cracking of both types of plastic are mainly in the boiling point ranging from C₆ to C₉ and for PP-derived crude oil C₉ is mainly obtained. The used catalyst can be regenerated easily by calcination and its activity remains comparable to the fresh catalyst.