- Title
- Study on the catalytic hydrogenolysis of cellulose and its derived molecules into value-added polyols using mesoporous catalyst
- Creator
- Mootabadi, Hamed
- Relation
- University of Newcastle Research Higher Degree Thesis
- Resource Type
- thesis
- Date
- 2020
- Description
- Masters Research - Master of Philosophy (MPhil)
- Description
- A high rate of global warming and environmental destruction due to excessive use of petroleum-based energy has triggered recent interest in a renewable energy source which must be feasible from both standpoints of economic and environmental. One of the abundantly available alternative sources for conventional fossil fuel is cellulose. Ethylene glycol (EG) and propylene glycol (PG) are valuable chemicals that can be derived from catalytic conversion of glycerol. The biomass route for EG, PG and glycerol production presents noticeable benefits including the renewable feedstock via a one-pot process compared to the non-renewable multi-step petroleum process. Catalytic conversion of large organic molecules such as cellulose requires catalysts with large pore channels which can accommodate bulky molecules. Therefore, well-ordered mesoporous materials with large pore sizes are an excellent choice to use as a catalyst support in cellulose hydrogenolysis. In the present study, a series of well-ordered aluminum SBA-15 (Al-SBA-15) were successfully synthesized with sensible control on textural properties and amount of acid sites. Nitrogen adsorption-desorption, scanning electron microscopy (SEM), TEM, temperature-programmed desorption (TPD), powder X-ray diffraction (XRD) were applied to characterize the catalysts. The results obtained from the current study suggest that the incorporation of aluminum species into the silica framework plays pivotal part information of the mesostructures. Al atoms could be institute into the mesoporous walls at tetrahedrally coordinated. Large and ordered pore structure was achieved at a hydrothermal time between 24 to 48 h, TEOS/TCP ratio of 2.0, the hydrothermal temperature of 110°C, pH value of 1.5 and Si/Al ratio of 15. The one-pot cellulose hydrogenolysis over Ni-W/Al-SBA-15 with different Ni and W loading was studied. The cellulose conversion of 83.9% achieved with estimated carbon balance of 93.0%. The maximum EG selectivity of 66.3% was obtained using 3%Ni15%W-Al-SBA-15 catalyst. Response surface methodology (RSM) was applied for the optimization of reaction parameters in the cellulose hydrogenolysis process. Based on the proposed model solution, the optimum cellulose conversion of 94.3% was achieved in the reaction the temperature of 229°C, the reaction time of 180 min, pressure of 60 bar and catalyst mass of 15% while a second-order polynomial model equation was suggested. Catalytic conversion of glycerol into PG and EG using Ni-Al-SBA-15 catalyst with different Ni loading was investigated. The glycerol conversion of 79.6% and a carbon balance of 96.0% was observed with a maximum PG selectivity of 64.0% over 10%Ni-Al-SBA-15 catalyst. Response surface methodology (RSM) was employed for the optimization of reaction parameters. The optimum glycerol conversion of 80.2% was achieved in the reaction temperature of 215°C, the reaction time of 11 h, the pressure of 57 bar and catalyst mass of 21% based on the proposed solution from the second-order polynomial model equation. The hexagonal ordering of p6mm symmetry of Al-SBA-15 mesoporous support was preserved after the impregnation of Al-SBA-15 with Ni and W species. The well-ordered structure, high surface area and large pore size of all the mesoporous catalyst were well preserved after catalytic conversion of cellulose as well as glycerol hydrogenolysis. Ni-Al-SBA-15 catalyst showed good stability after five cycles of reuse while a slight drop of 7% in glycerol conversion was observed after five cycles. The hexagonal ordering of Ni-Al-SBA-15 catalyst was also preserved with an insignificant amount of 3.2 ppm Ni leaching into a liquid product. The mass transfer assessment and kinetic reaction for the dehydration hydrogenation of glycerol over Ni/Al-SBA-15 catalysts were studied. The absence of external diffusion, internal particle diffusion, external mass transfer, and heat transfer limit was confirmed. The activation energies of 91, 86 and 95 (kJ/mol) for glycerol conversion, PG and Eg formation were observed, respectively.
- Subject
- mesoporous catalyst; hydrogenolysis; cellulose; value-added polyols; response surface methodology
- Identifier
- http://hdl.handle.net/1959.13/1412483
- Identifier
- uon:36489
- Rights
- Copyright 2020 Hamed Mootabadi
- Language
- eng
- Full Text
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