Simultaneous Absorption of Carbon Dioxide and Nitrogen Dioxide into Aqueous 2-amino-2-methy-1-propanol

Carbon dioxide and nitrogen dioxide were simultaneously absorbed into aqueous 2-amino-2-methyl-1-propanol (AMP) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–4.0 kmol/m³ of AMP, 0.03–0.3 atm of CO₂, 0.005–0.2 atm of NO₂, and 298–318 K. Absorption data of each gas in the CO₂-AMP and NO₂-AMP systems were obtained to verify their reaction regimes, based on film theory, respectively, which were then used to analyze the simultaneous absorption mechanisms of CO₂ and NO₂ in the CO₂-NO₂-AMP systems. The measured absorption rates of CO₂ and NO₂ were compared to those formulated by an approximate solution of the mass balances with simultaneous reactions.     

Simultaneous Absorption of Carbon Dioxide and Sulfur Dioxide into Aqueous 2-Amino-2-Methy-1-Propanol

Abstract

Carbon dioxide and sulfur dioxide were simultaneously absorbed into aqueous 2-amino-2-methyl-1-propanol (AMP) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–4.0 kmol/m³ of AMP, 0.03–0.3 mole fraction of CO₂, 0.005–2 mole fraction of SO₂, and 298–318 K. Absorption data of each gas in the CO₂-AMP and SO₂-AMP systems are obtained to verify their reaction regimes, based on film theory, respectively, which are used to analyze the simultaneous absorption mechanisms of CO₂ and SO₂ in the CO₂-SO₂-AMP systems. The measured absorption rates of CO₂ and SO₂ are compared to those formulated by an approximate solution of the mass balances with simultaneous reactions.     

(VO)2P2O7 Catalysed Partial Oxidation of Propane in Dense CO2

The aim of this study was to elucidate the catalytic partial oxidation of propane to oxygenates on vanadyl pyrophosphate ((VO)₂P₂O₇) in dense carbon dioxide acting as a solvent. The reaction was carried out in continuous flow experiments at 673 K at a molar ratio of CO₂ :synthetic airpropane of 86131, a residence time of 19 s and sub- to supercritical pressures ranging from 2.4 to 9.7 MPa. The catalytic tests revealed the formation of acrylic and acetic acid besides total oxidation products. The selectivity to acetic acid increased with rising pressure, whereas that of acrylic acid decreased. These results may be attributed to a diverging adsorption of both the oxygenates with pressure, which was investigated by supercritical fluid chromatography. Additionally, critical data of both the reaction feed and the product mixture were determined in a high-pressure optical cell by the opalescence method.     

1-氨丙基-3-甲基咪唑溴功能型离子液体对CO2的吸收性能

1-氨丙基-3-甲基咪唑溴盐([APMIm])对CO₂等酸性气体具有较强的选择性吸收性能,在能源及环保领域有较好应用前景。运用等容饱和吸收法在高压不锈钢反应釜中测得CO₂在3种不同含水量的1-氨丙基-3-甲基咪唑溴盐水溶液中的溶解度数据,实验的温度范围为278.15~348.15 K,实验压力由低于大气压到最高6.5 MPa。实验结果表明,当水的质量分数达到60.84%以上,离子液体水溶液吸收CO₂的能力和速率才会得到显著提升。尤其值得注意的是,在278.15 K、120 kPa达到吸收平衡时,CO₂在含水质量分数为60.84%的1-氨丙基-3-甲基咪唑溴盐水溶液中的溶解度达到0.459 mol CO₂ ·(mol IL)^-1,接近理论最大吸收值0.5 mol CO₂·(mol IL)^-1。在较高压力下(3.9 MPa)最大CO₂吸收量为1.894 mol CO₂·(mol IL)^-1。     

Synthesis of oligomer vinyl acetate with different topologies by RAFT/MADIX method and their phase behaviour in supercritical carbon dioxide

Poly(vinyl acetate) (PVAc) has been shown to exhibit anomalously high solubility in CO₂ as compared to other vinyl hydrocarbon polymers. Understanding the phase behaviour of PVAc with different topologies in CO₂ is very important for its potential applications as suitable surfactant, or phase transfer agent in a CO₂ solvent process. In this study, a series of PVAcs with different topologies (bi-arms, tri-arms, tetra-arms) were synthesized by RAFT/MADIX method. The structures and molecular weights of these polymers were characterized by ¹H NMR and GPC. The phase behaviours of PVAcs in dense carbon dioxide fluid were determined, and the results show that the PVAc with more arms has lower cloud point pressure.     

Simultaneous Absorption of Carbon Dioxide and Sulfur Dioxide into Aqueous 1,8-Diamino-p-menthane

Abstract

Carbon dioxide and sulfur dioxide were simultaneously absorbed into aqueous 1,8-diamino-p-menthane (DAM) in a stirred semi-batch tank with a planar gas-liquid interface within a range of 0–2.0 kmol/m³ of DAM, 0.01–0.12 mole fraction of CO₂, 0.001–0.012 mole fraction of SO₂, and 298-318 K. Absorption data of each gas in the CO₂-DAM and SO₂-DAM systems are obtained to verify their reaction regimes, based on film theory, respectively, which are used to analyze the simultaneous absorption mechanisms of CO₂ and SO₂ in the CO₂-SO₂- DAM systems. In the simultaneous absorption rate of CO₂ and SO₂ into DAM solution, the absorption of CO₂ belongs to the second-order reaction of finite rate and the absorption of SO₂ belongs to the instantaneous reaction regime.     

Effect of carbon dioxide on the selectivities obtained during the partial oxidation of methane and ethane over Li+/MgO catalysts

AtT 650 °C carbon dioxide either formed during reaction or added to the system increases the selectivity for the desired hydrocarbon products during the oxidative coupling of methane and the oxidative dehydrogenation of ethane reaction over Li⁺/MgO catalysts. Similarly, CO₂ inhibits secondary reactions of CH₃-radicals with the surface of the Li⁺/MgO. The improved selectivities are attributed to the poisoning effect that CO₂ has on the secondary reactions of alkyl radicals with the surface.     

Ni/Al2O3催化剂对高纯HCl中微量CO2甲烷化反应的催化性能

用浸渍法制备了以Al₂O₃为载体、Ni为活性组分的Ni/Al₂O₃二氧化碳甲烷化催化剂,在等温固定床反应器中研究了在Ni/Al₂O₃催化剂作用下,高纯氯化氢中微量CO₂甲烷化反应效果,并考察了温度、压力、氯化氢体积空速以及H₂/CO₂摩尔比对CO₂转化率的影响,同时研究了催化剂活性、稳定性及其再生性能。结果表明,在温度为250℃、压力为4.0 MPa、氯化氢空速为100 h^-1、H₂/CO₂摩尔比为500:1条件下,CO₂甲烷化反应效果最好,其转化率可达到90%左右,对于高纯氯化氢中微量CO₂的脱除起到很好的效果;催化剂在温度高于300℃时,反应不久后会迅速失活;催化剂再生性能只能部分恢复到新鲜水平。     

Absorption of Carbon Dioxide into Ionic Liquid of 2-Hydroxy Ethylammonium Lactate

Abstract

Absorption of carbon dioxide into organic solvents such as DMA, NMP, DMSO, and DMF with the 2-hydroxy ethylammonium lactate (HEAL) ionic liquid was investigated using a batch stirred tank with a plane of gas-liquid interface in a range of 0–2.0 kmol/m³ of HEAL and 298–318 K at 101.3 kPa. The absorption of CO₂ was analyzed with the film model accompanied by the zwitterion mechanism of CO₂ with HEAL. The proposed model fits the experimental data of the enhancement factor due to the ready, chemical absorption of CO₂ in different solvents, temperatures, and HEAL concentrations. The reaction rate constant of CO₂ with HEAL was correlated linearly with the solubility parameter of the solvent.     

Supercritical water oxidation of quinoline in a continuous plug flow reactor—part 1: effect of key operating parameters

This work presents the supercritical water oxidation (SCWO) of quinoline, a nitrogen‐containing organic compound found in pharmaceutical wastewaters, to products that are more readily biodegradable. The effects of the operating variables, namely process temperature, stoichiometric ratio of oxidant to organic, residence time and system pressure were studied in order to optimise quinoline removal efficiency and to investigate the fate of carbon and nitrogen after oxidation. Hydrolysis experiments undertaken in the range 480–650 °C showed no significant degradation of quinoline. The present study confirmed that, as an alternative to incineration, the process is fast and effective in treating quinoline in water, converting it into primarily carbon dioxide (CO₂), water (H₂O) and nitrogen gas (N₂) and to a lesser extent ammonium ions (NH₄⁺). Temperature was shown to be the primary variable in the complete destruction of quinoline and TOC reduction, upon operating at around 250 bars. Essentially, complete quinoline removal was observed above 575 °C and complete TOC removal was obtained at 650 °C, where CO₂ was the main reaction product. Copyright © 2006 Society of Chemical Industry     

Organic modification of ultrafine particles using carbon dioxide as the solvent

An organic modification of the surface of titanium dioxide particles precoated with SiO₂ and Al₂O₃ films in a CO₂ medium is performed, where CO₂ of different phases is used as the solvent and a titanate coupling reagent (CH₃)₂CHOTi(OP(O)(OH)OP(O)(OC₈H₁₇)₂)₃ is the modification reagent. The results are compared with the modification carried out in a conventional organic solvent. The interaction between the functional groups of the modification reagent and the hydroxyl groups on the surface of the particles is analyzed. Experimental results indicate that the surface of particles is modified efficiently when the CO₂ solvent is in a supercritical or liquid state. The particles are remarkably changed from hydrophilic to hydrophobic by the modification. A chemical bond of AlOTi is likely formed between the molecules of the organic modification reagent (CH₃)₂CHOTi(OP(O)(OH)OP(O)(OC₈H₁₇)₂)₃ and the particle surface. The actual maximum quantity order of organic modification reagent reacted on the particle surface is about 7.08×10⁻⁷ mol/m² (1.73% by weight) from thermogravimetric analysis. The organic modification process using supercritical or liquid CO₂ as the solvent has the advantages of being simple, effective, and green.     

Sorption of Carbon Dioxide onto Sodium Carbonate

Abstract

Sodium carbonate was used as a sorbent to capture CO₂ from a gaseous stream of carbon dioxide, nitrogen, and moisture. The breakthrough data of CO₂ were measured in a fixed bed to observe the reaction kinetics of CO₂‐carbonate reaction. Several models such as the shrinking‐core model, the homogeneous model, and the deactivation model in the non‐catalytic heterogeneous reaction systems were used to explain the kinetics of reaction among CO₂, Na₂CO₃, and moisture using analysis of the experimental breakthrough data. Good agreement of the deactivation model was obtained with the experimental breakthrough data. The sorption rate constant and the deactivation rate constant were evaluated by analysis of the experimental breakthrough data using a nonlinear least squares technique and described as Arrhenius form.     

Adsorption and Desorption of Carbon Dioxide and Nitrogen on Zeolite 5A

The adsorption equilibrium data of CO₂ and N₂ at (303, 333, 363, 393, 423) K ranging 0-1 bar on zeolite 5A is reported. The pressure and temperature range covers the operating pressure in adsorption units for CO₂ capture from power plants. Experimental data were fitted by the multi-site Langmuir model. The adsorbent is much more selective to CO₂: loading at 303 K and 100 kPa is 3.38 mol/kg while loading of N₂ at the same pressure is 0.22 mol/kg. The Clausius-Clapeyron equation was employed to calculate the isosteric enthalpy of adsorption. The fixed-bed adsorption and desorption of carbon dioxide and nitrogen on zeolite 5A pellets has been studied. A model based on the bi-LDF approximation for the mass transfer, taking into account the energy and momentum balances, had been used to describe the adsorption kinetics of carbon dioxide and nitrogen. The model predicted satisfactorily the breakthrough curves obtained with carbon dioxide–nitrogen mixtures. Desorption process (consisting of depressurization, blowdown, and purge) was also performed. Following the feasibility of concentration and capture of carbon dioxide from flue gases by Pressure Swing Adsorption (PSA) process was simulated. A CO₂ recovery of 91.0% with 53.9% purity was obtained using a five-step Skarstrom-type PSA cycle.     

Supercritical carbon dioxide assisted preparation of conductive polypyrrole/cellulose diacetate composites

Supercritical carbon dioxide (SC‐CO₂) has been used to assist the preparation of conductive polypyrrole/cellulose diacetate (PPy/CDa) composites by in situ chemical oxidative polymerization. The morphology and conductivity of resulted composites were investigated with scanning electron microscopy and four‐probe method, respectively. With the assistance of strong swelling effect of SC‐CO₂, composite films were obtained with a macroscopically homogeneous structure and conductivity up to 10^?1 S cm^?1 order of magnitude. Increasing the pressure of SC‐CO₂ increased conductivity, while increasing the temperature decreased conductivity. For comparison, PPy/CDa composite was also prepared with conventional oxidative method in aqueous solution. From the viewpoint of conductivity and environmental protection, the SC‐CO₂ method showed its superiority over the conventional one. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4575–4580, 2006     

High-temperature oxidation of aluminium in various gases

The oxidation of high-purity aluminium sheet in dry oxygen, moist oxygen, carbon dioxide and carbon monoxide (at total pressure 1.333 × 10³ Nm^?2) was studied in the range 673–923°K, using a vacuum microbalance to follow weight gains. ¹⁴CO₂ and ¹⁴CO were used to elucidate the mechanism of the oxidation in these gases and to estimate the extent of carbon deposition in the oxide layer. The rate of oxidation in moist oxygen was similar to that in dry oxygen, the principle reaction being 2Al + 3H₂O ← Al₂O₃ + 3H₂. It is suggested that there are three steps in the reaction in CO₂, viz. 2Al+3CO₂ ← Al₂O₃ + 3CO, followed by 2Al + 3CO ← Al₂O₃ + 3C, and about 10% of the deposited carbon reacting further by 4Al + 3C ← Al₄C₃. Only the last two reactions are operative in carbon monoxide. The Arrhenius plots show a distinct break in the region 773–823°K for both carbon monoxide and carbon dioxide, but not for dry or moist oxygen. This is tentatively explained by a change in the rate-determining process from diffusion via grain boundaries or cracks in the oxide, to lattice diffusion. It is suggested that carbon may become mobile in the oxide film between 773 and 823°K and may tend to congregate in the grain boundaries and cracks. The oxide film remained protective throughout the duration of the experiments in all the gases.     

Redeposition in CO2 textile dry cleaning

Perchloroethylene (PER) is commonly used as cleaning solvent in the textile dry-cleaning industry but this chemical is toxic by nature. One of the potential PER replacements is carbon dioxide (CO₂), which is non-toxic, cheap, and widely available. Previous studies have indicated that the particulate soil removal with CO₂ is lower compared to that of PER. While the particulate soil removal of the CO₂ dry-cleaning was studied, it was found that redeposition of particulate soil occurs. Several experiments have been carried out to study and reduce this problem. In these experiments, textiles stained with different kinds of particulate soils were cleaned using a 25 L CO₂ dry-cleaning set-up. It was found that the redeposition level increases along with washing time, while rinsing has little influence. Modifying the filtration system by using scavenger textile, or adding a cellulose compound to the cleaning vessel as anti redeposition agent can significantly reduce redeposition.     

Aerobic oxidation of secondary alcohols to ketones catalyzed by cobalt(II)/ZnO in poly(ethylene glycol)/CO2 system

The aerobic oxidation of benzhydrol, 1-phenylethanol and cyclohexanol to corresponding ketones was carried out in poly(ethylene glycol) (PEG-600)/supercritical CO₂ (SCCO₂) biphasic system using unsupported and supported CoCl₂·6H₂O as the catalysts. It was demonstrated that CoCl₂·6H₂O, Co(II)/Al₂O₃, and Co(II)/ZnO were all active and selective for the reactions. The reactivity of the substrates followed the order benzhydrol > 1-phenylethanol > cyclohexanol. Co(II)/ZnO was most stable and could be reused four times without considerable reduction of activity. The effect of CO₂ pressure, reaction time and solvent was further investigated. The Co(II)/ZnO/PEG-600 system is active, selective, cheap, clean, and recyclable for the aerobic oxidation of secondary alcohols.     

Phase behavior of water-insoluble simvastatin drug in supercritical mixtures of chlorodifluoromethane and carbon dioxide

Phase behavior data are presented for simvastatin, a water-insoluble drug, in supercritical solvent mixtures of chlorodifluoromethane (CHClF₂) and carbon dioxide (CO₂). The solubilities of the simvastatin drug in the solvent mixtures of CHClF₂ and CO₂ were determined by measuring the cloud point pressures using a variable-volume view cell apparatus as functions of temperature, solvent composition, and amount of the drug loaded into the solution. The cloud point pressure increased with increasing the system temperature. As the CHClF₂ composition in the solvent mixture increased, the cloud point pressure at a fixed temperature decreased. Addition of CHClF₂ to CO₂ caused an increase of the dissolving power of the mixed solvent for the simvastatin drug due to the increase of the solvent polarity. CHClF₂ acted as a solvent for simvastatin, while CO₂ acted as an anti-solvent. The cloud point pressure increased as the amount of the simvastatin drug in the solvent mixture increased. Consequently, the solubility of the simvastatin drug in the solvent mixture of CHClF₂ and CO₂ decreased with increasing the CO₂ content in the solvent mixture as well as with increasing the system temperature.     

The influence of cell design and electrolysis parameters on the cathodic coupling of butadiene and carbon dioxide in acetonitrile. I. Undivided parallel plate configurations

The reduction of carbon dioxide in the presence of excess butadiene in acetonitrile leads to a mixture of carboxylic acids, pentenoic acids (two isomers), hexenedioic acids (two isomers) and decadienedioic acids (three isomers). The total current yield can exceed 60%. The current efficiency and the ratio of products are functions of both cell design and other electrolysis parameters. This paper reports studies of this coupling reaction in several undivided flow cells, where cyclindrical cathodes (lead-plated nickel gauze, reticulated carbon of various porosity, carbon felt) were surrounded by a platinum gauze anode. The electrolyte was ditetraethylammonium oxalate and/or tetraethyl-ammonium formate so that the counter electrode reaction was the oxidation of the anions to CO₂ or CO₂+H⁺, respectively. This choice avoids solvent decomposition or other unwanted reactions at the anode, and may be helpful to the cathode chemistry by replenishing the cathode active species, CO₂, and possibly also creating a controlled supply of protons to the cathode.This paper was presented at the meeting on Electroorganic Process Engineering held in Perpignan, France, 19–20 September 1985.     

Progress in carbon dioxide capture and separation research for gasification-based power generation point sources

The purpose of the present work is to investigate novel approaches, materials, and molecules for the abatement of carbon dioxide (CO₂) at the pre-combustion stage of gasification-based power generation point sources. The capture/separation step for CO₂ from large point sources is a critical one with respect to the technical feasibility and cost of the overall carbon sequestration scenario. For large point sources, such as those found in power generation, the carbon dioxide capture techniques being investigated by the Office of Research and Development of the National Energy Technology Laboratory possess the potential for improved efficiency and reduced costs as compared to more conventional technologies. The investigated techniques can have wide applications, but the present research is focused on the capture/separation of carbon dioxide from fuel gas (pre-combustion gas) from processes such as the Integrated Gasification Combined Cycle (IGCC) process. For such applications, novel concepts are being developed in wet scrubbing with physical sorption, chemical sorption with solid sorbents, and separation by membranes. In one concept, a wet scrubbing technique is being investigated that uses a physical solvent process to remove CO₂ from fuel gas of an IGCC system at elevated temperature and pressure. The need to define an “ideal” solvent has led to the study of the solubility and mass transfer properties of various solvents. Pertaining to another separation technology, fabrication techniques and mechanistic studies for membranes separating CO₂ from the fuel gas produced by coal gasification are also being performed. Membranes that consist of CO₂-philic ionic liquids encapsulated into a polymeric substrate have been investigated for permeability and selectivity. Finally, processes based on dry, regenerable sorbents are additional techniques for CO₂ capture from fuel gas. An overview of these novel techniques is presented along with a research progress status of technologies related to membranes and physical solvents.