Activity and Selectivity Behavior of 1,2-Epoxyethylbenzne Hydrogenation in Carbon Dioxide Solvent

Hydrogenation of 4-t-butylphenol over an activated carbon-supported rhodium catalyst in carbon dioxide solvent was analyzed based on phase observation with a view cell and calculations of the solubility of 4-t-butylphenol using the Peng-Robinson equation of state as a function of carbon dioxide pressure. The reaction experiments showed that the initial reaction rate of 4-t-butylphenol at 313 K under 2 MPa of hydrogen pressure was increased by the addition of carbon dioxide, especially above a total pressure of 11 MPa. Direct visual observation showed that the solubility of 4-t-butylphenol increased with higher carbon dioxide pressure. The calculations based on the Peng-Robinson equation of state also showed that the solubility of 4-t-butylphenol in the 4-t-butylphenol–carbon dioxide–hydrogen (2 MPa) system at 313 K significantly increased by addition of carbon dioxide above a total pressure of 11 MPa. We concluded that the increase in the hydrogenation rates was caused by the increased concentration of 4-t-butylphenol substrate in the carbon dioxide solvent.

Catalytic hydrogenation of 2-tert-butylphenol over a charcoal-supported rhodium catalyst in carbon dioxide solvent at 313 K was studied in a batch reactor. To elucidate the effect of carbon dioxide pressure on the initial rate of reaction, the phase behavior of the ternary (2-tert-butylphenol−carbon dioxide−hydrogen) system was separately observed with a view cell, and the calculations of vapor−liquid equilibrium and compositions in the vapor and liquid phases inside the reactor were carried out using the Peng−Robinson equation of state. The hydrogenation behavior in the carbon dioxide solvent is discussed based on the phase behavior of the ternary system.

Catalytic hydrogenation of naphthalene to decalin was studied over a carbon-supported rhodium catalyst in supercritical carbon dioxide solvent at 333 K, and the results were compared with those in an organic solvent. cis-, trans-Decalin and tetralin were formed from the beginning of the reaction in supercritical carbon dioxide. Higher concentration of hydrogen in carbon dioxide solvent and on the active site, and also the suppression of desorption of partially hydrogenated tetralin molecules from the active site would be responsible for higher selectivity to cis-decalin in supercritical carbon dioxide than that in an organic solvent.

Bioactive compounds in animal and plant cells have many benefits for human health, such as antioxidants, antibacterial, anti-inflammatory, and anticancer. Extraction and separation of bioactive compounds from other compounds is an important step, and commonly, conventional methods are used, but these methods have disadvantages, like producing unwanted compounds. Alternative methods can be conducted using supercritical fluid extraction, but this equipment is expensive and has a small capacity. So, this study aims to produce functional and structural designs and manufacture supercritical fluid extraction machines using carbon dioxide solvents (CO2) operating with a semi-continuous system. This research succeeded in designing and manufacturing a supercritical fluid extraction machine using carbon dioxide (CO2) solvent that operates in a semi-continuous system for the extraction of bioactive compounds, with main components including cover frames, supercritical extractor chamber, low and high-pressure CO2 tubes, compressors and boosters, pipelines, direct valves, manometers, heating, cooler, and expanders, result from reservoirs and automatic control. Moreover, the preliminary simulation test studies revealed that the supercritical extractor chamber could withstand an absolute pressure of 1000 bar, a temperature of 300°C, and a work capacity of 1 L. It indicated that the supercritical CO2 fluid extractor system was performing well for the conditioning of the extractor chamber, which is generated using a booster and controlled by a one-way valve. Then, the extract is transferred to the separation chamber to separate the CO2 gas. Then, CO2 gas is returned to the low-pressure CO2 tubes for recycling and reuse for the following process.

The adjustable solvent properties, vanishingly low surface tensions, and environmentally green characteristics of supercritical carbon dioxide present certain advantages in nanoparticles synthesis and processing. Unfortunately, most current techniques employed to synthesize and disperse nanoparticles in carbon dioxide use environmentally persistent fluorinated compounds as metal precursors and/or stabilizing ligands. This paper illustrates a one-step process for synthesis and stabilization of silver nanoparticles in carbon dioxide using only fluorine-free compounds. Isostearic acid coated silver nanoaparticles were formed and stably dispersed through arrested precipitation. Silver bis(3,5,5-trimethyl-1-hexyl)sulfosuccinate (Ag-AOT-TMH) was reduced in the presence of isostearic acid as a capping ligand in carbon dioxide solvent to form silver nanoparticles. The addition of cyclohexane as cosolvent or an increase in carbon dioxide solvent density enhances the dispersibility of the particles due to an increase in solvent strength. The dispersibility of the isostearic acid capped silver nanoparticles diminished with time until a stable dispersion was achieved due to the precipitation of a fraction of particle sizes too large to be stabilized by the solvent medium, thereby leaving a smaller size fraction of nanoparticles stably dispersed in the CO2 mixtures. This paper presents the one-step synthesis and stabilization of metallic nanoparticles in neat carbon dioxide without the aid of any fluorinated compounds.

Hydrogenation of benzothiophene-free naphthalene over charcoal-supported metal catalysts in supercritical carbon dioxide solvent

The effects of negative pressure applied to just the upper airway on nasal and laryngeal muscle activity were studied in 14 spontaneously breathing anesthetized dogs. Moving average electromyograms were recorded from the alae nasi (AN) and posterior cricoarytenoid (PCA) muscles and compared with those of the genioglossus (GG) and diaphragm. The duration of inspiration and the length of inspiratory activity of all upper airway muscles was increased in a graded manner proportional to the amount of negative pressure applied. Phasic activation of upper airway muscles preceded inspiratory activity of the diaphragm under control conditions; upper airway negative pressure increased this amount of preactivation. Peak diaphragm activity was unchanged with negative pressure, although the rate of rise of muscle activity decreased. The average increases in peak upper airway muscle activity in response to all levels of negative pressure were 18 +/- 4% for the AN, 27 +/- 7% for the PCA, and 122 +/- 31% for the GG (P less than 0.001). Rates of rise of AN and PCA electrical activity increased at higher levels of negative pressure. Nasal negative pressure affected the AN more than the PCA, while laryngeal negative pressure had the opposite effect. The effects of nasal negative pressure could be abolished by topical anesthesia of the nasal passages, while the effects of laryngeal negative pressure could be abolished by either topical anesthesia of the larynx or section of the superior laryngeal nerve. Electrical stimulation of the superior laryngeal nerve caused depression of AN and PCA activity, and hence does not reproduce the effects of negative pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Biphenyl hydrogenation over supported transition metal catalysts under supercritical carbon dioxide solvent

A series of displacement tests was conducted on preserved reservoir core plugs to assist in estimating waterflood and miscible flood performance potential for the Eagle Lake Viking Reservoir in Saskatchewan. The reservoir rock is a heterogeneous sandstone, comprising thin interbeds of sand and shale with the sand lenses containing widely different amounts of smectite clays. To assess miscible recovery efficiencies in this complex sand, displacement tests were conducted with first-contact miscible propane and carbon dioxide solvents. Using standard waterflood relative permeabilities and a dual permeability model, all miscible displacements were matched by simulation with a Todd-Longstaff-type miscible mixing model. Introduction The Eagle Lake Viking Reservoir is located in southwest Saskatchewan as shown in Figure 1. It is a sandstone formation of Mississippian age. Discovered in 1957, one half of this 12.7 million m3 field was put on waterflood ten years later in 1967. Unfortunately, because of its low permeability, it has been possible to only inject 0.14 pore volumes of water in the subsequent 2O-year period. As a result, in the thirty years since discovery, only 15% of original oil- in-place has been produced. The cause of poor performance appears to be due to the abundant shales and days. Thin section analyses, however, show that bands of higher permeability are also found throughout the pay zone and often exist as thin to very thin sand stringers which are relatively free of days. In 1985, operations engineers decided that the half of the field which was still under primary depletion should be placed under some form of secondary recovery. Because the waterflood had been less than satisfactory, it was decided to examine miscible flooding as a potential alternative. Hence, a core flooding study using carbon dioxide as a flooding agent was designed with the following objectives;quantify carbon dioxide oil displacement efficiency;compare carbon dioxide with waterflood oil recovery; andcompare the potentially complex carbon dioxide miscible oil displacement process with a more conventional hydrocarbon solvent process using propane. To extend the initial objectives for reservoir design purposes, a fourth objective was to:obtain waterflood and miscible displacement parameters for use in numerical simulation of field applications, Reservoir Fluid and CO2 Miscibility Pressure The live oil used in this study was obtained by recombining separator gas and liquid to a bubble point pressure of 6509 kPa at 22 °C. Fluid densities were measured as a function of pressure at the reservoir temperatures of 22 °C and were matched with the Peng-Robinson(l) equation-of-state. The reference 2 characterization procedure was used and viscosity predictions were made with the Jossi, Stiel and Thodos correlation. Table 1 illustrates the accuracy or this prediction which involved proprietary correlations for heavy end parameters. This set of density and viscosity data was used in the simulation study. The oil composition is also shown in Table 1. To determine the first-contact miscibility pressure for CO2, oil and CO2 were blended in a visual cell at 22 °C. These results and the Peng-Robinson equation-of-state matches are presented in Table 2.

We applied the extended RISM integral equation theory to investigate the local solvation behavior of a naphthalene solute in a supercritical carbon dioxide solvent. A ten-site model potential for naphthalene (by Sediawan, Gupta, and Mclaughlin) and a three-site potential for carbon dioxide (by Murthy, Singer, and McDonald) were used to elucidate local orientation of the carbon dioxide solvent molecules around the solute. Important physical effects of the quadrupole of carbon dioxide as well as molecular geometry of naphthalene are, therefore, taken into account. To gain insight into preferential orientation of carbon dioxide around a naphthalene molecule in a supercritical carbon dioxide solvent, we used a novel supermolecule approach by which potential of mean force surfaces of a carbon dioxide−naphthalene pair were calculated. Effects of molecular shape of solute and solute−solvent attractive interactions on solute partial molar volume were examined.

Effect of negative pressure on superconducting transition temperature of MgB2

Extraction of sunflower ( Heliantus annuus L.) oil with supercritical CO 2 and subcritical propane: Experimental and modeling

The adsorption and hydrogenation of benzene and toluene on alumina- and silica- supported palladium and platinum catalysts

Solubility of carbon dioxide (CO2) in aqueous solution of 3-(dimethylamino)-1-propylamine (DMAPA)

Enhanced solubility of carbon dioxide for encapsulated ionic liquids in polymeric materials