Analysis by x-ray photoelectron spectroscopy/depth profiling of thin, gasoline-derived deposit films

• Published in: Industrial & engineering chemistry research Vol. 29; no. 9; pp. 1954 - 1962
• Main Author: Tseregounis, Spyros I
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 01.09.1990
• Subjects: 02 PETROLEUM; 023000 - Petroleum- Properties & Composition; 330101 - Internal Combustion Engines- Spark-Ignition; 360105 - Metals & Alloys- Corrosion & Erosion; 400101 - Activation, Nuclear Reaction, Radiometric & Radiochemical Procedures; ADVANCED PROPULSION SYSTEMS; Applied sciences; CARBON; CHEMICAL COMPOSITION; CORROSIVE EFFECTS; Crude oil, natural gas and petroleum products; DEPOSITS; ELEMENTS; Energy; ENGINES; Exact sciences and technology; FUEL INJECTION SYSTEMS; FUEL SYSTEMS; FUELS; GASOLINE; HEAT ENGINES; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; INTERNAL COMBUSTION ENGINES; LIQUID FUELS; MATERIALS SCIENCE; NITROGEN; NONMETALS; OXYGEN; PETROLEUM PRODUCTS; Petroleum products, gas and fuels. Motor fuels, lubricants and asphalts; SPECTRA; SULFUR; SURFACES; THIN FILMS; X-RAY SPECTRA; Autoxidation; Model compound; Gasoline; Deposit formation; Photoelectron spectrometry; Chemical composition; Steel; Experimental study; Engine; Thin film
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie00105a030

Fuel-derived deposits on injectors and elsewhere in engines can severely impair engine performance. This paper reports on a laboratory test procedure developed to produce thin deposit films from oxidized fuel on steel. The deposit films were analyzed by using x-ray photoelectron spectroscopy (XPS or ESCA) and depth profiling. The deposits were carbonaceous with lesser amounts of oxygen, sulfur, and nitrogen. The total sulfur concentration in the deposits was 5--10 times higher than the concentration of sulfur in the original gasoline. Ion bombardment preferentially removed oxygen from the deposit layer, revealing that sulfur in the deposits was in the form of oxygenated compounds (RSO{sub 2}R, RSO{sub 2}OR, ROSO{sub 2}OR, RSO{sub 2}OSO{sub 2}R) and removal of oxygen converted them to lesser or non-oxygen-containing compounds (RSR, RSOR, RSSR, RSSO{sub 2}R). Fuel samples were spiked with two sulfur-containing chemicals, thionanisole and thianaphthene. Neither compound participated directly in the deposit formation process. Thinner deposit films were formed on polished and oxidized surfaces rather than on polished-only surfaces.