ASTM: Gasoline Today and Tomorrow – An Executive Report

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Octane Week | ASTM: Gasoline Today and Tomorrow - An Executive Report Ethanol, Oil, Autos Ready for Ethanol Sulfate Round Robin This story appeared in January 2006. Ethanol, oil and auto companies are fast-tracking a round robin that will evaluate three test methods for determining sulfate concentrations in ethanol. Fuel samples have been prepared and are to be delivered in January to the labs participating in the effort, which has alternatively engendered cooperation and sparked tension among the representatives. Dispute over test methods nearly scuttled an agreement to set a 4 ppm sulfate limit in D-4806, ASTMʼs ethanol specification. After a fierce test method debate at ASTMʼs recent winter meeting, oil, ethanol and auto industry representatives agreed to initiate a round robin this month with the aim of establishing a 4 ppm ethanol sulfate specification later this year. The Renewable Fuels Association (RFA) has endorsed the new specification and is encouraging their membership to do the same. “The cooperation between automakers, gasoline marketers and ethanol producers in supporting this specification demonstrates that all facets of the gasoline industry understand the need for such a specification to protect their mutual customers,” said Citgo Petroleumʼs Dave Harvey, who has spearheaded the effort within ASTM. “With new federal legislation requiring increased use of ethanol as a component of automotive fuel, it is important to ensure that gasoline blend components conform to stricter standards, thereby providing the motoring public with a continued reliable energy source.” Although most ethanol producers do endorse a 4 ppm sulfate limit, few supported the lead potentiometric titration test that had seemed so promising. Ethanol industry representatives attending ASTMʼs December meeting blasted the method, but their objections were not sufficient to halt the entire “ballot,” the method ASTM uses to determine member support for changing or adopting specifications. The ballot to add a 4 ppm sulfate limit to D-4806 passed the D02.A subcommittee on gasoline and will be sent to the full D02 Committee in time for results to be available at ASTMʼs June meeting. To resolve the test method grievances, the D03.03 subcommittee on elemental analysis will conduct a round robin on three sulfate detection test methods – the lead titration method and two ion chromatography (IC) procedures. There too, the aim is to have test method results back in time for possible approval of both spec and test method at the next D02 meeting, which is scheduled for June. “The round robin will get started next week,” a source close to ASTM told Octane Week. “Fuel samples have been obtained and prepared.” Although the timetable is very short, the schedule should leave room for statistical analysis, which is central to the precision statement, the source said. Assuming the 4 ppm ballots with test method pass the appropriate ASTM committees in June, when might the spec take effect? “Sometime in the fall,” ASTM members say, but the exact timing depends on the date of publication, which can be several months after committee approval. That doesnʼt leave much time for ethanol producers to make plant modifications if any are needed to meet the new specification. A survey of ethanol producers revealed several plants produced ethanol containing more than 4 ppm sulfate. “If the spec takes effect in October, thatʼs only nine months for producers to design, build and install equipment if more than a process change is needed. Earlier is worse,” the source continued. The ballot faces its toughest test of support at the D02 Committee, where new ethanol producermembers will be voting in June. If the spec and the test method donʼt satisfy that growing population of ASTM members, the weight of their votes could spell trouble for the “unprecedented display of industry-wide cooperation” marshaled by Citgoʼs Harvey. – Carol Cole 12 February 2007
Octane Week | ASTM: Gasoline Today and Tomorrow - An Executive Report Fuel Ethanol Sulfate Specification Advances Despite Lacking Test Method This story appeared in July 2006. Members of ASTMʼs gasoline subcommittee voted to add a 4 ppm sulfate limit to D4806, ASTMʼs denatured fuel ethanol specification. The vote signaled acceptance by the ethanol industry, which had wavered in its support of a sulfate specification at any level. The vote is notable for another reason – it advances a specification that currently lacks an approved test method. A round robin on three sulfate detection test methods was conducted this spring but failed because of sample-related problems, and will be repeated this summer. The addition of a specification without an approved test method is unusual, but nothing has been usual in the effort to get a sulfate restriction into the ethanol standard. Since the beginning of the debate 18 months ago, oil and ethanol company representatives have hammered away at the issue, often with opposite goals. After resolving disputes over the need for a specification, the level and the placement – in the ethanol or the gasoline specification – one big issue remains unsettled – the test method. ASTMʼs D02.03 Subcommittee on Elemental Analysis conducted an inter laboratory study (ILS) of a lead potentiometric titration method and two ion chromatography (IC) procedures in support of the ethanol sulfate specification. Unfortunately, the sulfate results were disappointing due to problems with the samples used in the round robin. The IC methods are also capable of detecting chlorides, which are a concern to ethanol producers, and the chloride data were excellent. “The sulfate data were not usable by any method,” said a member of the D02.03 subcommittee which organized the round robin. “The methods are robust. Round robin sample stability was the problem.” The ILS utilized 16 samples, all were prepared in denatured ethanol with varying amounts of sodium sulfate and sodium chloride dissolved in water. Samples varied between 0 – 20 mg/kg total sulfate and 0 – 50 mg/kg total chloride. Unfortunately, the added sodium sulfate precipitated out of the samples during the duration of the round robin, rendering their results useless, while the sodium chloride remained in solution. “Concentrations of sulfates may change over time,” explained a D02.A member. “Through an oxidation reduction process, sulfates can change to sulfites or sulfides, which may not be detected by the test methods.” A second round robin will be conducted, and it will include an oxidation step in the IC methods to stabilize the sulfate in the ethanol samples. Hydrogen peroxide will be added to samples, which will convert other species to sulfate prior to testing, providing a measurement of “potential sulfate.” The procedure not adding the hydrogen peroxide will be retained for a total sulfate measurement. Because hydrogen peroxide will damage the lead sensor used in the lead titration method, the oxidation step will not be used in samples tested by the titration method. Despite the failure of the first ILS to yield useful sulfate precision data, DO2.A voted to accept a 4 ppm sulfate limit in D4806, with the understanding that a second round robin will be conducted and will likely produce useful data. The same labs agreed to participate in the second round robin, which could start as soon as next month. If the data are returned in time, the three methods will be balloted for approval with full precision statements in D02 at the December meeting. February 2007 13
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ASTM: Gasoline Today and Tomorrow – An Executive Report

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