Storage stability of petroleum-derived diesel fuel

Analysis of heavy oils: Method development and application to Cerro Negro heavy petroleum

“…In most modern VPO instruments, n is not measured.directly (i.e., as a pressure across a membrane), but indirectly as a voltage difference (AV) between two thermistors--one of which contacts pure solvent and another which contacts the solute-solvent solution. The details of the thermistor cell designs and their theory of operation can typically be found in instrument manuals; e.g., (63). The important point for this discussion is that this type of "osmometer" requir.es calibration with a pure compound, or a mixture with known m, to establ ish the proportional ity between AV and n. If the compound or components in the mixture used for calibration do not associate with the solvent to the same extent as the unknowns being measured, a net positive or negative error in MW, reflecting net contribution to total MW by the associated solvent molecules, will result.…”

“…In-house and literature evaluations of the class-separation abilities of chemically bonded silica HPLC packings have generally shown them to be inferior to ordinary adsorbents for one-dimensional class separations (61)(62)(63)(64).…”

“…Pyrrolic benzologs, especially alkylindoles, which survive the various refining processes and end up in finished products have been reported to be ? major contributors to gum formation (63)(64)(65)(66). Furthermore, gum formation is catalyzed by compounds with comparable or greater acidity than that of carboxyl ic acids (64,67).…”

Fast Determination of Diesel Fuel Oxidation Stability by 1H NMR Spectroscopy

“…2,3 It is well known that the formation of sediments during oxidation is a complex process in which many compounds of stocks are involved, but the chemical nature of fuel sediments and exact mechanism of the sediment formation are still not fully explained and understood. [4][5][6] It is generally accepted that oxidation reactions follow the free-radical mechanism. 2,7 It has been reported in the recent literature by many authors that deposit formation during oxidation of diesel fuel is related to the presence of olefins, polycyclic aromatic hydrocarbons, sulphur, nitrogen, oxygen and some metals, such as ferrum and copper.…”

“…6,8 Deposits are further increased in the presence of mercaptans, thiols, sulfides, disulfides and organic acids. 5,6,9 The study of OS has become exceptionally important due to an increasing demand for fuel quality and the need to store fuel for a longer period of time. A number of methods have been developed and proposed for determination of the diesel fuel OS.…”