ASTM: Gasoline Today and Tomorrow – An Executive Report

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Octane Week | ASTM: Gasoline Today and Tomorrow - An Executive Report Industry Awaits News of ASTMʼs Sulfur Test Method Round Robin This story appeared on June 19, 2006. Stakeholders in the fuel industry have suspected for some time that D2622, ASTMʼs Standard Test Method for Sulfur in Petroleum Products by Wavelength Dispersive X-ray Fluorescence Spectrometry (WDXRF), could perform better than its published precision statement indicates. With fuel sulfur levels plunging this year, it became imperative that D2622ʼs measurement capability be improved, and that a new precision statement be developed for one of the most widely used sulfur test methods going. That effort has been underway in earnest since the beginning of the year, and an update from the ASTM work group may be forthcoming at the ASTM D02.A Subcommittee on Gasoline and Oxygenated Fuelsʼ June meeting in Toronto, Ontario, Canada. The sulfur test method review has been undertaken by the D02.03 Subcommittee on Elemental Analysis. Method D2622 is a critical compliance method for fuels certification, but it does not reflect the state-of-the-art WDXRF technology. A significant revision to the test method is needed to do that. Although there are other test methods for determining sulfur content of fuels, D2622 provides rapid and precise measurement of total sulfur in petroleum and petroleum products with a minimum of sample preparation. A typical analysis time is one to two minutes per sample. Knowledge of sulfur concentration is necessary for refining as well as for certifying compliance with federal and state fuel sulfur regulations. Sulfur regulations tightened June 1, when the U.S. EPAʼs 15 ppm sulfur limit for highway diesel took effect. The tightening of the diesel spec follows the implementation Jan. 1 of a 30 ppm annual average sulfur cap under EPAʼs Tier 2 gasoline rules. The pooled limit of quantitation for D2622 is in the range of 15-20 ppm sulfur, making the test nearly obsolete in the ultra-low sulfur environment taking shape in 2006. “Equipment vendors and users realized the test had to do better, and they believed that it could,” said a source familiar with the research. A Task Group reviewing D2622 planned a roundrobin test program. A status update may be available in time for the D02.A meeting in Toronto June 26-27. For more information about the meeting, log on to www. astm.org. ASTM Members Consider 1-PPM Sulfate Spec for Ethanol This story appeared in July 2005. Pittsburgh, Pa. – ASTM subcommittee members will be asked whether they favor establishing a sulfate specification for ethanol. The D-02 A subcommittee voted to poll members by ballot to determine whether they favor modifying D-4806, ASTMʼs Standard Specification for Denatured Fuel Ethanol, to include a 1-ppm sulfate limit. The vote to “ballot” the issue came just hours after presentations from oil, auto and ethanol industry representatives on the issue of fuel injector damage, which has been tied to high sulfate content gasoline. The problem first surfaced in 2003 with equipment failures at service stations in Minnesota, St. Louis, Mo., Los Angeles, Chicago and the Pacific Northwest. “We have seen widespread and prolonged service station filter plugging,” said Mitch Oliver of ConocoPhillips. Filters failed in a matter of days or weeks, rather than the months of useful life they ordinarily have. An investigation revealed sodium sulfate salts. There were no issues with conventional fuels or sulfuric acid alkylation by-products, Oliver said. Detergents were also ruled out as a source, although they play a role. “The common denominator was fuel ethanol,” he said, and the presence of sodium sulfate salt was confirmed by a Bar Chart Haze test. ConocoPhillips surveyed its ethanol suppliers in the affected regions. The company performed 300 analyses using ion chromatography (IC), which showed sodium sulfate content ranged from non-detectible levels to 23 ppm in the worst sample. The average was 2-4 ppm. “Sulfates greater than 1 ppm cause severe problems on filter performance,” Oliver (continued on p11) 10 February 2007
Octane Week | ASTM: Gasoline Today and Tomorrow - An Executive Report (from p10) continued. Detergents impact the rate at which sulfates agglomerate on or pass through filters, “neither one a good option,” he added. ConocoPhillips worked with ethanol suppliers in a cooperative fashion and established a joint industry task force with other oil companies, automobile manufacturers and ethanol makers, Oliver told attendees at ASTMʼs D- 02 Committee meeting here. Since then, there has been little resolution of the issue, in part because there is no established test method. The IC method is thought to be impractical on an industry-wide basis. Decision on Ethanol Sulfate Detection With the cooperation of Flint Hills Resources, the two oil companies determined that a modified D-6174 test method could determine ethanol sulfate concentrations as low as 0.05 ppm. The modified test method results could also be correlated with the IC test results. “We need a sulfate spec in 4806,” Oliver said, referring to the standard specification for denatured ethanol. The industry investigation established a modified D 6174, the Standard Test Method for Inorganic Sulfate in Surfactants by Potentiometric Lead Titration, as an alternative to IC, he said. “We are asking that the industry support the method weʼve put forward.” Four presentations later, the morning meeting adjourned. At the afternoon roundtable that followed, Dave Harvey of Citgo made a motion to ballot whether to add a 1-ppm sulfate limit in ASTMʼs D-4806 ethanol specification, and to allow either test method, the IC D-6827, or the modified D-6174, the titration method, until a test method is finalized. Although supportive of the ASTM process, Bob Reynolds, representing the Renewable Fuels Association (RFA), objected to “fast tracking” the ballot. The modified titration test was only identified two weeks earlier and the correlation to the IC test only revealed hours earlier, he pointed out. “Weʼd be putting in spec controlled by a test method thatʼs not approved,” he told subcommittee members. “I would like to see it on a fast track,” countered Citgoʼs Harvey. While there are reasons to take the “more prudent” route and resolve the problem through ASTMʼs normal, deliberative process, Harvey argued, “The fact is, we have a problem now.” In 2004, drivers in Milwaukee, Wis., started reporting vehicle operating problems. Fuel from Citgo, a major marketer in the region, was implicated as a possible cause. After investigation, Citgo also discovered troublesome levels of sulfates in ethanol. Owners face “thousands of dollars of repairs” to out-of-warranty vehicles that might become affected, Harvey and others told roundtable participants. For and Against Members debated the issue extensively, raising numerous concerns. “Weʼve been shown clearly that high levels of sulfates, around 5 ppm, lead to a rise in field problems,” said Ronald Tharby of Tharby & Associates. “Seasonal use of ethanol has been tied in with a significant increase in field complaints, which are serious to drivers. What if there is a big breakout of this problem this winter?” Concerned that a 1-ppm sulfate spec might exclude a majority of ethanol from the gasoline pool, BPʼs Jim McGetrick sounded another alarm. As much as 75% of U.S. ethanol production is thought to exceed the proposed 1-ppm maximum sulfate standard. “Weʼve got mandates for ethanol,” he said, referring to California, New York and Connecticut, where MTBE is banned. “If we take 75% of supply away, weʼve got problems.” “Thatʼs right, if everyone sits back and does nothing,” Harvey responded. With a rapidly expanding ethanol industry and more “mom and pop” producers, “this problem only gets worse,” Harvey warned. Sulfates must be addressed, he said, “so that we can expand the use of ethanol.” One observer suggested that the ethanol industry is just going through typical growing problems. “Technology exists to remove sulfates from methanol, and the ethanol industry is just electing not to use them. They may be reluctant to do that, but we all have to improve our processes,” the commenter said. Ethanol producersʼ actual sulfate levels are far from certain, RFAʼs Reynolds said. Survey results are based on self-reporting using a variety of test methods. “We need to find out what our numbers are,” he admitted. “We support work on a test method,” he said, and RFA would favor making the modified titration test part of a round robin. After the debate, subcommittee members voted 23- 13 in favor of Harveyʼs motion to ballot the issue. By the time of D-02Aʼs December meeting, it should be known whether the subcommittee members favor the addition of a sulfate limit to ASTMʼs ethanol specification. — Carol Cole February 2007 11
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