Biological, chemical and mathematical sciences

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Browsing Biological, chemical and mathematical sciences by Subject "Alkenes—Analysis"

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    Catalytic conversion of glycerol to olefins over modified ZSM-5 zeolite catalysts
    (Universiti Teknologi Malaysia, 2014) Zakaria, Zaki Yamani
    Glycerol, an alcohol and oxygenated chemical byproduct from biodiesel production, has enormous potential to be converted into higher value-added fuels and chemicals. Due to the alarming excessive production of glycerol worldwide that have triggered environmental concerns, and the importance of olefins in the industry, it is therefore essential to explore the process of glycerol-to-olefin (GTO) in greater depth. This is mainly due to the fact that no dedicated study concerning GTO has been performed. In this present research, the activity and yield towards light olefin in the glycerol steam reforming process was tested and analyzed using zeolite ZSM-5 catalysts modified with selected metals across the periodic table and characterized using X-Ray Diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR), Temperature Programmed Desorption (TPD) and Temperature Programmed Reduction (TPR). Then GTO process involving the best performing catalyst, Cu/ZSM-5, yielding light olefin of 16.3% was further optimized using Response Surface Methodology (RSM) to obtain the most optimum operating condition. The best olefin selectivity and yield were 22.87% and 17.68%, respectively. Multi-Response Objective Genetic Algorithm (MRO-GA) was then performed to give optimum olefin selectivity of 22.06% and yield of 17.84% at the following optimum conditions: T=923K, WHSV=116.54hr-1 and glycerol concentration=26.91%. The reaction kinetic analysis revealed fractional positive values for the order of reaction for products whilst calculated reaction activation energy was 51.88 kJ/mol and pre-exponential constant was 3720.9 mmol.m-2s-1. A reaction model and the reaction mechanism consisting 18 reactions on the catalyst acid surface single-site based on Langmuir-Hinshelwood model were then generated. Thermodynamic analysis was also carried out to investigate the trend of light olefin yield as a function of temperature, pressure and glycerol to water ratio (GWR). The thermodynamic analysis revealed that light olefin formation is minute and occured at temperatures between 873 to 1073K for various GWR. The effect of co-feeding with CO2 shows more encouraging results towards light olefin formation. At thermoneutral point, optimum C2H4 production occurred at 778.44 K (GWR 2:1 and P=1 Bar). In conclusion, GTO offers viable, sustainable and environmental friendly technology for green olefins production from renewable resources, and concerted efforts should be geared to explore its potential
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    Ethylene yield from a large scale naphtha pyrolysis cracking utilizing response surface methodology
    (Universiti Teknologi Malaysia, 2022) Zakria, Mohamad Hafizi
    It is desirable in industry to optimize the production yield from olefin plant, for instance, to achieve the highest profit from the yield of ethylene. However, there are gaps associated with the restricted usage of the proprietary simulation software and the lack of a specific model to correlate the relationship between variables that has a significant impact on the processing parameters. In this study, response surface methodology (RSM) was used to evaluate the impact of critical operating parameters from large scale naphtha pyrolysis cracking. Those parameters include hearth burner flow, integral burner flow, naphtha feed flow, dilution steam flow, and coil outlet temperature (COT), with the addition of propylene yield towards the ethylene yield. The data was collected at the steam cracker furnace using process information management system (PIMS) software, PI process book version 2015. The analysis was conducted for naphtha feedstock with paraffins content at 57.60 - 70.73 vol % to evaluate the impact of operating at different naphtha feedstock compositions on the ethylene yield. Propylene yield, hearth burner flow, and naphtha feed flow consistently showed a significant relationship with ethylene yield from surface response analysis with the interaction factor ranges at -10.07 to 192.3, -0.001698 to 0.01938, and -2.383 to 820, respectively. The final equation models were successfully concluded in the form of quadratic with 2-way interaction at the high paraffins content and linear relation at the lower paraffins content after the models’ validation using probability plot, scatterplot, and Mann-Whitney hypothesis test. The maximum ethylene yield generated from response optimizer was observed dissimilar at 31.46 - 34.97 % for different paraffins content in naphtha feedstock, with the highest reading observed for the naphtha feedstock having the highest paraffins content. The best ethylene yield with consideration to the production cost for the naphtha with the highest paraffins content of 70.73 vol % was identified at the range 34.41 - 34.97 %, using the recommended process ranges at 12.22 - 12.25 % of propylene yield, 11033.90 - 11816.40 kg/hr of hearth burner flow, 66.67 - 67.05 t/hr of naphtha feed flow and 816.38 °C of COT. It is recommended for other large scale plants to adopt the same methodology that was proven successful in this study, for process monitoring and optimization.