• MUHAMMAD A DAOUS

      Articles written in Journal of Chemical Sciences

    • Ammonia treated Mo/AC catalysts for CO hydrogenation with improved oxygenates selectivity

      SHARIF F ZAMAN NAGARAJU PASUPULETY ABDULRAHIM A AL-ZAHRANI MUHAMMAD A DAOUS S S AL-SHAHRANI HITOSHI INOKAWA LACHEZAR A PETROV HAFEDH DRISS

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      A series of ammonia treated Mo/Activated Carbon (AC) catalysts were synthesized by wet impregnation method by nominal incorporation of 5, 10 and 15 wt% of molybdenum. The calcined catalysts (500◦C, 4 h, N₂ flow) were subjected to a stepwise ammonia treatment at temperatures from 25 up to 700◦C. This work reports for the first time, ammonia treated different loadings of Mo on DARCO mesoporous activated carbon for CO hydrogenation reaction. These catalysts were tested in the reaction temperature range of 250–325◦C, 7 MPa and 12000/h (GHSV for reactor volume 0.5 mL). At 250◦C, all the catalysts showed total oxygenate selectivity of ∼50%, mainly methanol. At 325◦C, total oxygenate selectivity of 16.5% with 18% CO conversion was obtained on 10Mo-N/AC. The result of alcohol distribution revealed high selectivity to propanol (39%) over methanol (34%) at 325◦C on 10Mo-N/AC which highlights its unique catalytic behavior in CO hydrogenation. Further, 10MoO3/AC catalyst, with no treatment of ammonia, showed only 4% of CO conversion with 96% hydrocarbon selectivity. Only 0.5% of CO conversion was observed on AC itself at 325◦C. The improved oxygenates selectivity on 10Mo-N/AC was associated with Moδ+ sites on AC generated viaammonolysis.

    • Highly efficient hydrotalcite supported palladium catalyst for hydrodechlorination of 1, 2, 4-tri chlorobenzene: Influence of Pd loading

      ARSHID M ALI SEETHARAMULU PODILA MUHAMMAD A DAOUS ABDULRAHIM A AL-ZAHRANI AISHAH MAHPUDZ

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      The influence of Pd loading was studied for the gas phase catalytic hydrodechlorination of 1,2,4-trichlorobenzene over Pd supported on Mg-Al mixed oxide support with Mg:Al ratio 2:1. The Mg-Al support was prepared from hydrotalcite precursor. A series of catalysts was prepared with different loadings of Pd (1–6 wt%) on Mg-Al mixed oxide support. The performance of catalytic material was evaluated at different temperatures ranging from 425–575K. The fresh and used catalysts were characterized with different analyticaltechniques such as BET surface area, X-ray diffraction studies, Temperature programmed reduction, X-ray photoelectron spectroscopy and CO-chemisorption studies. H2-Temperature programmed desorption studies was also performed to understand the metal-support interaction and suitable active sites. The 4wt% ofPd on Mg-Al mixed oxide catalyst showed the highest conversion and selectivity among all catalysts and maintained steady activity with 10 h of time-on-stream studies. The main reasons for high activity are suitable metal-support interactions, Pd particle size, high surface area, and high surface Pd atomicconcentration.

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