API Project 48
Synthesis, Properties, and Identification of Sulfur Compounds in Petroleum \V. D.
SKYFRIED,
Humble Oil & Refining Co., Baytown, Tex.
The increasing rate of production and refining of high sulfur contents crudes in recent years has directed considerable research toward the problems associated with the presence of sulfur i n petroleum . . . Much fundamental information is still lacking F υκ many .wars the petroleum industry has been confronted with a number of problems imposed by the presence oi sulfur compounds of various typos and in varying degrees () f concentration in crude oils charged to refinery processes. Among the problems caused by the presence of sulfur compounds in crudes and in refinery products are (1) the cor rosive effects encountered in refining, storage, transportation, and product > utilization; (2) the malodorous nature of certain compounds such as hydrogen sulfide and mercaptans. which must b» removed almost completely from many petroleum products to obtain customer acceptance; (3) the depressing effect on octane number of gasolines induced by certain types of sulfur compounds such as mercaptans. disulfides, and polysulfides; (4) the antagonistic effect toward lead susceptibility exerted by nearly all types of sulfur compounds; and (5) the adverse effects of sulfur compounds on product stability, burning characteristics, etc. Most of these problems are well recognized and need no amplification. Of special interest, however, is the effect of sulfur compounds on lead suscepti bility; the degree to which sulfur com pounds of various types affect lead sus ceptibility is illustrated by selected data, obtained orginally by Livingston, ( / ) in Fig. 1. It will be noted from this figure that the depressing effect of vari ous types of sulfur compounds on a 60 Fig. I .
Sulfur
antagonism
as a function c
2482
n-SH
iso-octane—40 /^-heptane blend contain ing 3 cc. T E L / g a l l o n ranged from about 4 octane numbers in the case of t h i o phenes to 14 octane numbers in the e a s e of thiophene mercaptans, when these compounds were present in concentra tions equivalent to 0.19'' sulfur in t h e fuel. These data are of importance i n that they illustrate that processes (such as doctor sweetening) for converting sul fur compounds from one form to a less objectionable form from s o m e .stand points do not necessarily s o l v e all t h e problems associated with the presence of sulfur compounds in petroleum prod ucts. On the other hand, processes that effect the complete removal of sulfur compounds may cause substantial y i e l d losses even for crude oils of o n l y moder ately high sulfur content, especially when it is considered that a crude oil c o n taining oVr by weight of atomic sulfur may contain as much as 40% of sulfur compounds. The problems associated with the presence of sulfur compounds in petro leum have become especially acute in recent years because of the increasing rate of production and refining of high sulfur content crudes. In Fig. 2 are plotted curves, published originally b y Smith and Blade (3), and subsequently revised by them, showing the production of crude oils of various sulfur contents in the U. S. over the period from 1915 to 1947. It will be noted that as of t h e end of 1947, about 152 million barrels of the 1,863 million barrels of crude oil produced in the U. S. contained over 2% sulfur, of structure while 674 million barrels contained over 0.5% sul fur. The large volumes of high (about 1.5 t o 2.5%) sulfur content crudes being produced i n the Middle East have a c j—j I centuated t h e problem Cent Total
Ί-\
1 1Η
Recovery-
F r e q u e n c i e s A s s i g n e d t o V i b r a t i o n s o f Several S u l f u r G r o u p i n g s Wave Length, Microns
Compound Typ
