Effect of carbon dioxide on oxy-fuel combustion of hydrogen sulfide: An experimental and kinetic modeling

CO₂ is an important component in the acid gas and it is necessary to study the effect of CO₂ presence on the oxy-fuel combustion of H₂S with particular focus on the formation of carbonyl sulfide(COS).The oxyfuel combustion of acid gas was conducted in a coaxial jet double channel burner.The distribution of flame temperature and products under stoichiometric condition along axial(R=0.0) and radial at about 3.0 mm(R=0.75) were analyzed,respectively.The Chemkin-Pro ...     

Characterization of Zn–Ni–Fe hydrotalcite-derived oxides and their application in the hydrolysis of carbonyl sulfide

A series of Zn, Ni and Fe containing hydrotalcite-like compounds with various M²⁺/M³⁺ ratios were synthesized by co-precipitation method at pH = 10. The products were characterized by XRD, SEM, TG-DTA, FTIR, CO₂-TPD and N₂ adsorption/desorption techniques. The results showed that M²⁺/M³⁺ ratio affected the formation of hydrotalcite crystal seriously. The precursors with M²⁺/M³⁺ mole ratio of 2 and 3 showed pure hydrotalcite phase. After calcination at 250 °C, the derived oxides with larger surface area and more basic sites were obtained. Desulfurization tests showed that the Zn–Ni–Fe hydrotalcite-derived oxide exhibited an excellent activity in low temperature hydrolysis of COS. The optimum M²⁺/M³⁺ mole ratio was 3.     

Ni–Mo and Ni–W sulfide catalysts prepared by decomposition of binary thiometallates

Ni–Mo and Ni–W sulfide catalysts with atomic ratio R = 0.5 (Ni/(Ni + M), with M = Mo or W) prepared by decomposition of Ni-impregnated thiometallates were evaluated in the reaction of thiophene hydrodesulfurization. Catalysts derived from impregnated thiometallates (DTI samples) presented improved catalytic activity and higher synergistic effect than catalysts prepared by co-precipitation (HSP samples) despite the fact that co-precipitated catalysts showed larger surface area. Structure characterization by high-resolution electron microscopy (HREM) and X-ray diffraction (XRD) revealed different crystalline phases in DTI and HSP catalysts. A mixture of phases (MS₂, NiS_1.03 and MO₂) was observed in catalysts obtained by co-precipitation. Only the poorly crystalline MS₂ phase was observed in DTI catalysts suggesting that the Ni promoter is very well dispersed on the chalcogenide structure.     

Measurement and model of density,viscosity, and hydrogen sulfide solubility in ferric chloride/trioctylmethylammonium chloride ionic liquid

The density and viscosity of ferric chloride/trioctylmethylammonium chloride ionic liquid(rFeCl₃/[A336]Cl) with different molar ratios(r=0.1–0.8) of FeCl₃ to [A336]Cl were measured at temperatures from 313.15 to 358.15 K and atmospheric pressure.The density and viscosity data were fitted by the relevant temperature variation equations,respectively.The variation of density and viscosity with temperature and r was obtained.The solubility of rFeCl₃/[A336]Cl to H     

Alternating copolymerization of carbonyl sulfide and Cyclohexene Oxide catalyzed by zinc–cobalt double metal cyanide complex

This paper describes the first example of alternating copolymerization of carbonyl sulfide (COS) with cyclohexene oxide (CHO) via heterogenous catalysis of a nano-lamellar zinc–cobalt(III) double metal cyanide complex (Zn–Co(III) DMCC), providing an efficient method for converting COS to poly(cyclohexene monothiocarbonate) (PCHMTC) with an alternating degree up to 93%. The number-average molecular weight (M_n) of PCHMTC was 6.5–25.0 kg/mol with polydispersities (PDIs) of 1.6–2.1. The productivity of the catalyst was up to 970 g polymer/g catalyst (5.0 h). The oxygen–sulfur exchange reaction (O/S ER) caused by Zn–Co(III) DMCC was largely suppressed when the reaction was performed at 100–110 °C in the presence of THF or CH₂Cl₂, and thus the selectivity of the monothiocarbonate over carbonate linkages was up to 98%. The mechanisms of the copolymerization and O/S ER were proposed based on the ESI-MS, GC–MS and FT-IR spectra. The obtained PCHMTC is highly transparent and exhibits good solubility in various organic solvents, high T_g of 112 °C, initial decomposition temperature of 214 °C and high refractive index of 1.705.     

Fabrication and characterization of hollow cuprous sulfide (Cu2−xS) microspheres by a simple template-free route

The hollow Cu_2−xS microspheres were successfully prepared via a novel template-free route in a simple system containing CuSO₄, Na₂S₂O₃ and H₂O at the ambient conditions. A possible formation mechanism was proposed.     

Effect of supports in hydrogen sulfide oxidation on vanadium−based catalysts

Selective oxidation of hydrogen sulfide to sulfur was carried out over V₂O₅ and V−Sb−O mixed−oxide catalysts supported on TiO₂, ZrO₂ and −Al₂O₃. TiO₂−supported catalysts exhibited the highest sulfur yield and the highest areal rate. Catalyst reducibility was studied by temperature−programmed reduction. This revised version was published online in July 2006 with corrections to the Cover Date.     

Filamentous carbon templated SiO2–NiO aerogel: structure and catalytic properties for direct oxidation of hydrogen sulfide into sulfur

Silica aerogels comprising nickel oxide nanoparticles were synthesized with no use of supercritical drying. A high specific surface area (more than 1000 m²/g), mesoporous structure and considerable stability to sintering up to 900 °C are characteristic of these aerogels. The aerogels were synthesized using the sol–gel method. Filamentous carbon was templated by silica, tetraethoxysilane being used for supplying silica. Carbon was burnt later. Analysis of the aerogel structure revealed the presence of silica nanotubes and nanofibers. Aerogel testing for direct oxidation of H₂S into S⁰ demonstrated as high as 60% conversion of hydrogen sulfide at almost 100% selectivity under stoichiometric conditions at the temperature range of 300–350 °C and 73% conversion at 100% selectivity at a considerable excess of oxygen at 160 °C. This revised version was published online in July 2006 with corrections to the Cover Date.     

Nickel–molybdenum and cobalt–molybdenum sulfide hydrogenation and hydrodesulphurization catalysts synthesized in situ from bimetallic precursors

Unsupported nickel–molybdenum and cobalt–molybdenum sulfide catalysts are synthesized via the in situ decomposition of water-soluble bimetallic precursors in a hydrocarbon feedstock using nickel–molybdenum and cobalt–molybdenum complexes with citric, oxalic, succinic, glutaric, and tartaric acids as precursors. The sulfide catalysts are characterized by means of transmission electron microscopy and X-ray photoelectron spectroscopy. The catalyst activity in the hydrogenation of bicyclic aromatic hydrocarbons and the hydrodesulfurization of dibenzothiophene is studied. The effect the composition of the precursor solution in the hydrocarbon feedstock emulsion has on the activity of the resulting catalyst is determined. It is shown that the activity reaches high values even after 1 h of reaction. The hydrogenation of mono-, di-, and trimethylnaphthalenes and ethylnaphthalene is studied. The optimum promoter-to-molybdenum ratio (0.25: 1) is found. It is shown that the catalyst activity does not fall during recycling, due to the elimination of the negative effect of water contained in the emulsion, which results in oxidation of the catalyst surface. After the second reaction cycle, the catalyst particles are longer and have a greater number of MoS₂ layers than the respective parameters of the catalyst particles after the first cycle. XPS shows that the content of oxygen on the catalyst’s surface falls during recycling, while the fraction of metals in the sulfide environment and the sulfur in the sulfide state grows.     

An experimental study of copper sulfide flotation in a packed cyclonic–static microbubble flotation column

A method using a cyclonic–static microbubble flotation column packed with fluid guiding media was proposed for improving flotation efficiency of copper sulfide. The installation of packed fluid guiding media in a cyclonic–static microbubble flotation column was for changing flow pattern in 10 the column by avoiding strong cyclonic flow in the upper region of the column, which can cause bubble-particle detachment. Therefore, the attached particles can be more likely to enter the froth zone instead of swirling in the column. The flow rectification contributed to a smaller bubble size in the column and significantly reduced the number of big bubbles with diameter above 1 mm. This scenario was caused by the damping of swirling liquid motion where bubbles tended to 15 concentrate and coalescence in the center of an eddy. The packed fluid guiding media changed the hydrodynamics in the upper column from a cyclonic flow to a gentle flow and as a result improve the column separation. The application of packed fluid guiding media can decrease the bubble-particle detachment and the flotation recovery of copper sulfide could constantly improve with the installation of packed fluid guiding media in the FCSMC column.     

Synthesis and Characterization of the Inclusion Complex of β-cyclodextrin and Azomethine

A β-cyclodextrin (β-Cyd) inclusion complex containing azomethine as a guest was prepared by kneading method with aliquot addition of ethanol. The product was characterized by Fourier Transform Infrared (FTIR) spectrometer, ¹H Nuclear Magnetic Resonance (¹H NMR) and Thermogravimetric Analyzer (TGA), which proves the formation of the inclusion complex where the benzyl part of azomethine has been encapsulated by the hydrophobic cavity of β-Cyd. The interaction of β-Cyd and azomethine was also analyzed by means of spectrometry by UV-Vis spectrophotometer to determine the formation constant. The formation constant was calculated by using a modified Benesi-Hildebrand equation at 25 °C. The apparent formation constant obtained was 1.29 × 10⁴ L/mol. Besides that, the stoichiometry ratio was also determined to be 1:1 for the inclusion complex of β-Cyd with azomethine.     

Production and investigation of structure and properties of polyethylene–polylactide composites

Under conditions of shear deformations, low-density polyethylene (LDPE) and polylactide (PLA) composites are obtained in rotor disperser. The production of these composites allows one to use polymers derived from natural raw and to reduce the cost of the materials on their base. The addition of rigid PLA leads to increase in elastic modulus from 200 for LDPE to 1190 for LDPE–PLA (50:50 wt %) composites and in tensile strength from 13.3 for LDPE to 17.8 for LDPE–PLA. By differential scanning calorimetry method, it is shown that LDPE and PLA are incompatible. Using X-ray diffraction analysis, it is found that degree of crystallinity of composites decreases from 46.1 at 50:50 wt % to 36.9 at 80:20 wt % component ratios with the rise in LDPE content. Tests on fungus resistance show that the composites containing 50 wt % PLA are more resistant than the composites containing 30 wt % PLA. First by gel-permeation chromatography method, it is shown that composite degradation after exposure in soil is accompanied by the PLA chain scission and depolymerization with formation of monomers and dimers (M _w of PLA decreases from 118,860 to 80,100). The obtained composites can be applied as packaging materials. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47598.     

Investigation of Structure and Oxidation Behavior of Pitch and Resin Resultant Carbon

The structure and oxidation behaviors of pitch carbon,resin carbon and their mixture re-sultant carbon have been investigated.The results indicate that the pitch carbon has relative higher true specific gravity,well developed crystalline and better oxidation resistance than resin carbon,With 20%-35% resin added to pitch,the structure of the resultant carbon can be modified and oxidation resistance will be improved significantly.     

Characteristics and Application of Andalusite Material and Andalusite-Based Refractory

Andalusite material and Andalusite-based refractory are very popular in Europe and Japan, but its applications are restrained because of its low quality and misunderstanding in China. The paper introduced in detail the characteristics of andalusite material and andalusite-based refractory based on the authors‘ research work in recent years and on some references. Some information is illustrated clearly by figures and microstructure photographs. It is concluded the property of raw material and refractory is not determined by alumina content but by type and quantity of the impurities and microstructure.Mullitisation provide andalusite-based refractories more excellent macro and micro properties that guarantee itspopular application.     

Low‐temperature selective oxidation of hydrogen sulfide into elemental sulfur on a NiS2/SiC catalyst

Nickel sulfide supported on SiC exhibits a very high activity and selectivity for the direct oxidation of H₂S into elemental sulfur at low reaction temperature (60°C). The presence of water on the catalyst surface could explain the absence of deactivation even at high sulfur loading of the surface. The chemical inertness of the SiC support allowed any detrimental reactions between the active phase and the support itself to be avoided.     

Synthesis and Characterization of the Inclusion Complex of Dicationic Ionic Liquid and β-Cyclodextrin

The supramolecular structure of the inclusion complex of β-cyclodextrin (β-CD) with 1,1',2,2'-tetramethyl-3,3'-(p-phenylenedimethylene) diimidazolium dibromide (TetraPhimBr), a dicationic ionic liquid, has been investigated. The inclusion complex with 1:1 molar ratio was prepared by a kneading method. Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD) analysis, (1)H NMR and thermogravimetric analysis (TGA) confirmed the formation of the inclusion complex. The results showed that the host-guest system is a fine crystalline powder. The decomposition temperature of the inclusion complex is lower than that of its parent molecules, TetraPhimBr and β-CD individually.     

Compositions and Properties of Hydration-Resistant Coating of Magnesia-Calcia Materials

The complex coating on the MgO-CaO clinker was prepared by dipping method and adding the second mineral to restrain the formation and expansion of the craks.Meansohile,the microstructure and the morphology of the coating and hydration resistance of the MgO-CaO clinker were also investigated.The result shows that the coating consists mainly of Ca2P2O7,MgO and CaCO3,its thickness ranges from 5μm to 20μm,and the coating is dense and even,no micro-cracks are observed.Also,the coating adheres closely to the matrix.The hydration resistance of the MgO-CaO clinker after treatment is improved greatly,and the castables prepared with the treated MgO-CaO clinker have better physical properties than MgO castable.     

Compaction and shear failure of refractory mortars – effects of porosity and binder hardening

With the aim to correlate the global properties of refractory mortars with the micro-mechanical processes, a series of uni-axial compression and shear tests was conducted. The test program was developed with the view that the shear grain slip and cracks are frequent failure mechanism under compressive loads. The micro-structural changes during compression were monitored by X-ray micro focus computed tomography. Discrete element modelling was used to highlight the effects of individual factors of influence. Mortars with a water glass binder of different maturity were tested. In compression the mortars demonstrated cracking and pore closure. Shear tests showed that the failure process consists of multiple local failure events. The combined effects of the porosity and immature binder promote increased tendency for crack branching and arrest. This results in low shear strength and high compressibility. Cohesion and interlocking between the grains prevents crack branching and increases the stiffness and the strength.