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Title: Carbon dioxide adsorption on porous materials and its catalytic hydrogenation in supercritical phase
Author: Capezzuoli, Fabio
ISNI:       0000 0004 2743 4095
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2007
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A manometric apparatus for the measurement of adsorption isotherms has been designed, built, tested alongside with an experimental method and used to study the adsorption of carbon dioxide on a small number of porous materials including a commercial silica Crosfield EP10, which is commonly used in research and industry, and zinc oxide catalysts supported on this material. Unfortunately the manometric apparatus and experimental method failed to provide adsorption measurements at supercritical pressures. Hydrogenation of carbon dioxide has been studied with a flow reactor rig optimised for high-pressure work: its salient components are a commercial supercritical pump providing the CO2 feed and a 70 MPa backpressure regulator. The reactant feed is 10% H2 in CO2 with 300 and 600 NmL/min flowrates; pressure is in the 7.5 - 15.0 MPa range and temperature in the packed bed is 225 °C; a gascromatograph connected to the reactor with trace-heated lines is used to analyse the output gas stream. The reactor has been loaded with a conventional packed bed of water-gas shift reaction catalyst (Katalco YAD746974 0.25-0.5 mm, diluted with SiC) obtaining the expected carbon monoxide, methanol and small amounts of heavier oxygenated compounds: acetic acid and methyl acetate. This is probably a result of the relatively long residence times combined with a high carbon dioxide pressure. In these conditions, external mass transfer controls the rate of carbon monoxide production. The reactor has also been loaded with a ceramic rod coated with the same catalyst (ground to a particle size of 38 - 75 vim and diluted with <5 μm zirconia powder), and with this setup, at the same pressures, flowrate and 200 °C at the top of the reactor tube, the rate of carbon monoxide production appears to be controlled by particle activity rather than mass transfer, allowing to calculate the surface reaction rate.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available