The project goal is to investigate the effective management of hydrogen during the upgrading of feedstocks with high aromatics content. It is proposed that this goal be accomplished through the development of an understanding of the relationship between the distribution of the hydrogenated products in the process streams and the conditions of their formation, i.e., temperature and pressure.
Oak Ridge National Laboratory (ORNL) , Oak Ridge, TN
This project is a continuation of FEAC315. Worldwide demand for petroleum products, especially cleaner products, continues to expand as more nations develop. However, when demand is analyzed in terms of the three major classes of petroleum cuts— light products such as gasoline and petrochemical feedstocks, middle distillates such as jet fuels and diesel, and heavy products such as fuel oils and lubricants—then it becomes apparent that there has been a drastic shift in emphasis toward light products. At the same time, the quality of crude oil processed by U.S. refineries has declined (sulfur and metals content has increased while API gravity has declined). As the API gravity of crude oil falls, the aromatic content increases, and optimum processing conditions for the light crudes no longer hold. The shift away from optimization, such as increased coke formation, is well-documented in the literature. New or revised process conditions are necessary for continued high thermal refining efficiency of the evolving crude slate. Before developing new correlations, it is necessary to characterize several crude oils that span the range of those entering the refinery. Detailed characterization of several crudes will set the bounds for the correlations and aid in their development with a minimum of experimental work. Catalytic hydroprocessing continues to be the core method for upgrading feedstocks with high sulfur and aromatics content, the content of which will come under increasingly tighter strictures in the years to come. The simultaneous reduction of both sulfur and aromatics in heavy petroleum will require careful management of hydrogen during hydroprocessing.
Other contributions to the problem in managing hydrogen result from mandated lower gasoline temperature endpoints and reduced sulfur levels. Hence, targeting the use of hydrogen exactly where it will do the most good is paramount to economic refining. Overhydrogenation will have to be minimized.
Small changes in hydrogenation efficiency (hydrogen use) for upgrading petroleum feedstock with high aromatics content can reduce the cost that a consumer sees at the gasoline or diesel pump. With increasing demands for cleaner motor fuels and declining crude oil quality that a refiner processes, these two conflicting demands make efficient use of hydrogen more critical than ever. Future fuel quality standards will demand even more hydrogen to make even cleaner products. With the U.S. consuming over 21 million barrels per day of petroleum products, small changes in efficiency can have a large dollar impact on the U.S. economy. The thermodynamic measurements that lead to an understanding of the relationship between the distribution of the hydrogenated products in the process streams, and the conditions of their formation, i.e., temperature and pressure, will impact hydrogenation process design and operation within a refinery.
In this ongoing portion of the program, four publications were completed and published in FY04, two published in FY05, and five published by January 2007.
The research is defining the boundaries within which both molecular simulations and molecular computations (at the B3LYP level of theory) can realistically and accurately define thermophysical properties for the heavier components of fossil fuels.
The research defined—for the first time other than by estimation—the conditions for the removal of benzothiophinic compounds from gasoline. Benzothiophinic compounds are the major sulfur-containing entities at the top end of the gasoline boiling range.
The goal of the heavy oil part of this project is to ascertain the effective management of hydrogen during the upgrading of feedstocks with high aromatic, sulfur, and/or other heteroatom content. It was proposed that this goal be accomplished through the development of an understanding of the relationship between the distribution of the hydrogenated products in the process streams and the conditions of their formation, i.e., temperature and pressure. Cost-effective development of hydrogenated fuels will lead, in turn, to increased energy density, hence less CO2 and better carbon management. A new fuel slate from heavy oil could be developed with a goal of increased energy density at little or no increased cost per BTU obtained. Among the options studied will be alkylation, ring-formation, naphthene redistribution, etc., individually and in combinations as means of increasing energy density. In part of the project, researchers will consider the main stages of "hydrogen economy"—the production, packaging, transport, storage, and transfer of elemental hydrogen—and relate the energy consumed for these functions to the energy content of the deliverable hydrogen. All the process analyses will be based on either ideal physics or chemistry or actual data from industry.
From the late 1970s until closing of the Bartlesville Laboratory, the Department of Energy invested more than $1,000,000 per year in support of world-class thermodynamics research. Unpublished results exist for a variety of organic compound types, which are key to the production of high quality, environmentally acceptable fuels. These benchmark-quality results will be compiled, analyzed, and published to aid the development of new processing technologies through provision of required properties for specific key materials, and for numerous related substances by benchmarking computational chemistry methods.
Project was terminated due to budget shortfall in oil and gas research program.
$639,000 (27% of total)
Steele, W.V., R.D. Chirico, A.B. Cowell, A. Nguyen, S.E, Knipmeyer, “Possible Precursors and Products of Deep Hydrodesulfurization of Gasoline and Distillate Fuels III: The Thermodynamic Properties of 1,2,3,4 tetrahydrodibenzothiophene,” J. Chem. Thermodynamics, V. 36, 2004, pp. 497-509.
Steele, W.V., R.D. Chirico, S.E. Knipmeyer, A. Nguyen, “Possible Precursors and Products of Deep Hydrodesulfurization of Gasoline and Distillate Fuels IV: Heat Capacities, Enthalpy Increments, and Derived Thermodynamic Functions for Dicyclohexylsulfide between the Temperatures (5 and 520) K,” J. Chem. Thermodynamics V. 36, 2004, pp. 845-855.
Chirico, R.D., W.V. Steele, “High-Energy Components of Designer Gasoline and Designer Diesel Fuel I: Heat Capacities, Enthalpy Increments, Vapor Pressures, Critical Properties, and Derived Thermodynamic Functions for Bicyclopentyl between the Temperatures T = (10 to 600) K,” J. Chem. Thermodynamics V. 36, 2004, pp. 633-643.
Steele, W.V., “Topical Report Synergies between Sulfur Removal and Aromatic Formation and/or Mitigation in the Development of Carbon-Saver Fuels” from Heavy Oil DOE-FE Internal Report, September 30, 2004, 24 pp., available from NETL at 918-699-2000.
Chirico, R.D.; W.V. Steele, “The Thermodynamic Properties of Diphenylmethane,” J. Chem. Eng. Data 50, pp. 1052-1059, 2005.
Chirico, R.D.; W.V. Steele, “The Thermodynamic Properties of 2-methylquinoline and 8-Methylquinoline,” J. Chem. Eng. Data 50, pp. 697-708, 2005.
Fern J.A.; D.J. Keffer, W.V. Steele, “Measuring coexisting densities from a two-phase molecular dynamics simulation by Voronoi tessellations,” Accepted for publication in the Journal of Physical Chemistry B, January 2007.
Kassaee, M.H.; D.J. Keffer, W.V. Steele, “Computing Thermophysical Properties of Aromatic Compounds: Comparison of Theory and Experiment,” paper presented at the Annual AIChE Conference, November 12-17, 2006, San Francisco, CA.
Fern, J.A.; D. J. Keffer, W.V. Steele, “Using Voronoi Tessellations to Measure Coexisting Densities for Molecular Simulations,” paper presented at the Annual AIChE Conference, November 12-17, 2006, San Francisco, CA.
Chirico, R.D., R.D. Johnson III, W.V. Steele, “Thermodynamic properties of methylquinolines: Experimental results for 2,6-dimethylquinoline and mutual validation between experiments and computational methods for methylquinolines,” accepted for publication in Journal of Chemical Thermodynamics, October 2006, available as doi:10.1016/jj.jct.2006.10.012.
Kassaee, M.H., D.J. Keffer, W.V. Steele, “A comparison between entropies of aromatic compounds from quantum mechanical calculations and experiment,” Journal of Molecular Structure Theochem. ,802, pp. 23-34, 2007.