Catalytic conversion of oxygenates to fuels
Master thesis
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http://hdl.handle.net/11250/2351699Utgivelsesdato
2015Metadata
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Sammendrag
A catalytic study of copper coated on silica CuSiO2, titanium dioxide, TiO2 with and without carbon nanotubes, CNT, as support material and zeolite, HZSM 5, has been performed for conversion of n-propanol into C9+ alkanes and alkenes for jet fuel production. A copper catalyst converts n-propanol to its corresponding aldehyde, propanal, and propanal reacts by aldol condensation over TiO2 to produce long chained alkanes alkenes, aldehydes and ketones. Carboxylic acid in the product was removed by ketonization over TiO2. Since n-propanol contains oxygen, zeolite was applied for removal of oxygen.
Various characterization methods where used to examine the different catalysts. Some of these methods where performed in the specialization project in fall 2014, and these are included in the report when necessary. The X-ray diffraction, XRD, spectra of TiO2 before and after calcination illustrates that the crystallite size of the TiO2 peaks are smaller after calcination and bigger peaks occur before calcination. Temperature programmed desorption, TPD, was used to examine the basic and acid sites of the four different loadings of TiO2 supported on CNT, synthesized in the specialization project, and for CNT and TiO2. Both acid and basic sites where found for all tested catalysts and support, and the basic sites where stronger when TiO2 was coated on CNT than for pure TiO2, except for the 30 wt. % TiO2 /CNT. Strength increased when the loading decreased for all TiO2 /CNT catalysts, except for the 40 wt. % TiO2 catalyst.
A reduction temperature of 230 °C is not high enough for full reduction of the copper catalyst, and a reduction temperature of 300°C gives a higher conversion of reactants to products. Reduction conditions of 1.2 bar and 300°C and reaction conditions of 5 bar and 300°C resulted in the highest selectivity towards C9 hydrocarbons for the tested reduction and reaction conditions. The applied zeolite removed oxygen, and the selectivity towards C9 hydrocarbons was the same for TiO2 with and without CNT a