均相体系中酸碱协同催化二氧化碳与环氧化物的环加成反应

基于“可持续发展”和“绿色化学”的概念,近年来CO₂的捕获、储存及资源化利用在工业上和学术上一直备受关注。通过具有100%原子经济性特点的CO₂与环氧化物环加成反应合成五元环状碳酸酯是最有前景的方法之一。基于均相催化剂的设计思想与方法,以CO₂和环氧化物的活化本质出发,从催化剂结构的角度综述了均相体系中酸碱协同催化CO₂与环氧化物环加成反应合成环状碳酸酯的研究进展,包括简单二元催化体系、功能型一元催化体系和金属配合物催化体系等。     

二氧化碳的活化及其催化加氢制二甲醚的研究进展

CO₂是一种稳定的物质,其化学惰性限制了CO₂转化技术的发展。本文介绍了化学催化、生物活化、光电活化及等离子体活化等CO₂活化方式,从CO₂催化加氢合成二甲醚的工艺研究、催化剂开发、催化加氢机理和本征动力学研究等方面综述了CO₂催化加氢合成二甲醚的研究进展,认为化学催化法是目前应用最广泛的一种CO₂活化方式。对于一步法催化CO₂加氢合成二甲醚的工艺,其难点是制备高效CO₂活化催化剂。开发高效的CO₂活化及转化催化剂及对CO₂合成二甲醚的反应过程进行机理探究,是推广CO₂转化技术的关键。     

钴卟啉-四丁基溴化铵串联催化苯乙烯在氧气和二氧化碳中合成碳酸苯乙烯酯

通过仿生催化，将苯乙烯、氧气（O₂）和二氧化碳（CO₂）直接合成环状碳酸酯在现代化学中极具学术研究意义和工业应用价值。采用钴卟啉-四丁基溴化铵为双组分催化剂，以2-氧代环戊烷羧酸甲酯为助剂，在O₂和CO₂条件下，直接将苯乙烯转化为碳酸苯乙烯酯。系统考察了催化剂用量等因素对催化性能的影响。在最佳反应条件下，苯乙烯的转化率高达99%，环状碳酸酯的收率可达35%。利用在线紫外与在线红外探讨了该串联反应可能的机理。结果表明，钴中心与2-氧代环戊烷羧酸甲酯的环内氧原子配位后活化氧气形成过氧活性物种，进而形成高价钴-氧中间体，其通过传递氧原子给苯乙烯而生成环氧苯乙烷。而后，环氧苯乙烷在四丁基溴化铵的催化作用下开环，并通过CO₂插入反应和分子内闭环反应最终生成环状碳酸酯。     

载体对铁基催化剂结构及CO2加氢制烯烃反应性能的影响特性

铁基催化剂CO₂加氢直接合成烯烃是实现CO₂减排及CO₂转化与利用的最佳途径之一。目前铁基催化剂的CO₂加氢活性及反应过程中铁基催化剂结构强度仍然较低，成为CO₂加氢制烯烃产业化生产的重要挑战。通过浸渍法制备一系列负载型铁基催化剂，研究载体材料性质对铁基催化剂结构及CO₂加氢直接合成烯烃的影响特性。研究发现，载体可诱导铁基催化剂在CO₂加氢反应过程中形成的铁物种，同时影响铁基催化剂表面碳物种的有序度，调变对CO₂吸附及活化能力；研究结果表明ZrO₂负载的Fe催化剂展现出最佳的CO₂加氢合成烯烃催化性能，在温度320℃和反应压力2.0 MPa时，CO₂转化率>30%，C₂~C₇烃类产物中烯烃选择性高达85%以上，烯烷比为8.2，且CO选择性较低为17.1%。     

环烯烃开环易位聚合物的合成

采用MoCl₅为核心的齐格勒-纳塔催化剂合成降冰片烯-四环十二烯的开环易位聚合物,实现稳定的100%单体转化率,凝胶率0%。并采用Al₂O₃负载的Ru催化剂和SiO₂/Al₂O₃负载的Ni金属催化剂对相同的降冰片烯-四环十二烯开环易位聚合物进行非均相加氢,可实现100%的加氢率,且简单过滤即可将催化剂与聚合物溶液完全分离。两种加氢催化剂的产品具有不同的性质,Ni负载催化剂最佳反应条件：催化剂含量10%、反应温度190℃、初始氢气压力4 MPa、反应时间2 h,加氢产物的熔融指数76 g·min^-1,玻璃化转变温度126℃;Ru负载催化剂最佳反应条件：催化剂含量2%、反应温度180℃、初始氢气压力4 MPa、反应时间2 h,加氢产物的熔融指数10 g·min^-1,玻璃化转变温度131℃。     

多孔超交联聚合物固载离子液体催化二氧化碳环加成反应的研究进展

CO₂是一种主要的温室气体,以CO₂为原料与环氧化物发生环加成反应可以制备各种环状碳酸酯,是一种绿色可行的CO₂捕集及利用途径。多孔超交联聚合物固载离子液体（hypercrosslinked polymers immobilized ionic liquids,HCP-ILs）催化CO₂环加成反应具有无需溶剂、金属和助催化剂等优点。本文对其近年来的最新研究进展进行了综述,总结了离子单体自聚/共聚或交联法、离子与交联一步法以及交联后修饰法三种制备超交联聚合物固载离子液体方法的特点,分析了目前还存在离子密度偏低、催化效率不够高以及制备成本偏高等不利于“CO₂化工”应用的问题,并指出为实现在常压下快速催化CO₂与环氧化物的环加成反应,应从提高离子密度、调控表面活化功能基团和离子微环境以及降低制备成本等方向加强理论研究和技术攻关。     

MOFs材料在CO2加氢制甲醇催化剂中的应用

作为最主要的温室气体，CO₂的大量排放引发了全球变暖等一系列环境问题。利用CO₂加氢合成甲醇是实现CO₂循环利用、解决环境问题的切实可行的途径。开发高效、高选择性的催化剂是实现CO₂加氢制甲醇工业化应用的关键。近年来，金属有机骨架(MOFs)材料由于其结构多样性、设计灵活性的特点在催化领域引起了广泛关注，MOFs材料应用于CO₂加氢制甲醇催化剂的合成，可以有效解决目前CO₂加氢制甲醇催化剂存在的反应选择性低、CO₂转化率低、合成速率低等一系列问题，提高催化性能。综述了CO₂加氢制甲醇MOFs材料催化剂的研究进展，论述了MOFs材料应用于CO₂加氢制甲醇催化剂的优势及合成方法，评价了MOFs材料对不同的金属基催化剂的改善作用及存在的不足，并对其应用的挑战和前景进行了讨论。     

非金属氮掺杂活性炭催化剂制备及其催化CH4-CO2重整反应

采用硝酸和尿素联合对活性炭进行改性,制备了富含氮元素的氮掺杂活性炭,考察了孔结构、氮含量和氮种类（吡啶氮、吡咯氮和石墨氮）对CH₄-CO₂重整反应催化性能的影响。采用BET、SEM、EA、FTIR、XPS、CO₂-TPD和TG表征手段对反应前后催化剂的物理化学性质进行了表征,对引入活性炭表面的含氮官能团的种类及其在重整过程中所起的作用进行了分析。相比于未改性的原活性炭,硝酸和尿素同时改性制备的氮掺杂活性炭（AC-U.NA）引入了更多的羟基官能团和含氮官能团。特别是通过两者共同改性后,所制备的氮掺杂活性炭引入的吡啶氮官能团比例明显提高,为CH₄-CO₂重整反应提供了更多的活性位点,初始CH₄和CO₂转化率达到55.94%和66.46%。同时经过两者联合改性后,所制备的AC-U.NA材料表面具有极性,不仅有利于酸性CO₂分子的吸附和活化,而且有利于CO₂消碳反应,减少了积炭的生成,对所制备的非金属重整催化剂的活性和抗积炭性具有重要的意义。     

活化气氛对CO2加氢制取低碳烯烃Fe-K催化剂构-效关系

CO₂加氢直接制取低碳烯烃是实现其资源化利用的重要途径。通过热分解法制备了5种不同K含量（1%、3%、5%、7%、9%）的Fe-K催化剂用于CO₂加氢反应,结果表明Fe95-K5（95% Fe-5% K,质量分数）催化剂具有最优的活性及C₂～C₄烯烃选择性;随后对Fe95-K5催化剂进行了10% H₂/Ar、10% CO/Ar及5% CO/5% H₂/Ar 3种不同气氛活化处理以及CO₂加氢反应。结果发现,10% CO/Ar活化的催化剂具有最高的C₂～C₄烯烃选择性（38.1%）及链增长能力（α=0.644）。此外,还通过X射线衍射、Raman、程序升温等表征技术揭示了催化剂在不同活化气氛下的结构演变历程。研究发现,10% CO/Ar与5% CO/5% H₂/Ar活化的催化剂会生成γ₁型碳化铁结构,而10% H₂/Ar活化的催化剂则会在反应过程中生成γ₂型碳化铁结构,两种碳化铁结构对CO₂解离均有促进作用。     

多位点离子液体聚合物催化CO2环加成反应研究

CO₂与环氧化物环加成反应制备环状碳酸酯是一条绿色经济的CO₂利用途径。针对现有CO₂与环氧化物环加成反应中非均相离子液体催化剂活性低和活性组分易流失等问题,设计制备了系列多位点离子液体超交联聚合物HCPs-[DmPhe]Br,研究了多位点协同作用、超交联聚合物组成和结构等因素对其催化CO₂与环氧化物环加成反应性能的影响。其中,同时含有双季铵-卤素离子对、羟基和叔胺结构的HCP-[DmPhe]Br-DCX离子液体超交联聚合物催化剂,在1.3 MPa, 130℃,8 h的条件下,可实现94%的碳酸丁烯酯收率,且催化剂循环稳定性好,重复使用5次,催化活性没有明显降低。另外,超交联聚合物的多孔结构以及大比表面积促进了离子液体的较好分散,使其与离子液体单体具有相当的活性。该工作对CO₂与环氧化物环加成反应高效非均相离子液体催化剂的开发与优化具有一定的借鉴意义。     

Chemical fixation of carbon dioxide to propylene carbonate over amine-functionalized silica catalysts

Amine-functionalized silica catalysts (NH₂/SiO₂, NH(CH₂)₂NH₂/SiO₂ and 1,5,7-triazabicyclo[4,4,0]dec-5-ene/SiO₂ (TBD/SiO₂)), which were characterized by ²⁹Si NMR, elemental analysis, N₂ adsorption–desorption method and indicator dye adsorption, were prepared by ultrasonic technique under mild conditions. Such hybrid solid bases showed high catalytic activity towards CO₂ coupling with epoxide. However, it was found that the reaction conditions had a great influence on the performance. Furthermore, silanols on the surface played an important role in the chemical fixation of CO₂. Based on these, the possible reaction mechanism was proposed for CO₂ coupling with epoxide over such type of catalysts.     

CO2合成醇酯类化学品和高分子材料研究进展

我国作为煤炭大国,燃烧化石燃料产生大量CO₂。通过化学作用将CO₂转化为能源燃料、基础化学品或高分子材料,有利于实现碳氧资源综合利用。从CO₂直接利用和间接利用的角度出发,分别综述了CO₂资源化利用研究进展。直接利用方面,重点阐述了CO₂直接加氢合成甲醇和乙醇;同时CO₂可作为羰化剂合成有机碳酸酯和高分子材料,包括碳酸二乙酯、聚碳酸酯和CO₂基可降解聚合物。在间接利用方面,重点综述了CO₂经碳酸乙烯酯的酯交换反应合成碳酸二甲酯,以及碳酸乙烯酯加氢制备甲醇联产乙二醇的研究进展。CO₂加氢直接合成甲醇催化剂主要包括铜基催化剂、贵金属催化剂,由于贵金属的成本高,廉价的Cu基催化剂研究较为广泛。CO₂加氢直接合成乙醇研究较广泛的催化剂为贵金属(Rh、Pd、Ru)基催化剂体系,还需进一步研究廉价、高活性和高稳定性的催化剂。CO₂与乙醇直接合成碳酸二乙酯(DEC)研究较多的催化剂为铈基多相催化剂,但由于生成物中水分的影响,限制了DEC的收率。环氧化物和CO₂耦合反应生成DEC过程中不产生水,可以有效克服热力学的限制,因此高能化合物与CO₂的耦合路线是高效制备DEC的有效途径。CO₂与环氧化物共聚制备聚碳酸酯材料多采用稀土三元催化剂体系,环氧化物的转化率和聚碳酸酯选择性较高,目前已经实现工业应用。CO₂通过碳酸乙烯酯与甲醇酯交换合成DMC,多使用碱性较强的催化剂和含碱性基团的离子交换树脂。CO₂经碳酸乙烯酯加氢制备甲醇和乙二醇的反应中,铜基催化剂展现出优异的催化性能。CO₂化学转化利用是CO₂碳氧资源综合利用的重要途径,将有效支撑我国未来碳中和目标实现。     

Efficient homogenous catalysis of CO2 to generate cyclic carbonates by heterogenous and recyclable polypyrazoles

The cycloaddition between CO₂ and epoxides to produce cyclic carbonate is an attractive and efficiency pathway for the utilization of CO₂ as C1 source. The development of catalyst to mediate cycloaddition between CO₂ and epoxides at low temperature and pressure is still a challenge. Herein, a series of polypyrazoles with glass transition temperature (T_g) in the range of 42.3–52.5 ℃ were synthesized and served as catalyst to mediate the cycloaddition of CO₂ and epoxides by the assistant of tetrabutylammonium bromide. The catalytic behaviors of polypyrazole on the model cycloaddition of CO₂ to epichlorohydrin, including the reaction parameters optimization and versatility were investigated in detail, and excellent yield (99.9%) and selectivity (99%) were obtained under the optimized reaction conditions of 70 ℃ and 1.0 MPa for 6.0 h. Noteworthily, the polypyrazole acts as homogeneous catalyst during reaction (higher than T_g). And under room temperature, polypyrazoles can be easily separated and recovered, which is a promising feature of a heterogeneous catalyst. Furthermore, the reaction mechanism was proposed. The DFT calculation suggested that the formation of hydrogen bond between pyrazole and epoxide greatly reduced the energy barrier, which play an important role in promoting CO₂ cycloaddition.     

A mini review on chemical fixation of CO 2 : Absorption and catalytic conversion into cyclic carbonates

In this article, we present our research results on chemical fixation of CO₂ using organobismuth compounds. We fabricated bismuth biphenoate complex, Zn-Mg-Al composite oxides, and SBA-15 or Al-SBA-15 immobilized hydroxyl ionic liquid for CO₂ cycloaddition onto epoxides. The hypervalent bismuth compounds show good ability for association and dissociation with CO₂. The bismuth biphenolate complexes are catalytically effective for the cycloaddition reaction. The heterogeneous catalysts, viz. Zn-Mg-Al oxides and SBA-15 or Al-SBA-15 immobilized ionic liquid, are efficient for the synthesis of cyclic carbonate from CO₂ and epoxide. It is found that the presence of a trace amount of water can improve the catalytic activity of the immobilized ionic liquid.     

Carbon dioxide: a renewable feedstock for the synthesis of fine and bulk chemicals

The syntheses of carbon dioxide (CO₂) based industrially important chemicals have gained considerable interest in view of the sustainable chemistry and “green chemistry” concepts. In this review, recent developments in the chemical fixation of CO₂ to valuable chemicals are discussed. The synthesis of five-member cyclic carbonates via, cycloaddition of CO₂ to epoxides is one of the promising reactions replacing the existing poisonous phosgene-based synthetic route. This review focuses on the synthesis of cyclic carbonates, vinyl carbamates, and quinazoline-2,4(1H,3H)-diones via reaction of CO₂ and epoxide, amines/phenyl acetylene, 2-aminobenzinitrile and other chemicals. Direct synthesis of dimethyl carbonate, 1,3-disubstituted urea and 2-oxazolidinones/2-imidazolidinones have limitations at present because of the reaction equilibrium and chemical inertness of CO₂. The preferred alternatives for their synthesis like transesterification of ethylene carbonate with methanol, transamination of ethylene carbonate with primary amine and transamination reaction of ethylene carbonate with diamines/β-aminoalcohols are discussed. These methodologies offer marked improvements for greener chemical fixation of CO₂ in to industrially important chemicals.     

多孔有机聚合物催化二氧化碳合成环状碳酸酯研究进展

二氧化碳（CO₂）捕集、利用和储存（CCUS）在全球能源结构转型中是一种极具潜力的策略,能够实现能源供给、基础原料产出以及限制气候变化。多孔有机聚合物（POPs）具有高CO₂吸附容量和吸附选择性、突出的结构特性以及优异的化学可调控性,其作为极具潜力的材料广泛应用于催化CO₂参与的有机反应中。其中,CO₂与环氧化物环加成生成环状碳酸酯的反应具有100%的原子经济性,且其产物也极具工业价值。本文基于CO₂环加成反应催化机制,从催化剂的合成方法、结构性质与组成特性角度出发,综述了POPs在CO₂/环氧化物环加成反应的研究进展,包括金属配合物类、氢键供体类、离子液体类、金属配合物/离子液体和氢键供体/离子液体等有机多孔聚合物体系。通过阐述POPs在催化CO₂制备高附加值环状碳酸酯反应中的研究现状和发展趋势,为POPs的开发与应用以及CO₂综合利用的工业化探索提供具有建设性的指导意见。     

Kinetic study of CO2 fixation into propylene carbonate with water as efficient medium using microreaction system

Carbon dioxide (CO₂) utilization and fixation have become one of the most important research areas nowadays due to the increase of global greenhouse effect. Cyclic carbonate, which is widely used in various fields, can be synthesized by fixation of CO₂ with epoxide in industry. Moreover, the synthesis of cyclic carbonate is a 100% atom economical reaction, which makes it eco-friendly and promising. To enhance the reaction efficiency and safety, a microreaction system was used as the platform for cycloaddition reaction. In this work, tetrabutylammonium bromide (TBAB) was chosen as catalyst, and propylene oxide (PO) as a mode substrate. Interestingly, the addition of water can increase the propylene carbonate (PC) yield and decrease the activation energy considerably, proving water as catalyst promoter for PC synthesis. PC yield and selectivity could reach 91.6% and 99.8%, respectively. The Influence factors and kinetic equation for CO₂ cycloaddition were obtained as well.     

ZnBr2–Ph4PI as highly efficient catalyst for cyclic carbonates synthesis from terminal epoxides and carbon dioxide

The catalyst systems composed of ZnBr₂ and different phosphonium salts were examined for solvent-free synthesis of cyclic carbonates from CO₂ and terminal epoxides under mild conditions. Among the catalysts investigated, ZnBr₂–Ph₄PI was found to be the best while those of ZnBr₂–phosphine oxide (Bu₃PO or Ph₃PO) show no catalytic effect. It is apparent that the halide ions of phosphonium salts have an essential role to play in the reaction. The catalytic activity of ZnBr₂–Ph₄PI increases with a rise of Ph₄PI to ZnBr₂ molar ratio up to 6, above which there is little change in catalytic activity. We observed that with a rise in ZnBr₂ to Ph₄PI molar ratio, there is increase in epoxide conversion but decline in TOF_PO (estimated based on the site number of Zn²⁺). The effect of water on the reaction was investigated for the first time. We found that the presence of even a trace amount of water would result in a marked decline in reactivity, and the observation provides a valid explanation for why reproducibility of results is poor among researchers so far. The influences of other parameters such as reaction temperature and CO₂ pressure on the catalytic performance of ZnBr₂–PPh₄I were also studied. It is shown that the catalyst is sensitive to reaction temperature, and a rise of reaction temperature up to 130 °C favors the formation of cyclic carbonates. We observed that activity increases with rise in CO₂ pressure and reaches a maximum at an initial CO₂ pressure of 2.5 MPa. Moreover, a plausible reaction mechanism has been proposed.     

CoTPP-TBAB catalyzed tandem transformation of styrene carbonate from styrene in the presence of O2 and CO2

The direct synthesis cyclic carbonate from styrene, O₂ and CO₂ is of great academic attraction and industrial value in modern chemistry. The metalloporphyrin/tetrabutylammonium bromide was employed as binary catalyst for this reaction in the presence of O₂ and CO₂ by using methyl 2-cyclopentanone-carboxylate as co-catalysts. The effects of reaction parameters on catalytic performance were investigated systematically. Under the optimal reaction conditions, conversion of styrene (99%) and selectivity to cyclic carbonate (35%) were obtained. The possible mechanism of cascade reaction was proposed by using in-situ ultraviolet and infrared spectroscopy. The results show that the cobalt center is coordinated with the ring oxygen atom of methyl 2-oxocyclopentanecarboxylate to activate oxygen to form a peroxy active species, thereby forming a high-valent cobalt-oxygen intermediate, which passes oxygen atoms to styrene and generate epoxy styrene. Then, styrene oxide opened ring under the catalysis of tetrabutylammonium bromide, and finally formed cyclic carbonate through CO₂ insertion reaction and intramolecular ring-closing reaction.