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Title: Oxidative dehydrogenation (ODH) of ethane to ethene over supported vanadium containing oxide catalysts
Author: Khan, Asad Ahmad
ISNI:       0000 0004 5915 0484
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2016
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Abstract:
In this thesis work oxidative dehydrogenation (ODH) of ethane to ethane over MoV oxide catalyst was investigated. The influence of the preparation techniques and different reaction conditions were studied thoroughly. It was found that the precipitation method for the catalyst preparation using variable pH produces a more active catalyst at pH values of 3 to 3.5. Slurry temperature and calcination temperature are also very important parameters which affect the selectivity pattern of the products. This selectivity pattern was found to be further influenced by reaction temperature, pressure, GHSV and ethane-oxygen ratio in the feed. The influence of the V: Mo ratio on the performance of the catalyst for the ODH was investigated by several characterisation techniques, such as BET, XRD, XPS, TEM, SEM, EDX coupled with catalytic performance tests in a fixed bed reactor. The optimum V: Mo ratio was found to be 0.25:1 (i.e., MoV0.40). At this ratio, the oxidation state of vanadium with respect to total vanadium concentration (V5+/Vtotal) is at an optimum in terms of the adsorption strength of the desired products. It was further fine-tuned by investigating the influence of reaction conditions. An improvement on the most active MoV oxide catalyst for the ODH reaction was developed with the addition of oxalic acid as the vanadium dissolution and pH adjustment agent. Addition of oxalic acid influenced the catalytic properties in a variety of ways as observed from characterisation and reaction results. Addition of either a smaller amount or an excess amount compared with the optimal amount has determental impact on the activity of the catalyst. Further catalytic activities were tested by the addition of different types of supports (e.g., ZrO2, TiO2, Nb2O5, SiO2, and AlO3) into the MoV oxide catalytic system. The alumina support was extensively tested with different amounts onto the base MoV oxide for the ethane ODH to ethane.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.687702  DOI: Not available
Keywords: QD Chemistry
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