Interest In CO2 Research Articles

H Sorption Based Materials for the Hydrogenation of CO2 to Added Value Fuel Products

Energy transformation through technological systems has always been a critical issue regarding how our society works. With the environmental consideration taking over these last years, the establishment of efficient energy conversion technology allowing storage of renewably produced electricity in simple non-environmentally harmful chemicals is one of the great challenges of our times. The interest in CO2 in this context is simple; it represents a largely distributed low-energy chemical available for green energy storage. The electrochemical reduction of CO2 to small fuel molecule has been largely investigated, but the reduction process inefficiency and the cost of the highly specialized catalysts act as drawback to the implementation of this technology to industrial applications. In this work, we explore bimetallic catalyst that moves away from the simple optimization of reaction rate by adjustment of adsorption energies of species (i.e. volcano plot). We propose to combine a material active for H adsorption to a conventional CO2 electrocatalyst to explore the effect of potential enhanced availability and transfer of H during the carbon species conversion. The Cu/Pd system has been selected as a model material for the studies. Although many structures are possible to combine the metals, we chose to plate the Cu on the Pd substrate by UPD technique [1] to reduce the large hydrogen evolution occurring at Pd. The system has been studied by conventional electrochemistry, including a diversity of potentiostatic measurements and cyclic voltammetry (CV). The isotherm of H sorption has been assessed using Lasia methodology [2] to insure that the H sorption on Pd and the CO2 reduction on Cu occur in the same potential region. The UPD has been optimized and combined to dilution method to allow CO2 reduction at Cu-free solution after the deposition of a designed monolayer (ML) content of Cu on Pd. CVs has been conducted to access the general behavior of the Cu/Pd system. Activity of the underlying substrate for H has been observed to occur at the 1ML Cu on Pd. Measurements point toward the preservation of some H sorption activity by the Pd through the Cu ML although activity of bare Pd in contact with the solution through ML defect is not to exclude. We propose that the preservation of the Pd structure and electronic effects at the 1 ML Cu explains the possibility of enhanced H adsorption after the reduction by Cu at the interface. Differential electrochemical mass spectrometry (DEMS) measurements are conducted to study the effect of different content of Cu ML at the surface of the catalyst on the product distribution during the electrolysis. The specific adsorption of the anion from the electrolyte being known to affect the reaction pathway by partial and scattered surface coverage [3], different electrolytes were used to gain insight on pathways that are privileged by the different Cu/Pd surfaces. To further rationalize the links between surface properties and reaction products, X-ray photoelectron spectroscopy at near-ambient pressures (APXPS) measurements has been collected. This technique uses X-rays that generate photoelectrons that enter a differentially pumped XPS analyzer with electronoptics that facilitate the characterization of a solid material that is exposed to gases to enable the observation of their interaction during the spectrum collection. This method has previously been used to highlight different modes of CO2 adsorption on Cu surface [4]. Several ML content of Cu over Pd has been exposed to CO2 and CO under H-present and H-absent regimes. The affinity of the CO for Pd dominant surfaces has been observed. The coverage of Cu on the Pd substrate also influences the charge transfer between the adsorbed CO and the surface. We believe that the close containment of domains active for H sorption and CO2 reduction can be used as a tool to control selectivity over CO2 reduction and to favor the production of small added value molecules. Acknowledgement The financial support of the Fonds de recherche du Québec – Nature et technologies (FRQNT), of the Natural Sciences and Engineering Research Council of Canada (NSERC) and of Rio Tinto Alcan are gratefully acknowledged. This research used resources of the Advanced Light Source, which is a DOE Office of Science User Facility under contract no. DE-AC02-05CH11231. References A. Kumar and D. A. Buttry, The Journal of Physical Chemistry C, 2015, 119(29), 16927-16933H. Duncan and A. Lasia, J. Electroanal. Chem., 2008, 621(1), 62−68.P. Dubé, G. Brisard, J. Electroanal. Chem., 2008, 582(1-2), 230-240M. Favaro, H. Xiao, T. Cheng, W. A. Goddard, J. Yano et E. J. Crumlin, PNAS, 2017, 201701405

Thermodynamic Performance Investigation of Commercial R744 Booster Refrigeration Plants Based on Advanced Exergy Analysis

After the recent renewed interest in CO2 as the refrigerant (R744) for the food retail industry, many researchers have focused on the performance enhancement of the basic transcritical R744 supermarket refrigeration unit in warm climates. This task is generally fulfilled with the aid of energy-based methods. However, the implementation of an advanced exergy analysis is mandatory to properly evaluate the best strategies needing to be implemented to achieve the greatest thermodynamic performance improvements. Such an assessment, in fact, is widely recognized as the most powerful thermodynamic tool for this purpose. In this work, the advanced exergy analysis was applied to a conventional R744 booster supermarket refrigerating system at the outdoor temperature of 40 °C. The results obtained suggested the adoption of a more sophisticated layout, i.e., the one outfitted with the multi-ejector block. It was found that the multi-ejector supported CO2 system can reduce the total exergy destruction rate by about 39% in comparison with the conventional booster unit. Additionally, the total avoidable exergy destruction rate was decreased from 67.60 to 45.57 kW as well as the total unavoidable exergy destruction rate was brought from 42.67 down to 21.91 kW.

CO2/H2 Selectivity Prediction of NaY, DD3R, and Silicalite Zeolite Membranes

Using DD3R, silicalite and NaY zeolite membrane for gas separation is an attractive prospect for the development of a sustainable green process industry. The interest in CO2 and H2 lies in their relatively strong and weak adsorption in zeolite, respectively, causing a peculiar behavior of membrane selectivity, which is here evaluated in a wide range of temperature (273–573 K), feed pressure (100–500 kPa) and CO2 molar fraction (0.05–0.95). As a result, CO2/H2 selectivity of the considered zeolite is found to be high at a low temperature owing to the relatively strong CO2 adsorption with respect to the weak H2 one. Differently, selectivity is much lower at a higher temperature because of the reduced adsorption strength. The temperature strongly affects the membrane selectivity through surface diffusion closely correlated to gas adsorption, and CO2 adsorption results responsible for the high membrane selectivity in the low-temperature range.

Wear study of metallic interfaces for air-conditioning compressors under submerged lubrication in the presence of carbon dioxide

The implementation of carbon dioxide (CO2) as an alternative refrigerant for air-conditioning compressors has gained significant attention recently. The main interest in CO2 is related to its zero ozone depletion potential (ODP) and low global warming potential (GWP) compared to commonly used hydroflurocarbon (HFCs) refrigerants such as R-134a. Friction and wear studies on tribological contacts commonly used in air-conditioning compressors under the presence of CO2 are scarce in the literature. The present study focuses on the tribological behavior of Al390-T6, gray cast iron, and Mn–Si–brass (UNS C67300). These materials were tested against 52100 steel shoes using a pin-on-disk configuration. The tests were performed under submerged lubrication conditions using polyalkylene glycol (PAG) lubricant in the presence of CO2. Results showed that the wear resistance of gray cast iron and Mn–Si–brass was higher compared to Al390-T6. In spite of the fact that Al390-T6 and Mn–Si–brass had similar hardness, Al390-T6 showed higher wear after testing. X-Ray Fluorescence (XRF) analysis of the lubricant after testing of Al390-T6 showed the presence of eutectic silicon particles. Also, Auger Electron Spectroscopy (AES) of Al390-T6 showed an atomic concentration decreased in silicon content after testing. Decreased in silicon content was attributed to the depletion of eutectic silicon particles, leading to a decrease in hardness and a subsequent increase in wear during the test.

Biocompatible, Lactide-Based Surfactants for the CO2−Water Interface: High-Pressure Contact Angle Goniometry, Tensiometry, and Emulsion Formation

The unique properties of compressed CO2, including its low cost, nontoxicity, easily tunable solvent strength, and favorable transport properties, make it an environmentally attractive alternative to volatile organic solvents. Suitable surface-active species can be utilized to realize the full potential of clean, CO2-based technologies, by helping to overcome the low solubility typically associated with many solutes of interest in CO2. In this work we synthesize and investigate the interfacial activity of a series of nonionic amphiphiles with a biocompatible and biodegradable CO2-phile at both the CO2-water (C|W) and CO2-water-solid (C|W|S) interfaces. We developed a high-pressure pendant drop tensiometer and contact angle goniometer that allows us to measure both tension and contact angle in tandem. The tension of the C|W interface was measured in the presence of the lactide (LA)-based surface active agents with varying molecular weight and hydrophilic-to-CO2-philic ratios. Emulsion studies with an optimum balanced surfactant were performed. The contact angle of water droplets against a silane-modified (hydrophobic) substrate under CO2 atmosphere was also measured in presence of a selected LA-based amphiphile. The results demonstrate that the nonionic copolymers with the biodegradable and biocompatible LA-based group can significantly reduce the tension of the C|W interface. The LA-based surface active species are also capable of forming stable emulsions of water and CO2 and reducing the angle of the three-phase C|W|S contact line.

Ship Transport of CO 2: Technical Solutions and Analysis of Costs, Energy Utilization, Exergy Efficiency and CO 2 Emissions

Increased focus on reducing CO2 emissions has created growing interest in CO2 capturing from industrial processes for storage in geologic formations or injection in oil reservoirs for enhanced oil recovery (EOR). Due to the scattered CO2 sources and the uncertainty in the growth of the CO2 market, a cost effective and flexible transport system is required. In this work a ship transport concept is developed as an alternative to pipeline transport. New technical solutions, cost-, energy-, exergy- and CO2 emission analysis for ship-based transport of CO2 are presented. The concept includes all the elements in the transport chain, namely liquefaction, intermediate storage, loading system, semi-pressurized ship and offshore unloading system. Economical large-scale transport of CO2 by ship could be done in semi-pressurized vessels of around 20 000 m3 at pressures near triple point (6.5 bara and –52°C) in order to use well established design for commercial construction of LPG carriers and intermediate storage. This condition also gives the highest density in the liquid state, which reduces the transport unit cost. Liquefaction of CO2 is best achieved in an open cycle, where the refrigeration is partly or fully provided by the feed gas itself. The offshore unloading system will transport the liquid CO2 from the dedicated CO2 ship to the wellhead on the platform at the required temperature and pressure. During the unloading phase the ship is connected to a submerged turret loading (STL) system. The CO2 is pumped to a pressure high enough to avoid phase transition in the transfer lines. A flexible riser, a subsea pipeline and an insulated pipeline in the platform shaft bring the CO2 from the unloading location to the topside of the platform. The CO2 is pumped to injection pressure and heated to avoid operational problems before it is injected into the reservoir for EOR using conventional water injection wells. The total specific energy requirement for the selected transport chain is 142 kWh tonne−1 CO2, where the liquefaction process accounts for 77%. An exergy analysis of the chain is performed showing that the minimum work required in the chain is 60 kWh tonne−1 CO2, giving a chain rational efficiency of 42%. The total CO2 emissions are estimated to be approximately 1.4% of the inlet CO2. The total costs of ship-based transport are calculated to be 20–30 USD tonne−1 for volumes larger than 2 Mt y−1 and distances limited to the North Sea. Ship transport offers a flexible alternative for bringing CO2 to offshore installations. Dedicated CO2 carriers for transport of CO2 directly from the source to the oil fields might be a key element in future CO2 infrastructures.

Interfacial phenomena at the compressed co2-water interface

Compressed CO2 is considered to be a viable alternative to toxic volatile organic solvents with potential applications in areas including separation reactions, and materials formation processes. Thus an interest in CO2 stems from the fact that it is very inexpensive, has low toxicity, and is not a regulated. However, compressed CO2 has a zero dipole moment and weak van der Waals forces and thus is a poor solvent for both polar and most high molecular weight solutes, characteristics that severely restrict its applicability. In order to overcome this inherent inability, surfactant-stabilized organic and aqueous dispersions in CO2 have been proposed. This work will discuss fundamentals and recent advances in the design of amphiphiles for the novel CO2-water interface.

Miscible Displacement In the Weyburn Reservoir: A Laboratory Study

Abstract Most Saskatchewan light and medium oil (LMO) reservoirs have reached their economic limit of production under current technology (primary and secondary recovery methods). The successful development of me miscible displacement process using CO2 and hydrocarbon gases will lead to a significant increase in Saskatchewan LMO reserves and substantially extend the production life of these pools. A laboratory study was conducted to evaluate the applicability of various solvents (including the potential source of CO2 extracted from flue gas) for the recovery of oil from a southeast Saskatchewan reservoir (Weybum). The physical, chemical, and phase behaviour (PVT) properties of the dead oil, reservoir fluid, and reservoir fluid with CO2 were determined. Slim tube tests were conducted for the Weyburn reservoir fluid with pure Cal, with wellhead gas from the Steelman gas plant, and with two impure CO2 gases (one containing 9.9. molCH4 and the other containing 5.1 mol % Ni 5.1 mol % CH4 in CO2 as contaminants) at various pressures and the reservoir temperature of 59 ºC. The tests were also carried out to determine the maximum amount of impurities in CO2 that can be tolerated for the miscible process. The minimum miscibility pressures (MMP) determined for the above four systems demonstrated that the miscible displacement process using pure CO2 or impure CO2 containing up to 9.9 mol % CH4 (contaminant) as a solvent is a promising enhanced oil recovery (EOR) technique for southeast Saskatchewan reservoirs. The MMPs' for these two systems are below the estimated reservoir fracture pressure. Carbon dioxide contaminated with 5.1 mol % N2 from flue gas and 5.1 mol % CH4 from the reservoir during recycling would require further purification to lower the MMP to an acceptable level. The wellhead gas from the Steelman gas plant is not a suitable EOR agent for the Weybum reservoir. Rising bubble (RBA) tests on the four reservoir fluid/solvent systems were conducted and the MMPs obtained from these systems were in good agreement with those obtained from slim tube experiments. The RBA test is much faster than the slim tube technique, requires only a small amount of fluids, and also allows direct visual observation of miscibility (vapourizing-gasdrive) development. The technique is thus considered to be superior to slim tube tests. Introduction Most Saskatchewan light and medium oil (LMO) reservoirs have reached their economic limit of production Under current technology (primary and secondary recovery methods)(1). The successful development of the miscible displacement process using CO2 and hydrocarbon gases will lead to significant increase in Saskatchewan LMO reserves and substantially extend the production life of these pools(2). Current industry interest in CO2 and hydrocarbon miscible flooding is high, as evidenced by the high level of activity in field testing worldwide(3). In spite of a general slowdown in enhanced oil recovery (EOR) during the last two years (the number of active US EOR projects decreased from 366 in 1988 to 295 in 1990s, oil production from the miscible projects showed a 113% increase by 49% (over the same period in 1988).

Production of CO2 From a Reservoir - A New Concept

Summary Very large reservoirs of approximately 985 CO2 have been discovered in southwestern Colorado. These reservoirs have pressures up to 2,700 psi (18.70 Mpa) and temperatures to 171°F (77°C). Wells are capable of flowing more than 10 MMcf/D (0.28×106 m3/d) CO2. The CO2 flows to the surface at pressures and temperatures below the critical and, therefore, in two-phase flow. For convenient handling, the CO2 must be heated to form a single-phase gas before it is transported, dehydrated, and compressed. This paper discusses a patented procedure for downhole pressuring followed by the production and processing of CO2 under continuous supercritical conditions. It also describes a field test of the procedure and the test results. The process is dependent on the properties of CO2 under continuous high pressure and even at high temperature, which approach those of a liquid. Thus, the CO2 can be produced by conventional pumping operations. The process appears applicable to production from any CO2 reservoir containing a fluid above its critical pressure. The results of the field test were very close to those anticipated by calculation. Introduction For at least the past 15 years, interest in CO2 as a tertiary recovery technique has grown. To date, most of the CO2 has been salvaged off-gas from sweetening operations in gasoline plants. This gas generally contained 10% or more extraneous gases, including nitrogen, hydrogen sulfide, and methane. The principal advantage of CO2 in tertiary recovery is its miscibility, under certain conditions of pressure and temperature, with the reservoir liquids. The first reservoir where large volumes of CO2 have been injected is the Canyon Reef reservoir of the SACROC unit in Scurry County, TX. The procedure and results of that operation are well documented.1–4 It was established that CO2 of less than approximately 87.5% pure would not be miscible with the reservoir liquids under the Canyon Reef conditions. The purity required varies from field to field because of differences in temperature, pressure, and reservoir liquids characteristics. Many fields in west Texas are reported candidates for CO2 flooding; however, some are at lower pressures than the Canyon Reef, and some can be expected to require higher purity of CO2 than 87.5%. Higher purity CO2 is miscible with reservoir fluids at considerably lower pressure. Fig. 1 shows the approximate conditions for miscibility of 87.5% pure CO2 with produced oil from various reservoirs as they existed in 1966. Reservoir pressures have decreased in some of these reservoirs because of fluid withdrawals; others have increased because of pressure maintenance. Therefore, it is fortunate that approximately 98% pure CO2 has become available in large volumes in the McElmo field in southwestern Colorado and in other areas.5 The peculiarities of CO2, particularly the characteristic that pure CO2 exists as a two-phase fluid at ambient temperature and pressures up to 1,080 psi (7.44 MPa), make it difficult to handle at the flowing conditions of the McElmo field. Consequently, the process of pumping the supercritical CO2 with a multistage centrifugal pump was conceived.6 The procedure has been tested in the field and has proved successful.