有机胺非水溶液吸收CO2的动力学研究进展

有机胺水溶液吸收法是CO₂捕集最常用且成熟的方法之一,但是再生能耗高和吸收剂严重降解等关键问题阻碍了其大规模推广和应用。采用有机溶剂代替强极性水溶剂构建的非水吸收剂体系,在降低能耗方面具有巨大潜力,在近年来受到格外关注。非水吸收剂的CO₂吸收动力学研究有助于了解吸收过程的反应机理以及不同有机胺和溶剂类型对反应动力学的影响。本文从有机胺在非水溶剂中的反应机理出发,介绍了CO₂吸收动力学研究的典型实验方法和原理,系统评述了采用不同结构的有机胺在不同溶剂体系中吸收CO₂的动力学研究进展,深入分析了溶剂特性与胺的反应级数和反应动力学常数之间的关联性,并指出了普遍的规律性特征即有机伯胺和仲胺的反应级数随溶剂极性的降低而增大,反应速率常数随着溶剂的溶解度参数增大而呈现近似线性变化。在分析目前动力学研究中存在的问题基础上,对今后非水体系动力学的研究方向进行了展望。     

Transforming rapeseed oil into fatty acid ethyl ester (FAEE) via the noncatalytic transesterification reaction

A simple methodology for producing biodiesel is presented. The noncatalytic transesterification was carried out via the thermochemical process because the main driving force of biodiesel conversion was temperature rather than pressure. Noncatalytic transformation of rapeseed oil into fatty acid ethyl ester (FAEE) was performed in a continuous flow system under ambient pressure in the presence of activated alumina, charcoal, and carbon dioxide (CO₂). The biodiesel conversion methodology introduced in this work enables the esterification of fatty acids (FFAs), and transesterification of triglycerides to be combined into a single process and leads to a 97.5 (±0.5)% conversion efficiency of biodiesel within 1 min at 420–500^°C. The new process has high potential to achieve a breakthrough in minimizing the cost of biodiesel production owing to its simplicity and technical advantages. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1468–1471, 2013     

An evaluation of autotrophic microbes for the removal of carbon dioxide from combustion gas streams

Carbon dioxide is a greenhouse gas that is believed to be a major contributor to global warming. Studies have shown that significant amounts of CO₂ are released into the atmosphere as a result of fossil fuels combustion. Therefore, considerable interest exists in effective and economical technologies for the removal of CO₂ from fossil fuel combustion gas streams. This work evaluated the use of autotrophic microbes for the removal of CO₂ from coal fired power plant combustion gas streams. The CO₂ removal rates of the following autotrophic microbes were determined: Chlorella pyrenoidosa, Euglena gracilis, Thiobacillus ferrooxidans, Aphanocapsa delicatissima, Isochrysis galbana, Phaodactylum tricornutum, Navicula tripunctata schizonemoids, Gomphonema parvulum, Surirella ovata ovata, and four algal consortia. Of those tested, Chlorella pyrenoidosa exhibited the highest removal rate with 2.6 g CO₂ per day per g dry weight of biomass being removed under optimized conditions. Extrapolation of these data indicated that to remove CO₂ from the combustion gases of a coal fired power plant burning 2.4 × 10⁴ metric tons of coal per day would require a bioreactor 386 km² × 1 m deep and would result in the production of 2.13 × 10⁵ metric tons (wet weight) of biomass per day. Based on these calculations, it was concluded that autotrophic CO₂ removal would not be feasible at most locations, and as a result, alternate technologies for CO₂ removal should be explored.     

脱碳工艺对制氢成本的影响分析

本文介绍了轻烃水蒸汽转化制氢装置中几种中变气脱碳工艺,分析了制氢流程中脱碳工序的利弊。通过对10000Nm3.h-1天然气制氢装置投资和能耗计算,分析了不同脱碳工艺流程对制氢成本的影响,结果表明:根据市场情况确定脱碳工艺,可以实现经济效益的最大化。     

Synthesis, kinetic observations and characteristics of polyarylene ether sulphones prepared via a potassium carbonate DMAC process

The classical route for the synthesis of this family of macromolecules is via nucleophilic aromatic substitution of 4,4′-dichlorodiphenyl sulphone with bisphenates using dimethylsulphoxide (DMSO) and aqueous sodium hydroxide. High molecular weight homopolymers can be synthesized in a relatively short time. However, hydrolytic side reactions can limit its scope for the synthesis of both homopolymers derived from insoluble bisphenates and for copolymers. An alternate route is discussed herein that uses potassium carbonate/dimethylacetamide as base and aprotic dipolar solvent, respectively, for the synthesis of several homopolymers and copolymers derived from various bisphenols. In this system, excess potassium carbonate, unlike aqueous caustic, does not prevent the synthesis of high molecular weight macromolecules. Investigations of the kinetics and mechanism of this process were conducted. These studies demonstrated that this route deviates from the relatively simple second order kinetics previously observed for the aqueous sodium hydroxide/DMSO system. This deviation has been rationalized as resulting from the partially heterogeneous nature of the potassium carbonate.     

活性炭改性对催化剂脱砷性能的影响

以K₂CO₃对活性炭进行化学改性,考察K₂CO₃加入量对活性炭比表面积、孔容及孔径等物化性质的影响。随K₂CO₃与活性炭质量比（碱炭比）的增大,活性炭的比表面积呈现先增加后减小的趋势。当碱炭比为6∶1时,活性炭比表面积由初始的653.3m²/g上升至1333.6m²/g。以小分子砷化物三乙胂和大分子砷化物三苯基胂为模型化合物,配制高砷催化裂化汽油,测定催化剂的砷容和脱砷效率。实验结果表明,改性后的催化剂具有丰富的中孔-大孔多级孔结构,表现出更加优异的脱砷性能：微孔保证催化剂具有大的比表面积,使得活性组分能够高效分散;中孔-大孔有利于液态石油烃介质的扩散,从而增大砷化物与活性相的作用,提高催化剂脱砷效率。     

CO2 removal by single and mixed amines in a hollow‐fiber membrane module—investigation of contactor performance

This work investigates CO₂ removal by single and blended amines in a hollow‐fiber membrane contactor (HFMC) under gas‐filled and partially liquid‐filled membrane pores conditions via a two‐scale, nonisothermal, steady‐state model accounting for CO₂ diffusion in gas‐filled pores, CO₂ and amines diffusion/reaction within liquid‐filled pores and CO₂ and amines diffusion/reaction in liquid boundary layer. Model predictions were compared with CO₂ absorption data under various experimental conditions. The model was used to analyze the effects of liquid and gas velocity, CO₂ partial pressure, single (primary, secondary, tertiary, and sterically hindered alkanolamines) and mixed amines solution type, membrane wetting, and cocurrent/countercurrent flow orientation on the HFMC performance. An insignificant difference between the absorption in cocurrent and countercurrent flow was observed in this study. The membrane wetting decreases significantly the performance of hollow‐fiber membrane module. The nonisothermal simulations reveal that the hollow‐fiber membrane module operation can be considered as nearly isothermal. © 2014 American Institute of Chemical Engineers AIChE J, 61: 955–971, 2015     

Quantification of specific interactions between CO2 and the carbonyl group in polymers via ATR-FTIR measurements

We have used in situ ATR-FTIR measurements to provide estimates of the strength of specific interactions between carbon dioxide (CO₂) and carbonyl groups in polymers such as poly(methyl methacrylate) (PMMA), poly(vinyl acetate) (PVAc), poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA). Polymer films were exposed to high pressure CO₂ and the carbonyl stretching vibration at 1700 cm⁻¹ and the CO₂ bending mode at 660 cm⁻¹ were studied. The observed shift in the carbonyl stretching band to higher wavenumber was attributed to dielectric effects according to the Kirkwood-Bauer-Magat (KBM) equation. On the other hand, the splitting of the CO₂ bending mode provided direct evidence of specific interactions between the polymer and CO₂. These interactions were quantified via an equilibrium constant for the association reaction between CO₂ and the carbonyl group.     

A kinetic investigation of the in situ polymerization of methyl methacrylate under supercritical fluid CO2 conditions using high‐pressure DSC

The polymerization kinetics of methyl methacrylate (MMA) under supercritical fluid CO₂ was studied by using high‐pressure DSC. The results indicate that CO₂ can significantly reduce the cage effect and improve the chain propagation reactions, with the observed solvent‐like effects being enhanced by increased CO₂ pressures. The polymerization of MMA under isothermal conditions and 56 atm of CO₂ was characterized by a first‐order kinetic rate expression over the conversion range 20–80%. The apparent activation energy for the reaction was found to be 51.6 kJ/mol, which is less than the value reported under ambient conditions (68.2 kJ/mol). The polymerization kinetics were also evaluated under nonisothermal conditions. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1236–1239, 2004     

CO2 Adsorption Kinetics of K2CO3/Activated Carbon for Low‐Concentration CO2 Removal from Confined Spaces

K₂CO₃ supported on activated carbon (K₂CO₃/AC) is a promising means to remove low‐concentration CO₂ from confined spaces. In this removal process, physical adsorption plays an important role but it is difficult to quantify the amount of CO₂ adsorbed when both H₂O and CO₂ are present. The linear driving force mass transfer model is adopted to study the CO₂ adsorption kinetic characteristics of K₂CO₃/AC by analyzing the experimental data. The effect of K₂CO₃ and H₂O on the adsorption of CO₂ in K₂CO₃/AC was also evaluated. K₂CO₃ loaded on the support is found to increase the mass transfer resistance but decrease the activation energy required for the physical adsorption process. The presence of water vapor is disadvantageous to achieve high physical adsorption capacity since it enhances the chemical sorption in the competitive dynamic sorption process.     

Reaction kinetic for poly(styrene-co-vinylbenzyl chloride)-supported catalyst containing pendant tetraethylammonium chloride in the reaction of glycidyl methacrylate with carbon dioxide

A soluble copolymer-supported catalyst containing pendant triethylammonium chloride was synthesized by the radical copolymerization of p-chloromethylated styrene with styrene followed by the addition reaction of the resulting copolymer with triethylamine. Initial absorption rate of carbon dioxide into glycidyl methacrylate (GMA) solutions containing the catalyst was measured in a semi-batch stirred tank with a plane gas–liquid interface at 101.3 kPa. The reaction rate constants of the reaction between carbon dioxide and GMA were evaluated from analysis of the mass transfer mechanism accompanied by the elementary reactions based on the film theory. Solvents such as toluene, N-methyl-2-pirrolidinone, and dimethyl sulfoxide influenced on the reaction rate constants. Furthermore, this catalyst was compared to the monomeric tetraethylammonium chloride under the same reaction conditions.     

稻壳炭基二氧化硅的提取及表征

以气化副产物稻壳炭为原料,以K₂CO₃作为提取剂制取SiO₂产品,考察了提取工艺和陈化工艺对产品得率的影响。得到最优工艺：K₂CO₃质量分数为20%,浸渍比为3.0,煮溶时间为3.5 h,陈化温度为3℃,陈化时间为3 h。最优工艺下制备的SiO₂得率为25.89%,酸处理后纯度为97.02%。采用场发射扫描电子显微镜（SEM）、X射线能谱仪（EDX）、X射线衍射仪（XRD）等对产品的性能进行了表征。     

Acceleration of the reaction of carbon dioxide into aqueous 2-amino-2-hydroxymethyl-1,3-propanediol solutions by piperazine addition

In this work, the kinetics of the reaction between CO₂ and piperazine-activated aqueous solutions of a sterically hindered alkanolamine, 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) was studied in a wetted wall column contactor at 303.15, 313.15 and 323.15 K. The AHPD concentration in the aqueous solutions was kept at while the piperazine (PZ) concentration varied in the range . Under pseudo-first-order CO₂ absorption conditions, the overall pseudo-first-order rate constants were determined and reaction rate parameters were calculated with a non-linear regression from the overall reaction rate constant. The ratio of the diffusivity and Henry's law constant for CO₂ in solutions was estimated by applying the N₂O analogy and the Higbie penetration theory, using the physical absorption data of CO₂ and N₂O in water and of N₂O in amine solutions. Piperazine was found to be an effective activator in the aqueous AHPD solutions, as the addition of small amounts of PZ to these solutions has a significant effect on the enhancement of the CO₂ absorption rate for all studied temperatures.     

A study of the ruthenium–alumina system

Ru/alumina catalysts (0.21–5.11 wt% Ru) were characterized using temperature programmed reduction (TPR), X-ray photoelectron spectroscopy (XPS) and H₂ and CO chemisorptions. The transformations of cyclohexene were used as test reactions. The TPR data showed, for the catalysts calcined at 500°C, two peaks at 190°C and 223°C. The high temperature peak becomes quantitatively more important as the Ru content is increased. With the aid of XPS and H₂ and CO chemisorption, the low temperature peak is associated with a well-dispersed ruthenium phase while the high temperature peak is related to the reduction of RuO₂ species. As expected from the dispersion measurements, the latter decreases with increasing Ru contents, in agreement with the literature.

The catalytic results are in line with the characterization studies, showing an increase in the activity for the hydrogenolysis reaction (formation of methane) over the hydrogenation–dehydrogenation reactions, as the Ru content is increased. The latter can be explained in terms of the structural requirements of the hydrogenolysis reaction reported previously.     

A kinetic and DRIFTS study of low-temperature carbon monoxide oxidation over Au-TiO2 catalysts

Titania-supported gold catalysts are extremely active for room temperature CO oxidation; however, deactivation is observed over long periods of time under our reaction conditions Impregnated AuTiO₂ is most active after a sequential pretreatment consisting of high temperature reduction at 773 K, calcination at 673 K and low temperature reduction at 473 K (HTR/C/LTR); the activity after either only low temperature reduction or calcination is much lower. A catalyst prepared by coprecipitation had much smaller Au particles than impregnated AuTiO₂ and was active at 273 K after either an HTR/C/LTR or a calcination pretreatment. Deposition of TiO_x overlayers onto an inactive Au powder produced high activity; this argues against an electronic effect in small Au particles as the major factor contributing to the activity of AuTiO₂ catalysts and argues for the formation of active sites at the AuTiO_x interface produced by the mobility of TiO_x species. DRIFTS (diffuse reflectance FTIR) spectra of impregnated AuTiO₂ reveal the presence of weak reversible CO adsorption on the Au surface but not on the TiO₂; however, a band for adsorbed CO is observed on the pure TiO₂. Kinetic studies with a 1.0 wt.-% impregnated AuTiO₂ sample showed a near half-order rate dependence on CO and a near zero-order rate dependence on O₂ between 273 and 313 K with an activation energy near 7 kcal/mol. A two-site model, with CO adsorbing on Au and O₂ adsorbing on TiO₂, is consistent with Langmuir-Hinselwood kinetics for noncompetitive adsorption, fits partial pressure data well and shows consistent enthalpies and entropies of adsorption. The formation of carbonate and car☐ylate species on the titania surface was detected but it appears that these are spectator species. DRIFTS experiments under reaction conditions also show the presence of weak, reversible adsorption of CO₂ (near 2340 cm⁻¹) which may be competing with CO for adsorption sites.     

Kinetics of the absorption of carbon dioxide into mixed aqueous solutions of 2-amino-2-methyl-l-propanol and piperazine

The reaction kinetics of the absorption of CO₂ into aqueous solutions of piperazine (PZ) and into mixed aqueous solutions of 2-amino-2-methyl-l-propanol (AMP) and PZ were investigated by wetted wall column at 30-40 °C. The physical properties such as density, viscosity, solubility, and diffusivity of the aqueous alkanolamine solutions were also measured. The N₂O analogy was applied to estimate the solubilities and diffusivities of CO₂ in aqueous amine systems. Based on the pseudo-first-order for the CO₂ absorption, the overall pseudo first-order reaction rate constants were determined from the kinetic measurements. For CO₂ absorption into aqueous PZ solutions, the obtained second-order reaction rate constants for the reaction of CO₂ with PZ are in a good agreement with the results of Bishnoi and Rochelle (Chem. Eng. Sci. 55 (2000) 5531). For CO₂ absorption into mixed aqueous solutions of AMP and PZ, it was found that the addition of small amounts of PZ to aqueous AMP solutions has significant effect on the enhancement of the CO₂ absorption rate. For the CO₂ absorption reaction rate model, a hybrid reaction rate model, a second-order reaction for the reaction of CO₂ with PZ and a zwitterion mechanism for the reaction of CO₂ with AMP was used to model the kinetic data. The overall absolute percentage deviation for the calculation of the apparent rate constant k_app is 7.7% for the kinetics data measured. The model is satisfactory to represent the CO₂ absorption into mixed aqueous solutions of AMP and PZ.     

Ni含量对介孔Ni-CaO-ZrO2催化剂上CH4-CO2重整反应的影响研究

采用并流共沉淀法制备了Ni含量不同的介孔Ni-CaO-ZrO2纳米复合氧化物催化剂,研究了其在CH4-CO2重整反应中的催化性能。利用N2吸附-脱附(BET)、X射线粉末衍射(XRD)、程序升温还原(TPR)以及程序升温氧化(TPO)等手段对催化剂进行了表征。结果表明,Ni含量对催化剂的物化性质和催化性能有较大影响,低Ni含量的催化剂具备较完善的介孔结构,该种结构非常有利于Ni物种的分散及其在高温下的抗烧结能力,从而提高了催化剂的稳定性;但过低的Ni负载量会造成催化剂表面Ni活性位过少,进而影响催化剂的活性;另一方面,Ni含量过高会导致催化剂介孔结构的坍塌,Ni在反应条件下烧结严重,大尺寸的Ni颗粒会大大增加积炭的生成,从而造成催化剂失活。     

A new recovery process of carbon dioxide from alkaline carbonate solution via electrodialysis

Bipolar membrane electrodialysis is applied to CO₂ recovery from alkaline carbonate solution. CO₂ in flue gas is captured by an alkaline hydroxide absorbing solution to form an alkaline carbonate solution. The captured CO₂ is recovered from the alkaline carbonate solution via bipolar membrane electrodialysis, and the alkaline solution is regenerated simultaneously. To reduce the power requirement for CO₂ recovery, this study considers optimal design and operation. Three membrane arrangements were compared, and the results indicate the membrane arrangement comprising a bipolar membrane and cation exchange membrane is the most energy saving. With further optimization of operation conditions, the minimum power requirement for CO₂ recovery was reduced to 2.1 MJ/kg‐CO₂ (or 2.1 GJ/t‐CO₂). © 2009 American Institute of Chemical Engineers AIChE J, 2009     

纳米K2CO3/CaO催化大豆油制备生物柴油

以K2CO3、纳米CaCO3(自制)为原料,K2CO3的负载质量分数为50%,在750℃焙烧3 h得到纳米K2CO3/CaO固体碱催化剂,并通过XRD、FT-IR及TG-DSC等手段进行确认.再用该催化剂催化制备生物柴油,结果表明:制备生物柴油的最佳条件为温度70℃,质量分数3%的纳米K2CO3/CaO,醇油摩尔比12...     

Effect of K2CO3 doping on CO2 sorption performance of silicate lithium-based sorbent prepared from citric acid treated sediment

In this paper, a low-cost and environmental-friendly leaching agent citric acid (C₆H₈O₇) was used to treat the sediment of Dianchi Lake (SDL) to synthesize lithium silicate (Li₄SiO₄) based CO₂ sorbent. The results were compared with that treated with strong acid. Moreover, the effects of preparation conditions, sorption conditions and desorption conditions on the CO₂ sorption performance of prepared Li₄SiO₄ were systematically studied. Under optimal conditions, the Li₄SiO₄ sorbent was successfully synthesized and its CO₂ sorption capacity reached 31.37% (mass), which is much higher than that synthesized from SDL treated with strong acid. It is speculated that the presence of some elements after C₆H₈O₇ treatment may promote the sorption of synthetic Li₄SiO₄ to CO₂. In addition, after doping with K₂CO₃, the CO₂ uptake increases from the original 12.02% and 22.12% to 23.96% and 32.41% (mass) under the 20% and 50% CO₂ partial pressure, respectively. More importantly, after doping K₂CO₃, the synthesized Li₄SiO₄ has a high cyclic stability under the low CO₂ partial pressure.