Sol-gel (solution-gelation) method was used to prepare Ni-Ti and Ni-Ti-Al catalysts for reforming of methane with carbon dioxide. This method, after optimizing the parameters such as hydrolysis and acid/alkoxide ratio, is able to make a Ni-Ti catalyst with a surface area as high as 426m2/g when calcined at 473K; but calcination at higher temperature lead to dramatic decrease in surface area. XRD, XPS, TEM and SEM were used to understand this change. Using a packed bed reactor, the catalysts were evaluated with the reforming reaction. It was found that the activity of the Ni-Ti catalyst increases with the Ni loading in the range of 1-10wt%. The reduction temperature has strong effect on activity of the reduced catalyst. Up to 973K, the activity increases with the reduction temperature; but after 973K, the activity decreases and become 0 when the temperature is over 1023K. The Ni-Ti catalyst also deactivated as 15% after 4h of time on stream. The XRD analysis shows that Ti3O5 formed in the catalyst after higher-temperature reduction as well as after the reaction for a period of time. The formation of Ti3O5 may render the catalyst to loss its activity. However, further study is expected to understand the mechanism. TG/DTA analysis shows that both Ni-Ti and Ni-Ti-Al catalysts had carbon deposition; but the latter maintained higher activity in a longer period of time.

Syngas is a mixture of hydrogen (H2), carbon monoxide (CO) and other species including nitrogen (N2), water (H2O), methane (CH4) and higher hydrocarbons. Syngas is a highly desired product because it is very versatile. It can be used for combustion in turbines or engines, converted to H2 for use in fuel cells, turned into diesel or other high-molecular weight fuels by the Fischer-Tropsch process and used as a chemical feedstock. Syngas can be derived from hydrocarbons in the presence of oxidizer or water as in steam reforming. There are many demonstrated methods to produce syngas with or without water addition including catalytic methods, plasma reforming and combustion. The goal of this study is to add to the understanding of non-catalytic conversion of hydrocarbon fuels to syngas, and this was accomplished through two investigations: the first on fuel conversion potential and the second on the effect of preheat temperature. A primarily experimental investigation of the conversion of jet fuel and butanol to syngas was undertaken to understand the potential of these fuels for conversion. With these new data and previously-published experimental data, a comparison amongst a larger set of fuels for conversion was also conducted. Significant soot formation was observed in experiments with both fuels, but soot formation was so significant in the jet fuel experiments that it limited the range of experimental operating conditions. The comparison amongst fuels indicated that higher conversion rates are observed with smaller molecular weight fuels, generally. However, equilibrium calculations, which are often used to determine trends in fuel conversion, showed the opposite trend. In order to investigate preheat temperature, which is one important aspect of non-catalytic conversion, experiments were undertaken with burner-stabilized flames that are effectively 1-D and steady-state. An extensive set of model calculations were compared to the obtained experimental data and was used to investigate the effect of preheat temperatures that were beyond what was achievable experimentally. Throughout the range of operating conditions that were tested experimentally, the computational model was excellent in its predictions. Experiments where the reactants were preheated showed a significant expansion of the stable operating range of the burner (increasing the equivalence ratio at which the flame blew off). However, increasing preheat temperature beyond what is required for stabilization did not improve syngas yields. / text

Cotton gins have a readily available supply of biomass that is a by-product of cotton ginning. A 40 bph - cotton gin processing stripped cotton must manage 2,600 to 20,000 tonnes of cotton gin trash (CGT) annually. CGT contains approximately 16.3 MJ/kg (7000 Btu/lb.). CGT has the potential to serve as a renewable energy source. Gasification of biomasses such as CGT can offer processing facilities the opportunity to transform their waste biomass into electricity. The gasification of CGT yields 80% synthesis gas (syngas) and 20% biochar. The concentration of biochar in the syngas needs to be reduced prior to the direct fueling of an internal combustion engine driving a generator for electricity production. It was estimated that direct fueling of an internal combustion engine with syngas to drive the generator to produce electricity would cost $1M per megawatt (MW). In contrast, a 1MW system that consists of a boiler and steam turbine would cost $2M/MW. The current provisional patent for the TAMU fluidized bed gasification (FBG) unit uses a 1D2D and 1D3D cyclone for the removal of biochar. A cyclone test stand was designed and constructed to evaluate cyclone capture efficiencies of biochar. A statistical experiment design was used to evaluate cyclone performances for varying concentrations of biochar. A total of 24 tests for the 1D2D and 36 tests for the 1D3D cyclone were conducted at ambient conditions. Average collection efficiency for the 1D2D cyclone was 96.6% and 96.9% for the 1D3D cyclone. An analysis on the cyclone’s pressure drop was performed to compare the change in pressure drop from air only passing through the cyclone and when the cyclones are loaded with biochar. The average change in pressure drop for the 1D2D cyclone was a decrease of 74%, and the average change in pressure drop for the 1D3D cyclone was a decrease of 36%. An economic feasibility study was conducted to determine the price per kWh to produce electricity for a CGT fueled internal combustion engine power plant (ICPP) and a boiler and steam turbine power plant (SPP). The simulated cotton gin is a 40 bph rated facility operating for 2,000 hours a season (200% utilization) processing stripped cotton that yields approximately 180 kg/bale (400 lbs/bale) of CGT. Revenues consist of the electricity and natural gas expenses incurred during the ginning season, along with the extra electricity produced and sold back to the utility company at the whole price. Loan payments and operating costs include labor, maintenance, taxes, and insurance. Labor costs, the selling price of electricity and biochar are varied in the economic model. The ICPP has a NPV of $1,480,000, and the SPP has a NPV of -$160,000, under the base assumptions. The sensitivity analysis resulted in the selling price of electricity as having the largest change on the NPV for both of the power plants. The average predicted purchase price of electricity is $0.10/kWh for the twenty year simulation. The average price to produce electricity, with no source of revenue generation for the ICPP is $0.20/kWh and $0.26/kWh for the SPP.

The performance characteristics of a diesel fuel piloted syngas compression ignition engine are presented in this thesis. A stock Hatz 1D81 engine was converted to operate in dual fuel mode through the elimination of the governor system and addition of an in-cylinder pressure transducer and custom intake system to facilitate the mixing of the gaseous fuel and combustion air. The engine was run on a Superflow water brake dynamometer and benchmarked with diesel to compare against manufacturer specifications. This was followed by dual fuel operation on methane and syngas, with the results being compared through performance characteristics. When operated on methane, the engine attained higher peak in-cylinder pressures along with higher torque, power, and thermal efficiency values for equal equivalence ratios. It was necessary to use greater amounts of syngas to reach comparable results with methane due to the lower energy content of syngas. The ignition delay was greater for syngas, and the onset of knock occurred earlier with syngas in comparison to methane. The heat release, Q, was comparable for both fuels and the exhaust gas emissions were significantly lower for operation with syngas. With emphasis on clean engine operation, syngas operation proved to be viable due to its renewable nature, significantly lower exhaust gas emissions, equal heat release characteristics, and larger useable operating range when compared to methane. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-05-28 15:02:49.227

Development of an effective High Temperature Fischer-Tropsch Synthesis (HTFTS) catalyst is of interest in process intensification that combines methane reforming with long chain hydrocarbon production. Literature indicates iron catalysts supported on mesoporous silica performed relatively well in high temperature applications. In this work, we investigated the effect of manganese promoter on iron catalysts for FTS at 430 °C as it was known from previous studies that manganese promotion could enhance the CO conversion with higher hydrocarbon yields. Also, the effect of temperature on FTS activity was evaluated by testing the base and promoted Fe/SBA-15 catalysts for temperature ranging from 370 to 430 °C. Incipient wetness impregnation method was used to prepare the catalysts. The catalysts used in this work were un-promoted iron (15 wt%) and Mn promoted (1.4, 2.8, 4.2, 5.6, 11.2 wt%) iron (15 wt%) catalysts supported on SBA-15. The catalysts were characterized using XRD, TPR, N2 Physisorption, and SEM. These catalysts were first activated in synthesis gas (H2: CO = 2:1) at 430 °C and then tested for their catalytic performance at the same temperature and atmospheric pressure. Prior work with SBA-15 supported iron catalysts showed that manganese promotion could improve the CO conversion when compared to copper and potassium. The main goal of this work was to study the effect of varying the manganese content on SBA-15 supported iron catalysts to determine the optimum loading of Mn along with the effect of temperature. It was found that CO conversion increases from 27% to74% with increasing the amount of manganese. The yield of CO2 increased substantially with higher Mn loadings. When different Mn promoted iron catalysts were compared, the catalysts with 2.8 wt% Mn loading showed the best performance in terms of the CO conversion and yield of C2+ hydrocarbons. Catalyst with 2.8 wt% of manganese loading yielded a CO conversion of 54%, with a methane yield of 17%, 32% (carbon) yield of C2- C4 and 9%(carbon) yields of C5+ hydrocarbon products, respectively. The effect of operating temperature on the catalytic performance of both the base catalyst 15Fe/SBA-15 and the promoted 2.8Mn/15Fe/SBA-15 catalyst was also examined. The unpromoted iron catalyst showed an improved catalytic activity at 400 °C with the total CO conversion of 38% and a higher yields of C5+ hydrocarbons. A significant decrease was also observed in the yields of CH4 and CO2. The methane and carbon dioxide yield increased from 11% and 8% to 25% and 40%, respectively, as the temperature increased from 400 to 450 °C. The catalyst with 2.8 wt% of manganese promotion gave better CO conversion and hydrocarbon product yields at 430 °C. Lower temperature showed negative effect on hydrocarbon product yield for manganese promoted catalysts.

Energy use around the world will rise in the coming decades. Renewable energy sources will help meet this demand, but renewable sources suffer from intermittency, uncontrollable power supply, geographic limitations, and other issues. Many of these issues can be mitigated by introducing energy storage technologies. These technologies facilitate load following and can effectively time-shift power. This analysis compares dedicated and synergistic energy storage technologies using energy efficiency as the primary metric. Energy storage will help renewable sources come to the grid, but fossil fuels still dominate energy sources for decades to come in nearly all projections. Carbon capture technologies can significantly reduce the negative environmental impact of these power plants. There are many carbon capture technologies under development. This analysis considers both the innovative and relatively new cryogenic carbon capture™ (CCC) process and more traditional solvent-based systems. The CCC process requires less energy than other leading technologies while simultaneously providing a means of energy storage for the power plant. This analysis shows CCC is effective as a means to capture CO2 from coal-fired power plants, natural-gas-fired power plants, and syngas production plants. Statistical analysis includes two carbon capture technologies and illustrates how uncertainty quantification (UQ) provides error bars for simulations. UQ provides information on data gaps, uncertainties for property models, and distributions for model predictions. In addition, UQ results provide a discrepancy function that can be introduced into the model to provide a better fit to data and better accuracy overall.

No description available.

This research studies the use of class=SpellE>titania (titanium dioxide, TiO2) as a catalyst for deoxygenation of class=SpellE>syngas derived oxygenates. These oxygenates are formed as byproducts when biomass derived syngas (CO & H2) is converted to ethanol on Rhodium or Molybdenum based catalysts. Conversion of these oxygenates to hydrocarbon would enhance the viability of class=SpellE>syngas to gasoline technology. This study revealed that class=SpellE>titania can indeed be used to convert syngas derived oxygenates to hydrocarbon at high temperature and pressure. Acetone condensation to mesitylene was studied very closely. The study revealed that the acid-base dual nature of class=SpellE>titania is key for the success of this reaction. When titaniawas combined with the zeolite H+/ZSM-5, a broad range of gasoline type hydrocarbon could be produced. Ethanol conversion to higher alcohols was studied as part of a partial deoxygenation of ethanol research. While this conversion was possible on class=GramE>titania, zirconia proved to be a better catalyst. Ethanol could be converted to 1-butanol and other higher alcohols at high temperature and pressure. The mechanism by which this occurs was studied as well.

The fermentation of syngas (a mixture of CO, CO2 and H2) to produce ethanol is of interest as an alternative fuel. Clostridium carboxidivorans, has been found to produce higher than average amounts of ethanol and butanol from CO-rich mixtures. This project sought to determine the effects of the redox level in the solution, partial pressures in the headspace and mass transfer limitations on the products obtained through fermentation of syngas. It was determined that cysteine sulfide has a greater effect on the redox level of the media used to grow bacteria, than does the gas composition. Therefore, changing gas composition during the process will have little effect on the redox. However, addition of cysteine sulfide may vary the redox level. When cells were first inoculated, the redox level dropped and leveled at -200 mV SHE for optimal growth. In addition, cells switch from acetic acid to ethanol production after a drop of 40-70 mV in the redox level. Different sizes of reactors were used, including 1 liter reactors (non-pressurized), 50 mL bottles (20 psig) and 100 mL bottles (20 psig). The 50 mL bottles have more than double the growth rate than the 100 mL bottles (0.57 day-1 compared to 0.20 day-1). Partial pressures were measured in these two sizes to determine the different consumptions and the effect of partial pressure on both growth and production of acetic acid/ethanol. It is clear that re-gassing the bottles every 12 hours to keep the pressure higher in the 100 mL bottles makes a significant difference in the growth, making them very similar to the 50 mL bottles. Both the 50 mL and 100 mL bottle were found to have essentially the same mass transfer rate (0.227 L/hr vs. 0.255 L/hr). However, because of headspace differences, there was more CO available for the 50 mL bottles (on a per liter basis) as compared to the 100 mL bottles. Mass transfer analysis proved useful in pointing out that all three reactors likely experienced mass transfer limitations such that mass transfer effects are critical to address when performing studies involving syngas fermentation.

Ethanol usage as a transportation fuel is rapidly increasing in the United States. Production of ethanol from cellulose feedstocks via gasification followed by syngas fermentation offers an environmentally friendly approach that mitigates many of the adverse effects associated with production from corn. In the syngas fermentation process, the hydrogenase enzyme of the fermentation bacterium, Clostridium P11 for this work, supplies electrons to the metabolic pathway, facilitating ethanol production. In this thesis, an assay for P11 hydrogenase activity was developed. It was determined that 1) less than 4 minutes of sparging with 50 sccm H2 is needed to reduce O2 levels to below 1 ppm in a 3 mL aqueous solution, while less than 1 minute of purging at the same rate is needed to fill an air-filled 3.5 mL cuvette to 99.9999% H2, 2) 12.5 mM DTT included in the reaction mixture at pH 6 helps scavenge O2, 3) H2 diffusion is slow compared to enzymatic reaction rates, 4) CO2 lowers media pH, 5) 0.084 atm CO causes 90% inhibition of P11 hydrogenase, 6) prolonged Triton X-100 exposure diminishes hydrogenase activity, and 7) variations in H2 pressure and electron acceptor identity and concentration affect measured hydrogenase activities. The assay developed for P11 hydrogenase activity was used to perform kinetic studies. The Okura rapid-equilibrium rate law best described this activity. A constant that regulates the effect of H2 pressure on hydrogenase activity, KH2, was determined to be independent of electron acceptor and to have a value of 0.31 atm, implying that H2 must be supplied to the syngas fermentation at ~3 atm to maximize hydrogenase activity. KBV and KMV, constants that regulate the effect of benzyl viologen and methyl viologen on hydrogenase activity, were determined to be 1.7-2.4 mM and 10.6 mM, respectively. Additionally, hydrogenase activity was temporally correlated with ethanol production in batch cultures of P11 and strongly dependent on pH. The intracellular pH of P11 was determined to be approximately 5.5.