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• 1. [Article] Upgrading of a model compound of bio-oil using carbon monoxide in high temperature water

  Meeting the energy demands of the future is one of the most important challenges facing the engineering community today. An example of this problem is transportation fuels. Most of the current transportation ...

  Citation × Citation Citation Abstract Copy Title: Upgrading of a model compound of bio-oil using carbon monoxide in high temperature water Author: Phipps, Ezra Daniel Meeting the energy demands of the future is one of the most important challenges facing the engineering community today. An example of this problem is transportation fuels. Most of the current transportation fuels are composed of petroleum hydrocarbons. Finding a viable alternative is important given the potential scarcity of these fuels. Alternatives have been explored including ethanol, biodiesel, hydrogen, and natural gas. It will be difficult for these fuels to replace petroleum fuels due to their inferior performance and, in some cases, the rising price of the feedstocks as they are produced on a larger scale. In addition, some of these fuels are not compatible with current infrastructures, including piping and filling stations, as well as being incompatible with the current fleet of cars. The ideal scenario for solving the energy problem is to produce a fuel that has the same level of performance as standard petroleum hydrocarbons and originates from a feedstock that is cheap and abundant. For these reasons, a large amount of research in the past couple decades has been dedicated to producing bio-oil from biomass by thermal degradation in the absence of oxygen. Biomass is composed of large oxygenated hydrocarbons containing as many as 60,000 carbons atoms. When subjected to high temperatures these molecules break apart and oil is produced that more closely resemble liquid fuels. The primary drawback of bio-oils is that they have high oxygen content. This high oxygen content causes them to have low energy density, low volatility, and a high viscosity. In order to meet the industry standards for transportation fuels, additional processing steps must be completed in order to reduce the oxygen content of the fuels. The most common processing step in use is hydrotreating. During this process bio-oils are heated up to high temperatures in the presence of an excess of hydrogen and a catalyst. The purpose of this is to initiate a hydrodeoxygenation reaction that removes oxygen from the oils in the form of water. This process has been shown to be effective; however the usefulness of the process is limited by the high cost and energy demands of producing hydrogen. Previous work has also been completed where bio-oils were treated in the absence of hydrogen using high temperature water as a solvent ¹. This process induces a separation of the oil into an aqueous phase and an oil phase which is low in oxygen content. Oxygen is also removed in the form of carbon dioxide due to a decarboxylation reaction. A more detailed review of the material balance for this process demonstrated that the overall amount of oxygen removed was actually quite low and may in fact be statistically insignificant. The purpose of this research project is to examine the process of treating bio-oils with supercritical water as a solvent in the presence of carbon monoxide. One reason for doing this is that at high temperatures, carbon monoxide reacts with water producing hydrogen and carbon dioxide. In addition, thermodynamic modeling demonstrates that carbon dioxide is one of the more favorable products formed when combining these reactants, which would consume additional oxygen. Guaiacol, a model compound for bio-oil was treated by heating to supercritical temperatures in the presence of water and varying concentrations of carbon monoxide. The resulting products were analyzed in order to determine the types of functional groups present, the elemental composition, water content, and in some cases the distribution of products. The analytical results suggest that catechol, methoxybenzene, and phenol are the primary reaction products with most of the catechol dissolved in the aqueous phase. There is some evidence that there is a relationship between the amount of carbon monoxide in the reactor enclosure and a reduction in oxygen content. Due to the small difference in oxygen content of the primary reaction products and the error inherent to the measurement methods it is not conclusive at this time if that the relationship between carbon monoxide and lower oxygen content is statistically significant. Future research is required to further validate the results. To supplement the findings of this research it would be helpful to perform a similar experiment under conditions that produce a larger spread in oxygen content. This can be done in several different ways. The reaction residence time could be increased, a different model compound could be used, the conditions could be more severe, and a catalyst could be used as well. By changing these conditions a greater spread of data could be produced and it would be easier to determine statistical significance on that basis. Title: Upgrading of a model compound of bio-oil using carbon monoxide in high temperature water Author: Phipps, Ezra Daniel Meeting the energy demands of the future is one of the most important challenges facing the engineering community today. An example of this problem is transportation fuels. Most of the current transportation fuels are composed of petroleum hydrocarbons. Finding a viable alternative is important given the potential scarcity of these fuels. Alternatives have been explored including ethanol, biodiesel, hydrogen, and natural gas. It will be difficult for these fuels to replace petroleum fuels due to their inferior performance and, in some cases, the rising price of the feedstocks as they are produced on a larger scale. In addition, some of these fuels are not compatible with current infrastructures, including piping and filling stations, as well as being incompatible with the current fleet of cars. The ideal scenario for solving the energy problem is to produce a fuel that has the same level of performance as standard petroleum hydrocarbons and originates from a feedstock that is cheap and abundant. For these reasons, a large amount of research in the past couple decades has been dedicated to producing bio-oil from biomass by thermal degradation in the absence of oxygen. Biomass is composed of large oxygenated hydrocarbons containing as many as 60,000 carbons atoms. When subjected to high temperatures these molecules break apart and oil is produced that more closely resemble liquid fuels. The primary drawback of bio-oils is that they have high oxygen content. This high oxygen content causes them to have low energy density, low volatility, and a high viscosity. In order to meet the industry standards for transportation fuels, additional processing steps must be completed in order to reduce the oxygen content of the fuels. The most common processing step in use is hydrotreating. During this process bio-oils are heated up to high temperatures in the presence of an excess of hydrogen and a catalyst. The purpose of this is to initiate a hydrodeoxygenation reaction that removes oxygen from the oils in the form of water. This process has been shown to be effective; however the usefulness of the process is limited by the high cost and energy demands of producing hydrogen. Previous work has also been completed where bio-oils were treated in the absence of hydrogen using high temperature water as a solvent ¹. This process induces a separation of the oil into an aqueous phase and an oil phase which is low in oxygen content. Oxygen is also removed in the form of carbon dioxide due to a decarboxylation reaction. A more detailed review of the material balance for this process demonstrated that the overall amount of oxygen removed was actually quite low and may in fact be statistically insignificant. The purpose of this research project is to examine the process of treating bio-oils with supercritical water as a solvent in the presence of carbon monoxide. One reason for doing this is that at high temperatures, carbon monoxide reacts with water producing hydrogen and carbon dioxide. In addition, thermodynamic modeling demonstrates that carbon dioxide is one of the more favorable products formed when combining these reactants, which would consume additional oxygen. Guaiacol, a model compound for bio-oil was treated by heating to supercritical temperatures in the presence of water and varying concentrations of carbon monoxide. The resulting products were analyzed in order to determine the types of functional groups present, the elemental composition, water content, and in some cases the distribution of products. The analytical results suggest that catechol, methoxybenzene, and phenol are the primary reaction products with most of the catechol dissolved in the aqueous phase. There is some evidence that there is a relationship between the amount of carbon monoxide in the reactor enclosure and a reduction in oxygen content. Due to the small difference in oxygen content of the primary reaction products and the error inherent to the measurement methods it is not conclusive at this time if that the relationship between carbon monoxide and lower oxygen content is statistically significant. Future research is required to further validate the results. To supplement the findings of this research it would be helpful to perform a similar experiment under conditions that produce a larger spread in oxygen content. This can be done in several different ways. The reaction residence time could be increased, a different model compound could be used, the conditions could be more severe, and a catalyst could be used as well. By changing these conditions a greater spread of data could be produced and it would be easier to determine statistical significance on that basis. 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