Synthesis of heterogenous zeolite-y from rice hull ash and its application in catalytical conversion of polyethylene to petrochemical

Abstract

Polyethylene waste had become one of the major environmental pollutants in Bangladesh. Conversion of polyethylene waste into valuable petrochemicals could serve as an economically viable way of sustainable waste management. Thermal degradation of waste polyethylene in presence of catalyst can offers useful products like high value fuel and aromatic hydrocarbons. The catalytic activity is related to the number of active sites on the catalyst surface. In the pyrolysis method, the waste polyethylene is converted to petrochemicals using a zeolite-Y catalyst. Zeolite-Y was synthesized from RHA (Rice Hull Ash) and its application in catalytical conversion of polythene into petrochemical. Silica was extracted from RHA in soluble form since it is soluble under alkaline condition. RHA was added to NaOH (1M) and reflux for several hours with continuous stirring and the solution was filtered through filter paper. The filtrate was titrated against acid with continuous stirring until pH 7, after sometimes gel (silica) was formed. Sodium aluminate was prepared from aluminum moister disk. 1M NaOH solution was prepared and required amount of aluminum moisture disk was added to this solution and warm gently. Then Zeolite-Y was prepared by adding the Na2SiO3 solution prepared from RHA into sodium aluminate solution under continuous stirring until the mixture become homogeneous. It was then left undisturbed to age at ambient temperature for 24 h, and crystallize at 110 °C for 1 day, the final product was filtered, washed, and dried in oven. The catalysts were characterized by Fourier Transform Infra-Red (FT-IR), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) combined with EDX. The crystalline structure and average particle size of Zeolite-Y were observed by XRD and SEM method. Waste polyethylene, and catalyst was placed in a specially fabricated and designed thermo cracking reactor, and well mixed by-passing air free by nitrogen gas. The temperature of the reactor was raised to 450 °C. Inert air free atmosphere was continued and the mixture will be stirred at a normal speed. The progress of the reaction will be monitored by thermocouple temperature sensor. After completion of reaction, the oil was collected from collection chamber. The oil was characterized by TIC method and GC-MS analysis. The area of percentage of 3-ethyl octane, which is the major product of the petrochemical produced from polythene, was observed by the GC-MS method. In conclusion, so my research showed a convenient way for the conversion of waste materials (polyethylene) into valuable petrochemicals by using zeolite-Y which was synthesized from another waste material RHA.