SYNTHESIS AND CHARACTERIZATION OF CATALYSTS FOR THE SELECTIVE TRANSFORMATION OF BIOMASS-DERIVED MATERIALS

The thermal conversion of lignocellulosic biomass into more fundamental components has gained considerable attention as an alternative energy source, driven by economic, security and environmental concerns of nonrenewable fossil fuels. The biomass-derived streams include liquid (bio-oil), gas (biosyngas) and solid (char) which could serve as a potential feedstock for fuels, chemicals and energy. Generally, the transformation of biosyngas and bio-oil into transportation fuels proceeds through catalytic routes. Biosyngas could be converted into alcohols and alkanes via Fischer-Tropsch synthesis (FTS), while fuels could be formed through the catalytic hydrodeoxygenation (HDO) upgrading of bio-oil. The development of robust catalytic systems to produce fungible fuels is a considerable challenge.
The primary stages of catalyst design include an insight into which fundamental factors affect the overall reactivity of the catalyst. In the first segment of this thesis, a series of silica materials with variable and highly controlled pore sizes were synthesized and used as support for FTS Co catalyst in order to gain insights into the influence of pore diameter on some of the key parameters which contribute to catalytic activity. The results of the present study indicate the importance of careful catalyst characterization in the estimation of the effectiveness of a catalyst.
The second section of this thesis deals with catalytic HDO upgrading of bio-oil. There are two significant challenges in this process: the prevention of coke formation/catalyst deactivation and the selective removal of oxygen without over hydrogenating aromatic and olefinic compounds. Guaiacol, a bio-oil model compound, embodies these challenges because of its propensity for coke formation, and also because of its intransigence to selective deoxygenation. The HDO of guaiacol was used to evaluate the catalytic performance of Mo nitride catalysts. The results show that Mo nitride catalysts have great potential as HDO catalysts due to its selectivity for the rapid transformation of guaiacol to phenol (a less coke-forming product) and its comparable or superior activities to conventional catalysts.