Hydrotreating processes play a vital role in petroleum refineries to meet the increasing demand of transportation fuels. The recent trends in processing of heavier crudes with higher sulphur contents and more stringent product specifications for cleaner transportation fuels, such as ultra-low sulphur diesel, are resulting in more severe operating conditions and higher hydrogen consumption of hydrotreating processes. In order to carry out any revamp or design projects for improving the performance and efficiency of hydrotreating units molecular kinetic models of hydrotreating reactions may be required to provide detailed and accurate information of the composition and properties of hydrotreating products. The overall hydrotreating process consisting of the hydrotreater, the separation system and the associated heat recovery system need to be modelled on a consistent basis of detailed characterisation of petroleum fractions and the interactions of these individual subsystems with each other and with the refinery hydrogen network handled simultaneously for overall process optimisation. A molecular pathways level model of diesel hydrotreating reactions using the molecular type and homologous series matrix is employed for prediction of detailed molecular level information of composition and properties of diesel hydrotreating products. The molecular type and homologous series matrix representation of petroleum fractions is a detailed characterisation approach that represents the composition of a stream in a matrix in terms of the carbon number range and compound classes existing in the petroleum fraction. A new strategy is developed for estimation of physical properties of middle distillate and heavy petroleum fractions with molecular type and homologous series matrix representation using group contribution methods.

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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.

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.

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No description available.

Hydrotreating is the response to the necessity of a cleaner feed for downstream processes and reduced pollution. Hydrotreating catalysts are vital in this process; hence catalyst deactivation is a key issue. The principal objective of this research was the experimental study of hydrotreating catalyst deactivation due to arsenic compounds. The hydrotreating of light gas oil, in the presence and absence of an arsenic compound over a commercial NiMoS catalyst, was investigated in a trickle bed reactor (temperature 315-360˚C, space velocity = 1-3 h-1, pressure = 3MPa). Kinetics of first order for nitrogen and sulphur were found and activation energies values of 32 kj/mol and 76 kj/mol respectively. Studies of activity changes, suggested that arsenic mainly affects the conversion of sulfur compounds; which might indicate that arsenic prefers mainly the S edge of the catalysts. Activation energy values decreased after arsenic introduction, which may suggest pore plugging of the catalyst. / Chemical Engineering

Thesis (M. S.)--Materials Science and Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Carter, W.B.; Committee Member: Cochran, Joseph; Committee Member: Venugopal, Ganesh. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Increased research efforts have recently been accelerated to develop liquid transportation fuels from bio-oil produced by fast pyrolysis. However, these bio-oils contain high levels of oxygenated compounds that require removal to produce viable transportation fuels. A variety of upgrading technologies have been proposed, of which catalytic hydroprocessing of the raw bio-oil has appears to have the best potential due to the fact that no fractionation of the bio-oil is required prior to treatment. The objective of this research was to apply two-stage catalytic hydroprocessing to bio-oil with heterogeneous catalysts to produce hydrocarbon fuels. To achieve this objective seven catalysts were initially compared in first-stage hydrotreating reactions. The result of the comparison of the seven hydrotreating catalysts showed that the MSU-1 catalyst had the significantly highest yield at 38 wt%, had the highest H/C ratio, and reduced oxygen adequately. The MSU-1 catalyst had an energy efficiency of 80%, reduced acid value by 45% and water content by 78%. Higher heating value was doubled by the hydrotreating process of raw bio-oil. Three catalysts were compared as second-stage hydrocracking catalysts. All liquid organic products produced by the catalytic reactions were compared with regard to yield and chemical and physical qualities. Results from these experiments showed that the MSU-2 catalyst had the significantly highest yield at 68 wt%; oxygen value was significantly lower than for the compared catalysts at zero percent. MSU-2 also produced the lowest amount of char at 3.5 wt%. Additionally, MSU-2 produced a high volume of methane gas as a byproduct, with a high value for utilization for production of process heat. A study of reaction time optimization found that best results from application of MSU-2 were for the shortest reaction time of 1 h. This short reaction time is important to reduce hydroprocessing costs. Simulated distillation of hydrocarbon mix results in distribution of these by fuel weights with gasoline comprising 37%, jet fuel 27%, diesel 25% and heavy fuel oil 11%.The energy efficiency of the hydrocracking of first-stage stabilized bio-oil with MSU-2 catalyst was 93.61%.

Hydrotreating reaction of vegetable oil is an alternative method for the production of renewable biodiesel fuel. This reaction involves conversion of triglycerides into normal alkanes, leads to a deoxygenated and stable product, which is fully compatible with petroleum derived diesel fuel. The hydrotreating process uses hydrogen to remove oxygen from triglyceride molecules at elevated temperature in the presence of a solid catalyst. This work focused on the development of microtechnology-based chemical reaction process for liquid biofuel production from oil-based biofuel feedstock. A hydrotreating reaction of oleic acid and triolein as model compounds and jatropha oil as real feedstock was studied in a continuous flow microchannel reactor of inner diameter 500 ��m and of varied length; 1.5 - 5 m. The microchannel reactor was fabricated from SS-316. The walls of the microreactor were coated with a thin Al���O��� film, which was then impregnated with Ni-Mo catalyst containing phosphorus as promoter. The reactions were carried out in the temperature range of 275-325 ��C, residence time in the range of 11-40 s and at constant system pressure of 500 psig. The results showed that the microchannel reactor was suitable for the hydrotreating process. Complete conversion of the fatty acid hydrotreating reaction was achieved at a reaction temperature of 325 ��C. Hydrotreating of fatty acids occurred primarily via hydrodeoxygenation and the main liquid products were octadecane and heptadecane. Fatty alcohol, fatty acid and long chain esters were formed as reaction intermediates. Hydrotreating of triglycerides proceeded via the hydrocracking of triglycerides into diglycerides, monoglycerides and fatty acids. Then fatty acids were subsequently deoxygenated to hydrocarbons. The conversion of fatty acids and triglycerides increased with increasing temperatures. A detailed mathematical model was developed to represent this two-phase chemical reaction process. The mathematical model was entirely based on first principles, i.e. no adjustable or correlation parameters were used. Kinetic parameter estimation was performed and the predicted results were in good agreement with experimental results. / Graduation date: 2013 / Access restricted to the OSU Community, at author's request, from Sept. 17, 2012 - Sept. 17, 2013