Mineralization of flue gas CO2 with coproduction of valuable magnesium carbonate by means of magnesium chloride

CO2 mineralization and utilization is a new area for reducing the CO2 emissions. By reacting with natural mineral or industrial waste, CO2 can be transformed into valuable solid carbonate （such as calcium carbonate or magnesium carbonate） with recovery of some products simultaneously. In this paper, a novel method was proposed to mineralize CO2 by means of magnesium chloride with small energy consumption. In this method, magnesium chloride was firstly transformed into magnesium hydroxide by electrolysis. The formed magnesium hydroxide showed high reactivity to mineralize CO2. In our study, even at low concentration, CO2 can be effectively mineralized by this method, which makes it possible to directly mineralize flue gas CO2, avoiding the expensive process of CO2 capture and purification. Moreover, valuable products such as hydromagnesite and nesquehonite can be recovered by this method. Because of the wide distribution of magnesium chloride in nature, largescale CO2 mineralization is potential by means of magnesium chloride.     

作图法求算碳酸钙水溶液的溶解度及pH值

导出了ＣａＣＯ３水溶液的溶解度（Ｓ）与溶液ｐＨ值间的关系式;建立了ＣａＣＯ３水溶液的溶解度由线及ＣａＣＯ３电离出的ＣＯ３＾２－的水解曲线;并得出了ＣａＣＯ３的溶解度及溶液的ｐＨ值。     

Observed and simulated features of the CO2 diurnal cycle in the boundary layer at Beijing and Hefei,China

The mechanism of the CO2diurnal cycle is a basis for investigating the carbon budget and its impacts on climate and environment change.Regional diurnal variations in CO2concentration based on observations and modeling have been studied widely.However,few studies have focused on the pattern of the CO2diurnal cycle in China.In this study,a three-dimensional global chemical transport model,Goddard Earth Observing System(GEOS)-Chem,was applied to simulate the CO2concentration and its variation over China from 2004 to 2012.Meanwhile,we also analyzed the CO2concentration as observed by two eddy covariance flux observation towers,one located in Beijing(39°580N,116°220E)and one in Hefei(31°550N,117°100E),using LI-COR 7500A infrared gas analyzers.Observations showed the amplitude of the CO2diurnal cycle at Hefei to be larger than at Beijing,due to stronger ecological activities.GEOS-Chem successfully captured the main aspects of the diurnal cycle of the CO2concentration in the boundary layer observed at both Beijing and Hefei.However,some discrepancies between the model and observations did exist;specifically,the model tended to underestimate the amplitude of the CO2diurnal cycle.The data also showed that traffic emissions significantly enhanced the CO2concentration in the boundary layer.     

Extraction of vanadium from high calcium vanadium slag using direct roasting and soda leaching

The extraction of vanadium from high calcium vanadium slag was attempted by direct roasting and soda leaching. The oxidation process of the vanadium slag at different temperatures was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). The effects of roasting temperature, roasting time, Na₂CO₃ concentration, leaching temperature, leaching time, and liquid to solid ratio on the extraction of vanadium were studied. The results showed that olivine phases and spinel phases in the vanadium slag were completely decomposed at 500 and 800℃, respectively. Vanadium-rich phases were formed at above 850℃. The leaching rate of vanadium reached above 90% under the optimum conditions:roasting temperature of 850℃, roasting time of 60 min, Na₂CO₃ concentration of 160 g/L, leaching temperature of 95℃, leaching time of 150 min, and liquid to solid ratio of 10:1 mL/g. The main impurities were Si and P in the leach liquor.     

Global warming： Take action or wait？

Of all the changes wrought by human activity, the buildup in our atmosphere of the greenhouse gases, carbon dioxide, methane and nitrous oxide, has gener- ated the most contentious debate. Environmentalists warn that in the absence of firm action, over th…     

A kinetic model for describing effect of the external surface concentration of TiO2 on the reactivity of eggshell activated carbon supported TiO2 photocatalyst

The porous support supported TiO2 is considered to be the promising photocatalyst due to the fact that it is easily recovered from water and has high capacity to mineralize pollutants. Obviously, the expected structure of this kind of photocatalyst is egg-shell, that is, TiO2 is mainly on the external surface of the porous support. The reactivity of the supported photocatalyst strongly depends on the concentration of TiO2 on the external surface of the porous support. In this study, a kinetic model was developed to describe the effect of the external surface concentration of TiO2 （CESC） on the reactivity of egg-shell activated carbon （AC） supported TiO2 photocatalysts. It was found that the obtained model precisely described the effect of CESC, on the reactivity of TiO2/AC photocatalysts. This study can be used to deeply understand the performance of TiO2/AC catalysts and to provide valuable information on designing efficient supported TiO2 photocatalysts.     

相变吸收剂捕集二氧化碳的研究进展

人类工业活动排放的大量CO_2气体是导致全球变暖的主要因素,CO_2捕集、封存与利用(CCUS)是实现碳减排和应对全球变暖最有效的技术方向。常用的CO_2捕集技术中,采用有机胺类化学吸收剂的水溶液捕集CO_2面临的主要技术难题是再生能耗高,如何降低能耗将直接关系到CCUS技术的未来走向。相变吸收剂在吸收CO_2时具有优异的吸收特性,而且可分离为液-液或液-固两相,其中一相富集CO_2,在降低能耗方面呈现出较大优势。通过对传统有机胺水溶液脱除CO_2工艺的能耗结构进行分析,综述了CO_2相变吸收体系在碳捕集方面的研究现状,并对相变吸收剂的研究动向和技术发展前景进行了展望:探索相变吸收剂的相变机理,解决其组成和工艺稳定性问题;开展微胶囊、极性摆动等新型吸收剂和耐热酶、固体酸等催化再生技术方面的研究。     

基于胺法的旋流喷淋气液吸收烟气CO2的性能

为了强化CO_2捕集过程的气液传质,设计了一类多级旋流喷淋反应器,实验研究了典型的醇胺(乙醇胺(MEA)、二乙醇胺(DEA))脱除CO_2的分离效率和传质系数,并分析了操作条件的影响.结果表明:在相同的实验条件下,MEA的脱碳效率(最大值95%)大于DEA的脱碳效率(最大值92.3%).与相关研究数据的对比表明,多级旋流喷淋可以有效增强醇胺-CO_2喷淋反应系统的传质过程.醇胺溶液旋流气液吸收烟气CO_2的脱碳效率受操作条件的影响,其随着吸收剂质量分数、吸收剂流量和反应温度的增加而提高,随着烟气中CO_2体积分数和烟气流量的增加而降低.     

Role of support in photothermal carbon dioxide hydrogenation catalysed by Ni/CexTiyO2

Nickel was supported on varied ratios of ceria-titania mixed oxides(Ni/Ce_xTi_yO_2) to evaluate the role the support plays in photothermal carbon dioxide hydrogenation to produce methane. In a batch photothermal reactor system, Ni/CeO_2 achieved the highest conversion rate, reaching a conversion of 93% in approximately60–90 min. To decouple the influence of light and heat, the CO_2 hydrogenation was examined in an in-house designed photothermal reactor, whereby heat can be applied externally. Decoupling experiments revealed that heat from the thermalisation by light was the main driving force for the reaction. In addition, the conversion and temperature profile of the different catalysts revealed that the catalyst performance was governed by catalyst reducibility. H_2-TPR analyses showed that the Ni became more readily reducible with increasing Ce O_2 content,suggesting that the oxide plays a role in activating the Ni. The reduction temperature of the nickel catalyst(following a reduction and passivation process) was below 200 °C, which meant that the inherent heating temperature of the photothermal reactor was sufficient to initiate Ni/CexTiyO_2 catalyst activity. The exothermic methanation reaction was then able to heat the system further, ultimately reaching a temperature of 285 °C. The ancillary rise in temperature promotes further nickel reduction and methane formation, leading to a "snow-ball"effect. The findings demonstrate that, to achieve a "snow-ball" effect in a photothermal system, designing a catalyst which is easy to reduce, active for CO_2 hydrogenation, and capable of converting light to heat for its initial activation is critical.     

Techno-economic evaluation of oxy-combustion coal-fired power plants

Increasing attention is being paid to the oxycombustion technique of coal-fired power plants because CO 2 produced from fossil fuel combustion can be captured and sequestrated by it. However, there are many questions about the economic properties of the oxy-combustion technique. In this paper, a detailed techno-economic evaluation study was performed on three typical power plants (2 × 300 MW subcritical, 2 × 600 MW supercritical, 2 × 1000 MW ultra supercritical), as conventional air fired and oxycombustion options in China, by utilizing the authoritative data published in 2010 for the design of coal-fired power plants. Techno-economic evaluation models were set up and costs of electricity generation, CO 2 avoidance costs as well as CO 2 capture costs, were calculated. Moreover, the effects of CO 2 tax and CO 2 sale price on the economic characteristics of oxycombustion power plants were also considered. Finally, a sensitivity analysis for parameters such as coal sample, coal price, air separation unit price, flue gas treatment unit price, CO 2 capture efficiency, as well as the air excess factor was conducted. The results revealed that: (1) because the oxy-combustion technique has advantages in thermal efficiency, desulfurization efficiency and denitration efficiency, oxy-combustion power plants will reach the economic properties of conventional air fired power plants if, (a) the CO 2 emission is taxed and the high purity CO 2 product can be sold, or (b) there are some policy preferences in financing and coal price for oxy-combustion power plants, or (c) the power consumption and cost of air separation units and flue gas treatment units can be reduced; (2) from subcritical plants to supercritical and finally ultra-supercritical plants, the economics are improving, regardless of whether they are conventional air fired power plants or oxy-combustion power plants.     

基于微流控芯片的无CO2环境下神经细胞与免疫细胞培养技术研究

空间站是空间生命科学研究的重要平台,而空间站难以提供细胞培养所需要的CO₂环境,并且需要可控且自动化的细胞培养方法,因此建立基于微流控芯片的无CO₂细胞培养系统至关重要.本研究从改变培养基成分的初始pH值入手（向培养基中添加外源CO₂或缓冲物质）,探寻无CO₂环境下培养细胞的可行性.用光学显微镜镜检细胞生存状态,用MTS法测定细胞活力.结果表明向培养基中添加不同比例的HEPES,在一定浓度的HEPES缓冲液条件下,可实现无CO₂环境下培养人神经相关细胞SH-SY5Y和U87MG以及人免疫相关细胞THP-1,并且向培养基添加3% HEPES可以使细胞至少存活5天,在此基础上又优化了结合微流控芯片培养细胞的条件.     

Thermodynamics and density functional theory study of potassium dichromate interaction with galena

The adsorption heat and reaction rate constant of potassium dichromate on the surface of galena were studied. The results indicate that potassium dichromate tends to adsorption on the galena surface. The reaction order is only 0.08385, suggesting that the concentration of potassium dichromate has little influence on its adsorption on the galena surface. In addition, the simulation of CrO₄2? adsorption on the PbS (100) surface in the absence and presence of O₂ was carried out by density functional theory (DFT). The calculated results show that CrO₄2? species adsorb energetically at the Pb-S bond site, and the presence of O₂ can enhance this adsorption.     

Response of leaf dark respiration of winter wheat to changes in CO2 concentration and temperature

Accurate evaluation of dark respiration of plants is important for estimation of the plant carbon budget.The response of leaf dark respiration of winter wheat to changes in CO 2 concentration and temperature was studied,using an open top chamber during 2011-2012,to understand how leaf dark respiration of winter wheat will respond to climate change.The results indicated that leaf dark respiration decreased linearly with increased CO2 concentration.Dark respiration decreased by about 11% under 560 μmol mol-1 CO2 compared with that under 390 μmol mol-1 CO2.Leaf dark respiration showed an exponential relationship with temperature,and the temperature constant(Q10) was close to 2.Moreover,the responses of leaf dark respiration to CO concentration and temperature were independent.A leaf dark respiration model based on CO2 concentration and temperature responses was developed.This model provides a method for estimation of the leaf dark respiration rate of winter wheat under future climate change and guidance for establishment of crop carbon countermeasures.     

硫氰酸钾/硫脲复合物对45碳钢的缓蚀性能评价

本研究借助静态腐蚀失重法确定了硫氰酸钾/硫脲缓蚀剂的最佳配方,并分别研究了该配方在5%硫酸、5%硝酸及5%盐酸中对45碳钢的缓蚀性能。结果表明:在5%硫酸溶液中,使用硫氰酸钾:硫脲为7:3的质量比配方,缓蚀剂为0.2%时对45碳钢的缓蚀达到最大,缓蚀率为82.3%;在5%硝酸溶液中,使用硫氰酸钾:硫脲为4:6的质量比配方,缓蚀剂的加入量为0.1%时对45碳钢的缓蚀率可达到99%以上;在5%盐酸中,只需加入0.2%的复合缓蚀剂(硫氰酸钾:硫脲=4:6),对45碳钢的缓蚀率可以达到76%。Tafel极化曲线表明硫氰酸钾/硫脲复合物的加入可以明显地降低45碳钢在3种酸溶液中的腐蚀电流。     

钙离子对高锰酸钾与天然有机物反应的影响

利用单宁酸做为天然有机物的代表研究了高锰酸钾与天然有机物的反应,考察了钙离子及钙离子和高锰酸钾不同投加顺序的影响及机理,并利用FTIR对反应进行了光谱学研究.结果表明,高锰酸钾与单宁酸反应生成可溶性分子,钙离子和高锰酸钾不同投加顺序对二者反应有一定的影响,先投加钙离子再投加高锰酸钾,溶液UV276.5的降低较多一些,D...     

Impact of technology advances on China’s CO2 emission reduction

Global warming tends to be the major characteristics of the dramatic global climate change. To deal with these changes, the impact of reducing greenhouse gas (GHG) emission on Chinese future economic and social development has to be assessed. In this paper, a Regional Integrated model of Climate and the Economy (RICE), which is well known and accepted widely, has been used for Chinese economic assessment of climate change after introduction, assimilation and verification. Based on a sensitivity analysis of technical parameters in the RICE model and constrained targets proposed for energy saving and emissions reduction technological advance programs of China from 2000 to 2050, the economic impact of the programs is examined. The results indicate that when technology advances, Chinese CO₂ emission, climate loss, and the growth rate of atmospheric CO₂ concentration and temperature will all decrease. It is assumed that in 2010, the CO₂ emission is 20% lower than in 2005, CO₂emission in 2050 would only double the level in 2000, the accumulative CO₂ emission would be decreased by 12.4 GtC, and the atmospheric CO2 concentration and temperature in 2050 would reduce by 35 GtC and 0.04°C respectively from 2000 to 2050. The accumulative climate loss from 2000 to 2050 will drop down by 4.6 billion dollar, which only accounts for 6% of the global total benefits. However, the economic benefit the developed countries will obtain is 10 times that for China under such a technological advance scenario. The decrease of the CO₂ emission control rate is 1% in cooperation policy while 4.6% in non-cooperation policy, which would relieve China’s burden in the control of CO₂ total emission and thereby benefit China in participation of the international cooperation for CO₂ emission reduction.     

Liquid-Liquid Equilibrium for 1-Butanol-Water-KF and 1-Butanol-Water-K2CO3 Systems

KF or K2CO3 was added into the 1-butanol-water system and two phases were formed： water-rich phase （water phase） and 1-butanol-rich phase （1-butanol phase）. The liquid liquid equilibrium （LLE） data for 1-butanol-water-KF and 1-butanol-water-K2CO3 systems were measured at 25℃ and showed that 1-butanol phase contained negligible salt and water phase contained negligible 1-butanol when the concentrations of KF and K2CO3 in the water phase were equal to or higher than 27.11% and 31.68% , respectively. Thus water could be separated efficiently from 1-butanol-water by adding KF or K2CO3 into the system. A theoretical calculation of LLE data was calculated by using the Pitzer theory to get water activity in the water phase, and by the models, such as the Wilson, NRTL or the UNIQUAC for the 1-butanol phase. For 1-hutanol-water-KF system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and Wilson equa tion, while for 1-butanol-water-K2CO3 system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and UNIQUAC eauation.     

Microstructure and physical properties of steel-ladle purging plug refractory materials

Three different castables were prepared as steel-ladle purging-plug refractory materials:corundum-based low-cement castable (C-LCC), corundum-spinel-based low-cement castable (C-S-LCC), and no-cement corundum-spinel castable (C-S-NCC) (hydratable alumina ρ-Al₂O₃ bonded). The properties of these castables were characterized with regard to water demand/flow ability, cold crushing strength (CCS), cold modulus of rupture (CMoR), permanent linear change (PLC), apparent porosity, and hot modulus of rupture (HMoR). The results show the CCS/CMoR and HMoR of C-LCC and C-S-LCC are greater than those of the castable C-S-NCC. According to the microstructure analysis, the sintering effect and the bonding type of the matrix material differ among the three castables. The calcium hexaluminate (CA₆) phase in the matrix of C-LCC enhances the cold and hot mechanical strengths. In the case of C-S-LCC, the CA₆ and 2CaO·2MgO·14Al₂O₃ (C₂M₂A₁₄) ternary phases generated from the matrix can greatly increase the cold and hot mechanical strengths. In the case of the no-cement castable, sintering becomes difficult, resulting in a lower mechanical strength.     

Trend, seasonal and diurnal variations of atmospheric CO2 in Beijing

The concentration of atmospheric CO₂ in Beijing increased rapidly at a mean growth rate of 3.7% · a⁻¹ from 1993 to 1995. After displaying a peak of (409.7±25.9) μmol · mol⁻¹ in 1995, it decreased slowly. Both the almost stable anthropogenic CO₂ source and increasing biotic CO₂ sink contribute to the drop of CO₂ concentration from 1995 to 2000. The seasonal variation of CO₂ concentration exhibits a clear cycle with a maximum in winter, averaging (426.8±20.6) μmol · mol⁻¹, and a minimum in summer, averaging (369.1±6.1) μmol·mol⁻¹. The seasonal variation of CO₂ concentration is mainly controlled by phenology. The mean diurnal variation of atmospheric CO₂ concentration for a year in Beijing is highly clear: daily maximum CO₂ concentration usually occurs at night, but daily minimum CO₂ concentration does in the daytime, with a mean diurnal difference more than 34.7 μmol·mol⁻¹. It has been revealed that the interannual variations of atmospheric CO₂ concentration in winter and autumn regulated the interannual trend of atmospheric CO₂, whereas the interannual variation of CO₂ concentration in summer affected the general tendency of atmospheric CO₂ in a less degree.     

Uncertainty in crossing time of 2 °C warming threshold over China

The 2 °C warming target has been used widely in global and regional climate change research. Previous studies have shown large uncertainties in the time when surface air temperature (SAT) change over China will reach 2 °C relative to the pre-industrial era. To understand the uncertainties, we analyzed the projected SAT in the twenty-first century using 40 state-of-the-art climate models under two Representative Concentration Pathways (RCP4.5 and RCP8.5) from the Coupled Model Intercomparison Project Phase 5. The 2 °C threshold-crossing time (TCT) of SAT averaged across China was around 2033 and 2029 for RCP4.5 and RCP8.5, respectively. Considering a ±1σ range of intermodel SAT change, the upper and lower bounds of the 2 °C TCT could differ by about 25 years or even more. Uncertainty in the projected SAT and the warming rate around the TCT are the two main factors responsible for the TCT uncertainty. The former is determined by the climate sensitivity represented by the global mean surface temperature response. About 45 % of the intermodel variance of the projected 2 °C TCT for averaged SAT over China can be explained by climate sensitivity across the models, which is contributed mainly by central and southern China. In a climate more sensitive to CO₂ forcing, stronger greenhouse effect, less stratus cloud over the East Asian monsoon region, and less snow cover on the Tibetan Plateau result in increased downward longwave radiation, increased shortwave radiation, and decreased shortwave radiation reflected by the surface, respectively, all of which may advance the TCT.