Synthesis and Characterization of Zeolite Y Catalyst from Ethiopian Ansho Kaolin for Heavy Hydrocarbon Cracking

Abstract

Zeolites are inorganic materials widely used in the chemical industry as catalysts. In this study, kaolin based Zeolite Y and P1have been synthesized successfully in the laboratory at 110oC, 24hrs. crystallization temperature and time respectively. The Synthesis process involves several steps, including collection of Ethiopian Hosanna kaolin, calcination of kaolin, dealumination to get the desired Si/Al ratio and final hydrothermal synthesis. Calcination of kaolin carried out with different temperature range to convert kaolin into the reactive metastable amorphous phase metakaolin. Amorphous metakaolin was obtained at a temperature of above 550oC at residence time of 3hrs. Dealumination technique; both conventional and novel methods were used to arrange metakaolin silica alumina ratio good enough for zeolite synthesis. The complete silica analysis results show that the composition of the Hosanna metakaolin changed considerably during dealumination by both the novel and conventional method. The zeolite Y was synthesized with hydrothermal method using teflon lined stainless steel autoclave reactor. A kaolin calcined at a temperature of 675oC was used as a source of silica and alumina. The stoichiometric amount of NaOH, metakaolin and water were used for the zeolite gel synthesis. Then the gel aged for 1 days at ambient condition and crystallize hydrothermally in an autoclave reactor at temperature of 110oC for 24 hrs. Finally, the synthesized zeolites were characterized by atomic absorption spectrophotometry (AAS), X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The results found from characterization confirms that zeolite Y synthesized successfully. The effects of calcination temperature of kaolin (ranging from 450oC up to 1050oC), gel aging time (1 up to 9 days) and crystallization time (1 up to 4 days) have been investigated. As a results, the kaolin calcination temperature above 550oC have found suitable for zeolite synthesis regardless of zeolite type. Zeolite transformation from zeolite Y to P1 took place by changing the gel aging and crystallization time in zeolite Y synthesis. This transformation was observed by powder X-ray diffraction. The performance of the zeolite Y was evaluated by decomposing polyethylene (PE) using TGA. The results obtained showed a decrease in the decomposition temperature, for all PE/Catalyst mixtures, as a results of the use of each of the additional catalyst dosage with respect to pure PE. Moreover, the PE-30 mass % zeolite Y mixture was reduced the xi

decomposition temperature of T10 (temperature at which 10% of sample mass decomposed) by 53oC relative to the pure.