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    Effect of SiO2/Al2O3 Ratio of Zeolite Beta in a Bi-functional System for Direct CO2 Hydrogenation into Value Added Chemicals

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    Final_Thesis_Ahmed_Alkhalaf_updated.docx.pdf
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    Ahmed Alkhalaf - Final Thesis
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    Type
    Thesis
    Authors
    Alkhalaf, Ahmed S. cc
    Advisors
    Gascon, Jorge cc
    Committee members
    Sarathy, Mani cc
    Huang, Kuo-Wei cc
    Program
    Chemical Engineering
    KAUST Department
    Physical Science and Engineering (PSE) Division
    Date
    2020-06
    Permanent link to this record
    http://hdl.handle.net/10754/664246
    
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    Abstract
    Carbon dioxide levels in atmosphere are linked with a number of adverse environmental impacts including climate change. CO2 utilization is one of the available technologies to reduce CO2 emissions released into atmosphere by its conversion into value added products. Hydrogenation of CO2 into hydrocarbons (with methanol being an intermediate) can be achieved in a single-pot using bi-functional catalysis system composed of metal/metal-oxide and zeolite. In this study, activated novel indium cobalt (InCo) and zeolite beta samples (BEA) were used for the conversion of CO2 into a hydrocarbon mixture rich of iso-paraffins via methanol in a single pot. The objective was to investigate the effect of zeolite beta acidity (represented by SiO2/Al2O3 ratio) and the configuration of the reactor on the overall performance of the above mentioned bi-functional system. Three samples of zeolite beta with different SiO2/Al2O3 ratios were synthesized in-house (Beta-20, Beta-100 and Beta-300) and used along with commercial beta as methanol to hydrocarbons catalysts. XRD patterns of the synthesized samples showed that all of the obtained samples are zeolite beta with high crystallinity. Adsorption-desorption isotherms of the studied zeolites revealed micro-mesoporosity of the samples. Analysis of SEM images suggests that the particles of the studied samples are of a similar range of size (100-200 nm). Each zeolite sample was used to fill two reactor configurations: dual bed and mixed bed. Samples were tested at a temperature of 300 oC, a pressure of 50 bar and CO2:H2 ratio of 1:4 except for Beta-100 sample which was tested at a CO2:H2 ratio of 1:3. CO2 conversion is a characteristic of the methanol synthesis catalyst (InCo) and it ranged between 15% to 20% for all cases. Dimethyl ether (DME) generation in dual bed configuration was much faster and at much higher rates than in mixed bed configuration for all tested samples, indicating that mixed bed configuration is more stable for this particular system. Heavier hydrocarbons (C6 and C7) are generated in higher amounts over low acidic zeolite beta than over beta of high acidity. More acidic zeolite beta, however, was found to be more stable than beta of less acidity.
    Citation
    Alkhalaf, A. S. (2020). Effect of SiO2/Al2O3 Ratio of Zeolite Beta in a Bi-functional System for Direct CO2 Hydrogenation into Value Added Chemicals. KAUST Research Repository. https://doi.org/10.25781/KAUST-73Z6U
    DOI
    10.25781/KAUST-73Z6U
    ae974a485f413a2113503eed53cd6c53
    10.25781/KAUST-73Z6U
    Scopus Count
    Collections
    Theses; Physical Science and Engineering (PSE) Division; Chemical Engineering Program

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