二氧化碳与环氧化合物共聚反应催化剂的研究进展

二氧化碳综合利用对于减轻温室效应和开发有机化工新碳源都具有重要价值。本文简要介绍了二氧化碳化学转化的研究意义,总结了其参与化学反应的主要途径,对比了二氧化碳基聚碳酸酯与双酚A型聚碳酸酯,指出开发催化二氧化碳与环氧化合物共聚反应的高效催化剂是该领域研究的重点。重点综述了二氧化碳与环氧化合物共聚各类催化剂的研究进展,并探讨了其优缺点。分析得出该研究领域进一步发展面临的主要问题是催化剂效率和共聚产物的性能与应用。产品由于具有生物降解性且其原料为储量丰富的二氧化碳,因而具有广阔的应用前景。     

CO2和CH3OH直接合成碳酸二甲酯催化剂研究进展

碳酸二甲酯是一种绿色的有机合成中间体,由CO2直接合成碳酸二甲酯备受关注。本文介绍了CO2和CH3OH直接合成碳酸二甲酯的各种催化剂,分析了催化剂的优缺点,探讨了催化反应的机理。同时介绍了合成碳酸二甲酯的新技术和新方法。最后指出了由CO2直接合成碳酸二甲酯的研究趋势。     

New perfluorinated rhodium-BINAP catalysts and hydrogenation of styrene in supercritical CO2

New perfluorinated BINAP ligands and their cationic rhodium complexes have been synthesized and characterized. The catalysts have been tested in homogeneous hydrogenation of the styrene in both methanol and supercritical carbon dioxide (scCO₂). The selective hydrogenations of the styrene in scCO₂ were carried out under the same reaction conditions of 343.15 K temperature and 120 bar CO₂ pressure after 3 h (molar ratio of substrate to catalyst = 500). While all catalysts showed 100% conversion in methanol, same activity was not carried out in scCO₂. (R)-6,6′-diperflorooktil-2,2′-bis(diphenylphosphino)-1,1′-binaphtyl-[Rh(COD)]BArF was showed the highest conversion (96.4%) in scCO₂. Furthermore, methanol was used as co-solvent in the supercritical media in hydrogenation of styrene for the perfluorinated catalysts, which were inactive in scCO₂. Addition of methanol in scCO₂ has rather increased the conversion.     

CO2甲烷化研究进展

CO_2是造成温室效应的主要气体,作为碳基能源使用的末端形态,CO_2也是种重要的基础碳源。因此,将CO_2转化为能源产品可以快速实现碳的循环,对环境与能源领域意义重大。介绍了CO_2的排放、回收以及资源化利用现状,从催化剂体系、反应机理、合成工艺以及工业化现状等方面系统地介绍了CO_2甲烷化的发展。针对H2供给对CO_2甲烷化应用的限制,分析了电解水制氢再与CO_2进行甲烷化反应的电制气(Pt G)技术的发展现状、工艺路线及其经济性,讨论了该技术在我国应用的可行性。提出随着CO_2捕集与新能源相关技术的发展,Pt G技术会更加成熟,将有望成为未来CO_2资源化利用的重要形式。     

Hydrogenation of CO2 to formic acid on supported ruthenium catalysts

We report on the preparation and application of novel heterogeneous supported ruthenium catalysts. The catalysts are active in the synthesis of formic acid from the hydrogenation of carbon dioxide and are characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction analysis and transmission electron microscopy. Abundant hydroxyl groups, which interact with the ruthenium components, play an important role in the catalytic reactions. Highly dispersed ruthenium hydroxide species enhance the hydrogenation of CO₂, while crystalline RuO₂ species, which are formed from the relatively high ruthenium content or the pH of the solution during preparation of the catalyst, restrict the production of formic acid. Optimal activity of ruthenium hydroxide as a catalyst for the hydrogenation of CO₂ to formic acid is achieved over a γ-Al₂O₃ supported 2.0 wt% ruthenium catalyst, which is prepared in a solution of pH 12.8 with NH₃·H₂O as a titration solvent. A possible hydrogenation mechanism for the hydroxide ruthenium catalyst is proposed.     

利用二氧化碳和甲基丙烯酸缩水甘油酯制备环碳酸酯的研究

以含有环氧基团和双键结构的甲基丙烯酸缩水甘油酯(GMA)与二氧化碳为原料合成用于制取新型环保材料非异氰酸酯聚氨酯的中间体环碳酸酯(DOMA),考察了催化剂、反应温度、压力、以及时间等反应条件对产物DOMA收率的影响,并对原料和产物通过TGA、红外进行分析,对产物通过碳谱、氢谱进行结构表征,表明在溶剂存在下,以四丁基溴化铵与碘化锌为共催化剂,在温度为110℃、压力为1.2MPa下反应4 h,产物DOMA收率可达75.6%。     

Sites for CO2 activation over amine-functionalized mesoporous Ti(Al)-SBA-15 catalysts

Activation of CO₂ and its utilization in the synthesis of chloropropene and styrene carbonates over functionalized, mesoporous SBA-15 solids, have been investigated. The surface basicity of SBA-15 was modified with nitrogen-based organic molecules of varying basicity viz., alkyl amines (–NH₂), adenine (Ade), imidazole (Im) and guanine (Gua). The surface of SBA-15 was also functionalized with Ti⁴⁺ and Al³⁺ species. The acid–base properties of these modified SBA-15 materials were investigated by temperature-programmed desorption (TPD) and diffuse-reflectance infrared Fourier transform (DRIFT) spectroscopy. NH₃ and pyridine were used as probe molecules for acid sites, while CO₂ was used to characterize the basic sites. CO₂ was activated at the basic amine sites forming surface carbamate species (IR peaks: 1609 and 1446 cm⁻¹). The latter reacted further with epoxides adsorbed on the acid sites forming cyclic carbonates. A correlation between the intensity of the IR peak at 1609 cm⁻¹ and cyclic carbonate yield has been observed. The cyclic carbonate yields were higher when both the acid and base functionalities were present on the surface. The Ti- and Al-SBA-15 functionalized with adenine exhibited the highest catalytic activity and selectivity. There is an optimal dependence (“volcanic plot”) of the yield of cyclic carbonates on the desorption temperature, T_max(CO₂) in the TPD experiments. These solid catalysts were structurally stable up to 473 K and could be recycled for repeated use. In addition to density, the strength and type of amine sites play a crucial role on CO₂ activation and utilization.     

CO2化学吸收系统污染物排放与控制研究进展

CO₂化学吸收技术因其捕集效率高、技术相对成熟和适应性好,是目前最具工业应用潜力的CO₂捕集技术,然而,CO₂化学吸收系统在使用吸收剂捕集烟气中CO₂的同时,部分吸收剂及其降解产物随烟气排出,不仅增加吸收剂损耗,且在大气中进一步反应生成强致癌物硝胺和亚硝胺。因此,有必要对CO₂化学吸收系统污染物排放进行有效控制。目前,通常通过调节系统运行参数、使用污染物控制手段对污染物进行控制,但缺乏普适性的控制方法,还未建立污染物排放的控制目标值。介绍了CO₂化学吸收系统污染物的3类排放形式,包括物理夹带、气体和气溶胶,其中气溶胶具有较高的排放量且难以被传统方式控制;梳理了研究机构测量到的排放情况,不同规模的CO₂化学吸收系统普遍具有较高的排放量;分析了气溶胶生成生长机理,气溶胶排放主要通过非均相成核产生,依赖于凝结核的存在和过饱和的环境;基于试验和模拟2种方法综述了烟气凝结核、贫液进口温度、贫液负荷、烟气CO₂含量等因素对气溶胶主导的有机胺排放影响。简要介绍了对降解产物排放的研究,包括氧化降解和热降解;最后对当前污染物排放控制手段的控制效果及优缺点进行了总结。传统水洗方法能有效控制有机胺气态排放,传统除雾器对大粒径气溶胶颗粒控制效果好,但对小颗粒脱除效率低。湿式电除尘、蒸汽注入、干床等方法虽有一定脱除效果,但成本较高。酸洗能解决氨气排放问题,但难以回收有机胺。胶质气体泡沫法对气溶胶脱除效率高,但缺乏工业级研究。未来对于污染物的排放需要开发新型控制手段,这一手段既要有效减少气相和气溶胶形式的污染物排放,又要控制工业投资成本,这将成为建立先进碳捕集工艺系统的关键环节。     

温室气体二氧化碳化学转化与利用的方法学

二氧化碳既是温室气体的主要组成又是储量丰富的碳资源,研究二氧化碳的化学转化和利用有着重要的意义。基于二氧化碳与催化剂的弱相互作用以及催化活化原理,通过采用环境友好的反应介质（如超临界二氧化碳、聚乙二醇和离子液体等）及催化剂的设计、分离和循环利用策略,设计各类单组分双功能或双组分双功能的高效催化剂用于合成有机碳酸酯和嗯唑啉酮类化合物,建立具有重要工业应用背景的碳酸酯、嗯唑啉酮和羧酸酯合成新方法以及环境友好的新工艺。超临界二氧化碳既作为一种反应物（可再生资源）,又作为环境友好、性质可调的反应介质。在高密度二氧化碳体系中的聚乙二醇自由基化学是一个环境友好的氧化体系。在一定的条件下,聚乙二醇通过氧化降解产生的自由基能应用于脂肪醇的甲酰化、苄醇的氧化、C—H键的活化等氧化反应。     

Hydrocarbon synthesis from CO2 over Fe–Cu catalysts

Hydrocarbons and carbon monoxide were produced from carbon dioxide and hydrogen at 400°C over copper-promoted iron catalysts containing sodium. The major surface phases of the catalysts were FeO and/or FeCO₃ although iron carbide is believed as an active phase of the hydrocarbon synthesis from carbon monoxide. Copper was present as metal on the surface and the surface density was considerably high even if the content of copper was less than 1 wt%. The surface density of sodium was not negligible in the catalysts containing sodium less than 0.1 wt% and the sodium ion can affect the surface basicity of the catalysts. The olefin content in the products is believed to relate to the surface basicity.     

Wastepaper gasification with CO2 or steam using catalysts of molten carbonates

In this paper, wastepaper gasification with carbon dioxide or steam has been investigated in the presence of molten carbonate catalysts. The reactions of wastepaper with steam or carbon dioxide have been compared. Hydrogen was the main product on the condition of steam used as reactant gas, but in the case where carbon dioxide was used, the amount of carbon monoxide generated from wastepaper gasification greatly increased via the Boudouard reaction. Different ratios of mixtures of lithium, sodium and potassium carbonates as the catalysts have been tested; the lithium carbonate was found to play a critical role. The reaction rate of carbon conversion was approximately first order for low carbon conversions. Both the rate constants and the activation energies have been calculated at different temperatures (923–1023 K). In additions, the flexibility of this technique was examined with three different types of wastepaper. The results suggest that this process can promote effective use of wastepaper and recovery of carbon dioxide. At 1023 K, a high value of cold gas efficiency of about 95% was acquired.     

碳酸钾-乙醇胺复合溶液吸收烟气中CO2的实验研究

分别以不同浓度的碳酸钾溶液及不同配比的碳酸钾—乙醇胺复合溶液作为吸收剂,以吸收速率和吸收量为指标,研究了吸收剂对烟气中CO2的吸收效果.结果表明,纯碳酸钾溶液吸收效果不佳,而掺入乙醇胺后的吸收效果显著改善,部分复合溶液的吸收效果甚至好于同浓度纯碳酸钾溶液与纯乙醇胺溶液的吸收效果之和,碳酸钾与乙醇胺在吸收过程中存在正交互作用.确定0.6 mol·L-1碳酸钾-0.4mol· L-1乙醇胺复合溶液为最佳的吸收剂,其饱和吸收量最大(0.185 mol)、再生温度最低(105℃)、再生率最高(98.8％).     

Hydrocarbon synthesis through CO2 hydrogenation over CuZnOZrO2/zeolite hybrid catalysts

Direct syntheses of hydrocarbons from CO₂ hydrogenation were investigated over hybrid catalysts consisting of methanol synthesis catalyst (CuZnOZrO₂) and zeolites (MFI and SAPO). The yield of hydrocarbons was strongly depending upon the amount of zeolite's acid sites as measured by NH₃ TPD, while the product distributions were hardly affected by the change of acidity. The main product was ethane in the case of MFI hybrid catalyst and C₃ or C₄ hydrocarbon in the case of SAPO hybrid catalyst. This difference in product distribution was attributed to different mechanism of hydrocarbon formation. Investigation based on the ethene co-reaction suggested that the consecutive mechanism operated for HZSM-5 and the carbon pool mechanism for SAPO.     

CO2吸附活化及催化加氢制低碳烯烃的研究进展

随着工业化的发展,CO2的排放与日俱增,给环境带来了不可忽视的严重后果。同时,石油资源日渐匮乏,使得以石油为原料制低碳烯烃的工业面临严峻的挑战。利用CO2制低碳烯烃是缓解环境与资源双重压力的有效途径之一。本文综述了CO2催化加氢制低碳烯烃的热力学分析,CO2在过渡金属单晶和氧化物表面的吸附活化机理以及CO2催化加氢制低碳烯烃催化剂的研究进展。分析比较了包括单金属催化剂、双金属催化剂和复合催化剂在内的CO2制低碳烯烃催化剂的优缺点。提出了催化反应过程中存在催化剂难以兼顾选择性和转化率的技术难题,并指出了今后的主要研究方向是加强催化反应机理和催化剂制备、改性技术的研究。     

有机胺改性MCM-41吸附富集CO2

采用浸渍法分别将二乙烯三胺(DETA),二乙醇胺(DEA),乙醇胺(MEA),三乙烯四胺(TETA),羟乙基乙二胺(AEE)负载到MCM-41介孔硅材料上,制成各种吸附剂,考察不同胺负载量的吸附剂对CO2的吸附和再生性能;结果表明质量负载量为50%的AEE/MCM-41吸附效果最佳,在80℃下具有很好的再生性能。     

Catalytic activation of CO2: Use of secondary CO2 for the production of synthesis gas and for methanol synthesis over copper-based zirconia-containing catalysts

Consumption of fossil fuel resources throughout the industrial era has resulted in an enormous increase in carbon dioxide concentration in the atmosphere. Developed countries have committed to reducing the atmospheric load of greenhouse gases and ratified the Kyoto Protocol. Chemical utilization of carbon dioxide captured from large scale stationary sources is one possible pathway to decrease the rate of emissions. Catalysis plays a crucial role in these carbon dioxide utilization reactions. In this paper, the production of synthesis gas from carbon dioxide-containing secondary gases and carbon dioxide hydrogenation to methanol over copper-based zirconia-containing catalysts have been investigated. Pathways of carbon dioxide utilization are outlined, research done on carbon dioxide hydrogenation over copper-based zirconia-containing catalysts is reviewed, and the challenges of these reactions are reported. It is argued that direct utilization of secondary carbon dioxide from industrial sources can be a significant step toward developing sustainable industrial practices and a critical part in sustainable energy strategies.     

Photocatalytic degradation of Chromotrope 2R using nanocrystalline TiO2/activated-carbon composite catalysts

Composite catalysts made of nanocrystalline TiO₂ and carbon were prepared by a modified sol–gel method over activated carbon (AC). The composite catalysts were characterized by N₂ adsorption–desorption isotherm, TG, diffuse reflectance UV–vis spectroscopy, XRD and SEM. The photocatalytic activity was tested on the degradation of Chromotrope 2R (C2R) in aqueous medium under UV radiation. The composite catalysts exhibited higher activities than commercial Degussa P25 alone and the photocatalytic process was more efficient than the pure photolytic degradation. A modified Langmuir–Hinshelwood approach was used to study the kinetics and to determine the adsorption equilibrium constant and the reaction rate constant. Two different mechanisms are proposed and discussed in order to explain the observed synergy.     

CO2 absorption and regeneration of alkali metal-based solid sorbents

Potassium-based sorbents were prepared by impregnation with potassium carbonate on supports such as activated carbon (AC), TiO₂, Al₂O₃, MgO, SiO₂ and various zeolites. The CO₂ capture capacity and regeneration property were measured in the presence of H₂O in a fixed-bed reactor, during multiple cycles at various temperature conditions (CO₂ capture at 60 °C and regeneration at 130–400 °C). Sorbents such as K₂CO₃/AC, K₂CO₃/TiO₂, K₂CO₃/MgO, and K₂CO₃/Al₂O₃, which showed excellent CO₂ capture capacity, could be completely regenerated above 130, 130, 350, and 400 °C, respectively. The decrease in the CO₂ capture capacity of K₂CO₃/Al₂O₃ and K₂CO₃/MgO, after regeneration at temperatures of less than 200 °C, could be explained through the formation of KAl(CO₃)₂(OH)₂, K₂Mg(CO₃)₂, and K₂Mg(CO₃)₂·4(H₂O), which did not completely converted to the original K₂CO₃ phase. In the case of K₂CO₃/AC and K₂CO₃/TiO₂, a KHCO₃ crystal structure was formed during CO₂ absorption, unlike K₂CO₃/Al₂O₃ and K₂CO₃/MgO. This phase could be easily converted into the original phase during regeneration, even at a low temperature (130 °C). Therefore, the formation of the KHCO₃ crystal structure after CO₂ absorption is an important factor for regeneration, even at the low temperature. The nature of support plays an important role for CO₂ absorption and regeneration capacities. In particular, the K₂CO₃/TiO₂ sorbent showed excellent characteristics in CO₂ absorption and regeneration in that it satisfies the requirements of a large amount of CO₂ absorption (mg CO₂/g sorbent) and fast and complete regeneration at a low temperature condition (1 atm, 150 °C).     

CO2 reforming of CH4 over nanocrystalline zirconia-supported nickel catalysts

Mesoporous nanocrystalline zirconia with high-surface area and pure tetragonal crystalline phase has been prepared by the surfactant-assisted route, using Pluronic P123 block copolymer surfactant. The synthesized zirconia showed a surface area of 174 m² g⁻¹ after calcination at 700 °C for 4 h. The prepared zirconia was employed as a support for nickel catalysts in dry reforming reaction. It was found that these catalysts possessed a mesoporous structure and even high-surface area. The activity results indicated that the nickel catalyst showed stable activity for syngas production with a decrease of about 4% in methane conversion after 50 h of reaction. Addition of promoters (CeO₂, La₂O₃ and K₂O) to the catalyst improved both the activity and stability of the nickel catalyst, without any decrease in methane conversion after 50 h of reaction.