Sulfur-Containing Hydrocarbons

The sulfides are chemically neutral they can have a linear or ring structure. For molecules of equal carbon number, their boiling points are higher than those of mercaptans they constitute the majority of sulfur containing hydrocarbons in the middie distillates (kerosene and gas oil). 

Hydrogen chloride released dissolves in water during condensation in the crude oil distillation column overhead or in the condenser, which cause corrosion of materials at these locations. The action of hydrochloric acid is favored and accelerated by the presence of hydrogen sulfide which results in the decomposition of sulfur-containing hydrocarbons this forces the refiner to inject a basic material like ammonia at the point where water condenses in the atmospheric distillation column. 

Because hydrocarbon feeds for steam reforming should be free of sulfur, feed desulfurization is required ahead of the steam reformer (see Sulfur REMOVAL AND RECOVERY). As seen in Figure 1, the first desulfurization step usually consists of passing the sulfur-containing hydrocarbon feed at about 300—400°C over a Co—Mo catalyst in the presence of 2—5% H2 to convert organic sulfur compounds to H2S. As much as 25% H2 may be used if olefins... 

Figure 9.6. Schematic representation of the catalytic cycle for the hydrodesulfurization of a sulfur-containing hydrocarbon (ethane thiol) by a sulfur vacancy on M0S2 The C2H5SH molecule adsorbs with its sulfur atom towards...

Effects of Sulfur Coverage. The kinetic results reported in the previous section are from reactions performed on surfaces that are initially clean. The surfaces after reaction were examined by AES and shown to be covered with carbon and sulfur at coverages close to a monolayer. It is interesting to note that although this is the case even after reaction times on the order of minutes the reaction rate is constant for a period of approximately one hour. Either the reaction is occurring on top of this oarbon/sulfur layer or these species are present as sulfur containing hydrocarbon fragments that are intermediates in the desulfurization process. 

For example, a simple and possibly too naive picture of the HDS reaction would be that a sulfur vacancy at the edge of an MoS2 slab is the active site. A sulfur-containing hydrocarbon such as thiophene adsorbs with its sulfur atom towards the exposed molybdenum. Next, the molecule becomes hydrogenated, the two C-S bonds in thiophene break, the sulfur-free hydrocarbon desorbs and the catalytic site is regenerated by the removal of sulfur by hydrogen. We refer to Prins et al. [50] for a discussion of reaction mechanisms. 

Volume 2 covers oxygenated hydrocarbons (such ns organic acids, ketones, aldehydes, ethers, and esters), nitrogen containing hydrocarbons, aromatic, cyclic hydrocarbons, and sulfur containing hydrocarbons... 

Figure 43 1. Vapor pressure ol sulfur-containing hydrocarbons from 75 C to 24(TC...

Figure 43 3, Vapor heat capacity of sulfur-containing hydrocarbons from Q C to 1CKXTC...

Figure 43-10. Liquid thermal conductivity of sulfur-containing hydrocarbons from -80X to +120 0...

The polysulfide and elemental sulfur were unstable to autoclaving. This fact necessitated the use of a membrane to achieve sterility in those cases. The surfactant not only provided greater surface area but also minimized the amount of sulfide in contact with atmospheric oxygen since the sulfide was generally dispersed throughout the medium. The fate of the non-sulfur-containing hydrocarbons, while of real interest, is beyond the scope of this present work. 

Nitrogen containing Sulfur containing Hydrocarbons and halo-genated organics Acids... 

M. Flytzani-Stephanopoulos and G.E. Voecks, Conversion of Hydrocarbons for Fuel Cell Applications Part I Autothermal Reforming of Sulfur-Free and Sulfur-Containing Hydrocarbon Liquids Part II Steam Reforming of n-Hexane on Pellet and Monolithic Catalyst Beds, Final Report DOE/ET-11326-1, Jet Propulsion Laboratory Publication 82-37, pp. 75-120 (1981). 

At the transformation of sulfiir- and high-sulfur containing hydrocarbon fractions, the desulphurization of gasoline takes place and sulfur evolves in the gas phase in H2S. With increases of the process temperature, the degree of desulphurization increases then it stabilizes and can reach 95-96 wt %. Liquid products contain about 300-600 PPM total sulfur. 

Bordwell, EG., Drucker, G.E., Andersen, N.H. and Denniston, A.D. (1986) Acidities of hydrocarbons and sulfur-containing hydrocarbons in dimethyl sulfoxide solutions. Journal of the American Chemical Society, 108, 7310-7313. 

Commercial sulfur is usually 99,9% or higher in purity. Dark" sulfur contains hydrocarbon impurities up to about 0,5% bright sulfur contains less than about 0.1% (measured as carbon). Dark sulfur causes difficulties in some types of sulfur-burning plants. However, methods for uar dark sulfur without difficulty have been developed. Another quality factor is the ash content, riiich should be quite low to avoid dust that will accumulate in the catalyst bed. Solid impurities can be removed from mdten sulfur by filtration 41. Alternatively, by using a hot gas filter, dust arising from ash in the sulfur can be removed from the hot gas leaving the sulfur burner. 

Acid consumption is also highly dependent on certain impurities in the feedstocks to the alkylation reactor. Some more vmdesired impurities include conjugated diolefins, acetylenic hydrocarbons, cyclopentene (found in C5 olefins), methyl f-butyl ethers, sulfur-containing hydrocarbons, and water (in either sulfuric acid as discussed earlier or in hydrocarbon feedstocks). Increased amounts of several of these impurities have resulted in the last 20-30 years because of changes in the operation of the catal3d ic cracking vmits in refineries. There are methods to reduce the impurities to a considerable extent some may be cost-effective. 

Hydrogen sulfide and various sulfur-containing hydrocarbons result In complex surface reactions. Treating the Inner surface... 

For the laboratory testing and evaluation, sulfur-containing diesel fuel vapor will be used as a typical interference. Headspace vapors will be diluted to 0.1% and 1% of equilibrium values and both simulant and agent vapors will be mixed with the diesel fuel vapors. It is realized that a number of other compounds are potential interference chemicals, however, sulfur-containing hydrocarbon represents a significant and realistic challenge as an interference. 

A biodesulfurization process has been reported by Energy Biosystems It involves the removal of sulfur-containing hydrocarbon compounds from distillate (diesel) fuel or naphtha (gasoline) streams using bacteria. The distillate stream is first mixed with an aqueous media containing the bacteria. 

A learning set of 1663 structurally diverse compounds was built. It contained 28 aliphatic hydrocarbons 52 aromatic hydrocarbons 74 alcohols, ethers, or phenols 27 aldehydes and ketones 42 acids and esters 66 amines and nitriles 23 amides and anilides 9 sulfur-containing hydrocarbons 18 nitro arenes 10 amino acids 54 halogenated hydrocarbons 35 nucleosides 25 nucleoside bases and 1200 multifunctional compounds. 

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