Ethanethiol Research Articles

The Removal of Sulfur Compounds Using Activated Carbon-Based Sorbents Impregnated with Alkali or Alkaline Earth Metal

To remove sulfur compounds, such as methyl mercaptan (M.M.), ethyl mercaptan (E.M.), dimethyl disulfide (DMDS) and diethyl disulfide (DEDS) in the fluidized catalytic cracking (FCC) process, various activated carbon (AC)-based sorbents impregnated with alkali and alkaline earth metal were tested in a fixed-bed quartz reactor at 30 °C. The sulfur removal capacities of the AC-based sorbents (e.g., the CaAC, NaAC and KAC series) prepared via impregnation with alkali or alkaline earth metal were more enhanced than those of the pure AC sorbents despite a notable decrease in their surface areas and pore volumes. It was found that the alkali/alkaline earth metal was the adsorption site of the sulfur compound. Moreover, the KAC-10 sorbent showed excellent sulfur removal capacity and regeneration ability.

Chemical transformations of sulfur compounds adsorbed onto activated carbon materials during thermal desorption

Four commercial activated carbon materials, including two fiber cloths, were studied as adsorbents for three organosulfurs in terms of adsorption and thermal regeneration, the organosulfurs being ethyl mercaptan, isopropyl mercaptan and tetrahydrothiophene. Their performance is interpreted using their inherent porosity and surface functional groups characteristics. The most porous granular carbon with acidic surface functional groups performed better than the other adsorbents at a high organosulfur concentration. However, at a low concentration the fiber cloths exhibit greater adsorption than granular materials, thereby confirming their potential to desulfurize various gases. Thermal desorption was performed in nitrogen and oxidizing atmosphere, the major role of oxygen in the degradation process of the organosulfurs has been pointed out. Mercaptans are oxidized to their respective sulfide, disulfide, sulfur dioxide, minor carbonyl compounds and elemental sulfur, whereas tetrahydrothiophene by-products are limited to thiophene, sulfur dioxide, elemental sulfur and traces of sulfone compound. Based on the various observed by-products, the oxidative degradation pathways for the three organosulfurs are presented in this study.

Final report on international key comparison CCQM-K65: Gas standards containing methyl and ethyl mercaptans (at the level of 20–30 µmol/mol) in methane

The key comparison CCQM-K65 was intended to compare the capabilities for the preparation and value assignment of gas standards for methyl and ethyl mercaptans in methane, maintained at the participating national metrological institutes: VNIIM (Russia), KRISS (Korea), VSL (Netherlands) and NPL (United Kingdom). The range of the nominal amount of substance fractions of the comparison gas mixtures was 20 µmol/mol to 30 µmol/mol, which is close to regulatory level (in several countries including Russia) for mercaptans in odorated natural gas. This comparison was proposed at the 12th GAWG meeting in October 2004 and was conducted in 2008.Conclusions are as follows: The results of all laboratories are consistent with the reference values. The observed differences between the reference and reported values are within ±0.9% for methyl mercaptan and ±0.75% for ethyl mercaptan relative to the gravimetric values, and do not exceed the appropriate assigned expanded uncertainties. The prepared mixtures were found to be stable during about a year within the uncertainty of the measurements. The gravimetric values were successfully validated with a dynamic method.Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Adsorption and photocatalytic oxidation of dimethyl sulfide and ethyl mercaptan over layered K 1-2 xMn xTiNbO 5 and K 1-2 xNi xTiNbO 5

Layered K 1-2 x M x TiNbO 5 (M = Mn, Ni) was prepared by ion-exchange of KTiNbO 5 obtained by the solid-state method with Mn 2+ and Ni 2+. The crystal structure and optical property of the as-prepared K 1-2 x M x TiNbO 5 were studied using powder X-ray diffraction and ultraviolet (UV)-visible light diffuse reflection spectroscopy. The adsorption feature and photocatalytic oxidation activity of dimethyl sulfide (DMS) and ethyl mercaptan (EM) over the as-prepared K 1-2 x M x TiNbO 5 were evaluated using infrared spectroscopy. K 1-2 x M x TiNbO 5 showed a higher interval between sheets and a stronger absorbance to visible light than KTiNbO 5. After ion-exchange with Mn 2+ and Ni 2+, the band-gap energy of KTiNbO 5 was shifted from 3.35 to 2.97 eV and 2.45 eV, respectively whereas the weak interaction between K 1-2 x M x TiNbO 5 and DMS/EM was little affected by the exchanged cation. The photocatalytic oxidation activity of K 1-2 x M x TiNbO 5 for DMS or EM depended on the special cation. K 1-2 x Mn x TiNbO 5 emerged a photocatalytic activity only under ultra-light irradiation, which converted DMS to sulfoxide and sulfone, and EM to sulfonic acid. However, K 1-2 x Ni x TiNbO 5 emerged the photocatalytic activity under visible light besides under ultra-light irradiation; EM was converted to sulfonic acid by visible irradiation, but to sulfate and carbonate by UV radiation.

Thermodynamic Role of Glutathione Oxidation by Peroxide and Peroxybicarbonate in the Prevention of Alzheimer’s Disease and Cancer

First principle quantum molecular computations have been carried out at the B3LYP/6-31G(d,p) and G3MP2B3 levels of theory on ethyl mercaptan and diethyl disulfide to study their full conformational space. The consequences of molecular axis chirality for the potential energy hypersurface of diethyl disulfide was fully explored. Thermodynamic functions (U, H, S, and G) have been computed for every conformer of the products as well as the reactants of the redox systems studied. Relative values of the thermodynamic functions were calculated with respect to the reference structures with anti orientation. The energetics of the following Red-Ox reactions Et-SH+HO-OH+HS-Et --> 2H2O+Et-S-S-Et Et-SH+HO-OCOO(-)+HS-Et --> H2O+Et-S-S-Et+HCO3- have been chosen to mimic the biologically important Red-Ox reactions of glutathione G-SH+H2O2+HS-G --> 2H2O+G-S-S-G G-SH+HCO4-+HS-G --> H2O+G-S-S-G+HCO3-. The Red-Ox reaction of Et-SH --> Et-S-S-Et was found to be exothermic by first principle molecular computations and the intramolecular interactions, such as the unusual C-H...H-C noncovalent bondings were studied by Bader's atoms in molecules analysis of the electron density topology. The present paper focuses attention on the thermodynamic aspect of the redox reaction of glutathione. It has been noted previously that on going from a cancerous to a healthy cell, the entropy change is negative, corresponding to information accumulation. Likewise, the dissociation of peptide parallel beta-sheets, that dominate the plaques in Alzheimer's Disease, governs negative entropy change. It may be interesting to note, according to the results obtained in the present paper, a negative entropy change, corresponding to information accumulation.

The role of gold adatoms in self‐assembled monolayers of thiol on Au(111)

AbstractThe role of Au adatoms in high‐density alkanethiol self‐assembled monolayers (SAMs) has been investigated. Surface reconstructions in ethylthiol (ET) SAMs due to gold adatoms have been studied using DFT calculations. Relative energies are compared based on binding and surface energies calculated for different lattices using the same unit cell. We have found a structure with two ET‐Au‐ET adatom moieties binding on top of surface gold atoms as the most stable structure. Our model is consistent with the structural parameters obtained from experiments. In particular, the simulated STM image displays the characteristic zig‐zag pattern. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009

Assessment of odorous VOCs released from a main MSW landfill site in Istanbul-Turkey via a modelling approach

An air pollution modeling study was conducted to investigate the odorous effects of volatile organic compounds (VOCs) emissions from a sanitary landfill area on ambient air quality. The atmospheric dispersion of hydrogen sulfide (H 2S) and 22 VOCs was modeled. Industrial Source Complex v3 Short Term (ISCST3) model was used to estimate hourly concentrations of odorous VOCs over the nearest residential area. Odor thresholds of VOCs of interest were also found in the literature. Results showed that short-term averages of three odorous VOCs, namely ethyl mercaptan, methyl mercaptan and hydrogen sulfide, exceeded their odor thresholds, which are reported to be 0.022, 0.138 and 11.1 μg/m 3, respectively, at several points within the domain. Their highest concentrations within Gokturk County were estimated to be 0.09387 μg/m 3 for ethyl mercaptan, 0.07934 μg/m 3 for methyl mercaptan and 6.315 μg/m 3 for hydrogen sulfide. Short-term model results revealed the occasional odor problems being reported for Gokturk County. Hourly concentrations were used to obtain frequencies of odor episodes in Gokturk County via a probability analysis. The results showed that ethyl mercaptan concentrations did not exceed its odor threshold during more than 8.84% of the time. Similarly, the maximum odor episode frequencies for methyl mercaptan and hydrogen sulfide were 0.98% and 0.34% of the time, respectively.

Removal of H2S and volatile organic sulfur compounds by silicone membrane extraction

AbstractBACKGROUND: This study explores an alternative process for the abatement and/or desulfurization of H2S and volatile organic sulfur compounds (VOSC) containing waste streams, which employs a silicone‐based membrane to simultaneously remove H2S and VOSC. An extractive membrane reactor allows the selective withdrawal of VOSC and H2S simultaneously from the waste stream, while preventing direct contact between the waste stream and the absorbing solution and/or the biological treatment system. The influence of the sulfur compounds, membrane characteristics, extractant and pH was studied.RESULTS: Sulfide and the VOCS studied, i.e. methanethiol (MT), ethanethiol (ET) and dimethylsulfide (DMS) were removed from the synthetic wastewater using a silicone rubber membrane. Methanethiol showed the highest (8.72 × 10−6 m s−1) overall mass transfer coefficient (kov) and sulfide the lowest kov value (1.23 × 10−6 m s−1). Adsorption of the VOCS into the silicone membrane reduced the overall mass transfer coefficient. The kov when using Fe(III)EDTA− as extractant (5.81 × 10−7 m s−1) for sulfide extraction was one order of magnitude lower than with anaerobic water (2.54 × 10−6 m s−1). On the other hand, the sulfide removal efficiency with Fe(III)EDTA− was higher (84%) compared with anaerobic water (60%) as extractant. An additional mass transfer resistance was formed by elemental sulfur which remained attached to the membrane surface.CONCLUSIONS: Extraction of sulfide and VOCS from a synthetic wastewater solution through a silicone rubber membrane is a feasible process as alternative to the techniques developed to treat VOSC emissions. Optimizing the aqueous absorption liquid can increase the efficiency of extraction based processes. Copyright © 2008 Society of Chemical Industry

Solid-phase microextraction—Gas chromatography to determine volatile organic sulfur compounds in the air at sewage treatment plants

Solid-phase microextraction (SPME) was applied to the determination of 7 volatile organic sulfur compounds (VOSCs), which were analysed by gas chromatography–mass spectrometry. The compounds studied were ethyl mercaptan (CH 3CH 2SH), dimethyl sulfide ((CH 3) 2S), carbon disulfide (CS 2), propyl mercaptan (C 3H 8S), butyl mercaptan (C 4H 10S), dimethyl disulfide ((CH 3) 2S 2) and 1-pentanethiol (C 5H 12S). Temperature and time conditions of SPME extraction were optimised and the method was validated, with good linearity in a calibration range between 0.1 and 1000 μg m −3. Method detection limits ranged between 0.01 and 0.08 μg m −3 and method quantification limits were between 0.10 and 0.25 μg m −3, allowing real samples taken from several different areas of a sewage treatment plant to be analysed. Repeatability of the method between samples went from 5.6% for pentanethiol up to 14.2% for carbon disulfide, and concentrations of total target compounds were found between 18 and 529 μg m −3, depending on the sampling site.

Morphological and chemical optimization of microcantilever surfaces for thyroid system biosensing and beyond

The development of biosensors is vital in many areas of biotechnology and biomedical research. A prominent new class of label-free biosensors are those based on ligand-induced nanomechanical responses of microcantilevers (MCs). The interaction between biologically significant ligands with bioreceptors (e.g., antibodies or nuclear receptor proteins) immobilized on one side of the MC surface causes an apparent surface stress, resulting in static bending of the MC, which can be detected by an optical beam bending technique. The three key performance metrics of sensitivity, selectivity, and reversibility are foci of the work reported herein. The nature of the MC surface and the method by which the bioreceptor is immobilized influence these performance metrics and, hence, optimization studies involving these were conducted. In our work, the gold surface on one side of the MC is first activated via self-assembled monolayer formation with amino ethane thiol (AET) then reacted with glutaraldehyde (GA) as a crosslinker before finally functionalizing with the protein receptor. We report the effect of concentration, reaction time, and pH for these reagents on the magnitude of the nanomechanical responses using an anti-immunoglobulin G (anti-IgG) receptor: IgG ligand test system. By vapor depositing an alloy of silver and gold and then etching away the former, a nanostructured “dealloyed” MC surface is created that outperforms a smooth gold MC in terms of nanomechanical responses. Optimization of the dealloying parameters (thickness, metal ratio) is also reported herein using the aforementioned anti-IgG–IgG system. Maximum response was obtained with these conditions: 150 nm dealloyed surface, 1 mM aqueous solution of AET-incubation time 1 h, 1% GA solution in 10 mM pH 8 phosphate buffered saline (PBS)-incubation time 3 h, and 0.5 mg mL −1 of receptor protein solution in 10 mM pH 7 PBS-incubation time 1 h. Additionally, surprising results are reported when Protein A is immobilized first to properly orient the bioreceptor IgG molecules. We also report the application of optimum and non-optimum conditions to detect thyroid disrupting chemicals (TDCs) using MCs functionalized with the transport protein thyroxine-binding globulin. Selectivity patterns are reported for several TDCs and sensitive detection of thyroxin at sub-nM levels is demonstrated.

Mercaptans emissions in diesel and biodiesel exhaust

Biodiesel and ethanol are fuels in clear growth and evidence, basically due to its relation with the greenhouse effect reduction. There are several works regarding regulated pollutants emissions, but there is a lack of reports in non-regulated emissions. In a previous paper (Corrêa and Arbilla, 2006) the emissions of aromatic hydrocarbons were reported and in 2007 another paper was published in 2008 focusing carbonyls emissions (Corrêa and Arbilla, 2008). In this work four mercaptans (methyl, ethyl, n-propyl and n-butyl mercaptans) were evaluated for a heavy-duty diesel engine, fueled with pure diesel (D) and biodiesel blends (v/v) of 2% (B2), 5% (B5), 10% (B10), and 20% (B20). The tests were carried using a six cylinder heavy-duty engine, typical of the Brazilian fleet of urban buses, during a real use across the city. The exhaust gases were diluted near 20 times and the mercaptans were sampled with glass fiber filters impregnated with mercuric acetate. The chemical analyses were performed by gas chromatography with mass spectrometry detection. The results indicated that the mercaptans emissions exhibit a reduction with the increase of biodiesel content, but this reduction is lower as the mercaptan molar mass increases. For B20 results the emission reduction was 18.4% for methyl mercaptan, 18.1% for ethyl mercaptan, 16.3% for n-propyl mercaptan, and 9.6% for n-butyl mercaptan.

Optimization of octanoic acid and sulfur donor concentrations for lipoic acid production by Pseudomonas reptilivora

Using the optimal concentrations of octanoic acid (0.75 mM) and ethyl mercaptan (2 mM), as the most effective sulfur donor, Pseudomonas reptilivora produced 74 microg lipoic acid per dry cell weight at pH 7.5 and 30 degrees C in a fermenter over 9 h. The dry cell weight was 13.9 g l(-1).

Synthesis, characterization and catalytic activity of cobalt phthalocyanine tetrasulphonamide in sweetening of LPG

Cobalt phthalocyanine tetrasulphonamide was synthesized by reacting cobalt phthalocyanine with chlorosulphonic acid at 130–135 °C followed by addition of thionyl chloride to convert free sulphonic acid to sulphonyl chloride and subsequently amidation with ammonia. It was isolated by acidifying the reaction mixture with hydrochloric acid followed by filtration. It was characterized by elemental IR and FAB mass spectral analysis. The activity of cobalt phthalocyanine tetrasulphonamide catalyst for extractive sweetening of LPG was evaluated by studying mercaptide oxidation using ethyl mercaptan as model sulfur compound in glass column. The stability of the catalyst was evaluated by studying liquid–liquid sweetening in a batch reactor using hexane thiol as a model compound and petroleum ether as an inert solvent. The performance of this catalyst with respect to activity and stability was found better than the commercial catalyst being used currently in the refineries. Commercial trial run of this catalyst has been successfully conducted for 4 months in FCC LPG Merox unit of Bharat Petroleum Corporation Limited (BPCL), Mumbai and the performance was found better than commercial catalyst. Another trial run of the catalyst has been conducted in one of the LPG Merox units at Reliance Industries Limited (RIL), Jamnagar for 8 months and the performance has been found to be excellent with less catalyst consumption than commercial catalyst.

Removal of sulfur compounds from utility pipelined synthetic natural gas using modified activated carbons

Synthetic natural gas (SNG), which is produced from petroleum and distributed via pipeline in Honolulu by The Gas Company, was analyzed using a gas chromatograph equipped with a sulfur chemiluminescence detector (GC/SCD). Hydrogen sulfide (H 2S), methyl mercaptan (MM), ethyl mercaptan (EM), dimethylsulfide (DMS), dimethyl disulfide (DMDS), tetrahydrothiophene (THT), ethyl disulfide (EDS), and one unidentified compound (UN1) were detected. Among these sulfur compounds, THT is added as an odorant and was present in the highest concentration. A commercial activated carbon (Calgon OLC plus 12X30) was modified by oxidation and impregnation methods and the resulting materials were evaluated for their ability to adsorb sulfur compounds present in SNG. The evaluation results indicate that all of the modification methods can improve the retention of individual sulfur compounds or the total sulfur capacity compared with the untreated virgin carbon. It is also found that activated carbons impregnated with metal impurities have different selectivity for sulfur compounds. Cu and Zn loaded carbons had the highest capacity for H 2S removal, Fe loaded carbon was more efficient for DMS removal (the most difficult S compound to remove), and carbon oxidized by HNO 3 was the best for THT removal. Based on these findings, a composite sorbent consisting of Cu loaded and Fe loaded carbons was designed and tested. The test results indicate that the composite sorbent had improved performance in the removal of individual sulfur compound. A linear programming model was used to design a composite sorbent optimized to minimize the required sorbent mass based on a 1-kW scale fuel cell system service target. Validation tests showed that the optimized sorbent required less of the individual modified carbon components than when they were individually used for the same sulfur removal target.

Performance of two biofilters with neutral and low pH treating off-gases

Two different functional biofilters were carried out and compared for the treatment of off-gas containing multicomponent odors and volatile organic compounds (VOCs) in this study. The effects of pH values and the empty bed retention time (EBRT) on the performance of the bioreactors were studied; and the characteristics of microbial populations in the two biofilters were also determined. The experimental results indicated that the removal efficiencies of hydrophilic compounds such as butyric acid and ammonia were higher in the neutral pH biofilter (NPB) than those in the low pH biofilter (LPB). In contrast, the removal efficiencies of the compounds with poor water solubility such as styrene and ethyl mercaptan were higher in the LPB than those in the NPB. The characteristics of microbial population in the two biofilters revealed that the heterotrophic bacteria, nonacidophilic thiobacteria, ammonia oxidizing bacteria, and nitrite oxidizing bacteria were major microorganisms in the NPB, whereas acidophilic thiobacteria and fungi were dominant in the LPB. Therefore, the performance of the biofilter depended on the characteristics of the compound being treated and the type of microorganisms.

Influence of Molecular Structure on Phase Transitions: A Study of Self-Assembled Monolayers of 2-(Aryl)-ethane Thiols

Self-assembled monolayers (SAMs) prepared on Au(111) substrates from solutions of ω-(4‘-methylbiphenyl-4-yl)ethane thiol (CH3(C6H4)2(CH2)nSH, n = 2, BP2), at room temperature and subsequently annealed at temperatures of up to 423 K were studied using scanning tunneling microscopy, low-energy electron diffraction, high-resolution X-ray photoelectron spectroscopy, and near-edge X-ray absorption fine structure spectroscopy. Upon annealing a phase transition occurs from the low-temperature (5√3 × 3) structure common to all SAMs prepared from the series of BPn homologues with n = even studied so far, to a new structure which is markedly different from the high-temperature phases of the higher BPn homologues. Although its basic structure can be approximated by a (2√3 × 2) unit cell, the regular occurrence of line defects running exclusively along the 〈112̄〉 direction is the most characteristic feature of this new phase. Irrespective of these defects the phase transition dramatically improves the stability of the BP2 monolayer as demonstrated by exchange experiments. In contrast to BP2, SAMs made from the closely related 2-phenylethane thiol (C6H5(CH2)2SH, P2) do not show any phase transition. The differences between BP2, its higher homologues, and P2 highlight the subtleties of the interplay of different factors determining the structure of a SAM.

Measurement of VLE (TPx or TPxy data) for hydrogen sulfide + (dimethylsulfide or ethylmethylsulfide or carbon disulfide) and methane solubilities in (dimethylsulfide or ethylmethylsulfide or methylmercaptan or ethylmercaptan)

VLE data (gas solubilities (TPx data) or complete TPxy data) were measured for the following systems: • hydrogen sulfide (H 2S) + dimethylsulfide (DMS) at 278, 293, 313, and 333 K. • H 2S + ethylmethylsulfide (EMS) at 293 and 313 K. • H 2S + carbon disulfide (CS 2) at 273, 298, 323, and 348 K. • methane (CH 4) + DMS at 253, 273, 293, and 313 K. • CH 4 + EMS at 248, 273, 293, and 313 K. • CH 4 + methylmercaptan (MM) at 243, 258, 273, 293, and 298 K. • CH 4 + ethylmercaptan (EM) at 273, 293, and 313 K. These data were used to establish new binary interaction parameters for the predictive Soave–Redlich–Kwong (PSRK) group contribution of state. The extension of the PSRK parameter matrix allows now to perform reliable phase equilibrium calculations for systems with any hydrocarbons and sulfur compounds. The mean relative deviation of PSRK compared to the experimental data for the bubble point pressures is less than 2% and the mean absolute deviation for the vapor phase composition is 0.03 in terms of mole fraction.

Determination of volatile organic sulfur compounds in the air at sewage management areas by thermal desorption and gas chromatography–mass spectrometry

The concentrations of seven volatile organic sulfur compounds (VOSCs) in air samples were determined by active collection on multisorbent tubes followed by two-stage thermal desorption and gas chromatography–mass spectrometry. The compounds studied were ethyl mercaptan (CH 3CH 2SH), dimethyl sulfide ((CH 3) 2S), carbon disulfide (CS 2), propyl mercaptan (C 3H 8S), butyl mercaptan (C 4H 10S), dimethyl disulfide ((CH 3) 2S 2) and 1-pentanethiol (C 5H 12S). Active collection on SilcoSteel multisorbent tubes enabled an air volume of 3000 ml to be sampled without observing breakthrough. This study focused on an exhaustive sampling of several process steps or sections from sewage management plants. A wide range of concentrations was observed. Dimethyl sulfide, carbon disulfide and dimethyl disulfide were the most abundant compounds in all samples, the highest concentrations being 608.5 μg m −3, 658.5 μg m −3 and 857.8 μg m −3, respectively. The less appearing compound was ethyl mercaptan, which was only detected in the sludge digestion process at a maximum concentration of 14.8 μg m −3. The remaining compounds were detected and measured in about half the samples. The sections with the maximum values of VOSCs involved sludge processes such as mixing, thickening and digestion. The results were also strongly influenced by the design characteristics of the sampling point, e.g. whether the sample was taken at a confined site or in the open air.

Selective Thiylation of 1‐Vinylpyrrole‐2‐carbaldehydes: Synthesis of the Novel Pyrrole Synthons 2‐[Bis(ethylsulfanyl)methyl]‐1‐vinylpyrroles and 1‐(2‐Ethylthioethyl)pyrrole‐2‐carbaldehydes.

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Selective adsorption of ethyl mercaptan on NaX zeolite

Adsorption on microporous solid is an alternative technique to remove mercaptans from natural gases. The present study gives equilibrium adsorption data on NaX faujasite for some pure gases representative of natural gas impurities (ethyl mercaptan, toluene and n-heptane) and their binary mixtures. The first part of the paper is devoted to the adsorption of pure gases. Experimental results show that the zeolite has a high adsorption affinity for ethyl mercaptan, toluene and n-heptane. In the second part, we examine adsorption isotherms for binary mixtures of ethyl mercaptan and toluene or n-heptane over a large domain of composition. Coadsorption enthalpies are also determined. These experimental data allow to obtain entropies of adsorbed phases and adsorption selectivities. The analysis of coadsorption data indicates that the zeolite preferentially adsorbs ethyl mercaptan over a large domain of micropore filling and that the adsorption selectivity is related to entropic effects inside zeolite micropores. A displacement of n-heptane by ethyl mercaptan is even observed. In contrast, toluene is preferentially adsorbed by the zeolite at high micropore filling.