Liquid Hydrogen Sulfide Research Articles

Sol gel fabrication of CeO2/SnO2 nanocomposite films for habilitation in optoelectronic and sensing properties

This study investigated the synthesis and characterization of CeO2/SnO2 composite powders and films by varying CeO2 concentration ranging from 2 to 10 mol%. The sol-gel process was utilized to create composites. X-ray diffraction demonstrated that the resulting CeO2/SnO2 powders were polycrystalline, whereas the composite films had amorphous structures. The morphology of the produced samples was studied with SEM and TEM. Also the specific surface area was measured using the Brunauer-Emmett-Teller (BET) technique and the optical characteristics were assessed using a UV–Vis spectrophotometer. The absorption coefficients, energy gaps, and refractive indices of the composite films were determined. Direct and indirect energy gaps were from 3.71 to 3.27 eV and 2.70 to 2.26 eV, respectively. The refractive index increases from 1.61 to 1.7 as the CeO2 concentration increases. The variation in the energy band gap and refractive index values indicate that CeO2/SnO2 nanocomposite films are a viable composite film for optoelectronic devices. The investigated films have electrical conductivity values ranging from 10−2 to 10−8 Ω−1 cm−1. The gas sensing test was studied using different gases as liquid petroleum gas (LPG), carbon monoxide (CO), and Hydrogen sulfide (H2S). CeO2/SnO2 films demonstrated the highest sensitivity for hydrogen sulfide (H2S), with a sensitivity of 0.988 % and a response time of 40 s.

Гуанідінійвмісний олігомер як інгібітор мікробної корозії металу

Guanidinium-containing oligomers, a poorly studied class of organic compounds, have attracted attention due to their bactericidal properties. A guanidinium-containing oligomer based on an aliphatic oligoepoxide is a newly synthesized substance with bactericidal activity, which gives it the prospects for use as a microbial corrosion inhibitor. Aim. The goal of the study was to synthesize oligomeric alkyl substituted guanidinium bromide and study of its anticorrosive properties in the presence of steel under the influence of corrosive active sulfate-reducing bacteria. Methods. The guanidine-containing alkyl substituted oligomer was obtained by the reaction of the aliphatic oligoepoxide DEG-1 with guanidine, followed by interaction with alkyl bromide. The anticorrosive properties of the guanidine-containing oligomer were studied using collection strains of sulfate-reducing bacteria: UCM B-11503 Desulfovibrio sp.10, UCM B-11501 Desulfovibrio desulfuricans DSM642, and UCM B-11502 Desulfovibrio vulgaris DSM644. The sulfate-reducing bacteria were grown on Postgate В medium for 14 days at a temperature of 28 ± 2 °C. The number of bacteria was determined by the method of tenfold dilution. The corrosion rate was determined by the gravimetric method. The physicochemical parameters of pH and redox potential of the bacterial culture liquid were studied by the potentiometric method. The accumulation of hydrogen sulfide in the culture liquid was determined by the iodometric method. Lipolytic activity was studied spectrophotometrically using a KFK-3 device by reaction with p-nitrophenyl palmitate, catalase activity — using 0.03% hydrogen peroxide, which formed a stable colored complex with a 4% molybdenum diphosphate solution. The specific activity of the studied enzymes was expressed as unit ∙ mg-1 protein. Protein was determined in the supernatant by the conventional Lowry method. Results. It was shown that the oligomer based on aliphatic oligoepoxide has biocidal properties. A significant inhibition of the development of sulfate-reducing bacteria (SRB) was observed after the oligomer was added; only dozens of bacterial cells were detected in the medium after the exposure period. The corrosion rate of steel in the presence of SBR without addition of inhibitors was 0.15 — 0.35 mg/cm2∙h. The addition of DPC (a quaternary ammonium compound based on N-decylpyridinium chloride) (Kyiv Polytechnic Institute (KPI), Ukraine) to the culture medium led to a decrease in the steel corrosion rate to 0.032 — 0.047 mg ∙ cm-2 h-1 (by 6.5—10.6 times). In the presence of Armohib CI-28 inhibitor (based on Diamine Ethoxylate) (Akzonobel, Holland), the corrosion rate was reduced to 0.02—0.039 mg ∙ cm-2 h-1 (by 4.2 — 12.7 times). The addition of guanidinium-containing oligomer to the medium with bacteria reduced the corrosion rate to 0.075—0.079 mg/cm2 ∙ h (by 2.5—2.7 times). According to the mass loss of steel samples, the degree of metal protection against microbial corrosion in the presence of guanidinium-containing oligomer was 60.15—63.17%. Conclusions. The obtained data indicate that the guanidinium-containing oligomer based on aliphatic oligoepoxy has biocidal and anticorrosive properties and is promising for use as a means of combating microbially induced corrosion.

Efek Jenis Rod dan Efisiensi Volumetrik pada Kinerja Pompa Angguk

<em>The productivity of the beam pump is influenced by the sucker rod type, material quality, and volumetric efficiency. Therefore, the beam pump should be designed to reach an optimum condition. The type of rod affects ability of the beam pump to lift liquid up from an oil reservoir to the surface as well as the horse power requirement to operate the pump. On the other hand, the productivity of the pump is also influenced by the characteristics of the reservoir rock and fluid such asreservoir productivity, gas liquid ratio, salinity and Hydrogen Sulfide (H<sub>2</sub>S) which are contained in the reservoir fluid. The purpose of this study is to observe Effect of Rod Type and Volumetric Efficiency on the Performance of a beam pump at X-1 well and production estimation in the future. In this research, several rod types were tested to find their liquid lifting efficiency. Based on result analysis, the highest production as well as liquid lifting efficiency is attained by applying ROD 96/05.The liquid production rate and lifting efficiency of the rod type are 1132 bpd and 15.6. The application of better quality sucker rod material (API grade D) and less corrosive fluid conditions (salt water) will be able to produce fluid with a higher flow rate. Furthermore, the effect of the crank-pitman ratio on the production rate is not large. Lower volumetric efficiency pumps require higher pump speed and horsepower to produce fluid with the same flow rate as high volumetric efficiency pumps. However, pumps with low volumetric efficiency have lower peak loads (PPRL).</em>

Development of a "Turn-on" Fluorescent Probe-Based Sensing System for Hydrogen Sulfide in Liquid and Gas Phase.

A “turn-on” fluorescence sensing system based on a BODIPY-cobaloxime complex for the detection of H2S in liquid and gas phase was developed. To that aim, two cobaloxime complexes bearing an axial pyridyl-BODIPY ligand were initially evaluated as sensitive fluorescent HS− indicators in aqueous solution. The sensing mechanism involves the selective substitution of the BODIPY ligand by the HS− anion at the cobalt center, which is accompanied by a strong fluorescence enhancement. The selection of a complex with an ideal stability and reactivity profile toward HS− relied on the optimal interaction between the cobalt metal-center and two different pyridyl BODIPY ligands. Loading the best performing BODIPY-cobaloxime complex onto a polymeric hydrogel membrane allowed us to study the selectivity of the probe for HS− against different anions and cysteine. Successful detection of H2S by the fluorescent “light-up” membrane was not only accomplished for surface water but could also be demonstrated for relevant H2S concentrations in gas phase.

HYDROGEN SULFIDE AND ALKANTHIOLS IN NUCLEOPHILIC SUBSTITUTION REACTIONS OF HYDROXY GROUPS IN ALIPHATIC ALCOHOLS

Hydrogen sulfide and alkanethiols are toxic compounds containing in the production of wells in many oil and gas condensate fields. Because the policy of hydrocarbon processing enterprises aimed at the development of new fundamental research, processes and technologies in order to find rational use of raw materials, the conversion of hydrogen sulfide and alkanethiols into valuable compounds is one of the strategic goals of the oil and gas industry. The methods of "green" chemistry are perspective processes for converting hydrogen sulfide and alkantiols into valuable organic compounds, which allow working in environmentally friendly conditions with minimal energy and resource costs. The reactions of direct nucleophilic substitution of butanol-2, pentanol-1 and hexanol-1 to HS- and RS- group by single-electron reduction of hydrogen sulfide and alkanthiol in acetonitrile and ionic liquid at room temperature and atmospheric pressure with a single by-product - H2O were described. The possibility of conducting an experiment without electrolyte due to the intrinsic electrical conductivity of the ionic liquid allows not only lowering the consumption of reagents, but also facilitating the isolation of the target product. Due to the structuring and the matrix effect in ionic liquids, the duration of electrolysis in the reactions under consideration is 2-3 times less than in the case of aprotic solvents.

MORPHOPHYSIOLOGICAL PROPERTIES OF SULFATE-REDUCING BAСTERIA ISOLATED FROM THE SYSTEM OF LVIV WASTEWATER TREATMENT

Aim: to isolate the sulfate-reducing bacteria from the system of sewage treatment in the city of Lviv, to study the morphological and physiological properties of isolated microorganisms. Methods. The research object was a strain of sulfatereducing bacteria, isolated from the system of treatment the domestic and industrial wastewater of the city of Lviv. Water and sludge samples were taken from the primary, secondary settlers and active sludge of the wastewater treatment system of the city of Lviv by the Stolbinov-Ryabov method. The isolated strain of bacteria was cultivated on a selective medium. Identification of the isolated strain of microorganisms was carried out according to morphophysiological features in accordance with the Bergey's manual. The morphology of the studied cultures was studied by electron microscopy. To determine the presence of spores in the cells, they were stained by the method of Peshkov. The content of sulfate and hydrogen sulfide in the culture liquid was determined photometrically. Results. From active sludge of the aerotank system of the treatment facilities of the city of Lviv allocated a strain of spore-forming sulfate-reducing bacteria, which also, in the absence of sulfate-ion, can use elemental sulfur as a final electron acceptor. In the presence of sulfate ion bacteria use lactate and acetate as a source of carbon. Microorganisms are in the form of short rods, Gram-negative. The isolated strain of bacteria belongs to neutrophilic and mesophilic microorganisms. The isolated strain is identified as Desulfotomaculum AR1 by the morphological and physiological properties. Conclusions. Sulfate-reducing bacteria Desulfotomaculum AR1, isolated from active sludge of aerotanks of the wastewater treatment system in the city of Lviv, accumulate up to 18 mM hydrogen sulfide in the presence of lactate or acetate in the medium as a source of carbon. In addition to sulfate ions, bacteria reduce elemental sulfur, using it as a final electron acceptor.

HYDROGEN SULFIDE IN NUCLEOPHILIC SUBSTITUTION REACTIONS OF HYDROXY GROUPS IN AROMATIC ALCOHOLS

Most methods of obtaining aromatic thiols are based on nucleophilic substitution reactions at halogen derivatives of aromatic hydrocarbons when used as nucleophilic reagents sodium thiolate, thiourea or potassium xanthate at high temperatures, pressure and in the presence of catalysts. The direct reaction of nucleophilic substitution of OH-groups in the phenols, pyrocatechol and benzyl alcohol to the HS-group in conditions of one-electron reducrion of hydrogen sulfide in acetonitrile and pyridinium ionic liquid was investigated for the first time. The proposed reactions proceed at room temperature and atmospheric pressure. The use of "green" solvent - ionic liquid - reduces the syntheses time in а half, improves ecological safety friendliness of the process and reduces the consumption of reagents. The main positive feature of these studies is not only ecological safety of reactions of nucleophilic substitution (due to the lack of harmful byproducts), but the use of electrochemical reactions in ionic liquid media, that is very relevant in modern science in terms of new environmental technologies development.
 For citation:
 Okhlobystina A.V., Okhlobystin A.O., Berberova N.T., Burmistrova D.A. Hydrogen sulfide in nucleophilic substitution reactions of hydroxy groups in aromatic alcohols. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 9-10. P. 36-41
 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Математическая модель инжекции сероводорода в пласт, частично насыщенный водой

Актуальность исследования связана с разработкой теоретических основ технологий подземного захоронения, вырабатываемого промышленными объектами сероводорода с целью снижения его эмиссии в атмосферу. Рассматривается метод утилизации сероводорода в газогидратном состоянии, в котором одинаковое количество газа может храниться при значительно меньших значениях давления. Целью исследования является выяснение особенностей протекания процесса образования газового гидрата H 2 S при инжекции жидкого сероводорода в пористый резервуар. Объект: пористый пласт, насыщенный нефтью и водой, исходное давление которого ниже равновесного давления образования газогидрата сероводорода. Методы исследования. На основе уравнений механики сплошной среды построена математическая модель тепломассопереноса в природном пласте, сопровождающегося образованием газогидрата сероводорода. Принято, что в рассматриваемом случае в пласте возникают три характерные зоны и соответственно два подвижных межфазных фронта - между первой и второй зонами, где происходит полный переход воды в газогидратное состояние (фронт гидратообразования), и между второй и третьей зонами, где осуществляется вытеснение нефти сероводородом (фронт вытеснения). Методом сведения к автомодельной переменной построены аналитические решения для безразмерных значений давления и температуры в каждой из трех областей пласта. Исследованы зависимости координаты и температуры межфазных границ от температуры закачиваемого сероводорода и исходной температуры пласта. Результаты. Установлено, что с повышением начальной температуры пласта и температуры инжектируемого жидкого сероводорода координата фронта образования газогидрата H 2 S уменьшается, а температура фронта вытеснения нефти сероводородом увеличивается. Показано, что при достаточно низких значениях температуры пласта и инжектируемого сероводорода может происходить выравнивание координат фронтов гидратообразования и вытеснения. На плоскости параметров «температура инжекции - начальная температура пласта» построены карты решений, т. е. критические диаграммы, определяющие существование режима, при котором фронт вытеснения нефти сероводородом опережает фронт образования газогидрата H 2 S.

Kinetic parameter estimation and simulation of trickle-bed reactor for hydrodesulfurization of whole fraction low-temperature coal tar

With whole-fraction low temperature coal tar (LTCT) as raw material, which boiling point range is 209–514 °C. This paper conducts hydrotreatment (HDT) test for 1176 h on trickle-bed reactor (TBR) with commercial NiMo/Al2O3-SiO2 catalyst. The reaction conditions are as follows: reaction temperature 613–653 K, reaction pressure 10–14 MPa, liquid hourly space velocity (LHSV) 0.2–0.4 h−1, and hydrogen-to-oil volume ratio 1000:1. Considering the short life of coal tar HDT catalyst, a kinetic model of whole-fraction LTCT hydrodesulfurization (HDS) including running time (t1) and catalyst half-life (tc) was established. The kinetic parameter estimation was conducted according to the experimental data, and the results are as follows: activation energy 94965 J/mol, reaction order 1.5, and the relative error of the model is less than 5%.Based on the premise of steady state operation, the HDS reaction happened in the three-phase trickle-bed reactor was simulated by combining the mass transfer, reaction kinetics model and physical property data of LTCT. The results show that the experimental and simulated values of sulphur content at the exit of the reactor are within the error range of 5%. By simulating the whole-fraction LTCT HDS reactor, the pattern of changes in the concentrations of hydrogen sulfide, hydrogen and sulfur in gas, liquid and solid phases according to the length of the reactor were obtained. Based on this, this paper discusses on the impacts of each process parameter and hydrogen sulfide partial pressure on LTCT HDS, and works out the reaction characteristics of whole-fraction LTCT HDS different from crude oil fraction. Finally, this paper analyzes the influence of different process conditions on internal gradients of catalyst, and concludes the influence of each parameter on effectiveness factor of particle. The increase of temperature, decrease of pressure or increase of LHSV can all cause the decrease of effectiveness factor, wherein the temperature has the most significant effect on the effectiveness factor, followed by LHSV, and pressure has the weakest effect. These findings contribute to a more in-depth understanding of the features and rules of LTCT HDS, and can also give us some guidance for industrial reactor simulation.

Anaerobic Reduction Process Characteristics and Microbial Community Analysis for Sulfate and Fe(Ⅱ) EDTA-NO/Fe(Ⅲ) EDTA

Based on biological flue gas desulfurization technology (Bio-FGD) and chelating absorption-biological regeneration technology (BioDeNOx), simultaneous desulfurization and denitrification by biological methods combined with chelating absorption technology has been proposed in this study. This technique uses an alkaline absorption liquid with Fe(Ⅱ) EDTA to absorb the SO2 and NO in the flue gas. In this study, an attempt is made to simultaneously remove sulfate (SO42-) and Fe(Ⅱ) EDTA-NO/Fe(Ⅲ) EDTA, which are the SO2 and NO absorption byproducts in an anaerobic reactor. The results indicate that average removal efficiencies for SO42- and Fe(Ⅱ) EDTA-NO of 95.16% and 96.61%, respectively, were achieved when the hydraulic residence time (HRT) and pH were controlled at 16 h and 7.0. The reduction products of SO42- were mainly in the form of S2- in the liquid phase and hydrogen sulfide (H2S) in the gas phase, while the reduction products of Fe(Ⅱ) EDTA-NO was N2. The reduction of Fe(Ⅲ) EDTA could be achieved at all stages of the operation, however, the reduction rate decreases with a reduction in the HRT. In the fifth stage, the main sulfate-reducing bacteria (SRB) in the reactor was Desulfomicrobium, a heterotrophic denitrifying bacteria, Pseudomonas, and two types of sulfur autotrophic denitrifying bacteria, Sulfurimonas and Sulfurovum, which coexisted. Two genera of bacteria that can also reduce sulfur, Thermovirga and Mesotoga, were also identified in the reactor.

Solubility of carbon dioxide and hydrogen sulfide in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate

Solubility of the single gases CO2 and H2S in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4mim][OTf]) was measured at temperatures from (303.15–343.15) K and pressures up to about 3.2 MPa for CO2 and 1.6 MPa for H2S. A modified isochoric saturation technique was developed in this study to determine the volume of the gas saturated liquid phase in the solubility measurements. The reliability of the experimental setup and measurement method was assessed through detailed comparison of generated data for CO2 + [C6mim][Tf2N] binary mixture with the most reliable data reported in the literature. The average of percent absolute relative deviation (AARD%) of pTx and specific volume data (in cm3·kg−1) measured in this work from the corresponding data in the literature is 3.7% and 0.23%, respectively. Comparison of the obtained solubility data shows that H2S is more than 4 times as soluble as CO2 in [C4mim][OTf]. The solubility of both gases in [C4mim][OTf] is higher than in the lower homologue [C2mim][OTf]. Furthermore, [C4mim][OTf] shows the highest absorption capacity for H2S and high H2S over CO2 selectivity relative to other [C4mim]/[C2mim] – based ionic liquids with different anions. The experimental data were correlated by using the extended Henry's law combined with a simplified Pitzer's model. The values of AARD% of correlated molalities from experimental data are 1.1% for CO2 + [C4mim][OTf] and H2S + [C4mim][OTf] binary mixtures. The Henry's law constants, partial molar volume at infinite dilution and thermodynamic functions for dissolution of CO2 and H2S gases in [C4mim][OTf], as a function of temperature, were calculated from the experimental data.

The influence of potassium dichromate on dissimilatory reduction of sulfate and nitrate ions by bacteria Desulfovibrio sp.

Sulfate reducing bacteria, capable to reductive transformation of different nature pollutants, used in biotechnologies of purification of sewage, contaminated by carbon, sulfur, nitrogen and metal compounds. H2S formed by them sediment metals to form of insoluble sulfides. Number of metals can be used by these microorganisms as electron acceptors during anaerobic respiration. Because under the influence of metal compounds observed slowing of bacteria metabolism, selection isolated from technologically modified ecotops resistant to pollutions strains is important task to create a new biotechnologies of purification. That’s why the purpose of this work was to study the influence of potassium dichromate, present in medium, on reduction of sulfate and nitrate ions by sulfate reducing bacteria Desulfovibrio desulfuricans IMV K-6, Desulfovibrio sp. Yav-6 and Desulfovibrio sp. Yav-8, isolated from Yavorivske Lake, to estimate the efficiency of possible usage of these bacteria in technologies of complex purification of environment from dangerous pollutants. Bacteria were cultivated in modified Kravtsov-Sorokin medium without SO42- and FeCl2×4H2O for 10 days. To study the influence of K2Cr2O7 on usage by bacteria SO42- or NO3- cells were seeded to media with Na2SO4×10H2O or NaNO3 and K2Cr2O7 at concentrations of 1.74 mM for total content of electron acceptors in medium 3.47 mM (concentration of SO42- in medium of standard composition). Cells were also seeded to media with 3.47 mM Na2SO4×10H2O, NaNO3 or K2Cr2O7 to investigate their growth in media with SO42-, NO3- or Cr2O72- as sole electron acceptor (control). Biomass was determined by turbidymetric method, content of sulfate, nitrate, dichromate, chromium (III) ions, hydrogen sulfide or ammonia ions in cultural liquid – by spectrophotometric method. It was found that K2Cr2O7 inhibits growth (2.2 and 1.3 times) and level of reduction by bacteria sulfate or nitrate ions (4.2 and 3.0 times, respectively) at simultaneous addition into cultivation medium of 1.74 mM SO42- or NO3- and 1.74 mM Cr2O72-, compared with growth and level of reduction of sulfate or nitrate ions in medium only with SO42- or NO3- as sole electron acceptor. Revealed that during cultivation of bacteria in presence of equimolar amount of SO42- or NO3- and Cr2O72-, last used by bacteria faster, content of Cr3+ during whole period of bacteria cultivation exceeded content H2S or NH4+. K2Cr2O7 in medium has most negative influence on dissimilatory reduction by bacteria SO42- than NO3-, since level of nitrate ions reduction by cells in medium with NO3- and Cr2O72- was a half times higher than level of sulfate ions reduction by it in medium with SO42- and Cr2O72-. The ability of bacteria Desulfovibrio sp. to priority reduction of Cr2O72- and after their exhaustion − NO3- and SO42- in the processes of anaerobic respiration can be used in technologies of complex purification of environment from toxic compounds.

Инжекция жидкого сероводорода в пласт, насыщенный нефтью и водой

Инжекция жидкого сероводорода в пласт, насыщенный нефтью и водой

Effect of slurry treatment approaches on the reduction of major odorant emissions at a hog barn facility in South Korea

ABSTRACTThe characteristics of malodor released from piggery excreta samples were investigated by measuring their emission concentrations both before and after such treatments as composting or aeration from field sites. These samples were then collected from field sites and brought into the lab for analysis with the aid of the dynamic flux chamber method. The dominating compounds in the emissions were reduced sulfur compounds, phenol, and indole. The results were examined in terms of two key odor indices: odor intensity (OI) and odor activity values (OAVs), after being grouped by some criteria. When the odor contribution in the composting facility was assessed by the OAV value, methanethiol (53.1%), trimethylamine (TMA) (25.5%), and skatole (10.1%) were dominant in the pretreatment facilities, while skatole (64.7%) and p-cresol (27.9%) in the post-treatment specimens. Likewise, in the liquid treatment facility, hydrogen sulfide (47.4%), p-cresol (26.9%), and skatole (20.2%) were dominant in the pretreatment, while only p-cresol (73.6%) in the post-treatment. In comparison to the composting facility, the liquid treatment facility proved to be more efficient in the treatment of diverse hog-barn-related odorants.

Molecular Dynamics Simulations of Small Clusters and Liquid Hydrogen Sulfide at Different Thermodynamic Conditions.

A new force field for the intermolecular H2S-H2S interaction has been used to study the most relevant properties of the hydrogen sulfide system from gaseous to liquid phases by means of molecular dynamics (MD) simulations. In order to check the validity of the interaction formulation, ab initio CCSD(T)/aug-cc-pVTZ calculations, including the counterpoise correction on the H2S, (H2S)2, and (H2S)3 structures optimized at the MP2/aug-cc-pVDZ level, have been performed. The (H2S)2,3 systems have been characterized by performing NVE MD simulations at decreasing values of the temperature, while the liquid sulfide behavior has been investigated considering a NpT ensemble of 512 molecules at several thermodynamic states, defined by different pressure and temperature values. Additional calculations using an ensemble of 2197 molecules at two different temperatures have been performed to investigate the liquid/vapor interface of the system. The S-S, S-H, and H-H radial distribution functions and the coordination number, calculated at the same conditions used in X-ray and neutron diffraction experiments, and the evaluated thermodynamic and structural properties have been compared successfully with experimental data, thus confirming the reliability of the force field formulation and of the MD predictions.

Copper doped nickel ferrite nano-crystalline thin films: A potential gas sensor towards reducing gases

NiFe2O4 and (1 wt% and 3 wt%) Cu:NiFe2O4 thin films have been fabricated using spray pyrolysis deposition technique at 350 °C and then sintered at 650 °C for 3 h. X-ray diffraction, SEM, EDAX, UV-VIS spectroscopy, SQUID VSM were carried out to investigate phase formation, microstructural and influence of Cu doping on magnetic properties of NiFe2O4 thin films. The gas response towards various gases viz. ethanol, Liquid Petroleum Gas (LPG), methanol and hydrogen sulfide (H2S) is investigated. The results of XRD revealed that all samples had shown the principal phase of nickel ferrite and the lattice parameter was found to vary from 8.294 Å to 8.314 Å on an incorporation of Cu, and the crystalline sizes were about 40–45 nm. The effect of Cu concentration on saturation magnetization and coercive force were studied. The maximum value of saturation magnetization calculated from hysteresis loop was 89.16 emu/g at room temperature and 96.88 emu/g at 50 K. Cu content on the film surface was found to be maximum for 1 wt% Cu:NiFe2O4 thin film and this film showed an improved response towards all gases. Response of ethanol for NiFe2O4 thin film was found to be higher as compared to all the other gases. The lowering of the optimum operating temperature is observed in 1 wt% Cu:NiFe2O4 thin film with higher selectivity towards ethanol than other gases. All results indicated that the Cu doping in nickel ferrite thin films has a significant influence on the properties.

Solubility of hydrogen sulfide in ionic liquids for gas removal processes using artificial neural networks

Artificial neural networks have been used for the correlation and prediction of solubility data of hydrogen sulfide in ionic liquids. The solubility of hydrogen sulfide is highly variable for different types of ionic liquids at the same temperature and pressure and its correlation and prediction is of special importance in the removal of hydrogen sulfide from flue gases for which effective and efficient solvents are required. Several network architectures were tested to finally choose a three layer network with 6, 10 and 1 neuron, respectively (6, 10, 1). Twelve binary hydrogen sulfide+ionic liquids mixtures were considered in the study. Solubility data (pressure, temperature, gas concentration in the liquid phase) for these systems were taken from the literature (392 data points for training and 104 data points for testing). The training variables are the temperature and the pressure of the binary systems being the target variable the solubility of hydrogen sulfide in the ionic liquid. Average absolute deviations are lower than 4.0% and the maximum individual absolute deviation in solubility is 12.6%. The proposed neural network model is a good alternative method for the estimation of solubility of hydrogen sulfide in ionic liquids for its use in process analysis, process design and process simulation.

Synthesis of SBA-15 Functionalized by a Sulfopropyl Group Anchored onto the Surface through a Si–C Covalent Bond

Abstract An allyl group was introduced to SBA-15 by the reaction of allylmagnesium bromide with chlorinated SBA-15 obtained by the treatment of calcined SBA-15 with thionyl chloride. The allyl group was converted to a mercaptopropyl group by photochemical reaction with liquid hydrogen sulfide, and then the sulfopropyl group-functionalized SBA-15 was obtained by acidification. The sulfopropyl group in the resulting material was anchored to the SBA-15 surface by a Si–C covalent bond and showed high thermal stability in comparison with that introduced by the conventional silane-coupling method.

A multidimensional gas chromatography method for the analysis of hydrogen sulfide in crude oil and crude oil headspace.

Two-dimensional heart-cutting gas chromatography is used to analyze dissolved hydrogen sulfide in crude samples. Liquid samples are separated first on an HP-PONA column, and the light sulfur gases are heart-cut to a GasPro column, where hydrogen sulfide is separated from other light sulfur gases and detected with a sulfur chemiluminescence detector. Heart-cutting is accomplished with the use of a Deans switch. Backflushing the columns after hydrogen sulfide detection eliminates any problems caused by high-boiling hydrocarbons in the samples. Dissolved hydrogen sulfide is quantified in 14 crude oil samples, and the results are shown in this work. The method is also applicable to the analysis of headspace hydrogen sulfide over crude oil samples. Gas hydrogen sulfide measurements are compared to liquid hydrogen sulfide measurements for the same sample set. The chromatographic system design is discussed, and chromatograms of representative gas and liquid measurements are shown.

CFD study of diesel oil hydrotreating process in the non-isothermal trickle bed reactor

In the present study, the Eulerian–Eulerian multiphase approach was implemented to simulate the hydrotreating processes (hydrodesulfurization (HDS) and hydrodearomatization (HDA)) in the trickle bed reactor (TBR) by means of computational fluid dynamics (CFD) technique. A new gas–liquid interphase heat transfer coefficient was used in the CFD model to predict the reactor performance at non-isothermal conditions. The effects of feed inlet temperature, gas and liquid velocities, operational pressure and hydrogen sulfide concentration of the gas phase were investigated to calculate the reactions conversions and the bed temperature distribution. Also, the influence of bed porosity and adiabatic operational conditions on the reactor temperature and HDS reaction conversion was discussed. The results showed at adiabatic reactor, HDS reaction conversion increased about 9% compared to constant wall temperature condition. Furthermore, it was found that neglecting the gas–liquid interphase heat transfer effect in the CFD model increases the average relative error between numerical and the experimental data at prediction of HDS conversion about 5% and also affects the bed temperature pattern.