Tert-butyl Mercaptan Research Articles

Properties of a manganese oxide octahedral molecular sieve (OMS-2) for adsorptive desulfurization of fuel gas for fuel cell applications

Properties and characteristics of cryptomelane manganese oxide octahedral molecular sieve (OMS-2)-based adsorbents for the adsorptive desulfurization of dimethyl sulfide (DMS), tert-butylmercaptan (TBM), and tetrahydrothiophene (THT) were investigated at ambient temperature and atmospheric pressure. OMS-2 adsorbents exhibited above 90% adsorption selectivity for TBM in a ternary mixture of DMS, TBM, and THT in a methane fuel stream, which is unique and unprecedented for zeolite-, metal oxide-, and activated carbon-based adsorbents. Hetero-metal doped M-OMS-2 (M=Ag, Ce, Co, Cu, Fe, La, Ni, Zn) adsorbents were prepared, and the effects of doped metal entities for TBM adsorption were studied. In particular, Cu-OMS-2 exhibited substantially enhanced TBM adsorption uptakes that were greater than 2.6 times that of the pristine OMS-2. A high TBM adsorption of 4.44mmolSg−1 was achieved on Cu-OMS-2 (2.5wt.% Cu doping), 2–7 times greater than the values reported for zeolite- and activated carbon-based adsorbents at similar experimental conditions. Structure and properties of OMS-2-based adsorbents were studied at various synthesis conditions and characterized with SEM, TEM, XRD, TGA, elemental analysis, N2 adsorption, and temperature programmed desorption (TPD) methods. The selective adsorption and thermal regeneration characteristics of OMS-2 were rationalized with a proposed mechanism. Thermal regeneration led to deactivation of OMS-2 due to a poisoning of adsorption sites by residual sulfur species and an alteration of the crystalline structure by reduction, in the case of thermal regeneration in an inert atmosphere, accompanying some collapse of the accessible pore structures.

Community Health Assessment Following Mercaptan Spill

In 2008, a lightning strike caused a leak of tert-butyl mercaptan from its storage tank at the Gulf South Natural Gas Pumping Station in Prichard, Alabama. On July 27, 2012, the Alabama Department of Public Health requested Centers for Disease Control and Prevention epidemiologic assistance investigating possible health effects resulting from airborne exposure to mercaptan from a contaminated groundwater spring, identified in January 2012. To assess the self-reported health effects in the community, to determine the scope of the reported medical services received, and to develop recommendations for prevention and response to future incidents. In September 2012, we performed a representative random sampling design survey of households, comparing reported exposures and health effects among residents living in 2 circular zones located within 1 and 2 miles from the contaminated source. Eight Mile community, Prichard, Alabama. We selected 204 adult residents of each household (≥ 18 years) to speak for all household members. Self-reported mercaptan odor exposure, physical and mental health outcomes, and medical-seeking practices, comparing residents in the 1- and 2-mile zones. In the past 6 months, 97.9% of respondents in the 1-mile zone and 77.6% in the 2-mile zone reported mercaptan odors. Odor severity was greater in the 1-mile zone, in which significantly more subjects reported exposures aggravating their physical and mental health including shortness of breath, eye irritations, and agitated behavior. Overall, 36.5% sought medical care for odor-related symptoms. Long-term odorous mercaptan exposures were reportedly associated with physical and psychological health complaints. Communication messages should include strategies to minimize exposures and advise those with cardiorespiratory conditions to have medications readily available. Health care practitioners should be provided information on mercaptan health effects and approaches to prevent exacerbating existing chronic diseases.

Desulfurization Performance of Cu(II)-Ce(IV)/13X Zeolites for C<sub>4</sub> Hydrocarbon

Basic research of adsorptive desulfurization was carried out concerning the high total sulfur concentration of C4hydrocarbon which was the reason for exceeding total sulfur concentration of MTBE. Based on the screening of active components, Cu (II)-Ce (IV) bimetal ion-exchanged 13X zeolites were prepared. Desulfurization performance of 13X zeolites modified with different metals was investigated by using model C4hydrocarbon which contained dimethyl disulfide (DMDS), dimethyl sulfide (DMS), and tert-butyl mercaptan (TBM). The Cu (II)-Ce (IV)/13X zeolites exhibited better desulfurization performance for C4hydrocarbon due to the formation of sulfur-metal (S-M) bond between metal and sulfur compounds.

Coordination of Metal Cations with Amino-Functionalized MCM-41 for Adsorptive Desulfurization

Functionalized MCM-41 have been prepared with 3-aminopropyltrimethoxysilane (APTMS) as organic component and metal cations as inorganic component. The effects of different metal cations and concentration of APTMS on desulfurization performance for tert-butyl mercaptan (TBM) were investigated. The transmission electron microscopy (TEM) results indicate that the hexagonally ordered structure of MCM-41 remained intact after functionalization. The presence of grafted organosilanes was confirmed by fourier transform infrared (FTIR) spectra.

Synthesis of Organically–Inorganically Functionalized MCM-41 for Adsorptive Desulfurization of C4 Hydrocarbons

A series of organically–inorganically functionalized MCM-41 compounds have been prepared with 3-aminopropyltrimethoxysilane (APTMS) as the organic component and CuO and/or Cu(NO3)2 as the inorganic component. The textural properties of functionalized MCM-41 were characterized by powder X-ray diffraction (XRD), nitrogen adsorption–desorption, and transmission electron microscopy (TEM). The results indicate that the hexagonally ordered structure of MCM-41 remained intact after functionalization. The presence of grafted organosilanes was confirmed by Fourier transform infrared (FTIR) spectra, 13C nuclear magnetic resonance (13C CP-MAS NMR), and 29Si nuclear magnetic resonance (29Si MAS NMR). All adsorbents showed similar desulfurization performances for different sulfur compounds in the order tert-butyl mercaptan (TBM) > dimethyl sulfide (DMS) > dimethyl disulfide (DMDS), which is due to the poor reactivities and polarities of DMS and DMDS. MCM-41-NH2-Cu functionalized with Cu2+ as the active sites is the mo...

Fiber Adsorbents for Odorant Removal from Pipeline Grade Natural Gas

Sulfur odorant removal from pipeline natural gas can prevent or delay corrosion in gas turbines to increase their lifetime and efficiency. Removal of the odorant tert-butyl mercaptan (TBM) by selective adsorption with fiber sorbent modules and removal with pellet packed beds are compared in terms of capital and operating costs. Capital costs are estimated based on sizing the equipment items needed for each system, which varies depending on the regeneration gas used. Operating costs are estimated based on the utilities needed to run each system, again varying depending on the regeneration gas used, and also on whether heat integration is considered. Using a fraction of the product gas for regeneration is safer, simpler, and more economical than compressed air or nitrogen. Due to the need for more adsorber beds to process the same amount of TBM-containing pipeline natural gas, the capital cost associated with the pellet packed bed system is significantly higher than that of the fiber sorbent system. Heat integration with the sorption system by using the energy generated from waste gas combustion to produce steam dramatically decreases the operating cost by reducing the parasitic load. Overall, this process analysis shows that the fiber sorbent system with heat integration can be an attractive technology compared to packed bed systems for TBM removal.

Selective adsorption of tert-butylmercaptan and tetrahydrothiophene on modified activated carbons for fuel processing in fuel cell applications

The effects of surface oxidation and KOH impregnation on activated carbon for the selective adsorption of tert-butylmercaptan (TBM) and tetrahydrothiophene (THT) present in natural fuel gas were studied. Physicochemical properties of the adsorbents were characterized by N2 adsorption, X-ray diffraction (XRD), temperature programmed desorption (TPD), scanning electron microscopy (SEM), and surface pH measurements. Oxidation treatments by HNO3 or H2O2 gave rise to considerable increases in both TBM and THT adsorption capacity, about a threefold enhancement from those on pristine activated carbon. Notably, it was found that the oxidative modifications led to an enhancement in THT adsorption selectivity, whereas KOH impregnation led to a marked increase in TBM adsorption selectivity. The properties of the adsorption sites and the adsorption strength of TBM and THT on the sites were characterized. These results agree well with the experimental sulfur adsorption capacities of the samples and can be explained by an adsorption model proposed in this work.

Excitation energy migration in yellow fluorescent protein (citrine) layers adsorbed on modified gold surfaces

The nature of functional proteins adsorbed on solid surfaces is interesting from the perspective of developing of bioelectronics and biomaterials. Here we present evidence that citrine (one of yellow fluorescent protein variants) adsorbed on modified gold surfaces would not undergo denaturation and energy transfer among the adsorbed citrine molecules would occur. Gold substrates were chemically modified with 3-mercaptopropionic acid and tert-butyl mercaptan for the preparation of hydrophilic and hydrophobic surfaces, respectively. A pure solution of citrine was dropped and dried on the modified gold substrates and their surface morphology was studied with scanning tunnelling microscopy (STM). The obtained STM images showed multilayers of citrine adsorbed on the modified surfaces. On hydrophobic surfaces, citrine was adsorbed more randomly, formed various non-uniform aggregates, while on hydrophilic surfaces, citrine appeared more aligned and isolated uniform protein clusters were observed. Fluorescence lifetime and anisotropy decay of these dried citrine layers were also measured using the time correlated single photon counting method. Fluorescence anisotropy of citrine on the hydrophobic surface decayed faster than citrine on the hydrophilic surface. From these results we concluded that fluorescence energy migration occurred faster among citrine molecules which were randomly adsorbed on the hydrophobic surface to compare with the hydrophilic surface.

ChemInform Abstract: Synthesis of Sulfur‐Substituted α‐Stereogenic Amides and Ketones: Highly Enantioselective Sulfa‐Michael Additions of 1,4‐Dicarbonylbut‐2‐enes.

AbstractHighly stereoselective formation of α‐sulfurated amides and ketones is possible.

Adsorptive removal of tert-butylmercaptan and tetrahydrothiophene using microporous molecular sieve ETS-10

The adsorptive removal of tert-butylmercaptan (TBM) and tetrahydrothiophene (THT) in methane gas using microporous molecular sieve ETS-10 was investigated at an ambient temperature and atmospheric pressure. Na,K-ETS-10 and Cu-exchanged Na,K-ETS-10 (Cu-ETS-10) were characterized by X-ray diffractometer (XRD) for the crystalline phase, X-ray fluorescence (XRF) analyzer for the chemical composition, and nitrogen adsorption-isotherm measurement for the BET surface area and porosity, respectively. Posterior to its treatment at 723K in He atmosphere for 2h, the Cu(II) in Cu-ETS-10 could be partially autoreduced to Cu(I), which was confirmed by X-ray photoelectron spectroscopy (XPS). The preferential adsorption of THT over TBM on Na,K-ETS-10 and the concurrent adsorption of TBM and THT on Cu-ETS-10 were achieved, which could be explained by the uptake curve in the binary component adsorption, the temperature-programmed desorption, and the apparent activation energy for desorption. The breakthrough sulfur adsorption capacity for both TBM and THT was attained to 2.50mmolS/g on Cu-ETS-10-0.1(4). This markedly high breakthrough sulfur adsorption capacity on Cu-ETS-10 is unprecedented in removing organic sulfur compounds from fuel gas by adsorption on zeolites.

A cataluminescence gas sensor based on nanosized V 2O 5 for tert-butyl mercaptan

This work proposed a gas sensor for the determination of tert-butyl mercaptan, one of the highly toxic volatile sulfur compounds, which was based on cataluminescence emission during its catalytic oxidation on the surface of nanosized V 2O 5. The cataluminescence characteristics and the optimum conditions, including the morphology of sensing material, the wavelength of cataluminescence emission, the oxygen flow rate and working temperature were investigated in detail. Under the optimized conditions, the calibration curve of the relative cataluminescence intensity versus the concentration of tert-butyl mercaptan vapor was made, with the linear range of 5.6–196 μg mL −1 and the detection limit of 0.5 μg mL −1 ( S/ N = 3). The relative standard deviation (R.S.D.) ( n = 5) of relative cataluminescence intensity for 84 μg mL −1 tert-butyl mercaptan was 3.6%. There is no or weak response to some common substances, such as formic acid, alcohol (methanol, ethanol, propanol, isopropanol, n-butanol, isoamyl alcohol), o-dichlorobenzene, acetonitrile, ethyl acetate, aldehyde (formaldehyde, acetaldehyde and propanal), 1,2-dichloroethane and ammonia. Furthermore, the proposed sensor was successfully used for determining tert-butyl mercaptan in four artificial samples, with a good recovery. The results demonstrated that the proposed gas sensor had a promising capability for the tert-butyl mercaptan in routine monitoring.

Study on the thermal stability of 2-hexyne, 1-pentyne, ethyl isocyanide, and n-butyl isocyanide as sulfur-free gas odorants

In Japan, tert-butyl mercaptan (TBM) is mainly employed as an odorant of LPG. However, the sulfur component in TBM gives the adverse effect for environment and human body and/or has a negative impact on reforming catalyst of fuel cell and other types of cogeneration systems. In this way, the development of sulfur-free odorant is expected. This study focuses on the thermal stability and combustibility of 2-hexyne, 1-pentyne, n-butyl isocyanide (BIC), and ethyl isocyanide (EIC) that is expected as the candidate odorants. As the result of DSC measurement, the comparison of TDSC indicated that 2-hexyne and 1-pentyne are more thermally stable than BIC and EIC. However, in 2-hexyne and 1-pentyne, the slight exothermic peaks were observed at lower temperature region before those main exothermic peaks. In 2-hexyne, copper or aluminum increased the heat amount of that slight exothermic peak observed before main peak. In 1-pentyne with zinc, TDSC was approximately decreased to 279 °C from 337 °C of 1-pentyne alone. As the results of ARC measurement, in the presence of oxygen, the exothermic heat of 2-hexyne and 1-pentyne was observed at approximately 50–100 °C. This heat release may be corresponding to the slight heat release observed by DSC, and it thought to be results from the reaction with atmospheric oxygen. In this way, for the practical application of 2-hexyne and 1-pentyne as odorants, it is important to suppress the invasion of oxygen in the cylinder to low as much as possible in respect of the storage of the candidate odorant. As a result of thermal equilibrium calculation, even if either candidate odorant is added at about 100 ppm, there is little influence on propane combustibility from the adiabatic flame temperature, species of combustion gas and their yields.

A new efficient enantioselective synthesis of (+)‐cis‐2‐methyl‐ 4‐propyl‐1,3‐oxathiane, a valuable ingredient for the aroma of passion fruit

A new simple route to (+)-cis-2-methyl-4-propyl-1,3-oxathiane, the main component responsible of the passion fruit aroma is shown. Such a procedure consists in the sequence of the asymmetric conjugated addition of a thiol to trans-2-hexenal/cleavage of sulfide moiety, which allows to prepare, in only two steps, its immediate precursor, (R)-3-mercaptohexan-1-ol. Various procedures have been investigated for both the steps, using benzyl and tert-butyl mercaptan as thiols. The best results have been achieved in the addition of benzyl thiol to trans-2-hexenal mediated by a proline-derived organocatalyst, followed by debenzylation with sodium naphthalenide, affording (R)-3-mercaptohexan-1-ol with 84% e.e. and a yield much higher (32%) than that previously reported (8.5%).

Adsorption of natural gas and biogas components on activated carbon

Experimental results are presented for the adsorption equilibria of methane, ethane, propane, butane, carbon dioxide, and nitrogen, as well as natural gas odorants tert-butyl mercaptan and tetrahydrothiophene, on an activated carbon with the desirable characteristics for use in a guard bed for adsorbed natural gas storage, but that can also be applied for separation of biogas components, such as carbon dioxide and nitrogen. The adsorption experiments were performed using both open- and closed-loop gravimetry over the pressure and temperature ranges of 0–9 MPa and 273–325 K, respectively. The two odorants were analyzed at the very low concentrations usually found in natural gas (0–25 mg/(N m 3)). The experimental data were successfully correlated by the adsorption potential theory and collapsed into a single temperature-independent characteristic curve. This analysis allows for extrapolation of the adsorption data to higher alkanes, for which no experimental data are available, in order to span the global composition of a typical natural gas stream. The adsorption equilibrium data for methane, carbon dioxide and nitrogen were fitted to the Toth and Sips isotherm models and their isosteric heats of adsorption were determined. The preferential adsorption capacity for carbon dioxide indicates that the carbon can be used for methane purification from natural gas, carbon dioxide sequestration from flue gas, or biogas purification.

Adsorptive removal of tetrahydrothiophene (THT) and tert-butylmercaptan (TBM) using Na-Y and AgNa-Y zeolites for fuel cell applications

Adsorptive removal of tetrahydrothiophene (THT) and tert-butylmercaptan (TBM) that are widely used sulfur odorants in pipeline natural gas was studied using AgNa-Y zeolites at ambient temperature and atmospheric pressure. The AgNa-Y were obtained via Ag+-exchange with Na+ of Na-Y at various exchange levels, and the contributions of formed adsorption sites (Ag+, Na+, Ag0, H+, and Ag2O) in the THT and TBM adsorption uptake and selectivity were characterized. THT adsorption strength on these sites followed an order of Ag+ > Na+ ∼ Ag0 > H+ > Ag2O. The adsorption strength of THT on Na+ sites was sufficiently high, thus an increase in the Ag+-exchange level did not lead to a notable increase in the breakthrough THT uptake. Differently, adsorption of TBM on Na+ sites was weak, whereas that on Ag+ sites was strong. This resulted in a marked increase in the breakthrough TBM uptake with an increase in the Ag+-exchange level, showing an order of magnitude higher uptake on AgNa-Y compared with that on Na-Y. Noticeably, the adsorption strength of THT on these adsorption sites was higher than that of TBM. This resulted in an almost 100% adsorption selectivity for THT over TBM, when these two sulfur species coexisted in the feed stream.

Effect of Surface Morphology on Dimerization of tert-Butyl Mercaptan on the Surface of Amorphous Aluminosilicate Impregnated with Mn and Cu

A powder of destructive adsorbent was prepared by impregnating Mn and Cu on the surface of amorphous aluminosilicate. It catalytically dimerized tert-butyl mercaptan into di-tert-butyl disulfide on its surface. Turnover of the dimerization was strongly dependent on the surface morphology of the adsorbent, which could be altered by modification of aluminosilicate support. During the process of impregnation, which involved heat treatment at 500 <TEX>${^{\circ}C}$</TEX>, the shape of the pore was preserved, though large fraction of micropores were eliminated. The reactive sites on the surface were poisoned as dimerization products strongly adhered on them. Therefore, high surface area was not always desirable. When the surface was heavily populated with “inkbottled” pores with a narrow entrance in uniform size, heavy poisoning of the reactive sites turned the destructive adsorbents almost useless.

Tertiary Butyl Mercaptan Adsorption in Soils. Determination of Kinetic and Transport Parameters from Experimental Data

The present paper addresses the importance of the adsorptive properties of argentinean soils in the odor fade odor problem that is faced in the presence of odorized natural gas leakages. Samples of soils were subjected to stimulus-response experiments in which the soils were exposed to a step change in odorant concentration. A typical S shaped breakhrough curve was obtained at the soil bed exit. The adsorption characteristics of each soil is associated to its composition. The results confirm that clay based soils adsorb the gas odorant (tert butyl mercaptan) more strongly than sand based soils or soils with high organic carbon content. The adsorption process was modeled. The model takes into account the following mass-transfer processes: plug flow of TBM along the solid bed, external resistances to the mass transfer, diffusion within the particle and adsorption/desorption of TBM between the gas phase of the intraparticle pore space and the particle surface. The model reproduces quite well the experimental data. The results suggest that the odorant adsorption process is controlled by the mass transfer steps.

Biochemistry of sulfur extraction in bio-corrosion of pyrite by Thiobacillus ferrooxidans

By adding a small amount of the amino acid cysteine to an acidic solution containing Thiobacillus ferroxidans cells and subsequent incubation with synthetic pyrite layers, the duration of the lag phase in the growth of T. ferrooxidans is minimized and the leaching rate of this sulfide is increased three times compared to the normal process without this biochemical additive. In the presence of cysteine, pyrite can be oxidized in the absence of bacteria with a leaching rate comparable with that attained by bacteria under normal leaching conditions. It seems that the sulfhydryl group of cysteine participates in a binding process with pyrite. Free-SH groups from the pyrite surface would be the counterpart for the formation of the corresponding disulfide. This thiol-disulfide reaction means that cysteine is consumed by the pyrite surface with the subsequent release of iron-sulfur species. This result is accounted for by the fact that pyrite without bacteria can be completely oxidized. Bacteria would take advantage of this biochemical corrosion process by uptake and oxidation of the released species which are continuously supplied to the acidic-biotope. The reactivity of cysteine with the pyrite surface, which improves the bacterial leaching rate, suggested the investigation of other mono-thiol molecules with the aim to mask the pyrite surface against bacterial attack. The latter can be relevant for protecting steel against microbiologically induced corrosion (MIC). S- tert-butyl mercaptan ((CH 3) 3C–SH, TBM)) was found to stop the bacterial corrosion by T. ferrooxidans. Permanent disulfide bonds between pyrite and the blocking SH-agent are presumably the cause for this protection.

Stereoselective 1,2-CIS-1-Thioglycosidation of Aldohexoses with Tert-Butyl Mercaptan in 90% Trifluoroacetic Acid

ABSTRACT tert-Butyl 1,2-cis-1-thioglycopyranosides of various aldohexoses (D-glucose, D-galactose, D-mannose, and L-rhamnose), and disaccharides (cellobiose, lactose, and maltose) were preferentially prepared in good yields by reacting the corresponding free sugars with tert-butyl mercaptan in 90% trifluoroacetic acid at room temperature. No selectivity, however, was observed at all in the case of 2-deoxy-D-arabino-hexopyranose. A possible mechanism for the 1,2-cis-selectivity was discussed from a standpoint of thermodynamic and kinetic control.

Inter- and intramolecular pathways for the formation of tetrahydrofurans from beta-(Phosphatoxy)alkyl radicals. Evidence for a dissociative mechanism

beta-(Phosphatoxy)alkyl radicals generated by photolysis of Barton PTOC esters in the presence of allyl alcohol and tert-butyl mercaptan undergo nucleophilic substitution followed by 5-exo-trig radical ring closure leading to tetrahydrofurans in good yield and with high trans selectivity. beta-(Phosphatoxy)alkyl radicals obtained by intramolecular hydrogen 1,5-abstraction with an alkoxyl radical undergo nucleophilic displacement providing tetrahydrofurans. The ensemble of results, including the effects of leaving groups and substituents, strongly support a dissociative mechanism for these radical nucleophilic displacement reactions.