Showing papers in "Journal of CO 2 Utilization in 2015"

Carbon capture, storage and utilisation technologies: A critical analysis and comparison of their life cycle environmental impacts

Abstract: This paper presents a first comprehensive comparison of environmental impacts of carbon capture and storage (CCS) and carbon capture and utilisation (CCU) technologies. Life cycle assessment studies found in the literature have been reviewed for these purposes. In total, 27 studies have been found of which 11 focus on CCS and 16 on CCU. The CCS studies suggest that the global warming potential (GWP) from power plants can be reduced by 63–82%, with the greatest reductions achieved by oxy-fuel combustion in pulverised coal and integrated gasification combined cycle (IGCC) plants and the lowest by post-combustion capture in combined cycle gas turbine (CCGT) plants. However, other environmental impacts such as acidification and human toxicity are higher with than without CCS. For CCU, the GWP varies widely depending on the utilisation option. Mineral carbonation can reduce the GWP by 4–48% compared to no CCU. Utilising CO2 for production of chemicals, specifically, dimethylcarbonate (DMC) reduces the GWP by 4.3 times and ozone layer depletion by 13 times compared to the conventional DMC process. Enhanced oil recovery has the GWP 2.3 times lower compared to discharging CO2 to the atmosphere but acidification is three times higher. Capturing CO2 by microalgae to produce biodiesel has 2.5 times higher GWP than fossil diesel with other environmental impacts also significantly higher. On average, the GWP of CCS is significantly lower than of the CCU options. However, its other environmental impacts are higher compared to CCU except for DMC production which is the worst CCU option overall.

Hydrogenation of CO2 to methanol over In2O3 catalyst

Abstract: The superior catalytic activity of In2O3 for CO2 hydrogenation to methanol is demonstrated here. The experimental results demonstrate that the reaction temperature and pressure have a significant influence on methanol yield. The conversion of CO2 over In2O3 increases with the increase of reaction temperature and pressure. The yield and formation rate of methanol also increase with the increase of reaction pressure. However, they increase firstly with the increase of reaction temperature but start to decrease when the temperature rises above 330 °C. At 330 °C and 4 MPa, the yield of methanol reaches 2.82%, while the methanol production rate reaches 3.69 mol h−1 kgcat−1, higher than many other reported catalysts, which normally show very low selectivity of methanol at such high temperature. This confirms the previous theoretical study that In2O3 inhibits the reverse water gas shift, a competitive endothermic reaction for methanol synthesis from CO2 hydrogenation. The mechanism for CO2 hydrogenation to methanol over In2O3 catalyst has been discussed.

CO2 utilization in the perspective of industrial ecology, an overview

Abstract: Carbon dioxide emissions from anthropic activities have accumulated in the atmosphere in excess of 800 Gigatons since preindustrial times, and are continuously increasing. Among other strategies, CO2 capture and storage is one option to mitigate the emissions from large point sources. In addition, carbon dioxide extraction from ambient air is assessed to reduce the atmospheric concentration of CO2. Both direct and indirect (through photosynthesis) pathways are possible. Geological sequestration has significant disadvantages (high cost, low public acceptance, long term uncertainty) whereas carbon dioxide recycling (or utilization) is more consistent with the basic principle of industrial ecology, almost closing material cycles. In this article, a series of technologies for CO2 capture and valorization is described as integrated and optimized pathways. This integration increases the environmental and economic benefits of each technology. Depending on the source of carbon dioxide, appropriate capture and valorization processes are evaluated based on material and energy constraints.

Selective formation of light olefins from CO2 hydrogenation over Fe–Zn–K catalysts

Abstract: Fe–Zn–K catalysts were prepared in varied Fe/Zn molar ratios using microwave-aided hydrothermal procedure followed by K modification with impregnation method and applied to CO2 hydrogenation reaction via Fischer–Tropsch synthesis for the selective production of C2–C4 olefins. Results showed that the prepared catalysts had uniform particles within about 100 nm. Addition of zinc to iron matrix formed ZnFe2O4 spinel phase and ZnO phase, and caused increase of the surface areas, enhanced the interaction between iron and zinc and altered the reduction and CO2 adsorption behaviors. The catalysts displayed high activity for the CO2 conversion and significant improvement in the product distribution. The proper interactions between Fe and Zn proved to be advantageous to suppress the production of C5+ hydrocarbons and promote the production of C2–C4 olefin. At set reaction conditions of H2/CO2 of 3, GHSV of 1000 h−1, 320 °C, and 0.5 MPa, the 1Fe–1Zn–K catalyst with H2/CO reduction showed the best performance with the CO2 conversion of 51.03%. The selectivity of C2–C4 olefins in overall hydrocarbons and the ratio of olefin to paraffin in the C2–C4 fraction reached 53.58% and 6.86, respectively.

Evaluating CO2 sources for power-to-gas applications – A case study for Austria

Abstract: The intermittent nature of wind and solar power requires long-term energy storage options such as power-to-gas. This technology utilizes (surplus) electricity from renewable power sources to produce hydrogen in an electrolyzer. The produced hydrogen can be either directly utilized as an energy carrier or combined with CO2 and further converted to methane. This article evaluates different CO2 sources concerning their potential utilization within the power-to-gas energy storage technology with regard to capture costs, specific energy requirement and CO2 penalties. The results of a case study for Austria indicate that there is enough CO2 available from point sources to store all of the electricity produced from fluctuating renewable power sources (wind power plants and photovoltaics) via power-to-gas. Due to low capture costs, low CO2 penalties, biogenic origins, and short distances to wind power plants, biogas upgrading facilities and a bioethanol plant were determined to be the CO2 sources best suited for utilization in novel power-to-gas plants. However, as the total amount of CO2 produced from these facilities is relatively low in Austria, other CO2 sources would also be required. With moderate capture costs and CO2 penalties, power plants and an existing refinery could also provide CO2 for power-to-gas. Although large amounts of CO2 are available from iron, steel, and cement production facilities, these sources are not recommended for CO2 utilization in power-to-gas, as the CO2 penalty is relatively high and the facilities are rarely located near wind power plants in Austria.

A model-based analysis of CO2 utilization in methanol synthesis plant

Abstract: Utilizing the greenhouse gas CO 2 as a feedstock in chemical processing could offer alternative solutions to long-term storage. Large-scale production of light hydrocarbons such as methanol (MeOH) is one of the predominant and sensible schemes for such utilization. This proposal will not only recycle the CO 2 gas within methanol synthesis process, but will also reduce the uptake of raw materials such as natural gas (NG) and reduce the greenhouse-gas (GHG) emissions of a comparable stand-alone NG-based methanol synthesis plant. In this paper, a comprehensive model for CO 2 integration in NG-based methanol synthesis plant has been developed. The reformer product (syngas) is mixed with the high-purity CO 2 stream that comes out of power-plant carbon capture (PCC) process. It is found that this integration may reduce methane uptake by 25.6% and decrease the combined CO 2 emissions for both power-plant and MeOH-plant by 21.9%. The energy intensity for this integration is 33.45 GJ th /tonne MeOH and 0.64 GJ el /tonne MeOH . The energy efficiency of this integration is 59% and the product to feed ratio is 2.27 tonne MeOH /tonne CH 4 higher than 1.69 tonne MeOH /tonne CH 4 calculated for a comparable standalone NG-based methanol synthesis plant with 68% efficiency.

Bio-electrocatalytic reduction of CO2: Enrichment of homoacetogens and pH optimization towards enhancement of carboxylic acids biosynthesis

Abstract: The microbial catalyzed electrochemical reduction of CO2 is gaining significant attention in the field of energy and environment as it provides dual benefits of product recovery with simultaneous CO2 neutrality. Specific reduction of single carbon unit (C1-CO2) to two-carbon (C2-CH3COOH) carboxylic acids was studied in a bio-electrochemical system (BES) via a three stage experimental design using BESA treated and untreated (control) anaerobic consortia. During stage-I, enrichment of homoacetogenic culture was carried out by supplementing H2 and CO2 in the reactors containing BESA treated and control cultures respectively. Optimization of pH was carried out in stage-II to enhance the carboxylic acids production at diverse pH range (acidic to alkaline viz., pH 5, 6.5, 8.5 and 10), where pH 10 was found to be optimum for maximum carboxylic acids (VFA: volatile fatty acids) generation in BESA treated (3500 mg/l) and control cultures (1200 mg/l) respectively followed by pH 8.5 utilizing bicarbonate. Interestingly, reduction in VFA concentration was observed after 24 h which can be attributed to its consumption by other groups of bacteria that co-exist along with the enriched culture. During stage-III, bioelectro-catalytic production of acetate was evaluated by considering the optimized pH 10 and under applied potential of -0.8 V vs Ag/AgCl (S) in two BES viz., BESB (BES with BESA treated consortia) and BESC (BES with parent consortia as control) using CO2 and bicarbonate respectively. Maximum acetate production of 1.7 g/l (2.88 mmol/d)/2.1 g/l (3.55 mmol/d) was recovered in BESB through the bio-electrochemical reduction of CO2/bicarbonate, which correlated well with the observed higher reduction currents and columbic efficiency.

Kinetics of CO2 methanation over Ru/γ-Al2O3 and implications for renewable energy storage applications

Abstract: Kinetics of CO₂ hydrogenation over a 10% Ru/γ-Al₂O₃ catalyst were investigated using thermogravimetric analysis and a differential reactor approach at atmospheric pressure and 230–245 °C. The data is consistent with an Eley–Rideal mechanism where H2 gas reacts with adsorbed CO₂ species. Activation energy, pre-exponential factor and reaction orders with respect to CO₂, H₂, CH₄, and H₂O were determined to develop an empirical rate equation. Methane was the only hydrocarbon product observed during CO₂ hydrogenation. The activation energy was found to be 66.1 kJ/g-mole CH₄. The reaction order for H₂ was 0.88 and for CO₂ 0.34. Product reaction orders were essentially zero. This work is part of a larger study related to capture and conversion of CO₂ to synthetic natural gas.

Recent advances in carbon dioxide based copolymers

Abstract: Carbon dioxide is becoming increasingly important synthetic feedstock for chemicals and materials, since it is abundant, low-cost, non-toxic. One growing area in CO2 chemistry utilization is the development of catalysts for the polymerization of CO2 and epoxides to prepare CO2 based copolymers, including high molecular weight aliphatic polycarbonates and low molecular weight poly(carbonate-ether) polyols. Among all the aliphatic polycarbonates, poly(propylene carbonate) (PPC) has the best opportunity for scale-up commercialization. PPC is not only cheap since it contains over 40 wt% CO2, but it also exhibits good biodegradability, which has wide application in throw-away packaging materials, or even gas barrier films. Poly(carbonate-ether) polyols are low-molecular weight polyether carbonates with terminating hydroxyl groups, which are potential large scale raw materials in polyurethane industry. Herein, the recent progress of the CO2 based polymers will be highlighted, and the future in this area will be discussed.

A comparative study of CO2 utilization in methanol synthesis with various syngas production technologies

Abstract: This paper explores a possible ‘methanol economy’ transition strategy—a novel carbon capture and utilization (CCU) configuration for methanol (MeOH) production (CCU–MeOH). In this CCU–MeOH, the captured CO2 is co-fed with natural gas (NG) to produce syngas suitable for MeOH synthesis. The main objective of this work is to compare two aspects, namely CO2 emission intensity and the extent of methane reliance, of six CCU–MeOH scenarios derived from four reforming methodologies (steam methane reforming (SMR), dry methane reforming (DMR), bireforming and trireforming). Among the studied CCU–MeOH scenarios, Scenario 2 (DMR with H2 addition) significantly outperformed the other scenarios by 12.7% and 22% on average in terms of CO2 emission intensity and methane reliance, respectively. The outperformance of Scenario 2 in CO2 emission intensity is found to originate from a 22% reduction in CH4 consumption on average compared to the other scenarios. In intermediate term, Scenario 2 may provide an attractive option for transitioning into ‘methanol economy’ of the future.

CO2-CH4 conversion and syngas formation at atmospheric pressure using a multi-electrode dielectric barrier discharge

Abstract: The conversion of CO2 and CH4 into value-added chemicals is studied in a new geometry of a dielectric barrier discharge (DBD) with multi-electrodes, dedicated to the treatment of high gas flow rates. Gas chromatography is used to define the CO2 and CH4 conversion as well as the yields of the products of decomposition (CO, O2 and H2) and of recombination (C2H4, C2H6 and CH2O). The influence of three parameters is investigated on the conversion: the CO2 and CH4 flow rates, the plasma power and the nature of the carrier gas (argon or helium). The energy efficiency of the CO2 conversion is estimated and compared with those of similar atmospheric plasma sources. Our DBD reactor shows a good compromise between a good energy efficiency and the treatment of a large CO2 flow rate.

Modifying alumina with CaO or MgO in supported Ni and Ni–Co catalysts and its effect on dry reforming of CH4

Abstract: Modifying the support of the alumina (Al 2 O 3 ) supported Ni and Ni–Co catalysts with limited amounts of CaO and MgO had an effect on the catalytic activity during the reforming of CH 4 with CO 2 at 873 K. The presence of CaO had a favorable effect on the catalytic activity of the supported catalysts. In contrast, the presence of MgO had an adverse effect due to the strong interaction of MgO with the Ni and Co phases under the present synthesis conditions. Characterization of the supported Ni and Ni–Co catalysts revealed that modifying the support with CaO or MgO had an effect on the reducibility, amount and type of H 2 and CO 2 chemisorbed and the nature of the metal crystallite. The characterization studies also revealed that the limited interaction of CaO with Ni phase in supported Ni and Ni–Co catalysts gave rise to additional sites that were able to chemisorb H 2 and CO 2 at higher temperatures without having a significant effect on the reducibility of the catalysts. The presence of these additional sites may be the reason for the improved activity of the modified-Al 2 O 3 supported Ni and Ni–Co catalysts containing CaO.

Cu/Zn/Al/Zr catalysts via phase-pure hydrotalcite-like compounds for methanol synthesis from carbon dioxide

Abstract: Cu/Zn/Al/Zr catalysts with Cu2+:Zn2+:Al3+:Zr4+ = 2:1:x:0.1 (x = 0.6–1.5) were prepared from hydrotalcite-like precursors by co-precipitation method and tested for the CO2 hydrogenation to methanol. Both Cu/Zn/Al/Zr hydrotalcite-like and malachite phase were formed at low Al content. However, with the increase of Al content, the yield of hydrotalcite-like phase increased and phase-pure Cu/Zn/Al/Zr hydrotalcite-like compound was obtained for x ≥ 0.9. In addition, both the specific surface area and the dispersion of Cu increased gradually with the increase of Al, while the exposed Cu surface area first increased until Al content was 27.9 mol%, then decreased. The results of catalytic test for CO2 hydrogenation revealed that Cu/Zn/Al/Zr catalysts via phase-pure hydrotalcite-like compounds exhibited much better catalytic performance with higher CO2 conversion and CH3OH selectivity compared with the catalyst derived from mixed phase (hydrotalcite-like and malachite). The Cu/Zn/Al/Zr catalysts with Cu2+:Zn2+:Al3+:Zr4+ = 2:1:1.2:0.1 resulting from phase-pure hydrotalcite-like precursors afforded the substantial stability and the best catalytic performance.

Key techniques of reservoir engineering and injection–production process for CO2 flooding in China's SINOPEC Shengli Oilfield

Abstract: This paper addresses the geological problems and engineering hot points of the CO 2 flooding, such as the big vertical span of the beach-bar sand, the strong reservoir heterogeneity, the distribution of residual oil, and the problem of gas channeling. The core identification, log analysis, seismic interpretation, laboratory test and numerical simulation of reservoir engineering are integrated to investigate the geological characteristics of the reservoir in the demonstration zone of SINOPEC Shengli Oilfield. It demonstrates the reservoir is large but it has thin thickness, low porosity and super-low permeability. Due to some great differences between the beach sand and the bar sand, the oil reservoirs of demonstration zone are divided into 2 sand groups, 8 small layers, and 17 sand bodies in total. Then, a 3D geological model and qualitative evaluation system of safety of vertical faults are built. The optimal evaluation method of CO 2 flooding and sequestration is established. According to the engineering optimization of the CO 2 flooding, the results of a recommendation scheme indicate that the enhance oil recovery can increase by 6.7%, the total injection volume is expected to reach to 563 × 10 4 t, and CO 2 sequestration rate is 60.5%. Finally, the multi-level umbrella downhole gas separator is designed, and the high gas–oil ratio (GOR) production string and free kill gas injection string are also successfully developed for the CO 2 -EOR.

Synthesis of Cr-doped SrTiO3 photocatalyst and its application in visible-light-driven transformation of CO2 into CH4

Abstract: Visible-light-driven Cr-doped SrTiO3 was synthesized through ultrasonic chemical method. Its specific surface area is 54.3 m2 g–1 due to the relatively small particle size. X-ray diffraction pattern and X-ray photoelectron spectra confirmed the crystal structure and Sr substitution. UV–vis absorption spectra indicated that the Cr doping can lead to visible-light absorption. In addition, the oxygen vacancy in Cr-doped SrTiO3 also showed visible-light absorption. The obtained Cr-doped SrTiO3 was used to photocatalytically reduce CO2 into CH4 with a yield of 8.8 μmol g–1 after 10-h reaction. Moreover, the Cr-doped SrTiO3 exhibited good photostability.

The ability of artificial neural network in prediction of the acid gases solubility in different ionic liquids

Abstract: In this work, the solubility of carbon dioxide and hydrogen sulfide, in different ionic liquids (ILs) have been investigated by applying the artificial neural networks (ANNs). According to the economic benefits of CO 2 as an inexpensive, non-toxic sources of carbon, many studies have done in capturing of CO 2 from the main resources in ILs due to their specific properties such as negligible vapor pressure. Solubility is a key parameter in the phase equilibria calculations. According to the complexity of ILs structure, the phase behavior modeling for these systems is complicated. ANNs are the nonlinear mathematical models which can make a relation between the inputs and the outputs. In this paper 2930 and 664 solubility data of CO 2 and H 2 S are used respectively. Network was trained, validated and tested by 70, 15 and 15 percent of total data with one hidden layer through hyperbolic tangent sigmoid transfer function. Optimum neurons are 23 and 14 for CO 2 and H 2 S solubility respectively. AAD% and R 2 are 3.58 percent and 0.9947 for CO 2 and 2.07 and 0.9987 for H 2 S system. In addition, the Peng–Robinson EoS with and without optimized k ij and an empirical correlation with different constants are used to compare their deviations with the ANN model. Results showed that the ANN model can correlate the solubility of acid gases in ILs with a high accuracy and its error is minimum among three approaches.

CO2 hydrogenation to methanol and dimethyl ether by Pd–Pd2Ga catalysts supported over Ga2O3 polymorphs

Abstract: The production of methanol and dimethyl ether (DME) via CO2 hydrogenation was studied using Pd catalysts supported on α-Ga2O3, α-β-Ga2O3 and β-Ga2O3 polymorphs. The formation of a Pd2Ga intermetallic compound was observed using XRD and XPS. The catalytic activity improves with an increase in the content of the Pd2Ga intermetallic compound. The content of Pd2Ga on Pd/Ga2O3 depends on the Ga2O3 crystalline phase of the catalyst. A slight catalytic deactivation was observed for all samples studied. The Pd/α-β-Ga2O3 catalyst displayed the largest deactivation. The deactivation appears to be caused by a loss of basic sites. The selectivity to dimethyl ether is not dependent on the Pd2Ga content, but depends on the catalyst acidity. This assertion was tested by adding niobia to the catalysts, thus increasing the DME selectivity from 0 to 53%. The content of Pd2Ga over Pd/Ga2O3 catalysts was identified to be a crucial parameter for CO2 hydrogenation to methanol.

Regional resource distribution of onshore carbon geological utilization in China

Abstract: CO 2 geological utilization (CGU) technologies have a great potential to enable large-scale CO 2 storage at reasonable cost and is widely considered to be a strategic technology option to help reduce CO 2 emissions. CGU technology can be applied to enhance the recovery of oil (CO 2 -EOR), natural gas (CO 2 -EGR), underground water (CO 2 -EWR), coal-bed methane (CO 2 -ECBM), shale gas (CO 2 -ESGR), geothermal energy (CO 2 -EGS), in situ uranium leaching (CO 2 -IUL), and others. The first step in evaluating of CGU technologies is to determine the storage resource, technical readiness, and geographical distribution of CO 2 storage resources. This paper presents preliminary evaluation results on storage resource, technology readiness level and geographic distribution of onshore CGU in China; the results were obtained by performing a resource evaluation methodology, technology readiness level (TRL) method, and geographic information system tool. Results indicate a significant resource for onshore CGU technologies and good proximity in some parts of China. However, CO 2 storage resources with high TRLs and low cost are located in the northeast, northwest, and southeast regions and not in the south and coastal areas of China, where most CO 2 emission sources locate. Therefore, the timeframes and options for CGU deployment in different regions vary. This situation indicates that different regions have to perform CO 2 mitigation by employing different CGU technologies at different timeframes.

Experimental study of enhanced phosphogypsum carbonation with ammonia under increased CO2 pressure

Abstract: Phosphogypsum is the byproduct discharged from phosphate industry. A novel process was proposed for converting phosphogypsum into ammonium sulfate via phosphogypsum carbonation with ammonia. The effects of stirring speed, reaction time, initial temperature, CO2 partial pressure, liquid–solid ratio and excess ammonia ratio were evaluated. The main phases presented before and after the carbonation process were identified using X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and carbon-sulfur (CS) analytical techniques. The phosphogypsum was found to have the highest carbonation conversion of approximately 97% in 5 min. The product collected from the reaction was characterized as calcite with the average particle size smaller than the raw phosphogypsum.

Carbon dioxide sequestration in wastewater by a consortium of elevated carbon dioxide-tolerant microalgae

Abstract: The emission of the green house gas (GHG) carbon dioxide (CO2) in the atmosphere at an increasingly high rate is the primary cause of global warming. A study was performed to isolate an elevated CO2-tolerant microalgal consortium (CMAC) and then characterize growth-influencing environmental factors, CO2 sequestration capacity and the potential applications of CMAC for elevated CO2 sequestration. The CMAC was isolated from a wastewater treatment plant under a selection condition consisting of 50% CO2 in air (v/v). The CMAC species were identified as Chlorella sp., Scenedesmus sp., Sphaerocystis sp. and Spirulina sp. Multiple variables including 20% CO2, culture medium pH of 8–9, and an illumination intensity of 50–80 μmol m−2 s−1 were found to be optimal for high density growth of CMAC for uptake of elevated CO2, although the CMAC were demonstrated to grow well in up to 50% CO2. The CMAC showed high CO2 sequestration (53–100%; 150–291 mg g−1) with strong growth performance in wastewater. The lipid content of CMAC was high (350 ± 0.31 mg g−1), which gave a high biodiesel yielding capacity (420 ± 0.43 mg g−1). CMAC was also found to have high nutrient removal abilities (PO4-P, up to 59% and NH4-N, up to 39%). These characteristics all indicate that the isolated CMAC could be used as an efficient tool for biofuel generation from wastewater as well as bioremediation of pollutants. Thus by coupling the identified CO2 sequestration potential of the CMAC with the wastewater tolerance characteristics, there is novel potential to integrate wastewater treatment with CO2 sequestration and biomass utilization in order to mitigate the problems of increased GHG in response to global warming.

Solubility of n-alkanes in supercritical CO2 at diverse temperature and pressure

Abstract: Poor solubility of heavy hydrocarbons in CO 2 has limited the application of CO 2 -EOR (enhanced oil recovery) in modern oil recovery industry to some extent. Therefore, it is crucial to investigate the solubility regularity of different hydrocarbons in supercritical carbon dioxide (scCO 2 ) in the first place. In this paper, our objective is to explore the solubility of n -alkanes (C 6 H 14 –C 18 H 38 ) in scCO 2 . To measure cloud point pressures, the experiment utilizes high-pressure view chamber, and results for accuracy and repeatability of the experimental method and instrument are evidently positive. Then, cloud point pressures for n -alkanes from 318 K to 343 K show a proximately linear and positive correlation with the temperature; they also increase with expanding chain length of n -alkanes. In addition, the result of x (molar fraction of n -alkane at cloud point pressure) indicates that x has a positive correlation with the pressure at identical temperature, and when pressure is constant, temperature increase will reduce x . Finally, relationship studies between density of CO 2 and x reveal that, density of CO 2 has a positive influence on the solubility of n -alkane, and the Chrastil model corrects ln ρ and ln S data. The measured data align with the Chrastil model, with a maximum AARD value of 9.85%.

Generalized thermodynamic analysis of methanol synthesis: Effect of feed composition

Abstract: Synthesis of methanol is one of the ways of conversion of the greenhouse gas CO 2 into an useful chemical. Methanol is synthesized from a feed mixture comprising of primarily CO, H 2 , and CO 2 . The objective of the present work is to study the effect of feed composition on synthesis of methanol. First, the conditions under which the kinetic approach and the thermodynamic approach are equivalent are established. The performance characteristics of the reactor under single phase and two phase conditions are then analyzed using the thermodynamic approach. The Gibbs free energy minimization approach is implemented using Aspen Plus for this purpose. The effect of feed composition on the overall conversion of CO + CO 2 to methanol and conversion of CO 2 is depicted as contour plots for isothermal and adiabatic operations. These can be viewed as performance characteristics of the reactor which aid in selection of suitable feed composition for maximum methanol productivity and CO 2 utilization.

The research progress of CO2 sequestration by algal bio-fertilizer in China

Abstract: Algae are very large and diverse groups of simple, autotrophic organisms, ranging from unicellular to multicellular form. Most of them can conduct photosynthesis, in which the CO2 and solar energy are transformed into sugar, subsequently become biomass. The ability of certain species of blue-green algae (also called cyanobacteria) carry out both photosynthesis and nitrogen fixation, which provide them ecological and agricultural advantages as a new type of bio-fertilizer, which can improve soil structure, especially saline-alkaline soil, and increase the yielding and quality of crops. These algae can also sequester CO2 emitted from the industry or electric generation plant. Furthermore, the biomass of algae will increase over 30 times in rice filed at the right conditions; therefore the capacity of CO2 sequestration is dramatically increased. In this communication, the principle and the research progress of algal bio-fertilizer in the world, especially in China were reviewed. The capacity of CO2 sequestration by algal bio-fertilizer and the technical problems of algal bio-fertilizer were also discussed. (C) 2015 Elsevier Ltd. All rights reserved.

CO2 photoreduction with water: Catalyst and process investigation

Abstract: Economic development should not be separated from the concept of sustainability. The goal can be pursued by means of technologically advanced materials and processes that enable environmental protection. Carbon dioxide photoreduction using water as reducing agent could be a green and effective way to pursue this aim and titania is a good photocatalyst for this reaction. In this work the performances of N doped CuO–TiO2 photocatalysts in gas phase CO2 reduction have been studied. We have focused the attention on both the catalysts design and the process optimization. We have investigated, in particular, the effect of the presence of nitrogen and copper amount on the final catalysts performances. In order to learn high control of the catalytic process and to manage productivity and selectivity, by operating in very mild reaction conditions, the last part of the work has been centered on tuning the process parameters (CO2/H2O ratio). It has been observed that the CH4 formation is sensitive to copper amount and that exists a close correlation between the catalytic behavior and the reagents ratio.

Carbon dioxide dissociation to carbon monoxide by non-thermal plasma

Abstract: The decomposition of carbon dioxide was investigated in a non-thermal plasma dielectric barrier discharge reactor filled with glass balls. The CO2 conversion was maximum by using a sinusoidal excitation compared to pulsed excitation. The CO2 conversion and the CO selectivity are increased in the presence of helium, particularly with the AC power supply, but with a decrease in energy efficiency. The formation of solid materials composed of carbon but also of silica was highlighted for the first time, proving that carbon was incorporated into the silica network along with CO2 dissociation under non-thermal plasma conditions. The temperature control of the reactor wall has shown that the CO selectivity is favored by a low temperature wall, whereas the CO2 conversion remained constant, suggesting that the carbon balance default is due to the CO decomposition on the reactor wall.

Carbon capture and reuse in an industrial district: A technical and economic feasibility study

Abstract: In recent years, increasing attention from both industries and research has been focused on carbon capture and, subsequently, storage technologies. These technologies will contribute to companies’ strategies for reducing greenhouse gas emissions from fossils fuels. However, less effort has been spent on evaluating another interesting option after carbon capture: carbon utilisation or reuse. A feasibility study regarding an Italian industrial district is discussed: the district is characterised by the nearby locations of a CO2 producer (i.e. an natural gas combined cycle power plant) and a CO2 user (i.e. a sugar factory). The annual average CO2 emission by the power plant is about 1.7 million tonnes. Under current conditions the sugar factory ‘produces’ CO2 to use it in the sugar refining process; thus, the idea is to evaluate the feasibility of capturing CO2 emitted from the power plant and reusing it in the sugar factory process from both a technological and an economic point of view. The results indicated a cost saving of about 42% in the operational costs of the sugar factory due to the introduction of the carbon reuse technology.

Efficiency evaluation of CO2 utilization technologies in China: A super-efficiency DEA analysis based on expert survey

Abstract: As the largest coal consumer and leading CO2 emitter, China faces huge pressure on emission reduction and addressing climate change. Moreover, the feature of coal dominated energy constitute system determines that Carbon Capture, Utilization and Storage (CCUS) technology would be of vital importance for China, especially the CO2 utilization technology due to its benefit creating effect. While CO2 utilization technology in current China is still in juvenility and needs to be predictively evaluated. Thus, this paper aims to assess the potential efficiency of CO2 utilization technologies in China. First, two sets of index systems of efficiency evaluation are established, and each of which contains three input indicators and three output indicators. We then conduct the Data Envelopment Analysis (DEA) efficiency evaluation on 20 key CO2 utilization technologies, which are classified into three categories, i.e. chemical, biological and geological utilizations, using so-called CCR, BCC and SE-CCR DEA models respectively. The results show that: (1) CO2 utilization technologies receive different DEA scores, while that with score 1 or more are dominated by chemical utilization; (2) CO2 geological utilization exhibits relatively higher sore under the direct-emission-reduction scenario than it does under comprehensive-emission-reduction scenario; (3) there are significant differences among the four types of biological utilization technologies; (4) DEA efficiency performance of CO2 utilization technologies gain improvement in 2030 than that in 2020, which in part provide evidence for the rationality of our study; and (5) DEA score rank has no correlation with emission reduction. Finally, some policy implications are proposed.

Sulfonic acid functionalized mesoporous SBA-15 as catalyst for styrene carbonate synthesis from CO2 and styrene oxide at moderate reaction conditions

Abstract: A sulfonic acid tethered mesoporous silica material (SBA-15-SO3H) was successfully synthesized and characterized using SAXS, N2 physisorption studies, TEM, EA and XPS. This metal-free heterogeneous catalyst with terabutyl ammonium bromide (TBAB) co-catalyst was found to be an efficient catalyst system for styrene carbonate synthesis from CO2 and styrene oxide. The synergistic mechanistic pathways of SBA-15-SO3H with TBAB have been explained by hydrogen bond interactions and nucleophilic effects. A turn over number of 920 was obtained at mild reaction temperature of 80 °C. The catalyst was thermally stable and reused for five times without loss of any significant activity.

Photocatalytic reduction of carbon dioxide with water on InVO4 with NiO cocatalysts

Abstract: InVO 4 was synthesized by solid-state reaction method using In 2 O 3 and V 3 O 4 as the starting materials. NiO was added as the cocatalyst. The catalysts were characterized by powder X-ray diffraction, scanning electron microscope, and ultraviolet–visible spectroscopy. The photocatalytic reduction of CO 2 with water was carried out in a Pyrex reactor with KHCO 3 aqueous solution bubbled with CO 2 gas under visible light illumination. Many pinholes were observed on the InVO 4 particles after loading with NiO cocatalyst. The band gap of NiO/InVO 4 was lower than that of InVO 4 due to the formation of subband in valence band by creating more defect sites on the surface of InVO 4 . Both NiO/InVO 4 and InVO 4 can reduce CO 2 to methanol under visible light irradiation. The reaction rate increased with an increase of the loading of NiO cocatalysts.

Effect of silica and alumina promoters on co-precipitated Fe–Cu–K based catalysts for the enhancement of CO2 utilization during Fischer–Tropsch synthesis

Abstract: Silica and alumina were used as structural promoters to increase the catalytic activity of a co-precipitated Fe–Cu–K catalyst for the CO2 and CO hydrogenation during Fischer–Tropsch (FT) synthesis. The doubly-promoted Fe–Cu–K–Si–Al catalyst achieved higher CO and CO2 conversions than the Fe–Cu–K catalyst and singly-promoted Fe–Cu–K–Al and Fe–Cu–K–Si catalysts. The CO and CO2 conversions of the syngas with 54% H2/10% CO/29% CO2/7% N2 over the doubly-promoted catalyst were 88.3% and 25.2%, respectively, compared to 81.8% and 18.5% for the Fe–Cu–K catalyst. In this case, the C5+ selectivity of the doubly-promoted catalyst was 71.9%, which was slightly lower than 75.5% for the Fe–Cu–K catalyst. The CO2 was converted to hydrocarbons using the doubly-promoted catalyst when the CO2/(CO + CO2) ratio was higher than 0.35 for H2-balanced syngas at H2/(2CO + 3CO2) = 1.0, and 0.5 for H2-deficient syngas at H2/(2CO + 3CO2) = 0.5. The increase of hydrogen content in the syngas increased the methane selectivity at the expense of decrease in the liquid hydrocarbon selectivity.