The development of metal deactivator additives for the petroleum industry is reviewed from the first additive used in gasoline to the present. The chemistry of how these additives are thought to work is detailed and related to chemical structure. Discussions of the three classes of action attributed to metal deactivators: chelation, surface passivation, and bulk phase reactivity, are provided. In this regard, special emphasis is given to the metal deactivator N,N′-disalicylidine-1,2-propane diamine (MDA) in aviation turbine fuels. Previously reported work, especially work from 1991 to the present, investigating the impact of MDA on jet fuel thermal stability is reviewed. A discussion of the six classes of metal deactivators most commonly found in the literature is also provided.

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing the burden, to Department of Defense, Executive Services and Communications Directorate (0704-0188). Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number.

Public reporting burden for the collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to a penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. iii EXECUTIVE SUMMARY Project ObjectivesThe objective of this project was to characterize the aviation fuel contaminant known as apple jelly with respect to the compositional and process conditions required for its formation, and to determine possible methods, both compositional and process, whereby its formation can be reduced or prevented. ApproachThe following tasks were involved in the investigation of this problem:• Review past studies and pertinent literature for relevant information.• Collect and analyze samples from military installations around the world.• Conduct site visits to gather information regarding fuel-handling procedures and fuel storage/dispensing equipment.• Based on all collected information, synthesize apple jelly in the laboratory. ResultsThe project team conducted 31 separate site visits to collect information and samples. Samples were also collected from sites other than those visited. SwRI received 139 samples of apple jelly, fuel, and other types of samples related to apple jelly contamination. Samples were analyzed for a number of compositional, physical, and chemical properties. The test results were analyzed to determine data relationships and information regarding the various properties of apple jelly. Based on these analyses, examples of both thin and thick apple jelly were synthesized in the laboratory. The synthetic apple jellies exhibited physical and chemical properties consistent with samples from the field. Conclusions and RecommendationsIt is important to reiterate that we started this work with no constraints regarding what is and what is not apple jelly. We simply asked users in the field to submit samples of apple jelly whenever it was discovered. The samples we received varied in color, viscosity, and numerous other properties. We were told by some people that only thick apple jelly is really apple jelly, the rest is simply contaminated water bottoms. [We contend that all apple jelly is a form of contaminated water bottoms.] However, DESC instructed us to not limit our study because all the samples represented a potential problem for the user.This work has demonstrated that apple jelly is a complex mixture. It begins with water and DiEGME. This mixture reacts w...