Oxidation and Gum Formation in Diesel Fuels.
Abstract
Rates of oxygen absorption (R sub O) and gum formation (R sub g) are now related by the R sub g/ R sub o ratio, the reciprocal of the ratio previously used. The change was made because when the oxygen content of the gum is known, the R sub g/ R sub o ratio is proportional to the fraction of oxygen absorbed that appears in the gum. Oxidations of tetralin (TET) and 2-ethyl-naphthalene (EtN) at 130 C are initially fast but the rates decrease regularly. The oxidation of n-dodecane (DOD) is clearly autocatalytic; it requires the most oxygen to produce a milligram of gum while EtN, among the pure hydrocarbons, requires the least. Rates of oxygen absorption for DOD at 100 C appear to be erratic. Part of the problem is autocatalysis; part is near exhaustion of oxygen. The best results are those for K92A and K92C. R sub o without t-Bu2O2 is autocatalytic. Trends in oxidations of Fuels 14 and 14A, which are different at 130 C, are not yet clear at 100 deg, and 60 C. The important points in the above discussion are: The oxidation of DOD is autocatalytic; oxidations of TET, EtN, and Fuel 14 are self-retarding. In our oxidations of Fuel 14 with shaking, all the deposits at 100 deg. and 130 C appear as films on glass; no deposits have yet been obtained at lower temperatures. The ratio R sub g/ R sub o, still appears to be essentially constant for any fuel at a single temperature, even with large differences in R sub o from addition of t-Bu202. Thus, gum can be accumulated relatively rapidly for experimental purposes. We are accumulating new data at 43 deg. and 60 deg. C. These findings should assist materially in our efforts to understand and devise a test for fuel stability.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 03, 1985
- Accession Number
- ADA157410
Entities
People
- F. R. Mayo
Organizations
- SRI International