冶炼烟气中SO2催化还原为元素S的研究进展

冶炼烟气中SO2催化还原为元素S是利用适当的还原剂将烟道气中的SO2选择性地催化还原成单质硫,这种方法的最终产物是固态单质硫,无废水废渣排放。因此,把烟气中的SO2选择性的还原为单质硫将是一种既具有经济效益又具有社会效益的适合我国国情的烟气脱硫方法。本文综述了目前将烟气中SO2催化还原为元素硫进行回收的主要方法,分析了每种方法的优缺点,并提出烟气中SO2直接还原脱硫技术所存在的问题和发展趋势。     

膜吸收法烟气脱碳研究进展

介绍了采用膜吸收法进行烟气脱碳过程中膜材料的种类、吸收液的选择以及膜吸收的耦合对脱碳的影响。综述了工艺流程、工艺参数及传质模型对膜吸收过程的影响,指出了膜吸收法烟气脱碳工程应用的经济性及发展方向。     

Ionic liquids for CO2 capture—Development and progress

Innovative off-the-shelf CO₂ capture approaches are burgeoning in the literature, among which, ionic liquids seem to have been omitted in the recent Intergovernmental Panel on Climate Change (IPCC) survey. Ionic liquids (ILs), because of their tunable properties, wide liquid range, reasonable thermal stability, and negligible vapor pressure, are emerging as promising candidates rivaling with conventional amine scrubbing. Due to substantial solubility, room-temperature ionic liquids (RTILs) are quite useful for CO₂ separation from flue gases. Their absorption capacity can be greatly enhanced by functionalization with an amine moiety but with concurrent increase in viscosity making process handling difficult. However this downside can be overcome by making use of supported ionic-liquid membranes (SILMs), especially where high pressures and temperatures are involved. Moreover, due to negligible loss of ionic liquids during recycling, these technologies will also decrease the CO₂ capture cost to a reasonable extent when employed on industrial scale. There is also need to look deeply into the noxious behavior of these unique species. Nevertheless, the flexibility in synthetic structure of ionic liquids may make them opportunistic in CO₂ capture scenarios.     

CO2气保焊的故障模式与影响分析

焊接是商用空调设备压力容器制造过程中的主要操作工序。CO2气体保护焊主要在蒸发器、冷凝器的装配过程中被使用。在实际生产过程中,焊接造成的故障泄漏严重影响产品质量,需要使用试验设计方法对焊接参数进行优化．但影响焊缝质量的因素众多,在进行参数设计之前,为使因素选择更准确、有效,使用FMEA（failure mode effects analysis）方法对气保焊故障模式进行分析,从中选择出关键因素。     

Molecular Simulation Study for CO2 Clathrate Hydrate

The present work has concentrated on the structure of CO₂ hydrate in the NPT ensemble using SPC (simple point charge) intermolecular potential model of water by the Monte Carlo (MC) molecular simulation. A mixture of water and CO₂ placed arbitrarily in a cubic cell has been used as a model system to simulate the CO₂ clathrate hydrate at temperatures ranging from 150–280 K and pressure up to 10 MPa. The result shows that the obtained MC simulation agrees well with the results obtained by molecular dynamic (MD) simulation. The present work is also directed to the study of structure with TIP4P potential model of water.     

离子液体膜材料分离二氧化碳的研究进展

离子液体由于具有不易挥发、结构可调、对CO₂有良好的吸收性能等特点而成为当前CO₂分离领域的研究热点,但因高黏度和高成本问题而限制了其工业化应用。将离子液体与气体分离膜材料结合,得到的新型分离膜材料兼具离子液体和膜的优势,成为当前离子液体研究领域的趋势之一。针对这一热点问题,综述了离子液体支撑液膜、聚离子液体膜和离子液体共混/杂化膜在CO₂分离方面的研究现状和进展,讨论了离子液体结构和含量对膜分离性能、稳定性等的影响。相关研究表明,离子液体共混/杂化膜具有较高的分离性能和稳定性,是一种很有应用前景的CO₂分离材料。提出该领域的重点发展方向,即开发新的功能化离子液体共混/杂化膜材料是解决高渗透通量与高稳定性之间矛盾、强化CO₂分离性能的有效途径,深入研究离子液体共混/杂化膜的形成机制、气体在膜中的渗透行为以及CO₂分离机理。     

Prediction of the Removal Efficiency of a Novel Two‐Stage Hybrid Scrubber for Flue Gas Desulfurization

Emission of SO₂ from various industrial sources occurs in varying concentrations and quantities. The operation of scrubbers as SO₂ control devices is getting more and more attention as pollution control regulations are tightened. Experimental investigations on the scrubbing of SO₂ in a novel two‐stage hybrid (spray‐cum‐bubble column) scrubber using water and dilute sodium alkali are reported. Empirical and semi‐empirical correlations are developed for the prediction of the performances of the bubble and the spray sections in terms of various pertinent variables of the system for water and alkaline scrubbing, respectively. The contribution of the mass transfer enhancement factor towards the removal of SO₂ has been exploited while developing the semi‐empirical correlation for the prediction of performance in alkaline scrubbing. The predicted values are in excellent agreement with the experimental values. Finally, the operating features of the scrubber and design aspects are discussed in order to develop our understanding for practical applications.     

Spirulina platensis Culture with Flue Gas Feeding as a Cyanobacteria‐Based Carbon Sequestration Option

The scientific community is currently examining potential approaches in order to reduce the anthropical contributions to global warming. One approach is carbon capture and its storage, i.e., capturing CO₂ at its source and storing it indefinitely to avoid its release into the atmosphere. Conversion of CO₂ by microalgae or cyanobacteria is a sequestration option. Here, the application of an air‐lift reactor to flue gas treatment using cyanobacteria for the absorption of CO₂ was investigated, with the simultaneous abatement of NO_x. A Spirulina platensis culture was fed with CO₂ and NO_x, simulating a flue gas. The preliminary test yielded positive indications on the process feasibility, both in terms of cell productivity (86.8 mg L^–1d^–1) and CO₂ abatement (229 mg d^–1). Opportune dosages of flue gas used in fed‐batch test achieved a high abatement of CO₂ (407 mg d^–1), 90.0 % removal of NO_x, and a biomass production of 188.7 mg L^–1d^–1.     

CO2 hydrogenation to methanol at pressures up to 950 bar

The methanol synthesis from CO₂ hydrogenation is of great interest because it offers a way to mitigate the anthropogenic CO₂ emissions and gives the opportunity to produce methanol from renewable and recyclable feedstock. Methanol is a key component in the chemical industry and can serve as fuel. In this work the high pressure approach of the transformation of CO₂ to methanol is investigated based on the energy balance for the production of 1 Mt methanol per year from air-captured CO₂ and hydrogen from water electrolysis. The energy efficiency is almost pressure independent and is comparable to literature values. The energy consumption for the compression of CO₂ and H₂ accounts only for 26% of the total energy consumption. Experimental investigations of the CO₂ hydrogenation at 950 bar show up to 15 times larger methanol space time yields (STY_methanol) compared to literature values where CO₂ was hydrogenated to methanol at 30 bar.     

二氧化碳加氢直接合成二甲醚的研究进展

综述了二氧化碳直接加氢合成二甲醚的研究进展及二氧化碳加氢合成二甲醚催化剂的研究现状。     

Optimization of a Pilot‐Scale Amine Scrubber to Remove SO2: Higher Selectivity and Lower Solvent Consumption

A pilot‐scale study of flue gas desulfurization based on an amine‐based solvent using applicable industrial values was carried out for sulfur dioxide (SO₂) removal. The plant consisting of absorption and desorption columns was operated with different working parameters such as solvent flow rate, inlet concentration of SO₂, temperature of desorption column, and pH of absorption agent. The Taguchi method was utilized to obtain the best combination of working parameters for the most efficient reduction of SO₂ outlet concentration. The industrial gas‐to‐liquid ratio could be optimized by applying a defined SO₂ concentration, stripper temperature, and solvent pH value. The achieved efficiency is much better compared to our previous study while the gas‐to‐liquid ratio is higher in this work.     

Recent progress of amine modified sorbents for capturing CO2 from flue gas

Under the Paris agreement, China has committed to reducing CO₂ emissions by 60%–65% per unit of GDP by 2030. Since CO₂ emissions from coal-fired power plants currently account for over 30% of the total carbon emissions in China, it will be necessary to mitigate at least some of these emissions to achieve this goal. Studies by the International Energy Agency (IEA) indicate CCS technology has the potential to contribute 14% of global emission reductions, followed by 40% of higher energy efficiency and 35% of renewable energy, which is considered as the most promising technology to significantly reduce carbon emissions for current coal-fired power plants. Moreover, the announcement of a Chinese national carbon trading market in late 2017 signals an opportunity for the commercial deployment of CO₂ capture technologies.Currently, the only commercially demonstrated technology for post-combustion CO₂ capture technology from power plants is solvent-based absorption. While commercially viable, the costs of deploying this technology are high. This has motivated efforts to develop more affordable alternatives, including advanced solvents, membranes, and sorbent capture systems. Of these approaches, advanced solvents have received the most attention in terms of research and demonstration. In contrast, sorbent capture technology has less attention, despite its potential for much lower energy consumption due to the absence of water in the sorbent. This paper reviews recent progress in the development of sorbent materials modified by amine functionalities with an emphasis on material characterization methods and the effects of operating conditions on performance. The main problems and challenges that need to be overcome to improve the competitiveness of sorbent-based capture technologies are discussed.     

Recent advances on the membrane processes for CO2 separation

Membrane separation technology has popularized rapidly and attracts much interest in gas industry as a promising sort of newly chemical separation unit operation. In this paper, recent advances on membrane processes for CO₂ separation are reviewed. The researches indicate that the optimization of operating process designs could improve the separation performance, reduce the energy consumption and decrease the cost of membrane separation systems. With the improvement of membrane materials recently, membrane processes are beginning to be competitive enough for CO₂ separation, especially for post-combustion CO₂ capture, biogas upgrading and natural gas carbon dioxide removal, compared with the traditional separation methods. We summarize the needs and most promising research directions for membrane processes for CO₂ separation in current and future membrane applications. As the time goes by, novel membrane materials developed according to the requirement proposed by process optimization with increased selectivity and/or permeance will accelerate the industrialization of membrane process in the near future. Based on the data collected in a pilot scale test, more effort could be made on the optimization of membrane separation processes. This work would open up a new horizon for CO₂ separation/Capture on Carbon Capture Utilization and Storage (CCUS).     

Low temperature TiO2 based gas sensors for CO2

Monitoring the level of CO₂, especially in closed spaces, is more and more required in technological applications, or in human activities. Since most of the literature data reveal CO₂ detection materials with high sensitivities over 300 °C, here we have concentrated on the gas sensing abilities of Cr doped TiO₂ thin films in front of CO₂, close to the room temperature and at atmospheric pressure. The films were obtained by RF reactive sputtering. The undoped films contain a mixture of anatase and rutile phases. With the increase of Cr content, the crystallites size decreases, and the films become pure rutile for a 4 at% Cr concentration. We found out that these material based sensors are more sensitive to CO₂ for higher Cr concentration, the optimum operating temperature approaching to the room temperature, determining in fact low energy consumption. The explanation is related to the observed increase of oxygen vacancies number (which we have evidenced and clarified), and also to the presence of the rutile phase, whose higher dielectric constant (compared to anatase), and its finer crystallites, determine a better gas sensing. More, the surface active area in front of CO₂ increases, as the films become rougher for higher Cr contents. The increase of Cr³⁺ percentage enhance the power of interaction with the adsorbed species (O₂ and/or CO₂). A grain boundary model was proposed for the thermal activation of the electrical conductivity. The energy barrier height at the grain boundary, the impurities concentration (characteristic parameters of this model) were calculated and found to agree well with the data in the literature.     

Cadmium-based metal-organic frameworks for high-performance electrochemical CO2 reduction to CO over wide potential range

Electrochemical CO₂ reduction (ECR) powered by renewable energy sources provides a sustainable avenue to producing carbon–neutral fuels and chemicals. The design and development of high performance, cost-effective, and stable catalysts for ECR remain a focus of intense research. Here, we report a novel electrocatalyst, two-dimensional cadmium-based 1,4-benzenedicarboxylate metal–organic frameworks (Cd-BDC MOFs) which can effectively convert CO₂ to CO with a faradaic efficiency (FE) of more than 80.0% over the voltage range between -0.9 and -1.1 V (versus reversible hydrogen electrode, vs. RHE) in 0.1 mol·L^-1 CO₂-saturated KHCO₃ solution with an H-type cell, reaching up to 88.9% at -1.0 V (vs. RHE). The performance outperforms commercial CdO and many other MOF-based materials demonstrated in prior literature. The catalytic property can be readily tuned by manipulating synthesis conditions as well as electrolyte type. Especially, high CO FEs exceeding 90.0% can be attained on the Cd-BDC electrode at potentials ranging from -0.16 to -1.06 V (vs. RHE) in 0.5 mol·L^-1 KHCO₃ solution by using a gas diffusion electrode cell system. The maximum CO FE approaches ~97.6% at -0.26 V (vs. RHE) and the CO partial geometric current density is as high as about 108.1 mA cm^-2 at -1.1 V (vs. RHE). This work offers an efficient, low cost, and alternative electrocatalyst for CO₂ transformation.     

Impregnation of carbonaceous nanofibers into glassy polymer-based composite membrane for CO2 separation

The development of defect-free composite membrane (CM) is often challenging due to poor dispersion and distribution of filler particles in the polymer matrix. Despite the attractive physicochemical properties and gas separation performance of carbon nanotube (CNT) based CM, CNT displayed poor dispersion characteristics in most polymer matrix domain. Instead of incorporating CNT, a viable alternative, carbon nanofiber (CNF) which exhibits similar properties as CNT, but improved dispersion quality in the polymer matrix is found. In this work, CNF particles were incorporated in poly(2,6-dimethyl-1,4-phenylene oxide) (PPO_dm) polymer continuous phase for CM development. The optimum gas separation performance of the PPO_dm-CNF CM (11.25 at 197.02 barrer of CO₂ permeability) was obtained at 3 wt% of CNF loading. Compared to pristine PPO_dm membrane, CO₂ permeability and CO₂/CH₄ selectivity of PPO_dm-3 wt% CNF CM were enhanced by 180% and 55%, respectively. At 3 wt% CNF loading, the filler particles were dispersed and distributed more homogenously, in which no obvious CNF agglomeration was observed. In addition, the incorporation of CNF particles also enhanced the mechanical and thermal properties of the resultant CM.     

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.     

CHEMICAL ABSORPTION OF CO2 AND SO2 INTO Ca(OH) 2 SLURRY

Chemical absorption of CO₂ and SO₂2 as single gases and as a mixture into slurries of Ca(OH) ₂ was studied in a stirred vessel with a flat gas-liquid interface. In the case of CO₂, the reaction product interrupted the subsequent gas absorption in the absence of a surface active agent. With single gases, the enhancement factor for SO₂ was much larger than that for CO₂, though both were larger than that into saturated solution. With the mixed gases, the enhancement factor for S02 was almost equal to that for the single gas absorption, but for CO₂ it was only slightly larger than that into the saturated solution     

Feasibility analysis and process simulation of CO2 dehydration using triethylene glycol for CO2 pipeline transportation

The operation of dehydration is very important in the process of gas transportation. This study aims to evaluate the application feasibility of CO₂ dehydration using triethylene glycol, which is also called TEG for short. Aspen Plus software was used to simulate the dehydration process system of CO₂ gas transportation using TEG dehydration. Parameter analysis and process improvement were carried out for the simulation of dehydration process. At first, a sensitivity analysis was conducted to analyze and optimize operating conditions of conventional CO₂-TEG dehydration process system. Subsequently, a recycle unit was introduced into the conventional CO₂-TEG dehydration process system, it can be found that the improved process system with the recycle unit has a higher CO₂ recovery rate which was about 9.8% than the conventional one. Moreover, the improved process system showed excellent operation stability through the comparison of simulation results of several processes with various water contents in their feed gases. Although the energy consumption is increased by about 2%, the improved process was economically and technically feasible for the long-term availability of CO₂ pipeline transportation. The simulated results showed that the improved CO₂-TEG process system has promising application prospects in CO₂ dehydration of CO₂ gas transportation with high stability.     

Estimation of Interfacial Tension for Geological CO2 Storage

The effective CO₂ sequestration in saline aquifers as a climate change‐lessening solution is mainly governed by the interfacial tension (IFT) behavior between CO₂ and brine. An innovative and competent decision tree‐based approach called stochastic gradient boosting (SGB) tree algorithm was applied to predict the CO₂‐aquifer brine IFT as a function of temperature, pressure, and brine salinities. The produced results were compared with the previously reported outcomes of other machine learning models, namely, radial basis function networks, multilayer perceptron networks, least squares support vector machine, and adaptive neuro fuzzy inference system. Amongst all models, the developed SGB tree algorithm provided superior outputs and turned out to be the most accurate tool.