Sulfided thiophene

Although desulfurization is a process, which has been in use in the oil industry for many years, renewed research has recently been started, aimed at improving the efficiency of the process. Envii onmental pressure and legislation to further reduce Sulfur levels in the various fuels has forced process development to place an increased emphasis on hydrodesulfurization (HDS). For a clear comprehension of the process kinetics involved in HDS, a detailed analyses of all the organosulfur compounds clarifying the desulfurization chemistry is a prerequisite. The reactivities of the Sulfur-containing structures present in middle distillates decrease sharply in the sequence thiols sulfides thiophenes benzothiophenes dibenzothio-phenes (32). However, in addition, within the various families the reactivities of the Substituted species are different. 

The System described in the previous section has been extended with a sulfur chemiluminescence detector (SCO) for the detection of Sulfur compounds (32). The separated fractions were thiols + sulfides + thiophenes (as one group), benzothio-phenes, dibenzothiophenes and benzonaphtho-thiophenes. These four groups have been subsequently injected on-line into and separated by the GC unit. Again, no overlap between these groups has been detected, as can be seen from Figure 14.20, in which the total sulfur compounds are shown and from Figure 14.21 in which the separated dibenzothiophenes fraction is presented. The lower limit of detection of this method proved to be 1 ppm (mg kg ) sulfur per compound. 

Alkyl disulfides Alkyl sulfides Elemental sulfur Aryl disulfides Aryl sulfides Thiophenes... 

Shibamoto and Russell (46) heated an aqueous glucose-ammonia-hydrogen sulfide solution at 100° for two hours. Of the 34 major com- ponents identified, 2-methylthiophene accounted for 24.9% of the area of the chromatographic peaks ethyl sulfide, thiophene, furfural, and 2-acetylfuran each accounted for 10-11%, and methyl sulfide and 2,5-di-methylthiophene, 7% each. The reaction mixture as a whole was deemed by sensory panel evaluation to have a cooked beef odor. 

Sample Depth (m) Asphaltene (%) Sulfides Thiophenes (% of maltene) Biodegraded... 

Coal S Accounted Thiolic Thiophenolic Sulfide Sulfide Thiophenes ... 

Sulfur is present in petroleum as sulfides, thiophenes, benzothiophenes, and dibenzothiophenes. In most cases, the presence of sulfur is detrimental to the processing because sulfur can act as catalytic poisons during processing. 

Sulfur-containing compounds These may be thiols, sulfides, thiophenes, benzo- and dibenzo-thiophenes, and more complex structures. Solvent extraction reduces measured sulfur levels and therefore the content of sulfur compounds in solvent refined lubes in solvent refined lubes, oxidation studies show that there appears to be an optimum level for sulfur compounds. Lube hydrocracking generally will reduce sulfur to about 10 ppm or less in the base stocks. The 4,6-di-alkyl... 

Crude oil contains a number of organosulfur compounds (RS), including thiols, sulfides, thiophenes and alkyl-substituted thiophenes 18],... 

Figures 4 and 5 show the sulfur specific chromatograms (S-GCxGC) of the two above FCC and SCN samples. The sulfiir compounds were also resolved by the GCxGC process into sulfur classes with distinct bands for mercaptans + sulfides, thiophenes, and benzothiophenes. Note that there was a sulfur conm nd in the steam cracked naphtha at approximately X=55 min, Y=110 s. This unknown compound was also found to contain carbon, hydrogen, and oxygen by further GCxGC/AED analysis. Further characterization of the compound may be possible by GC/Mass Spectrometry (GC/MS) using a comprehensive GCxGC/GC/MS set up very similarly to that described in this paper.

Palladium oxide on a ceramic honeycomb Brick kiln contaminants including fluorides, hydrocarbons, mercaptans, dimethyl sulfide, thiophene 400 - 450 NR 34.560 hr- Evaluation of a Decatox system to remove brick kiln effluent contaminants 54... 

Boduszynski and co-workers [114] and Andersson and Sielex [115] have used GC-AED to examine the sulfur-containing molecules in petroleum and its heavier processed products. Both groups found a preponderance of thiophenic sulfur compounds in processed materials, in contrast to petroleum. The unprocessed petroleum had mercaptans, sulfides, thiophenes, as well as other species containing other heteroatoms in addition to the sulfur. These two studies also showed that this detector has the selectivity for sulfur that is attainable with the two older commonly used sulfur detectors, the flame photometric detector (EPD) and the chemiluminescent detectors. The first of these, however, suffers from a very non-linear response. This effect is very compound-class dependent. This is due to the fact that the light-emitting species that is detected is a two-sulfur atom one that results from recombination of the sulfur atoms in the combusted sample peak. The efficiency of combustion and the rate of recombination are both dependent on the... 

Coal Organic S (% w/w) % Organic S Accounted Thiolic Thiophenolic Aliphatic Sulfide Aryl Sulfide Thiophenes... 

The hydrodesulfurization process is the removal of sulfur from organic sulfur compounds, such as thiols, sulfides, thiophene, and substituted thiophenes from petroleum feedstocks, to avoid or minimize sulfur poisoning of metallic or bimetallic reforming catalysts and to avoid introduction of S into the environment. 

Sasaki et al. [33] reported equilibrium concentration of minor snUhr-based impurities in the fuel cell fuels in the temperature range 400-1000 C. As sulfur-based impurities in the fuel cell gases, H2S, elementary sulfur, inorganic sulfur compounds, mercaptans alkyl (di-)sulfides, thiophenes, and related compounds have been taken into account. 

OSC (organic sulfur compounds) Sulfide Thiophenes Thiazoles Thiols Sulfonic adds SPE OASIS-MCX cartridges (waters) SPME 65 ji.m divinylbenzene-polydimethyl siloxane fiber (DVB-PDMS) CGC MS PFPD Groundwater [4]... 

---