Sulfur in oil

Since 1970, in OECD countries the problem of air quality has become the subject of studies at many scientific centers. Oil from the Middle East became the main source of energy. The content of sulfur in oil constitutes 2.5%-3%. In 1985 some European countries signed the CLRTAP protocol on a 30% reduction of sulfur emissions. As a result, present day levels of S02 emissions have decreased by more than 50% compared with 1980. Of course, this was possibly largely due to Europe going over to the use of Russian gas. 

Removal of sulfur compounds from fuel oils is usually accomplished at the refinery. Although most of the sulfur in oil is in the high boiling fraction, some middle distillates have high sulfur contents. A better understanding of the chemistry of sulfur compounds in oil will also facilitate their efficient removal. 

The rest of the sulfur in oil sand asphaltenes, which is not in the form of thiane and thiolane, is present as thiophenes. Indeed, the asphaltene pyrolysis oil contains homologous series of a and a,a n-alkyl substituted thiophenes, 2-, 4- and 2,4-... 

Sensitivity of exhaust - after treatment devices. It is clear that excessive deposition of phosphorus and sulfur on the catalyst can cause the reduction in system efficiency. Oil phosphorus contaminant comes from the oil additive ZDDP. The reduction in its use adversely affects both antiwear and antioxidation performance. Sulfur comes from the base oil, antiwear additives, detergents, organomolybdenum friction modifiers, and from the fuel. There is strong pressure from OEMs to reduce the sulfur level of the fuel, and to reduce the sulfur contamination of the catalyst, which results from presence of sulfur in oil. 

Most of the sulfur in oil shale occurs in pyrite and a smaller amount is contained in the kerogen. The major source of H2S during oil shale pyrolysis appears to be the reaction of pyrite with organic matter. In an autogenous atmosphere, most of the H2S evolves between 400 and 500°C. Addition of finely ground pyrite increases the amount of H2S evolved but does not change the evolution profile. In an argon atmosphere, however, added pyrite causes a substantial increase in H2S evolution... 

Section 15.1.1 (Repeatability) of ASTM D 4294 expresses the r-value for the measurement of sulfur in oils using EDXRF to be ... 

Specific applications in the laboratory or factory environment that cannot readily be satisfied by other techniques for example, the determination of sulfur in oil or chlorine in brines and liquors (competitive techniques based on optical emission, for example, are often insensitive to the electronegative elements). 

The content of sulfur in oil products must be controlled at very low level (mass fraction of about lOx 10 for environmental protection and the follow-up process (such as the reforming process). In petroleum industry, in order to meet this requirement, hydrodesulfurization (HDS) process is mainly adopted with Mo [Mo-Co(Ni)]/Al203 as catalyst. The catalyst must be sulfurized to obtain activity for HDS. The natme of active phase on HDS catalyst has been a hot topic of research. The methods from the complex apparatus, such as EXAFS, XPS, and FTIR to the conventional XRD, TPR, and TPS have been effectively adopted. 

---