The measurement and prediction of the solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution

The solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution has been determined at temperatures of 40°C and 100°C. Partial pressures of CO₂ ranged from 0.7 to 5630 kPa, while partial pressures of H₂S ranged from 0.7 to 3780 kPa. The present results extend the published data on this system which were limited to partial pressures below 200 kPa. The results have been compared with two methods of prediction based upon a thermodynamic model.     

Solubility of acid gases in a mixed solvent

The solubility of the acid gases, H₂S and CO₂, and their mixtures in a mixed solvent consisting of 55 mass% 2-piperidineethanol, 10 mass% sulfolane and 35 mass% water has been determined at 40° and 100°C. Partial pressures of the acid gases ranged from 0.05 to 5550 kPa.     

Equilibrium between carbon dioxide and aqueous monoethanolamine solutions

The partial pressure of carbon dioxide has been measured over aqueous monoethanolamine solutions (1.0, 2.5, 3.75 and 5.0 N) at temperatures of 25, 40, 60, 80, 100 and 120°C. Partial pressures of CO₂ ranged between 0.2 and 6616 kPa.^b The results extend previously published data to higher partial pressures. Comparisons have been made with two methods of prediction based upon a thermodynamic model.     

The solubility of H2S and CO2 in a diethanolamine solution at low partial pressures

The solubility of H₂S, CO₂ and their mixtures in a 2.0 kmol m^?3 aqueous solution of diethanolamine has been determined at 40°C and 100°C at partial pressures of the acid gases between 0.003 and 6.5 kPa. The results have been compared with values calculated by a method of prediction.     

Oxidative coupling of methane in a bubbling fluidized bed reactor

The oxidative coupling of methane to higher hydrocarbons (C₂₊) was studied in a bubbling fluidized bed reactor between 700°C and 820°C, and with partial pressures of methane from 40 to 70 kPa and of oxygen from 2 to 20 kPa; the total pressure was ca 100 kPa. CaO, Na₂CO₃/CaO and PbO/γ-Al₂O₃ were used as catalytic materials. C₂₊ selectivity depends markedly on temperature and oxygen partial pressure. The optimum temperature for maximizing C₂₊ selectivity varies between 720 and 800°C depending on the catalyst. Maximum C₂₊ selectivities were achieved at low oxygen and high methane partial pressures and amounted to 46% for CaO (T = 780°C; P_CH4 = 70 kPa; P_O2 = 5 kPa), 53% for Na₂CO₃/CaO (T = 760°C; P_CH4 = 60 kPa; P_O2 = 6 kPa) and 70% for PbO/γ-Al₂O₃ (T = 720°C; P_CH4 = 60 kPa; P_O2 = 5 kPa). Maximum yields were obtained at low methane-to-oxygen ratios; they amounted to 4.5% for CaO (T = 800°C; P_CH4 = 70 kPa; P_O2 = 12 kPa), 8.8% for Na₂CO₃/CaO (T = 820°C; P_CH4 = 60 kPa; P_O2 = 20 kPa) and 11.3% for PbO/γ-Al₂O₃ (T 2= 800°C; P_CH4 = 60 kPa; P_O2 = 20 kPa).     

The solubility of carbon dioxide and hydrogen sulfide in a 35 wt% aqueous solution of methyldiethanolamine

The solubility of hydrogen sulfide and carbon dioxide in an aqueous solution containing 35 wt% methyldiethanolamine (MDEA) (3.04 kmol/m³, 4.52 mol/kg) has been measured at 40° and 100°C at partial pressures of the acid gas up to 530 kPa. Some data for hydrogen sulfide in a 50 wt% solution of MDEA (4.38 kmol/m³, 8.39 mol/kg) were also obtained. Also, densities of CO₂-aqueous MDEA solutions were measured at 40°C.     

Solubility of H2S and CO2 in sulfolane

The solubility of H, S and CO₂ in sulfolane (tetrahydrothiophene-1, 1—dioxide) has been measured at 40°C and 100°C at pressures up to 2350 kPa and 5900 kPa respectively. The Henry's constants obtained from the data are in agreement with those of Rivas and Prausnitz.     

Equilibria of H2S and CO2 in triethanolamine solutions

The equilibrium solubility of H₂S and CO₂ has been measured in 2.0, 3.5 and 5.0 mol/L triethanolamine solutions. Data were obtained at temperatures of 25°, 50°, 75°, 100° and 125°C at partial pressures of the acid gases ranging from 0.01 to 6360 kPa. Enthalpies of solution were calculated from the solubility data.     

The solubility of H2S and CO2 in aqueous monoethanolamine solutions

The solubility of hydrogen sulphide and carbon dioxide, respectively, in 2.5 and 5.0 N aqueous monoethanolamine solutions has been determined at temperatures of 40°C and 100°C. Partial pressures of CO₂ ranged from 0.1 to 1000 psia, while partial pressures of H₂S ranged from 0.3 to 650 psia. The results have been used, together with literature data, to calculate enthalpies of solution.     

The measurement and prediction of the solubility of acid gases in monoethanolamine solutions at low partial pressures

An apparatus for the determination of the solubility of hydrogen sulphide, carbon dioxide and their mixtures in ethanolamine solutions at low pressures is described. With this apparatus, the solubility of H₂S, CO₂ and their mixtures in aqueous solutions of monoethanolamine has been measured at partial pressures between 0.001 kPa and 9 kPa at temperatures of 80° and 100°C. The results for the mixture have been compared with two methods of prediction based on a thermodynamic model.     

Kinetics of the hydroformylation of soybean oil by ligand-modified homogeneous rhodium catalysis

The kinetics and mechanism of the hydroformylation of soybean oil by homogeneous ligand-modified rhodium catalysts were investigated at 70–130°C and 4000–11,000 kPa. The effects of reaction rates on systematic variations in reaction parameters were evaluated in order to develop an industrial process to convert vegetable oils to polyaldehydes. The activation energies in the presence of triphenylphosphine (Ph₃P) (61.1±0.8 kJ/mol) (mean±SD) and triphenyl phosphite [(PhO)₃P] (77.4±5.0 kJ/mol) were determined. The catalyst was deactivated at temperatures higher than 100°C. An evaluation of the effects of the reaction parameters on initial rates yielded the rate laws for Ph₃P {rate=k [olefin][Rh(CO)₂Acac]^1.1 [Ph₃P]^−0.5 (pH₂+pCO)^1.4, where Rh(CO)₂Acac is (acetylacetonato)dicarbonylrhodium (I)} and (PhO)₃P {rate=[olefin] [Rh(CO)₂Acac]^1.2 [(PhO)₃P]^−0.8 (pH₂+pCO)^0.9 at total pressures lower than 7000 kPa, and rate =[olefin] [Rh(CO)₂Acac]^1.2 [(PhO)₃P]^−0.8(pH₂+pCO)^1.7 at total pressures higher than 7000 kPa}.     

CO<Subscript>2</Subscript> adsorption at high pressures in MCM-41 and derived alkali-containing samples: the role of the textural properties and chemical affinity

The adsorption properties of N₂ and CO₂ of MCM-41 and derived alkali-containing samples were analyzed over a wide range of pressures (up to ~4500 kPa) and temperatures (between 30 and 300 °C). The high-pressure and high-temperature experiments were carried out on pure MCM-41 and K- and Na-impregnated derived samples. It was analyzed the influence of pressure and temperature on the CO₂ capture capacity on pure and impregnated samples. The adsorption performance was correlated to the structure and textural properties of the materials using X-ray diffraction and N₂ adsorption–desorption measurements. The addition of an alkaline element changes the textural properties of the material increasing the pore size, which positively affected the CO₂ adsorption capacity of these materials at high pressure. In addition, the isosteric heats of adsorption gave information about the chemical affinity between the impregnated materials and CO₂. The CO₂ adsorption at ~ 4500 kPa for the samples with 5 wt% Na at 100 and 200 °C were 77.98 and 9.79 mmol g^?1, respectively, while the pure MCM-41 adsorbs only 8.92 mmol g^?1.     

The solubility of CO2 in a 30 mass percent monoethanolamine solution

The solubility of CO₂ in a 30 mass % monoethanolamine (MEA) solution has been measured at eight temperatures between 0 and 150°C at partial pressures of CO₂ ranging from 0.001 to 20,000 kPa. The data have been correlated using the Deshmukh-Mather (1981) model.     

Sintering‐induced aromatization during n‐heptane reforming on Pt/Al2O3 catalysts

A platinum/alumina catalyst was sintered in oxygen and hydrogen atmospheres using two metal loadings of the catalyst: 0.3% Pt and 0.6% Pt. After sintering, the aromatization selectivity was investigated with the reforming of n‐heptane as the model reaction at a temperature of 500 °C and a pressure of 391.8 kPa. The primary products of n‐heptane reforming on the fresh platinum catalysts were methane and toluene, with subsequent conversion of benzene from toluene demethylation. To induce sintering, the catalysts were treated with oxygen at a flow rate of 60 mL min^?1, pressure of 195.9 kPa and temperatures between 500 and 800 °C. The 0.3% Pt/Al₂O₃ catalyst exhibited enhanced aromatization selectivity at various sintering temperatures while the 0.6% Pt/Al₂O₃ catalyst was inherently hydrogenolytic. The fact that aromatization was absent on the 0.6% Pt/Al₂O₃ catalyst was attributed to the presence of surface structures with dimensionality between two and three as opposed to essentially 2‐D structures on the 0.3% Pt/Al₂O₃ catalyst surface. On the 0.3% Pt/Al₂O₃ catalyst, the reaction product ranged from only toluene at a 500 °C sintering temperature to predominantly cracked product at a sintering temperature of 650 °C and no reaction at 800 °C. For sintering at about 650 °C, subsequent conversion of n‐heptane was complete and dropped thereafter. The turnover number was observed to change from 0.07 to 2.26 s^?1 as the dispersion changed from 0.33 to 0.09. The Koros–Nowark (K–N) test was used to check for the presence of internal diffusional incursions and Boudart's criterion was used for structural sensitivity determination. The K–N test indicated the absence of diffusional resistances while n‐heptane reforming was found to be structure sensitive on the Pt/Al₂O₃ catalyst. Copyright © 2006 Society of Chemical Industry     

Oxidation resistance and microstructure evolution of ZrB2–SiC–La2O3/SiC dual-layer coating on siliconized graphite at 1800 °C under low air pressures

The oxidation behaviors of a ZrB₂–SiC–La₂O₃/SiC dual-layer coating on siliconized graphite at 1800 °C under low air pressures (50, 5 and 0.5 kPa) were investigated. The results showed that with the decrease of air pressure, the oxidation kinetics of the coated samples changed from parabolic weight gain to linear weight loss. A protective oxide scale consisted of ZrO₂ and SiO₂ with La dispersed was formed on the coating surface after oxidation in 50 kPa air. The oxide scale formed in 5 kPa air was full of bubbles. Only porous ZrO₂ layer was left on the coating surface after oxidation in 0.5 kPa air. At 1800 °C, the active oxidation of SiC occurred and gaseous SiO formed at the coating/oxide interface. The surface volatilization of SiO became severe with the decrease of air pressure, resulting in the presence of non-protective oxide scale.     

Kinetic studies of the oxidation of highly oriented pyrolytic graphites

Two highly oriented stress-recrystallized pyrolytic graphites have been used to study the kinetics of the carbon-O₂ reaction. Experimental conditions ranged from 700 to 800°C with O₂ pressures from 6 to 60 Torr. Activation energies were determined at 20 Torr O₂ pressure and the order of reaction determined at 725–750°C. Prior to the reaction, specimens were outgassed at about 10^-6 Torr for 8–12 hr at 950°C. The reaction was then followed by continuously monitoring the weight loss using a microbalance. An initial, high transient oxidation rate was shown to be due to surface irregularities at the basal plane edges. Oxidation then occurred at a constant rate (provided that the O₂ pressure was not significantly depleted) with an activation energy of 47–53 kcal/mole, which was shown to be due to the reaction of O₂ with carbon atoms at edges of graphite basal planes. There was no indication of retardation of reaction by concurrent formation of a surface oxygen complex. Reaction order was 0·5andO·6 for the two graphites.     

Investigation of sorption and diffusion of supercritical carbon dioxide into poly(vinyl chloride)

The interaction of supercritical carbon dioxide (scCO₂) with poly(vinyl chloride) (PVC) was systematically investigated. PVC films of 0.5 mm thickness were treated with CO₂ at pressures between 5 and 40 MPa, at temperatures between 40 and 70°C and soaking times between 0.5 and 7 h. The gravimetric desorption data were kinetically and thermodynamically evaluated assuming Fickian diffusion and the morphology changes due to the CO₂ treatment investigated by microscopic methods. The sorbed amount of CO₂, q (q=g_CO2/g_polymer) ranged between 0.03 (5 MPa, 70°C) and 0.13 (15 MPa, 40°C). The desorption diffusivities, D_d, were in the order of 0.1×10⁻¹¹ m²/s and decreased with decreasing amounts of CO₂. In contrast, the sorption diffusivities, D_s, were markedly higher and varied between 0.7×10⁻¹¹ and 2.5×10⁻¹¹ m²/s (20 MPa, 40–70°C). The CO₂ treatment changed the polymer chain structure, macroscopically visualized by the film opaqueness and by the density decrease to 1.05 g/cm³. Microcellular structures were not detected.     

Reactivity of Australian coal-derived chars to carbon dioxide

The reactivities to CO₂ of four chars derived from Australian coals at 610 °C, were measured thermogravimetrically. Reaction rates in 100% CO₂ (total pressure, 101 kPa) varied from 0.026 mg h^?1 mg^?1 at 803 °C for char derived from a Lithgow coal to 6.3 mg h^?1 mg^?1 at 968 °C for a Millmerran coal char. Activation energies for the four chars were in the range 219–233 kJ mol^?1. The results show that for Lithgow (Hartley Vale) coal char, reactivity increases with CO₂ concentration and decreasing particle size. The apparent reaction order for this char with respect to CO₂ concentration was found to be 0.7. For different chars, reactivity is inversely proportional to the rank of the parent coal. No general correlation has been established between total mineral content (ash) and char reactivity.     

Synthesis and characterization of some aromatic polyimides

The diamine 2‐methyl‐1,3‐bis(4‐aminophenyloxy)benzene was prepared via a nucleophilic substitution reaction and was characterized with Fourier transform infrared, elemental analysis, and ¹H‐ and ¹³C‐NMR spectroscopy. The prepared diamine was also characterized with single‐crystal analysis. The geometric parameters of C₁₉H₁₈N₂O₂ were in the usual ranges. The dihedral angles between the central phenyl ring and the two terminal aromatic rings were 88.9 and 91.6°. The crystal structure was stabilized by N? H···N hydrogen bonds. The diamine was then polymerized with 3,3′,4,4′‐benzophenone tetracarboxylic acid dianhydride, 4,4′‐(hexafluoroisopropylidene)diphthalic anhydride, 3,4,9,10‐perylenetetracarboxylic acid dianhydride, and pyromellitic dianhydride by either a one‐step solution polymerization reaction or a two‐step procedure. These polymers had inherent viscosities ranging from 0.61 to 0.85 dL/gm. Some of the polymers were soluble in most common organic solvents even at room temperature, and some were soluble on heating. The degradation temperatures of the resultant polymers fell in the range of 260–500°C in nitrogen (with only 10% weight loss). The specific heat capacity at 200°C ranged from 1.0 to 2.21 J g^?1 K^?1. The temperatures at which the maximum degradation of the polymer occurred ranged from 510 to 610°C. The glass‐transition temperatures of the polyimides ranged from 182 to 191°C. The activation energy and enthalpy of the polyimides ranged from 44.44 to 73.91 kJ/mol and from 42.58 to 72.08 kJ/mol K, respectively. The moisture absorption was found in the range of 0.23–0.71%. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

The formation and thermal stability of spurrite,Ca5(SiO4)2CO3

The reversible equilibrium: 2Ca₂SiO₄ + CaO + CO₂ ? Ca₅(SiO₄)₂CO₃ has been studied using F^? and C?^? ions as mineralizers. A pressure-temperature curve is given for the reaction in the range of CO₂ pressures between 0.08 and 1 atmosphere. At these pressures, the decomposition temperatures of spurrite are 790 ± 5°C and 912 ± 5°C respectively. At a given CO₂ pressure the thermal stability of spurrite is greater than that of CaCO₃.