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Title: Catalytic hydrodeoxygenation of bio-oil and model compounds
Author: Liu, Kai
ISNI:       0000 0004 6423 5247
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2016
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The upgrading of the Norwegian spruce derived bio-oil was carried out in a batch reactor with conditions of 50 bar H2 (cold) and 3 to 13 hr of batch time at 175 to 250 ℃. The emphasis was given on the effect of operating conditions on the hydrodeoxygenation (HDO) performance of unsupported NiMo nano sulphide catalysts. It is found that the degree of deoxygenation of the bio-oil increases and that of hydrogenation of the upgraded products declines with increasing the reaction temperature. The addition of sulphur to prevent the nanosulphide catalyst leaching problem is not essential. Extending the batch time produces more saturated products with less oxygen content, but it can be optimised as the deoxygenation reaction rate decreases along the time. As for HDO solvent, dodecane is preferred comparing with tetralin. The HDO of p-cresol over Co/Al2O3 and Ni/Al2O3 catalysts at 250 to 375 ℃ and 50 bar of H2 (hot) in a batch reactor gives 4-methylcyclohexanol, methylcyclohexane and toluene as the major products. Both catalysts are active leading to almost complete conversion (≥98%) of p-cresol at all temperatures. The degree of deoxygenation and the product distribution of toluene increases with temperature. Toluene can be produced by the direct deoxygenation of p-cresol and by the disproportionation of methylcyclohexenes at high temperature (i.e. 375 ℃). Sulphur suppresses the HDO of p-cresol. It deactivates the hydrogenation sites but does not appear to be a poison for the hydrogenolysis sites. Same conditions were used for the HDO of guaiacol, except the H2 pressure being used was 40 bar (cold). Dominant products are cyclohexanol, methoxycyclohexanols and cyclohexane at 300 ℃ and below and those at 325 ℃ and above are cyclohexane, benzene and ring contraction products (i.e. cyclopentane and methylcyclopentane). High temperatures facilitate deoxygenation and benzene production. As the temperature increases, the methoxyl group is firstly removed and then the hydroxyl group. At 350 ℃, reducing the pressure from 40 bar (cold) to 20 bar (cold) increases the benzene product distribution from 2 wt% to 40 wt%. Sulphur has a detrimental effect on the HDO of guaiacol. Catechol is the main product from guaiacol in the presence of sulphur.
Supervisor: Chadwick, David Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral