Browsing by Author "Ameh, Alechine E."

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    Acylation of anisole with benzoyl chloride over rapidly synthesized fly ash–based hbea zeolite
    (Frontiers Media, 2021) Ameh, Alechine E.; Musyoka, Nicholas M.; Oyekola, Oluwaseun
    Stable HBEA zeolite with high surface area and strong acid sites was synthesized from coal fly ash–based silica extract via indirect hydrothermal synthesis. The rapid HBEA hydrothermal crystallization times of 8, 10, and 12 h were achieved through a reduced molar water fraction in the synthesis composition. The HBEA zeolites prepared from fly ash silica extract exhibited well-defined spheroidal-shaped crystal morphology with uniform particle sizes of 192, 190, or 239 nm obtained after 8, 10, or 12 h of synthesis time, respectively. The high surface area and the microporous area of 702 and 722 m2 /g were achieved as a function of shorter hydrothermal synthesis durations (10 and 24 h, respectively) compared to 48 or 72 h, which resulted in HBEA zeolites with lower surface areas of 538 and 670 m2 /g. Likewise, temperature-programmed desorption measurements of fly ash–based HBEA zeolites revealed the presence of weak and strong acid sites in the zeolite.
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    Fusion-assisted hydrothermal synthesis and post-synthesis modification of mesoporous hydroxy sodalite zeolite prepared from waste coal fly ash for biodiesel production
    (MDPI, 2022) Shabani, Juvet Malonda; Ameh, Alechine E.; Petrik, Leslie
    Increases in biodiesel prices remains a challenge, mainly due to the high cost of conventional oil feedstocks used during biodiesel production and the challenges associated with using homogeneous catalysts in the process. This study investigated the conversion of waste-derived black soldier fly (BSF) maggot oil feedstock over hydroxy sodalite (HS) zeolite synthesized from waste coal fly ash (CFA) in biodiesel production. The zeolite product prepared after fusion of CFA followed by hydrothermal synthesis (F-HS) resulted in a highly crystalline, mesoporous F-HS zeolite with a considerable surface area of 45 m2/g. The impact of post-synthesis modification of the parent HS catalyst (F-HS) by ion exchange with an alkali source (KOH) on its performance in biodiesel production was investigated. The parent F-HS zeolite catalyst resulted in a high biodiesel yield of 84.10%, with a good quality of 65% fatty acid methyl ester (FAME) content and fuel characteristics compliant with standard biodiesel specifications. After ion exchange, the modified HS zeolite catalyst (K/F-HS) decreased in crystallinity, mesoporosity and total surface area.
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    Transformation of fly ash based nanosilica extract to BEA zeolite and its durability in hot liquid
    (Elsevier, 2020) Ameh, Alechine E.; Fatoba, O. O.; Musyoka, Nicholas M.
    Power generation in South Africa relies heavily on the combustion of coal and during this process, coal fly ash (CFA) is generated as by-product, which raises several environmental issues. The transformation of CFA into a value added zeolite product is a potential beneficial way to manage and reduce the negative environmental impact of the waste. The present study describes suitable formulations of the synthesis of BEA zeolite from South Africa CFA via an indirect hydrothermal process without the addition of an external silica or aluminium source. Herein, the Si/Al ratio of the nanosilica extract significantly increased from 11 to 48, 53 or 61 depending on applied conditions, thus elucidating that the major component in the extract is 92% silica, with a high purity of 94%. A pure phase BEA zeolite was obtained after the hydrothermal crystallisation of the synthesis precursor with Si/Al ratio of 53 or 61 at 140 °C for 24, 48 or 72 h. The BEA zeolites are micron-sized crystals with high thermal framework stability, high surface area and contained mainly framework but some extra framework Al acid sites. Under hot liquid phase treatment, the BEA zeolite framework maintained structural integrity with no phase transformation at elevated treatment duration and temperature.