Anaerobic digestion (AD) is a biochemical process consisting of the microbiological conversion of organic materials for the purpose of generating biogas. Biogas is typically composed of 50 to 70% methane (CH4) and 50 to 30% carbon dioxide (CO2) with trace amounts of other compounds. Anaerobic digestion technology is a bioprocessing technology that has the potential to be integrated into an ethanol facility to further capture energy, in the form of methane gas, for use in a combined heat and power (CHP) generator or for integration into the natural gas pipeline grid after undergoing an upgrading process. The most simplistic design of an AD system is the solid state digester (SSD) which is able to process very high solids content materials (greater than 15% solids). A SSD has the potential to be utilized as a manure management system in a beef cattle feedlot and it has the potential to integrate seamlessly into a combined ethanol- feedlot operation to capitalize on the eco-cluster concept in bioenergy production. This thesis investigates the biogas and digestate composition seen from four material blends in a solid-state digester (SSD) system operated as a batch reactor. Wet distiller grains (WDG) from a grain ethanol process and cattle manure were the substrates investigated. To assess the biogas composition the system was operated over a period of time to achieve a quasi steady state within the microbial population to maximize the CH4 concentration in the biogas composition. To assess the robustness of the microbial population within each substrate blend, the biogas concentrations were measured over three cycle periods where a portion of the used substrate was replaced with an equal amount of fresh substrate. The digestate composition was analyzed at the end of each of the cycles and compared with the raw substrate to determine changes in solids and nutrient values. The biogas production calculated in this study determined 0.17, 0.21, 0.18, and 0.12L per gram (VS) within 100% WDG, 75%WDG and 25% manure, 25% WDG and 75% manure and the 100% manure substrate (Group 1 through 4) respectively, averaged over all three digestion cycles. At the end of three cycles of digestion the biogas within the substrate blend containing 25% WDG and 75% manure (Group 3) achieved a measured CH4 concentration of 49% and the biogas within the 100% manure substrate (Group 4) achieved a 59% concentration of CH4. The duration for each of Group 3 and Group 4 to achieve the production of viable biogas was 100 and 90 days of operation respectively. Thus it can be concluded that a SSD system start up duration will be between three and four months in duration. The gas data gathered in this research study indicates Group 3 had the most robust methanogenic culture established as it has the lowest overall N2 and CO2 concentration detected in the biogas, and the most consistent performance of CH4 production during each cycle. The investigation conducted on the nutrient data gathered in this research supports the conclusion drawn from the gas data regarding the overall methanogenic performance of the substrate blends. The nutrient data for Group 3 maintained an average carbon to nitrogen (C:N) ratio of 25:1 over all three digestion cycles. The nitrogen, phosphorous, potassium, and sulphur components of the manure fertilizer value were maintained through the digestion process of this investigation thus typical manure application rate calculations are applicable when field applying digestate.

A crucial question in drug addiction research concerns whether the varying reports of dopamine-independent and dopamine-dependent motivation can be integrated. According to one theory, the prior drug history of a subject — that is to say, whether they have received minimal or chronic drug exposure — determines whether opiate motivation is dependent upon the brainstem tegmental pedunculopontine nucleus (TPP) or dopamine neurotransmission. The biological analogue of this change is thought to be a switch in the signalling properties (from hyperpolarizing to depolarizing) of ventral tegmental area (VTA) gamma-aminobutyric acid subtype-A (GABAA) receptors. In this thesis, I demonstrate that the mechanisms underlying opiate motivation can be selected artificially by manipulating the signalling properties of VTA GABAA receptors, irrespective of the past drug history of the subject. Furthermore, I suggest that these same VTA GABAA receptors also play a similar role in controlling ethanol motivation. Indeed, the mechanisms underlying ethanol motivation can be doubly dissociated in a manner similar to that observed with opiates. However, whereas opiate motivation is TPP-dependent in the drug-naive state, I found that ethanol motivation was dependent on dopamine neurotransmission (via the D2 receptor) in drug-naive animals. Conversely, ethanol motivation was TPP-dependent in ethanol-deprived mice (as opposed to opiate motivation being dopamine-dependent in opiate-deprived animals). These effects are consistent with a VTA GABAA receptor switching mechanism identical to the one seen in the case of opiate motivation.

Many recent studies on the relative costs and benefits of biofuels have raised the need for a detailed and rigorous analysis of the operations of a biorefinery that is focused on optimization. The current thesis concentrates on the design and optimization of plants for producing biodiesel and ethanol from cellulosic biomass. We have performed numerical simulations combined with systematic parametric analyses to investigate the effect of various parameters on the overall material and energy balances of each biorefinery. The efficiency of the simulated processes was investigated by introducing and/or estimating various metrics in order to select the more beneficial directions for process improvements. Particular emphasis has been paid on heat integration and the design of highly efficient combined heat and power (CHP) units that generate the steam and electricity needed for the purification of biofuels and their co-products. The first part of the thesis is focused on biodiesel production via transesterification of soybean oil with methanol, under alkali-catalyzed conditions. We have analyzed the performance of several reactor configurations in order to improve the conversion of the reversible transesterification reactions. The effect of the oil to alcohol ratio has also been extensively explored. Furthermore, the energy requirements of the simulated process have been rigorously calculated. Since biodiesel facilities can be used either for small-scale, distributed applications or for large-scale production, we have explored whether it is more energy efficient to burn the glycerol-rich stream in a combined heat and power (CHP) plant, or purify the glycerol and use it a feedstock for producing higher-value chemicals with further biotechnological processes. The second part of the thesis focuses on the production of cellulosic ethanol. Having developed the process model, a detailed parametric analysis was carried out to determine how the energy balances and overall efficiency of the biorefinery were influenced by changes in (a) the composition of the biomass feedstock, and (b) the conversion levels of the hydrolysis and fermentation stages. Furthermore, the requirements of the utility section of the ethanol plant were calculated. The utility section included a combined heat and power unit where by-product streams of the production process were utilized for energy generation. The parametric analysis indicated that these streams were in most cases an insufficient fuel source for meeting the energy requirements of the plant and thus, additional fuel was required (biomass, coal, or natural gas). The calculations of this section indicated a significant trade-off between ethanol production and external energy inputs, thus casting some doubt on the ultimate effectiveness of efforts to develop genetically modified energy crops (with high carbohydrate content) in order to maximize fuel production.

The conversion of ethanol to hydrogen or syngas can be achieved by reacting ethanol with water via steam reforming, CH3CH2OH + (1-x)H2O = (4-x)H2 + (2-x)CO + xCO2 (R.1) CH3CH2OH + H2O = 4H2 + 2CO (R.2) CO + H2O = H2 + CO2 (R.3) Ideally, the ethanol steam reforming reaction can achieve a hydrogen yield of 6 moles of hydrogen per mole of ethanol when the value of x in (R.1) equals 2. High theoretical H2 yield makes ethanol steam reforming a very attractive route for H2 production. Thermodynamic equilibrium studies have shown that ethanol steam reforming produces mixtures of H2, CO, CO2, and CH4 below 950 K, while above 950 K the ethanol steam reforming reaction (R.1) adequately describes the product composition In this study a series of 10wt% Ni loaded Mg-Al mixed oxide supported catalysts were evaluated for the production of hydrogen via the steam reforming of ethanol. Mg-Al mixed oxide supported nickel catalysts were found to give superior activity, steam reforming product selectivity (H2 and COx), and improved catalyst stability than the pure oxide supported nickel catalyst at both temperatures investigated. Activity, product selectivity, and catalyst stability were dependent upon the Al and Mg content of the support. At 923 K, the Mg-Al mixed oxide supported nickel catalysts were the best performing catalysts exhibiting the highest steam reforming product yield and were highly stable, showing no signs of deactivation after 20 h of operation. The improved performance of the Mg-Al mixed oxide supported catalysts was related to the incorporation of the pure oxides, MgO and Al2O3, into MgAl2O4. The formation of MgAl2O4 reduced nickel incorporation with the support material since MgAl2O4 does not react with Ni; therefore, nickel was retained in its active form. In addition, incorporation of Mg and Al in to MgAl2O4, a slight basic material, modified the acid-base properties resulting in a catalyst that exhibited moderate acidic and basic site strength and density compared to the pure oxide supported catalysts. Moderation of the acid-base properties improved the activity, selectivity, and stability of the catalysts by reducing activity for by-product reactions producing ethylene and acetaldehyde. At lower reaction temperatures, below 823 K, Mg-Al mixed oxide supported nickel catalysts experienced substantial deactivation resulting in reduced ethanol conversion but interestingly, the H2 and CO2 yields increased, exceeding equilibrium expectations with time on stream while CH4 yield decreased far below equilibrium expectations, suggesting a direct ethanol steam reforming reaction pathway. Over stabilized Mg-Al mixed oxide supported nickel catalysts, direct ethanol steam reforming was activated by a reduction in the catalyst’s activity for the production and desorption of CH4 from the surface. The effect of pressure on the direct ethanol steam reforming reaction pathway over stabilized Mg-Al mixed oxide supported nickel catalysts was investigated at 673 and 823 K. At 823 K, increasing the total pressure resulted in a product distribution that closely matched the thermodynamic expectations. However, at 673 K, the product distribution deviated from thermodynamic expectations, giving substantially greater yields for the steam reforming products, H2, CO, and CO2, while CH4 yield was consistently less than equilibrium expectations. The identification of an alternative direct ethanol steam reforming reaction pathway at relatively low temperatures (below 823 K) that could be operated at elevated pressures will result in an energy efficient process for the production of hydrogen from bio-ethanol.

The increasing use of ethanol as a gasoline additive has raised concerns over the potential impacts ethanol might have on groundwater contamination. In North America, 10% ethanol is commonly being added to gasoline (termed E10). Ethanol is usually denaturated with gasoline compounds before being transported; consequently E95 (95% ethanol) mixtures are also common. Therefore, spills with compositions ranging from E10 to E95 can be anticipated. The compounds of main concern associated with gasoline spills are benzene, toluene, ethylbenzene and xylenes (BTEX), trimethylbenzenes (TMBs) and naphthalene, due to their higher mobility and potential risks to human health. Ethanol is thought to increase mobility of the NAPL, create higher hydrocarbon concentrations in groundwater due to cosolvency, and decrease the rate of gasoline hydrocarbon biodegradation, with consequent increase in the length of the dissolved plumes. The objective of this research was to improve the knowledge about ethanol fate in the subsurface and the impacts it might have on the fate of gasoline compounds. To investigate that, laboratory experiments and controlled field tests supported by numerical modeling were conducted. To evaluate the impact of ethanol on dissolved hydrocarbon plumes, data from a controlled field test were evaluated using a numerical model. The mass discharge of BTEX, TMB and naphthalene from three sources (E0, E10 and E95) emplaced below the water table was compared to simulation results obtained in the numerical model BIONAPL/3D. It was shown that if ethanol fuel mixtures get below the water table, ethanol is dissolved and travels downgradient fast, in a short slug. Mass discharge from the E0 and E10 sources had similar hydrocarbon decay rates, indicating that ethanol from E10 had no impact on hydrocarbon degradation. In contrast, the estimated hydrocarbon decay rates were significantly lower when the source was E95. The aquifer did not have enough oxygen to support the mass loss observed assuming complete mineralization. Assuming a heterogeneous distribution of hydraulic conductivity did little to overcome this discrepancy. A better match between the numerical model and the field data was obtained assuming partial degradation of hydrocarbons to intermediate compounds, with consequent less demand for oxygen. Besides depending on the concentration of ethanol in the groundwater, the impact of ethanol on hydrocarbon degradation appears to be highly dependent on the aquifer conditions, such as availability of electron acceptors and adaptation of the microbial community. Another concern related to ethanol biodegradation is formation of explosive levels of methane. In this study, methane δ13C from toluene and ethanol as substrates was evaluated in microcosm tests. It was shown that methane is enriched in δ13C when ethanol is the substrate. Ethanol derived methane δ13C is in the range of -20‰ to 30‰, while methane from gasoline is around -55‰. The different ranges of δ13C allow it to be used as a tool to identify methane’s origin. This tool was applied to seven ethanol-gasoline contaminated sites. Methane origin could be clearly distinguished in five of the seven sites, while in the other two sites methane appears to have been produced from both ethanol and gasoline. Both ethanol and gasoline were identified as the source of methane in hazardous concentrations. The behaviour of ethanol fuels in the unsaturated zone was evaluated in 2-dimensional (2-D) lab tests and in a controlled field test. In the 2-D lab tests, dyed gasoline and ethanol were injected in the unsaturated zone simulated in a transparent plexiglass box packed with glass beads. Tests were performed under both static conditions and with horizontal groundwater flow. It was confirmed that some ethanol can be retained in the unsaturated zone pore water. However, most of the ethanol went through the unsaturated zone and reached the pre-existing gasoline pool. Ethanol displaced the NAPL to deeper positions, and it was shown that for large ethanol releases much of the gasoline can be displaced to below the water table. The ethanol that reaches the capillary fringe was shown to travel downgradient rapidly at the top of the capillary fringe, while ethanol was also retained in the unsaturated zone. The behaviour of ethanol fuel spills was further evaluated in a controlled field test. 200L of E10 containing around 5% MTBE was released into the unsaturated zone. Groundwater concentrations of ethanol, MTBE, BTEX, TMB and naphthalene above and below the water table were monitored downgradient of the source in multilevel wells. Lab tests were performed to evaluate the applicability of these samplers for volatile organic compounds. It was shown that volatilization losses might be significant when bubbles formation in the sampling line could not be avoided. A method for losses estimation and correction of the concentrations was developed. Concentrations in the source zone were measured in soil samples. Despite the thin (35 cm) unsaturated zone at the site, most of the ethanol was retained in the unsaturated zone pore water, above the capillary fringe. Being in zones of low effective hydraulic conductivity, ethanol was not transported downgradient, and remained in the unsaturated zone for more than 100 days. Ethanol mass discharge was much lower than would be anticipated based solely on the ethanol fraction in the gasoline and on its solubility. Oscillations in the water table, particularly when a shallow position was maintained for prolonged periods, flushed some ethanol to zones with high water saturation, where horizontal transport occurred. The ethanol that reaches the saturated zone appears in the downgradient wells as a slug, with relatively low concentrations. No effect of ethanol on gasoline hydrocarbons was observed, a consequence of most of the ethanol being retained in the unsaturated zone. In summary, spills of ethanol fuels might have two different outcomes, depending on whether most of the ethanol is retained in the unsaturated zone or if most reaches the capillary fringe and the saturated zone. The relation between the ethanol volume spilled and the retention capacity of the unsaturated zone will control the spill behaviour. The volume of ethanol that can be retained in the unsaturated zone is a function of the volume of water that is contacted by the infiltrating NAPL. Therefore, the type of soil, heterogeneities, depth to the water table and area of the spill will be determinant factors. If a relatively large volume of ethanol reaches the capillary fringe, ethanol will travel rapidly in the groundwater possibly in high concentrations, potentially enhancing dissolved hydrocarbon plumes. However, when most of the ethanol is retained in the unsaturated zone, it will likely be detected downgradient only in low concentration, and in pulses spread in time. In this scenario, impact on hydrocarbon plumes will be minor.

This essay is written within my education for Technical Officer in the Swedish armed forces. The essay describes the alternative fuels that the Swedish armed forces can make use of if the supply of fossil fuels is insecure. The alternative fuels that are described and compared are; Synthetic diesel, Organic diesel, Methanol and Ethanol. The essay describes the process of producing the alternatives, the need for modification and the economics for each alternative. The alternatives are compared and assessed for their ability to secure the supply of fuel to the Swedish Armed Forces. The result of the study is that, while synthetic diesel has the best chemical constitution but is not produced in Sweden, the best alternative fuel for the Swedish armed forces at this moment is organic diesel.

The conversion of ethanol to hydrogen or syngas can be achieved by reacting ethanol with water via steam reforming, CH3CH2OH + (1-x)H2O = (4-x)H2 + (2-x)CO + xCO2 (R.1) CH3CH2OH + H2O = 4H2 + 2CO (R.2) CO + H2O = H2 + CO2 (R.3) Ideally, the ethanol steam reforming reaction can achieve a hydrogen yield of 6 moles of hydrogen per mole of ethanol when the value of x in (R.1) equals 2. High theoretical H2 yield makes ethanol steam reforming a very attractive route for H2 production. Thermodynamic equilibrium studies have shown that ethanol steam reforming produces mixtures of H2, CO, CO2, and CH4 below 950 K, while above 950 K the ethanol steam reforming reaction (R.1) adequately describes the product composition In this study a series of 10wt% Ni loaded Mg-Al mixed oxide supported catalysts were evaluated for the production of hydrogen via the steam reforming of ethanol. Mg-Al mixed oxide supported nickel catalysts were found to give superior activity, steam reforming product selectivity (H2 and COx), and improved catalyst stability than the pure oxide supported nickel catalyst at both temperatures investigated. Activity, product selectivity, and catalyst stability were dependent upon the Al and Mg content of the support. At 923 K, the Mg-Al mixed oxide supported nickel catalysts were the best performing catalysts exhibiting the highest steam reforming product yield and were highly stable, showing no signs of deactivation after 20 h of operation. The improved performance of the Mg-Al mixed oxide supported catalysts was related to the incorporation of the pure oxides, MgO and Al2O3, into MgAl2O4. The formation of MgAl2O4 reduced nickel incorporation with the support material since MgAl2O4 does not react with Ni; therefore, nickel was retained in its active form. In addition, incorporation of Mg and Al in to MgAl2O4, a slight basic material, modified the acid-base properties resulting in a catalyst that exhibited moderate acidic and basic site strength and density compared to the pure oxide supported catalysts. Moderation of the acid-base properties improved the activity, selectivity, and stability of the catalysts by reducing activity for by-product reactions producing ethylene and acetaldehyde. At lower reaction temperatures, below 823 K, Mg-Al mixed oxide supported nickel catalysts experienced substantial deactivation resulting in reduced ethanol conversion but interestingly, the H2 and CO2 yields increased, exceeding equilibrium expectations with time on stream while CH4 yield decreased far below equilibrium expectations, suggesting a direct ethanol steam reforming reaction pathway. Over stabilized Mg-Al mixed oxide supported nickel catalysts, direct ethanol steam reforming was activated by a reduction in the catalyst’s activity for the production and desorption of CH4 from the surface. The effect of pressure on the direct ethanol steam reforming reaction pathway over stabilized Mg-Al mixed oxide supported nickel catalysts was investigated at 673 and 823 K. At 823 K, increasing the total pressure resulted in a product distribution that closely matched the thermodynamic expectations. However, at 673 K, the product distribution deviated from thermodynamic expectations, giving substantially greater yields for the steam reforming products, H2, CO, and CO2, while CH4 yield was consistently less than equilibrium expectations. The identification of an alternative direct ethanol steam reforming reaction pathway at relatively low temperatures (below 823 K) that could be operated at elevated pressures will result in an energy efficient process for the production of hydrogen from bio-ethanol.

The increasing use of ethanol as a gasoline additive has raised concerns over the potential impacts ethanol might have on groundwater contamination. In North America, 10% ethanol is commonly being added to gasoline (termed E10). Ethanol is usually denaturated with gasoline compounds before being transported; consequently E95 (95% ethanol) mixtures are also common. Therefore, spills with compositions ranging from E10 to E95 can be anticipated. The compounds of main concern associated with gasoline spills are benzene, toluene, ethylbenzene and xylenes (BTEX), trimethylbenzenes (TMBs) and naphthalene, due to their higher mobility and potential risks to human health. Ethanol is thought to increase mobility of the NAPL, create higher hydrocarbon concentrations in groundwater due to cosolvency, and decrease the rate of gasoline hydrocarbon biodegradation, with consequent increase in the length of the dissolved plumes. The objective of this research was to improve the knowledge about ethanol fate in the subsurface and the impacts it might have on the fate of gasoline compounds. To investigate that, laboratory experiments and controlled field tests supported by numerical modeling were conducted. To evaluate the impact of ethanol on dissolved hydrocarbon plumes, data from a controlled field test were evaluated using a numerical model. The mass discharge of BTEX, TMB and naphthalene from three sources (E0, E10 and E95) emplaced below the water table was compared to simulation results obtained in the numerical model BIONAPL/3D. It was shown that if ethanol fuel mixtures get below the water table, ethanol is dissolved and travels downgradient fast, in a short slug. Mass discharge from the E0 and E10 sources had similar hydrocarbon decay rates, indicating that ethanol from E10 had no impact on hydrocarbon degradation. In contrast, the estimated hydrocarbon decay rates were significantly lower when the source was E95. The aquifer did not have enough oxygen to support the mass loss observed assuming complete mineralization. Assuming a heterogeneous distribution of hydraulic conductivity did little to overcome this discrepancy. A better match between the numerical model and the field data was obtained assuming partial degradation of hydrocarbons to intermediate compounds, with consequent less demand for oxygen. Besides depending on the concentration of ethanol in the groundwater, the impact of ethanol on hydrocarbon degradation appears to be highly dependent on the aquifer conditions, such as availability of electron acceptors and adaptation of the microbial community. Another concern related to ethanol biodegradation is formation of explosive levels of methane. In this study, methane δ13C from toluene and ethanol as substrates was evaluated in microcosm tests. It was shown that methane is enriched in δ13C when ethanol is the substrate. Ethanol derived methane δ13C is in the range of -20‰ to 30‰, while methane from gasoline is around -55‰. The different ranges of δ13C allow it to be used as a tool to identify methane’s origin. This tool was applied to seven ethanol-gasoline contaminated sites. Methane origin could be clearly distinguished in five of the seven sites, while in the other two sites methane appears to have been produced from both ethanol and gasoline. Both ethanol and gasoline were identified as the source of methane in hazardous concentrations. The behaviour of ethanol fuels in the unsaturated zone was evaluated in 2-dimensional (2-D) lab tests and in a controlled field test. In the 2-D lab tests, dyed gasoline and ethanol were injected in the unsaturated zone simulated in a transparent plexiglass box packed with glass beads. Tests were performed under both static conditions and with horizontal groundwater flow. It was confirmed that some ethanol can be retained in the unsaturated zone pore water. However, most of the ethanol went through the unsaturated zone and reached the pre-existing gasoline pool. Ethanol displaced the NAPL to deeper positions, and it was shown that for large ethanol releases much of the gasoline can be displaced to below the water table. The ethanol that reaches the capillary fringe was shown to travel downgradient rapidly at the top of the capillary fringe, while ethanol was also retained in the unsaturated zone. The behaviour of ethanol fuel spills was further evaluated in a controlled field test. 200L of E10 containing around 5% MTBE was released into the unsaturated zone. Groundwater concentrations of ethanol, MTBE, BTEX, TMB and naphthalene above and below the water table were monitored downgradient of the source in multilevel wells. Lab tests were performed to evaluate the applicability of these samplers for volatile organic compounds. It was shown that volatilization losses might be significant when bubbles formation in the sampling line could not be avoided. A method for losses estimation and correction of the concentrations was developed. Concentrations in the source zone were measured in soil samples. Despite the thin (35 cm) unsaturated zone at the site, most of the ethanol was retained in the unsaturated zone pore water, above the capillary fringe. Being in zones of low effective hydraulic conductivity, ethanol was not transported downgradient, and remained in the unsaturated zone for more than 100 days. Ethanol mass discharge was much lower than would be anticipated based solely on the ethanol fraction in the gasoline and on its solubility. Oscillations in the water table, particularly when a shallow position was maintained for prolonged periods, flushed some ethanol to zones with high water saturation, where horizontal transport occurred. The ethanol that reaches the saturated zone appears in the downgradient wells as a slug, with relatively low concentrations. No effect of ethanol on gasoline hydrocarbons was observed, a consequence of most of the ethanol being retained in the unsaturated zone. In summary, spills of ethanol fuels might have two different outcomes, depending on whether most of the ethanol is retained in the unsaturated zone or if most reaches the capillary fringe and the saturated zone. The relation between the ethanol volume spilled and the retention capacity of the unsaturated zone will control the spill behaviour. The volume of ethanol that can be retained in the unsaturated zone is a function of the volume of water that is contacted by the infiltrating NAPL. Therefore, the type of soil, heterogeneities, depth to the water table and area of the spill will be determinant factors. If a relatively large volume of ethanol reaches the capillary fringe, ethanol will travel rapidly in the groundwater possibly in high concentrations, potentially enhancing dissolved hydrocarbon plumes. However, when most of the ethanol is retained in the unsaturated zone, it will likely be detected downgradient only in low concentration, and in pulses spread in time. In this scenario, impact on hydrocarbon plumes will be minor.

<p>The purpose of this work was to design and to develop a high performance catalyst for the production of hydrogen from reforming of crude ethanol and also, to develop the kinetics and reactor model of crude ethanol reforming process. Crude ethanol reforming is an endothermic reaction of ethanol and other oxygenated hydrocarbons such as (lactic acid, glycerol and maltose) with water present in fermentation broth to produce hydrogen (H2) and carbon dioxide (CO2). Ni/Al2O3 catalysts were prepared using different preparation methods such as coprecipitation, precipitation and impregnation methods with different Ni loadings of 10 25 wt.%, 10-20 wt.%, and 10-20 wt.% respectively.</p><p>All catalysts were characterised by thermogravimetric/differential scanning calorimetry (TG/DSC), X-ray diffraction (XRD), (including X-ray line broadening), temperature programmed reduction (TPR), BET surface area measurements, pore volume and pore size distribution analysis. TG/DSC analyses for the uncalcined catalysts showed the catalyst were stable up from 600oC. XRD analyses showed the presence of NiO, NiAl2O4 and Al2O3 species on the calcined catalysts whereas Ni, NiAl2O4, and Al2O3 were present on reduced catalysts. BET surface area decreased and average pore diameter reached a maximum and then decreased as the Ni loading increased. The temperature programmed reduction profiles showed peaks corresponding to the reduction of NiO between 400-600oC and reduction of NiAl2O4 between 700-800oC. Catalyst screening was performed in a micro reactor with calcination temperature, reaction temperature and the ratio of catalyst weight to crude ethanol flow rate (W/Fcrude-C2H5OH) of 600 oC, 400oC and 0.59 h respectively. Maximum crude-ethanol conversion of 85 mol% was observed for catalyst with 15wt% Ni loading prepared by precipitation method (PT15), while maximum hydrogen yield (= 4.33 moles H2 / mol crude-ethanol feed) was observed for catalyst with 15wt% Ni loading prepared by coprecipitation (CP15). </p><p>Performance tests were carried out on (CP15) in which variables such as space velocity (WHSV) 1.68h-1to 4.68h-1, reduction temperature 400 to 600oC and reaction temperature 320 to 520 oC, were changed for optimum performance evaluation of the selected catalyst. The catalyst deactivated over first three hours of 11 hours time-on-stream (TOS) before it stabilized, the reaction conditions resulted in a drop of ethanol conversion from 80 to 70mol%.</p><p>The compounds identified in the liqiud products in all cases were ethanoic acid, butanoic acid, butanal, propanone, propanoic acid, propylene glycol and butanedioic acid. The kinetic analysis was carried out for the rate data obtained for the reforming of crude ethanol reaction that produced only hydrogen and carbon dioxide. These data were fitted to the power law model and Eldey Rideal models for the entire temperature range of 320-520 oC. The activation energy found were 4405 and 4428 kJ/kmol respectively. Also the simulation of reactor model showed that irrespective of the operating temperature, the benefit of an increase in reactor length is limited. It also showed that by neglecting the axial dispersion term in the model the crude ethanol conversion is under predicted. In addition the beneficial effects of W/FAO start to diminish as its value increases (i.e. at lower flow rates).

The renewable energy industry continues to expand at a rapid pace. New advances in cellulosic ethanol technologies have the potential to reduce our dependency on foreign oil. The evolution of these new biofuel markets could have significant effects on future production levels, market prices, and world trade levels for various agricultural commodities. Alternative scenarios involving new biofuel technologies, primary factor availability, and government policy will result in very different outcomes for the agricultural economy. The interactions of current and new biofuel technologies, including conventional ethanol production (from corn grain) and cellulosic ethanol production (from corn stover and switchgrass), and the agricultural economy were examined in a general equilibrium framework. Various outcomes were examined with attention primarily focused on (1) trade offs among competing uses of agricultural commodities, (2) changes in the output of major agricultural producers competing with the U.S., (3) effects on the livestock industry, (4) profitability of the agricultural industry, (5) changes in input costs, including land rents, and (6) changes in land use patterns. Results indicated that advances in cellulosic ethanol technology led to less grain ethanol production and more stover ethanol production in the United States. The production of switchgrass ethanol was not economically feasible under any scenario, which was expected due to the availability of lower priced corn stover. Overall, it was expected that a decrease in the costs of cellulosic ethanol production would lead to a higher increase in total U.S. ethanol production than actually occurred. As a result, the effects on the world economy were smaller than expected.