Browsing by Author "Mdleleni, Masikana"

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    Dehydrogenation of alkanes using sulfided metal catalysts
    (University of Western Cape, 2021) Tahier, Tayyibah; Mdleleni, Masikana
    Light olefins are some of the main raw materials for the petrochemical industry. With the rise in oil prices and increasing demand for olefins, there is an increasing interest in finding cheaper alternatives for processes in the petrochemical industry (PETROSA 2017). Research into the dehydrogenation of light alkanes has received significant attention. This dehydrogenation process represents a route to obtain olefins from inexpensive hydrocarbon feedstocks. The use of inexpensive hydrocarbons as a feedstock in the petrochemical industry could reduce the dependence on oil. Commercially used catalysts based on chromium or platinum have major disadvantages, including the harmful effects of chromium and the high cost of platinum, which limit their application to a certain extent. Therefore, research into developing efficient dehydrogenation systems using environmentally friendly and inexpensive metals have become highly desirable. Sulfide-containing metal catalysts have gained significant research interest for use in the dehydrogenation process and display interesting catalytic activity.
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    Effect of Fe-Mo promoters on HZSM-5 zeolitecatalyst for 1-hexene aromatization
    (Elsevier B.V., 2018-11-15) Key, David; Mdleleni, Masikana
    The promotional effect of Fe-Mo species introduced into HZSM-5 (Zeolyst Int.,SiO2/Al2O3 30) zeolite catalyst by the wetness impregnation method for the 1-hexene aromatiza-tion was investigated. The structure and catalytic performance for the aromatization of 1-hexeneover xFeyMo-ZSM-5 catalysts in comparison with unmodified HZSM-5 catalysts were studied.The xFeyMo-ZSM-5 catalysts contain fixed loading (5 wt%) and variable Fe/Mo ratio. The cata-lysts were characterized by BET, ICP-AES, HRSEM-EDS, HRTEM, XRD, FTIR, H2-TPR,NH3-TPD, and pyridine DRIFT spectroscopy. The characterization data confirmed the existenceof Fe and Mo species in the zeolite matrix. With Fe and Mo species implementation to HZSM-5zeolite, the amount of the acid sites decreased, but the selectivities to C9+aromatics increased.The catalyst evaluation was performed at 350°C for 6 h on-stream at atmospheric pressure usinga fixed-bed quartz tube reactor. The selectivity to products of different carbon number was affectedby the Fe/Mo ratio within the zeolite. It was found the product distribution of grouped fractions ofC1–C17+from the liquid product. The results indicate that the optimum ratio of Fe/Mo is 1–1.5.The highest selectivity for gasoline and distillate ranges was obtained for the 2.5wt%Fe2.5wt%Mo- and 3wt%Fe2wt%Mo-ZSM-5 samples, which was higher than that for parent HZSM-5 cata-lyst.
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    Hydrothermal synthesis of hierarchical ZSM-5 with different Si/Al ratio and their evaluation as catalysts in the catalytic cracking of hexane
    (University of Western Cape, 2021) Nqakala, Loyiso Clemence; Mdleleni, Masikana; Mohiuddin, Ebrahim; Mpungose, Philani Perfect
    Ethylene and propylene are greatly used for their importance as feedstocks for producing useful materials. Due to rise in prices and the demand of ethylene and propylene, the need to increase the selective production of these light olefins is necessary. To achieve this, zeolites, specifically ZSM-5 has been used to investigate catalytic cracking of several types of hydrocarbons for the production of these light olefins. This study focuses on developing hierarchical macro and/or mesoporous ZSM-5 zeolites with variable Si/Al ratios. The synthesized materials were then evaluated on their performance via catalytic cracking of hexane, dodecane and tyre derived oil [TDO] to produce light olefins, particularly ethylene and propylene.
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    Synthesis of metal modified Mesoporous Zeolites catalysts: application in conversion of Olefins to Valuable liquid products
    (University of the Western Cape, 2016) Mthethwa, Londiwe Yvonne; Mdleleni, Masikana
    The effects of temperature, synthesis duration and silica source were studied to obtain suitable conditions for our laboratory experiment concerned with the synthesis of MCM-41 catalyst. The transformation of 1-hexene was studied using modified mesoporous MCM-41as a catalyst. Catalysts were synthesised by co-precipitation and wet impregnation methods doped with aluminium, chromium and iron. Tetraethylorthosilane (TEOS) was used as silica source due to its ability to show improved results than sodium silicate sources. Catalysts were synthesised with single metal doping for the production of Al-MCM-41, Cr-MCM-41 and Fe- MCM-41. Double doped metal catalysts were also synthesised for the production of Cr/Al- MCM-41 and Fe/Al-MCM-41. Catalysts were hydrothermally synthesised at 150 ?C for 72 h then calcined at 560 ?C after drying. XRD, SEM, FTIR spectroscopy, BET surface area measurents, ammonia-TPD and NMR spectroscopy were used for characterisation of synthesised materials to understand the structural frame and interior as well as exterior surface.