Ronald C. Timpe

The use of stable sulfur isotope ratio analysis to assess selectivity of chemical analyses and extractions of forms of sulfur in coal

Abstract Natural variation in the abundance of sulfur isotopes has been used to characterize the different forms of sulfur in four Illinois basin coals. Isotopic determinations have been made on the sulfur yields from various extraction procedures. These enable the extent to which extractions mix sulfur from different forms to be estimated. The results show that the standard ASTM methods routinely used may not be selective for the chemical forms of sulfur they purport to analyse.

Determination of elemental sulphur in coal by supercritical fluid extraction and gas chromatography with atomic emission detection

Abstract A rapid and reproducible method to quantify elemental sulphur in coal has been developed using supercritical fluid extraction (s.f.e.) and gas chromatography with atomic emission detection (g.c./a.e.d.). Quantitative spike recoveries of elemental sulphur were obtained from both sand (97 ± 6%) and pre-extracted coal (96 ± 3%). The total amount of elemental sulphur removed was found to be independent of the coal particle size, which indicates that elemental sulphur in coal is located at the surface of the coal particles. North Dakota (Beulah) lignite, Alaska (Beluga) subbituminous coal, and Illinois Basin bituminous coal samples contained elemental sulphur in the range of 2–3500 μg S 8 g − 1 coal. As much as 35.7% of the ‘organic’ sulphur in coal (as determined in accordance with ASTM guidelines) is, in fact, elemental sulphur rather than true organic sulphur. In addition, the elemental sulphur values for the coals used in this study correlate well with the inorganic sulphur fractions of coal but not with ASTM-defined ‘organic’ sulphur.

AN IMPROVED METHOD FOR EXTRACTING SULFATE FROM BITUMINOUS COALS USING FORMIC-ACID

In connection with the determination of sulfate S, the sulfur mass balance for four bituminous coals was determined using different extraction procedures, including use of 1 M and 4.8 M HCl under nitrogen and under air, and at room temperature, 95 degrees C and boiling point. Since HCl extractions yielded poor S mass balances (as low as 83%), acid extraction with formic acid was also evaluated, Extractions with formic acid gave better S mass balances than those obtained using HCl, and the sulfate S yields agreed with those measured by the ASTM D-2492 HCl procedure. S-34/S-32 ratios determined by stable sulfur isotope mass spectrometry demonstrated that formic acid extraction was more selective for sulfate sulfur than the more rigorous HCl extractions.

Ester fuels and chemicals from biomass

Bench-scale research demonstrated that using an efficient esterification step to integrate an ethanol with a carboxylic acid fermentation stream offers potential for producing valuable ester feedstocks and fuels. Polar organic acids from bacterial fermentations are difficult to extract and purify, but formation of the ammonium salts and their conversion to esters facilitates the purifications. An improved esterification procedure gave high yields of esters, and this method will lower the cost of ester production. Fuel characteristics have been determined for a number of ester-gasoline blends with promising results for lowering Reid vapor pressure and raising octane numbers.

Vapor Pressure Response to Denaturant and Water in E10 Blends

On December 16, 1993, the U.S. Environmental Protection Agency (EPA) released the final rule on reformulated gasoline (RFG). This rule will affect the composition of as much as 45% of the gasoline used in the United States by the summer of 1995. The acceptance of any gasoline component lies in its ability to contribute to the RFG programs environmental goals. This study was conducted to determine the effect of water and ethanol denaturant on gasoline Reid vapor pressure (RVP) for which little quantitative data are available. This paper addresses two new areas where environmental goals may be achieved while maintaining the use of ethanol-blended gasolines within ozone nonattainment areas.

Sulfur removal from coal by analytical-scale supercritical fluid extraction (SFE) under pyrolysis conditions

Sulfur removal methods were developed using analytical-scale supercritical fluid extraction (SFE) under pyrolysis (450 °C) conditions on a bituminous coal sample (IBC-101) obtained from the Illinois Basin Coal Sample Program (IBCSP) and on physically cleaned Indiana No. 3 coal samples from AMAX Research and Development Center. Approximately one-half of the total sulfur was removed from IBC-101 using supercritical CO2 (40.53 MPa) under pyrolysis-SFE conditions. Using on-line SFE gas chromatography-mass spectrometry (SFE-g.c.-m.s.), the major organic sulfur forms removed by pyrolysis-SFE were identified as alkyl-thiophenes (C0-C5). When phosphoric acid was added to the coal prior to pyrolysis-SFE, about 80% of the total sulfur was removed from both coals regardless of whether the sulfatic sulfur, or both the sulfatic and pyritic sulfur, were removed (by HCl and HNO3 extraction, respectively) prior to pyrolysis-SFE. These results demonstrate that the major fraction of sulfatic, pyritic and organic sulfur were extracted in the presence of phosphoric acid. In contrast, pyrolysis-SFE with CO2-methanol appears to preferentially extract organic sulfur species, since only about 60% of the total sulfur was removed from the raw coal by pyrolysis-SFE using CO2 modified with 10% methanol, while about 80% of the total sulfur was extracted if the sulfatic and pyritic sulfur were removed prior to extraction.

On-Demand Hydrogen via High-Pressure Water Reforming for Military Fuel Cell Applications

Researchers have developed a high-pressure water-reforming (HPWR) process that produces high-pressure hydrogen from a jet fuel feedstock. Converting petroleum-based fuels to hydrogen for fuel cell use is a unique approach to reducing military petroleum consumption by improving petroleum utilization efficiency. HPWR is an attractive option because, unlike traditional steam methane reforming, it does not require postreformer hydrogen compression and storage. A HPWR apparatus was designed and manufactured. Several catalysts were tested for their ability to produce high-pressure hydrogen from jet fuel. S-8, which is a jet fuel derived from natural gas, was used as a model feedstock for initial experiments because the fuel is sulfur and aromatics free. After optimizing with S-8, JP-8 will be utilized for future experiments. The most promising catalyst produced a 4000 psi (gauge) product gas stream that contained 54 trial % hydrogen. These experimental results show that HPWR is a promising solution for high-pressure hydrogen production as a key step toward reducing military petroleum use.

Hydrothermal Energy Systems Development in the USA

A revolutionary hydrothermal steam generator is being developed by a federal, state university and industry partnership in the US to enhance economic growth and trade. The new generator is designed to accept solutions and slurries without corrosion and deposition on heat transfer surfaces up to the supercritical conditions of water, above 221 bar (3205 psia) and 374 C (705 F). The generator will produce steam from low quality water, such as from geothermal sources, for increased electric power generation. Water treatment costs and effluents will be eliminated for “zero discharge.” To improve efficiency and limit carbon dioxide and other emissions, the new steam generator will be tested for converting wastewater slurries of low-cost fuels and “negative value” wastes such as hazardous wastes, composted municipal wastes and sludges, to clean gas turbine fuel, hydrocarbon liquids, and activated carbon. Bench-scale results at sub- and supercritical conditions for lignite, refuse derived fuel, tire rubber and activated carbon are presented. An advanced continuous-flow pilot plant is being designed to test the generator over a wide range of operating conditions, including slurry feed up to 30 percent solids. Demonstration of the hydrothermal steam generator will be followed by design and construction of combined-cycle energy systems.Copyright

Cleaning and Dewatering of Low-Rank Coal by Oil Agglomeration

The preparation of manageable low-ash, low-moisture coal combustion and/or conversion (i.e., liquefaction, gasification) feedstocks is a priority for future energy development Physical cleaning by conventional washability techniques, followed by dilute acid leaching, has produced lignite, subbiluminous, and brown coal products with less than I wt, % ash on a dry basis on a laboratory scale. Agglomeration yields have ranged from 85 to 99wt. %. Ash contents have been less than 2wt. % moisture- and oil-free for a North Dakota lignite. After air-drying the agglomerates overnight, Karl-Fischer moisture analysis indicates the moisture levels are less than 5 wt. % in the agglomerates. After thermal drying of the coal, the moisture levels are less than 0.5wt. %.