T-butyl Mercaptan Research Articles

(Invited) Electrochemical Pumping for Hydrogen Storage and Distribution in the Natural Gas Pipeline

Over the next decade, the production and use of hydrogen in various sectors of the global economy is anticipated to grow significantly. It is an already important feedstock in the production of ammonia and desulfurization of fuels in addition to being used in metals refining and as a coolant in thermal electric power plants. More recently, hydrogen is being considered for long-term seasonal energy storage for energy derived from renewables like solar and wind. To alleviate the severe costs of building out completely new infrastructure, the U.S. natural gas pipeline represents an enticing proposition for hydrogen storage and a potential distribution network from centralized production facilities. Embrittlement concerns of the pipeline with hydrogen limit the hydrogen partial pressure/concentration of hydrogen to be stored. Because many end use applications often require high purity hydrogen, it is necessary to separate/de-blend hydrogen from natural gas and compress it at the point-of-use. This talk presents high-temperature polymer electrolyte membrane (HT-PEM) electrochemical hydrogen pumps for separating hydrogen from gas mixtures. Hydrogen purification to +99% from syngas (25mol% hydrogen and 40mol% carbon monoxide (CO)) at 1 A cm-2 and cell voltage of 0.4 V with an electrochemical hydrogen pump was demonstrated. About 90% of hydrogen used in the United States today derives from steam-reformed natural gas that contains large concentrations of CO – which is a potent platinum electrocatalyst poison at temperatures below 100 °C. The hydrogen purification from syngas was possible with an electrochemical hydrogen pump operated at 220 °C and by using: i.) an ion pair HT-PEM that exploits electrostatic interactions to prevent phosphoric acid leaching at elevated temperatures from the membrane matrix and in the presence of water and ii.) a phosphonic acid ionomer electrode binder. The membrane electrode assembly (MEA) with the said materials and platinum on carbon (Pt/C) electrocatalyst was also effective for purifying hydrogen from other types of reformed hydrocarbons with different CO and hydrogen concentrations. Unexpectedly, operating the HT-PEM hydrogen pump at 220 °C minimized CO impact on cell polarization. At this temperature, cell polarization was governed by the hydrogen concentration in the gas feed. These observations motivate future work to develop new electrodes and electrode binders that can extract, purify, and compress hydrogen with feed streams that have low hydrogen content and contain other constituents in natural gas (methane, ethane, t-butyl mercaptan, etc).

Selective monitoring of natural gas sulphur-based odorant mixture of t-butyl mercaptan and methyl ethyl sulphide using an array of microfluidic gas sensors

A natural gas (NG) odorization system requires continuous monitoring as well as an optimal injection to satisfy the odorization guidelines, minimize over-odorization, and prevent hazardous gas leaks. NG consists of hydrocarbons such as methane, odorants such as tert-butyl mercaptan, and other sulphur-based VOCs such as hydrogen sulphide; therefore, selectivity is paramount for the reliable and accurate monitoring of odorants. In this study, we developed a portable device integrated with an array of five different sensors to detect a mixture of tert-butyl mercaptan and methyl ethyl sulphide for a concentration range of 1 ppm to 10 ppm. A machine learning model was developed to predict the presence and concentration of NG odorants from the sensor data. The best-performing sensors in the array achieved high sensitivity and selectivity indicators (measured using the Davies-Bouldin index) of 0.3667 (1⁄ppm) and 0.125, respectively. The sensor system achieved a classification accuracy of 98.75% between NG odorants and hydrogen sulphide, with an overall Mean Squared Error (MSE) and R2 error (for the regression model) of 0.50 and 95.16%. These results indicate that the developed portable device and the machine learning model have promising applications for the selective monitoring of NG odorants.

Functional UiO-66 for the removal of sulfur-containing compounds in gas and liquid mixtures: A molecular simulation study

In chemical and pharmaceutical industries, sulfur-containing compounds may exist in gas and liquid mixtures, and need to be removed. In this study, we report a molecular simulation study to investigate the adsorption and separation of t-butyl-mercaptan (TBM) in natural gas, as well as dimethyl sulfoxide (DMSO) in aqueous solution, by UiO-66 and its functional derivatives UiO-66-F4, -(CH3)2, -(COOH)2, -(CF3)2, and -naphthyl. It is revealed that the functional groups can act as additional adsorption sites and create stronger surface potential overlap, thus generally enhance adsorption capability. All the six UiO-66s show high adsorption capacity for TBM, except UiO-66-naphthyl due to reduced porosity and surface area. The TBM/CH4 selectivity is predicted to be high in these UiO-66s, ranging from 2.2 × 104 to 2.4 × 105; intriguingly, the TBM separation is not affected by the presence of trace H2O. The UiO-66s also exhibit good adsorption capacity and high selectivity for DMSO from aqueous solution, with DMSO/water selectivity up to 570 in UiO-66. This study provides microscopic insights into the selective adsorption of sulfur-containing compounds in both gas and liquid mixtures, and suggests that UiO-66s might be promising nanoporous materials for industry-relevant separation.

Indium-catalyzed reductive three-component coupling reaction of aliphatic/aromatic carboxylic acids with t-butyl mercaptan leading to unsymmetrical dialkyl sulfides

An InI3–TMDS (1,1,3,3-tetramethyldisiloxane) reducing system efficiently catalyzed a sequential three-component coupling of aliphatic carboxylic acids, aromatic carboxylic acids, and t-butyl mercaptan (t-butylthiol), to produce unsymmetrical dialkyl sulfides. With this reducing system, t-butyl mercaptan became a new source of sulfidation via an alkyl t-butyl sulfide that functioned as the reaction intermediate.

Hybrid Polymer/UiO-66(Zr) and Polymer/NaY Fiber Sorbents for Mercaptan Removal from Natural Gas.

Zeolite NaY and metal organic frameworks MIL-53(Al) and UiO-66(Zr) are spun with cellulose acetate (CA) polymer to create hybrid porous composite fibers for the selective adsorption of sulfur odorant compounds from pipeline natural gas. Odorant removal is desirable to limit corrosion associated with sulfur oxide production, thereby increasing lifetime in gas turbines used for electricity generation. In line with these goals, the performance of the hybrid fibers is evaluated on the basis of sulfur sorption capacity and selectivity, as well as fiber stability and regenerability, compared to their polymer-free sorbent counterparts. The capacities of the powder sorbents are also measured using various desorption temperatures to evaluate the potential for lower temperature, energy, and cost-efficient system operation. Both NaY/CA and UiO-66(Zr)/CA hybrid fibers are prepared with high sorbent loadings, and both have high capacities and selectivities for t-butyl mercaptan (TBM) odorant sorption from a model natural gas (NG), while being stable to multiple regeneration cycles. The different advantages and disadvantages of both types of fibers relative are discussed, with both offering the potential advantages of low pressure drop, rapid heat and mass transfer, and low energy requirements over traditional sulfur removal technologies such as hydrodesulfurization (HDS) or adsorption in a pellet packed beds.

Metal Organic Frameworks for Selective Adsorption of t-Butyl Mercaptan from Natural Gas

Pipeline natural gas is typically “odorized” with ∼10 ppm of sulfur-containing components, such as mercaptans, for ease of detection. Such odorants can be removed before being burned in electricity generation gas turbines to prevent or limit turbine corrosion and increase turbine lifetime. Selective adsorption of these odorants onto solid materials is an attractive approach to address this problem because of the ability to remove these trace levels of sulfur and to be operated at low temperatures, meaning that it is less energy-intensive than other traditional sulfur removal methods. Adsorbent material selection is important for this approach, and a material with high sulfur capacity, selectivity, and regenerability is desired for a practical implementation of such an adsorption system. In this study, several adsorbent materials are gravimetrically screened for t-butyl mercaptan (TBM) adsorption capacity and the best candidates, Cu-BTC, MIL-53(Al), and UiO-66(Zr), are compared to a benchmark material, zeolite NaY. These selected materials are evaluated with regard to their cyclic regenerability/stability and selectivity toward TBM over methane and other impurities. From the results of this study, UiO-66(Zr) emerges as a promising candidate material for this application.

Photocatalytic Purification of Wastewater Polluted by Odorant Sulfur Compounds Using Titanium Oxide in a Continuous Photoreactor

Abstract Using titanium dioxide, photocatalytic degradation of waste water polluted by commercial mercaptans (80% t-butyl mercaptan and 20% methyl ethyl sulfide) was investigated in a continuous photoreactor in the presence of UV irradiation. The reaction was performed at different pH of solution, intensity of irradiation, and initial concentration of odorant. Kinetics and mechanism of photocatalytic decomposition of mercaptans were studied by ex situ FTIR measurements of intermediates. The results showed that the photocatalytic process for degradation of mercaptans was an efficient method for mineralization of sulfur odorants in waste water. A proposed mechanism of mineralization of mercaptan was presented based on the results.

Effect of Al 2O 3 content on the adsorptive properties of Cu/ZnO/Al 2O 3 for removal of odorant sulfur compounds

Cu/ZnO/Al 2O 3 adsorbents for removal of odorant sulfur compounds were prepared with various Al/Cu molar ratios by co-precipitation method. The sulfur removing ability as a function of Al/Cu molar ratio of the adsorbents for t-butyl mercaptan (TBM), tetrahydro thiophene (THT), dimethyl disulfide (DMS) and H 2S were investigated at 250 °C and 6000 h −1 space velocity. Based on the results of adsorption capacity and characterization by various techniques, the optimum Al/Cu ratio for maximum sulfur removal capacity is found to be at Al/Cu molar ratio of 0.15 which possesses the well-dispersed Cu species with high reducibility. The adsorption capacity is highest for H 2S followed by TBM, DMS and THT. The main role of Al 2O 3 component is to provide the dispersion of CuO species homogeneously with small particle formation and high reducibility.

Desulfurization of odorant-containing gas: Removal of t-butylmercaptan on Cu/ZnO/Al 2O 3

The removal of t-butylmercaptan (TBM) from gas fuel has been investigated by using sorption. The sorbents, Cu/Al 2O 3, ZnO/Al 2O 3 and Cu/ZnO/Al 2O 3, were prepared by co-precipitation method. As the sorption temperature increased to 250 ∘ C , the sorption capacity of TBM on Cu/ZnO/Al 2O 3 increased up to 8.84 mmol/g, and then decreased. In the comparison of sorbents, the order of sorption capacity was Cu / ZnO / Al 2 O 3 > Cu / Al 2 O 3 > ZnO / Al 2 O 3 indicating the increase of that under co-existence of Cu and ZnO. The maximum crystallinity of CuS and ZnS was showed after the sorption of TBM at 250 ∘ C using Cu/ZnO/Al 2O 3. The increased crystallinity of CuS and ZnS resulted in decreases in surface areas. The results imply that the sulfur compound is decomposed by both Cu and ZnO and subsequently S was bound to Cu and Zn.

Adsorptive removal of dimethylsulfide and t-butylmercaptan from pipeline natural gas fuel on Ag zeolites under ambient conditions

Desulfurization of pipeline natural gas fuel at ambient conditions before introduction to reforming processes is strongly needed for stationary applications of fuel cells. Adsorptive removal of dimethlysulfide (DMS) and t-butylmercaptan (TBM) from pipeline natural gas was efficiently carried out by using silver exchanged Y zeolites (AgNa-Y) in the presence of water at room temperature and normal pressure. The capacity and adsorptivity for DMS and TBM on AgNa-Y were improved by an increase in silver content of AgNa-Y. Adsorption runs for DMS and TBM were carried out separately to compare their adsorptivity on AgNa-Y. The sulfur adsorption capacity for DMS on Ag(18)Na-Y (1.9mmolg−1) was much higher than that for TBM (0.6mmolg−1). The clear color change of AgNa-Y during the period of adsorption run provides information regarding the formation of silver sulfide species on AgNa-Y. The used AgNa-Y was regenerated easily by heat treatment in air at 500°C.

A Thio-Staudinger Reaction: Thermolysis of a Vinyl Azide in the Presence of t -Butyl Mercaptan

The thermal decomposition of E-3-azido-3-hexene-2,5-dione ( 1 ) in protic media gave rise to several novel reactions of the azide 1 including adducts derived from keteneimine 11 . Reaction with t-butyl mercaptan yielded two products, keteneimine-derived mercaptan addition product 20 and a sulfenimine 6 . Trapping of a vinyl nitrene intermediate or a thio-Staudinger reaction was considered as a possible mechanism for the formation of sulfenimine 6 . The absence of the vinyl nitrene addition products 3 and 5 when the thermal decomposition was conducted in either methanol or t-butylamine suggests a thio-Staudinger reaction is operative.

Removal of dimethyl sulfide and t-butylmercaptan from city gas by adsorption on zeolites

The removal of dimethyl sulfide (DMS) and t-butylmercaptan (TBM) from city gas by use of zeolites was studied. Na-Y, Na-X, and Ca-X showed high removal ratios of the sulfur compounds at 1 h after the start of the adsorption run in city gas flow, though DMS broke through rapidly for a few hours. On the other hand, H-β and USY showed continuously high removal ratios for 9 h, and trace amounts of H 2S were detected in the effluent gas. The adsorption mechanisms on Na-Y and H-β were studied by adsorption in the absence of hydrocarbons, IR spectroscopy, and temperature programmed desorption (TPD). The desorbed peaks of DMS and TBM during TPD of binary components on Na-Y were located over the same temperature ranges as the peak during TPD of DMS and that of TBM, respectively, which findings suggested that the adsorption states at binary adsorption were similar to those at single component adsorption. The main adsorption site was presumably Na +. On H-β, TBM reacted to H 2S on Brönsted acidic sites. On the adsorption run in the absence of hydrocarbons, the removal ratio of TBM was enhanced on H-β in the presence of DMS. During TPD of binary components on H-β, a peak of m/ e=41 at 120°C grew, which findings indicated that the polymerization of isobutene-like compounds produced from TBM was depressed by co-existent DMS.

Microwave Fourier transform spectrum of t-butyl mercaptan

The microwave spectrum of t-butyl mercaptan, (CH3)3CSH, in its vibrational ground state has been measured in the range from 8 to 26GHz, and 542 transitions were newly assigned. The spectrum was analysed using the combined axis method. The three rotational constants, four quartic centrifugal distortion constants according to Watson's S-reduction, the threefold hindering potential V3 for the CSH torsion, the moment of inertia of the t-butyl group Iα, and the angle between the internal rotation axis i and the principal inertia axis a ∠(i, a) were accurately determined. However, the standard deviation of the fit, 200kHz, is about two orders of magnitude larger than the experimental uncertainty and the residuals rapidly increase with J indicating that the rigid top–rigid frame assumption is not a perfect one and that a more sophisticated model should be used.

Kinetics of chemical beam epitaxy for high quality ZnS film growth

A comprehensive study is reported of the chemical and metalorganic molecular beam epitaxy ( CBE MOMBE ) growth of ZnS on Si and GaAs(100) substrates for applications in advanced electroluminescent displays and for optoelectronic device integration on Si. Growth kinetics studies of conventional and photoassisted MOMBE and CBE using diethylzinc (DeZn) with H 2S, di-isopropylsulfide (DipS) and a novel precursor, t-butyl mercaptan (t-BuSH), are reported. The results obtained indicated that the low temperature growth of ZnS using cracked DeZn and DipS was hindered. This was attributed to the reattachment of the alkyl radicals to surface growth sites, which resulted in a lower growth rate. However, by using uncracked DeZn and H 2S or cracked DeZn and t-BuSH, this growth hindrance was removed by the surface reaction of hydrogen with the alkyl radicals. The addition of a thin CaF 2 buffer layer was found to remarkably improve the growth of ZnS on Si.

Comparison of on-line SPE-HPLC and SPME-GC for the analysis of microcontaminants in water

Solid-phase preconcentration coupled on-line with liquid chromatography, and solid-phase microextraction coupled with gas chromatography have been applied to the determination of trace-level concentrations of benzene and sulfur compounds (tetrahydrothiophene (THT),t-butyl mercaptan (TBM), andn-butyl mercaptan (nBM)) in aqueous media.

Single step syntheses of lactosylated clusters by telomerizations

N-Acryloylated lactoside derivatives containing spacer arms of different length were polymerized in the presence of thiols acting as radical scavengers to provide small oligomeric clusters (telomers) in a single step. t-Butyl mercaptan and methyl 3-mercaptopropionate chosen as chain transfer reagents, were used for further attachment to L-lysine methyl ester.

Mercaptans Decrease Selenium-Dependent Glutathione Peroxidase Activity in the Chick

A variety of mercaptans, especially the β-mercaptocarboxylic acids, inhibited the selenium (Se)-dependent glutathione peroxidase (SeGSHpx) activity of chick liver postmitochondrial supernatant or cytosol and of purified bovine erythrocyte SeGSHpx. The effects of mercaptans and a glutathione analogue on Se utilization were determined by subcutaneous injection of test compounds into vitamin E–deficient chicks fed diets containing 0.1 ppm Se (as Na2SeO3) at times when > 50% of vitamin E– and Se-deficient chicks showed the vitamin E–, Se-deficiency disease exudative diathesis (ED). D-(-)-Penicillamine hydrochloride (the positive control model compound), sodium β-mercaptopyruvate, t-butyl mercaptan and S-methylglutathione (nonmercaptan glutathione analogue) decreased SeGSHpx activity in chick liver postmitchondrial supernatants within 24 h of injection and increased the incidence of ED within 4 d. Other mercaptans tested did not increase ED incidence or affect liver, kidney or plasma SeGSHpx activities. Although mercaptosuccinic acid, N-(2-mercaptopropionyl)glycine and sodium thioglycolate each strongly inhibited SeGSHpx in vitro, each also significantly increased chick mortality in the dosage range tested; therefore, their effects on SeGSHpx in vivo could not be evaluated. It appears that the β-mercaptocarboxylic acids, mercaptans with a high degree of steric hinderance in close proximity to the thiol group and a close structural analogue of glutathione are capable of altering selenium status in chicks.

Decarboxylation of Bridgehead Carboxylic Acids by the Barton Procedure

Reductive decarboxylation of a series of bicyclic and polycyclic acids in which the carboxyl group is attached to the bridgehead position has been investigated. Conversion of the acids into thiohydroxamic esters occurs via reaction of the derived acid chlorides with N- hydroxypyridine-2-thione. Decomposition of the esters proceeds smoothly in boiling benzene in the presence of t-butyl mercaptan to give the reduced product in high yield. The procedure appears to be generally applicable, and is unaffected by functional groups such as esters and acetals.

Raney metal catalysts: I. comparative properties of raney nickel proceeding from Ni-Ai intermetallic phases

Raney nickel catalysts, prepared from well defined pure phases, have been characterised by bulk composition, total and nickel surface areas, structure, activity and sensitivity to sulfur compounds. The catalyst formed from the Ni 2Al 3 phase has 3 times more residual aluminium than that obtained from the NiAl 3 phase and it also develops the highest surface areas. Raney nickel prepared from a commercial 50–50 wt% Ni-AI alloy is a mixture of the samples obtained from the two pure phases. The origin of the catalyst has no effect upon either its activity and selectivity to benzene and isoprene hydrogenation or its catalytic properties in presence of thiophene or t-butyl mercaptan.

Reaction of the unsaturated anion [Re 3H 4(CO) 10] − with mercaptans. Synthesis and X-ray Characterization of the anion [ Re 3H 3 (CO) 9(μ 3-SBu t)] −

The novel anion [Re 3H 3(CO) 9(μ 3-SBu t)] −, obtained by reaction of [Re 3H 4(CO) 10] − with t-butyl mercaptan, has been characterized by IR, NMR and X-ray diffraction studies. It contains an equilateral Re 3 triangle (mean ReRe 3.091 Å), with nine terminal carbonyl groups, three for each metal atom, and a triply-bridging thiolate ligand (mean ReS 2.393 Å). The three hydrides are bridging on the edges of the triangle of metal atoms.