Fuels from biomass (biofuels) are used to mitigate the greenhouse gases produced through the utilization of fossil fuels. Non-edible or waste biomass can be pyrolized to produce bio-oil. The oil (an unstable and low energy product) can be further upgraded through hydrodeoxygenation to produce gas and/or diesel range hydrocarbons and value added chemicals. In this research, the valorization of fast pyrolysis bio-oil from maple sawdust was explored in two steps. Primarily, solvent extraction was carried out to remove water from the bio-oil (35% water, 55% oxygen and a heating value of 21.6 MJ/kg). The solvents explored were benzene, ethanol, and chloroform. Chloroform reduced the amount of high molecular oxygenates from 58 to 30%, increased the amount of hydrocarbons from 20 to 41%, and reduced the moisture content to <0.2%. The modified bio-oil was comprised almost entirely of phenol and phenol derivatives. It possessed 42% oxygen and a heating value of 44.0 MJ/kg. Then, the objective was to remove oxygen while obtaining a high yield of hydrocarbons suitable for use as transportation fuels through hydrodeoxygenation. Hydrodeoxygenation of the modified bio-oil was studied with different metal catalysts impregnated on H-ZSM-5 in a batch reactor. H-ZSM-5 was chosen based on results from model compound testing and its use in industry. 8.5-13% Mo, 1-5% Ni, 2.5-5% Sr, 5-10% W, CoMo and NiMo were loaded onto H-ZSM-5 (average pore size, 0.54 nm). The experiments were carried out over a temperature range of 250-350°C, pressure range of 2-5 MPa, stirring speed of 500 rpm, catalyst loading 2-10wt%, and a tetralin to oil ratio of 2-10:1. Tetralin was added as a hydrogen donor solvent and lignin dilutant to prevent polymerization of the feed. The products were coke/tar, gas, water, and an organic liquid. 2.5% Ni/ZSM-5 proved to be the most effective catalyst with 95% oxygen removal and 89.0% yield of hydrocarbons (20% of which were aliphatic). The least effective was 2.5% Sr/ZSM-5 with 87% oxygen removal and 24.5% hydrocarbon yield. The liquid products obtained via 2.5% Ni had a heating value of 47.0 MJ/kg, a moisture content of 0.07%, and a crystallization point of -81.3°C. The products were fully miscible with diesel fuel.
Optimization of the process utilizing statistical design software and 2.5% Ni/ZSM-5 catalyst yielded an experimental hydrocarbon yield of 94.3% (predicted value of 95.3%). The optimum conditions were found to be T=350°C, P=3 MPa, catalyst loading=3.5 g (7 wt%), solvent to oil ratio of 10, rpm=500, and a reaction time of 45 min. The liquid products obtained under optimum conditions contained 22wt% aliphatic hydrocarbons. The physical properties of the liquid product included a high heating value of 47.3 MJ/kg, a low moisture content of 0.07wt%, a close-to-neutral pH of 6.4, and a crystallization temperature of -88.4°C. This data suggests these liquid hydrocarbons could be used as a transportation fuel.
| Identifer | oai:union.ndltd.org:USASK/oai:usask.ca:etd-03192011-172129 |
| Date | 14 April 2011 |
| Creators | Jacobson, Kathlene Laurie |
| Contributors | Dalai, Ajay, Sparks, Gordon, Wang, Hui, Hill, Gordon |
| Publisher | University of Saskatchewan |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-03192011-172129/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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