SBA-15 grafted with 3-aminopropyl triethoxysilane in supercritical propane for CO2 capture

Supercritical propane (SC-propane) was found to be a promising solvent for grafting (3-aminopropyl)triethoxysilane (APS) onto synthesized SBA-15 for CO₂ capture. The influence of operating conditions in SC-propane for CO₂ adsorption at different pressures (8.3–13.8 MPa), temperatures (85–120 °C), and periods of time (4–16 h) were evaluated. The CO₂ adsorption conditions under different partial pressures, temperatures and moisture were evaluated. The results showed a reduction in pore characteristics and an increased amount of grafted APS with increasing pressure and temperature after grafting. After grafting in SC-propane at 11.0 MPa and various temperatures for 16 h, a 3–20% increase in the amount of grafted APS and a 6–49% increase in the CO₂ adsorption capacity over the toluene refluxing was observed. The time required for grafting in SC-propane could be reduced while maintaining higher nitrogen content and CO₂ adsorption capacity compared with grafting in toluene refluxing.     

碳酸二甲酯吸收捕集CO_2工艺流程

采用在线气相色谱测定了碳酸二甲酯(DMC)-CO2体系的气液相平衡,并得到了25,35,45℃下的亨利系数分别为6.566,7.614,8.784 MPa。同时建立了一套连续吸收-解吸小试装置,考察了DMC用于捕集CO2的吸收-解吸连续运行情况。并结合Aspen Plus模拟软件,分析了DMC在连续吸收-解吸小试装置上运行的最佳操作参数,并得到整体工艺能耗。结果表明:实验研究范围内,最佳的操作参数为液气摩尔比1.556、吸收温度20.0℃、解吸温度为63.2℃,相应的吸收率为94.34%,捕集CO2能耗为1.72 GJ/t。     

燃煤电厂烟气脱碳技术研究

对目前国内外各种脱碳技术进行了介绍和分析,并根据烟气特点提出了燃煤电厂烟气脱碳技术的选择条件,推荐了目前适合于燃煤电厂烟气脱碳的醇胺法脱碳技术。在此基础上,对醇胺法吸收剂的选择及工艺配置给出了具体的建议。     

燃煤电厂烟气脱碳枝术研究

对目前国内外各种脱碳技术进行了介绍和分析,并根据烟气特点提出了燃煤电厂烟气脱碳技术的选择条件,推荐了目前适合于燃煤电厂烟气脱碳的醇胺法脱碳技术.在此基础上,对醇胺法吸收剂的选择及工艺配置给出了具体的建议.     

Investigation mechanism of DEA as an activator on aqueous MEA solution for postcombustion CO2 capture

In this work, Diethanolamine (DEA) was considered as an activator to enhance the CO₂ capture performance of Monoethanolamine (MEA). The addition of DEA into MEA system was expected to improve disadvantages of MEA on regeneration heat, degradation, and corrosivity. To understand the reaction mechanism of blended MEA‐DEA solvent and CO₂, ¹³C nuclear magnetic resonance (NMR) technique was used to study the ions (MEACOO^‐, DEACOO^–, MEA, DEA, MEAH⁺, DEAH⁺, , ) speciation in the blended MEA‐DEA‐CO₂‐H₂O systems with CO₂ loading range from 0 to 0.7 mol CO₂/mol amine at the temperature of 301 K. The different ratios of MEA and DEA (MEA: DEA = 2.0:0, 1.5:0.5, 1.0:1.0, and 0:2.0) were studied to comprehensively investigate the role of DEA in the system of MEA‐DEA‐CO₂‐H₂O. The results revealed that DEA performs the coordinative role at the low CO₂ loading and the competitive role at high CO₂ loading. Additionally, the mechanism was also proposed to interpret the reaction process of the blended solvent with CO₂. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2515–2525, 2018     

Facilitated transport of carbon dioxide through an immobilized liquid membrane of K2CO3/KHCO3 aqueous solution

The facilitated transport of CO₂ through a hydrophilic polymeric membrane immobilized with K₂CO₃/ KHCO₃ buffer solution has been investigated. The reactions of dissolved CO₂ in electrolyzed alkaline solution must consider hydration of CO₂ with water, chemical reaction of CO₂ with OH^- and dissociation of HCO ₃ ^2- into CO ₃ ^2- . It is necessary to simplify these reactions as a simple model, which is used to analyze the transport system. From experiments in the liquid membrane with alkaline buffer solution, it is shown that the flux of CO₂ into K₂CO₃KHCO₃ aqueous solution can be enhanced by the presence of CO ₃ ^2- . A diffusion model with an overall reaction based on the film theory is proposed that predicts the experimentally observed facilitation factor with reasonable accuracy. The present model is compared with the rigorous diffusion model involving the complicated conventional chemical reactions.     

碳酸钾催化苯酚在超临界CO2中合成水杨酸的实验研究

在超临界CO2中以K2CO3为催化剂,由苯酚一步直接合成了水杨酸.改进了传统的有机酚酸(Kolbe-Schmitt 反应)的两步法合成工艺.在CO2压力4～14 MPa、温度160～220℃,考察温度、压力、反应时间、催化剂用量等条件对水杨酸收率的影响.水杨酸最高得率接近54%,产物的选择性在99%以上,副产物有极少量...     

Electronic and geometric effects of alkali promoters in CO hydrogenation over K/Mo2C catalysts

When potassium salts such as K₂CO₃, KOH, CH₃COOK, and K₂S were added to Mo₂C, the promoted catalysts showed high selectivities to alcohols and light olefins in CO hydrogenation at 573 K and 1.0 MPa. However, K₂SO₄ and KCl caused only slight increase in olefin selectivity with negligible alcohol formation. These two groups of promoters showed different physical and chemical states during the reaction as observed by AES, EDS, EPMA, IR and transient reaction behavior. This difference accounted for the observed difference in selectivity.     

Co-carbonization of coking coal with K2CO3: structure of the resulting chars

Oakdale coking coal was co-carbonized with up to 30 wt% of K₂CO₃ to 900 °C. The resulting chars were examined for optical texture and morphology by scanning electron microscopy. No changes in optical texture were observed with additions of < 1 wt% K₂CO₃. Increased additions created an isotropic, non-fusing layer of char around the particles and this prevented the formation of a coherent coke. The size of the remaining anisotropy was also reduced, some char fragments being composed of isotropic carbon. Severe fissuring occurred in the particles of char, causing fragmentation; this was presumably due to diffusion of potassium into the char structure. X-ray studies indicated increased peak half-widths of (002) diffractions for the isotropic carbon.     

Control strategies for flexible operation of power plant with CO2 capture plant

About 20% power output penalties will be incurred for implementing CO₂ capture from power plant. This loss can be partially compensated by flexible operation of capture plant. However, daily large variations of liquid and gas flows may cause operation problems to packed columns. Control schemes were proposed to improve the flexibility of power output without causing substantial hydraulic disturbances in capture plant is presented. Simulations were implemented using ASPEN Plus. In varying lean solvent flow strategy, the flow rate of recycling solvent was manipulated to control the CO₂ capture rate. The liquid flow of the absorber and gas flow of the stripper will vary substantially. In an alternative strategy, the lean solvent loading will be varied. Variation of gas throughput in the stripper is avoided by recycling part of CO₂ vapor to stripper. This strategy provided more stable hydraulics condition in both columns and is recommended for flexible operation. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

Biodegradability of nonionic surfactants: Screening test for predicting rate and ultimate biodegradation

Environmental water quality evaluations of raw materials in consumer products occupy a position of critical importance in many industries throughout the world. The rapid growth and diversity of the household detergent market requires continuous consideration of new materials needed to meet the demands of new, improved and modified products. As household cleaning products are normally disposed of as a component of domestic sewage, surface active compounds, including nonionic surfactants, would reach surface waters only as a part of a sewage effluent and would be subject to the same degree of biological treatment as the balance of the waste. For this reason, evaluations of such new materials include an environmental assessment in which biodegradability testing of organic materials is an important first step. Biodegradability characteristics of nonionic surfactants, as a class, are generally more difficult to ascertain because of wide structural diversity and a usual lack of functional groups. Such determinations usually involve intricate and laborious test methods which necessitate development of analytical techniques for each degradation product of a given material. A method has been developed, modified and used in our laboratory, that provides, after reasonable opportunity for biological acclimation, a measure of the rate and degree of ultimate biodegradation (conversion to CO₂ and H₂O). This method, which uses simple equipment, has been used to assess the biodegradability of a wide variety of nonionic surfactants, without necessitating the development of specific analytical methods for each surfactant under consideration. Additionally, this method can be adapted to measure degradation under conditions of anaerobiosis or low temperature.     

CO2 capture in a multistage CFB: Part II: Riser with multiple cooling stages

A 1 m in diameter and 3.55 m tall fluidized bed riser internally with water tubes, which required six equilibrium stage of riser‐sorber for capturing about 95% of CO₂ emitted from a coal power plant, were designed to replace the multisingle risers. At the optimum operating condition, the temperature of the cooling tubes in the bottom, the middle and the top of the riser were kept constant values at 50, 40, and 30°C, respectively. The hot water (57°C) from lowest exchanger section can be used to preheat the spent sorbent for the regeneration in a downer. The rest of the heat for the regenertion is obtained from the stack gas (100–130°C). This new concept promises to reduce the energy consumption for CO₂ removal from flue gas. The only energy requirement is for pumping fluid and fluidizing particles in the bed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5280–5289, 2017     

碳酸钾换热器中物料垢的成因及清洗

碳酸钾生产装置中的物料垢经过低真空扫描电子显微镜X射线能量散谱仪进行表面形貌的观察和元素组成的分析后,明确了其形成原因及清洗过程,表明污垢的形成与原料的产地及所含阴离子的种类、工艺过程的温度以及树脂有关。     

碳酸钾喷雾造粒涂布效率的初步研究

提出了造粒过程的聚集总效率等式，通过研究碳酸钾的层式成长过程，考察了影响涂布效率的主要因素：床层温度，操作气速和料液浓度，从而为进一步研究聚集效率提供了参考。     

CO2 capture in a multistage CFB: Part I: Number of stages

The most common technology for postcombustion of CO₂ capture is the amine solvent scrubber. The energy consumption for capturing CO₂ from flue gases using amine solvent technology is 15–30% of the power plant electricity production. Hence, there is a need to develop more efficient methods of removing CO₂. A circulating fluidized bed using sodium or potassium carbonates is potentially such a process, as their high decomposition pressures allow regeneration at low temperatures using waste heat rather than steam from the power plant. But equilibrium data for the sorbents require the use of several cooled stages to achieve high CO₂ conversions. Here, a method of computing such a number of stages for a given CO₂ conversion was developed using multiphase computational fluid dynamics. It was found that it required six equilibrium stages to remove 96% of CO₂ with the initial mole fraction of 0.15 in a sorption riser. © 2017 American Institute of Chemical Engineers AIChE J, 63: 5267–5279, 2017     

Oxidized K2CO3/MoS2 as a novel sulfur-resistant catalyst for Fischer-Tropsch reaction

Potassium-promoted MoS₂ is an active catalyst for mixed alcohol synthesis from CO and H₂. When K₂CO₃/MoS₂ is oxidized, however, it produces mostly hydrocarbons, of which 40–50 wt% are C₂–C₄ alkanes. The reaction rates also substantially increase. Since oxidized K₂CO₃/MoS₂ can tolerate a high level (up to 300 ppm) of H₂S in the CO-H₂ feed, it could serve as a novel sulfur-resistant Fischer-Tropsch catalyst.     

Structure and composition of CO2/H2 and CO2/H2/C3H8 hydrate in relation to simultaneous CO2 capture and H2 production

Gas hydrates from a (40/60 mol %) CO₂/H₂ mixture, and from a (38.2/59.2/2.6 mol %) CO₂/H₂/C₃H₈ mixture, were synthesized using ice powder. The gas uptake curves were determined from pressure drop measurements and samples were analyzed using spectroscopic techniques to identify the structure and determine the cage occupancies. Powder X‐ray diffraction (PXRD) analysis at ?110°C was used to determine the crystal structure. From the PXRD measurement it was found that the CO₂/H₂ hydrate is structure I and shows a self‐preservation behavior similar to that of CO₂ hydrate. The ternary gas mixture was found to form pure structure II hydrate at 3.8 MPa. We have applied attenuated total reflection infrared spectroscopic analysis to measure the CO₂ distribution over the large and small cavities. ¹H MAS NMR and Raman were used to follow H₂ enclathration in the small cages of structure I, as well as structure II hydrate. © 2009 American Institute of Chemical Engineers AIChE J, 2009