The Novel Porous Tissue-Like Carbon-Based Solid Acid for Biodiesel Synthesis from Waste Oil

Kinetics and Catalysis - The novel porous tissue-like carbon based solid acid has been synthesized by the molten salt-induced carbonization and sulfonation. The novel solid acid owned the special...     

One-pot synthesis of a novel magnetic carbon based solid acid for alkylation

Magnetic carbon based solid acid has been synthesized via the one-pot hydrothermal carbonization of chitosan, magnetic core and hydroxyethylsulfonic acid at 160°C for 4 h. Chitosan was used as the carbon resource to protect the magnetic core from hydroxyethylsulfonic acid. The magnetic carbon based solid acid owned high BET surface and core shell structure, which provided the easily accessible acid sites on the carbon shell. The novel carbon based solid acid exhibited high activities for the hydrophobic alkylation of 1- dodecene and benzene, which was difficult to activate by traditional carbon based solid acids. The simple magnetic recovery added the advantages of the solid acid. The high activities for hydrophobic reactions, high stability and magnetic recovery were the key properties of the solid acid, which greatly enlarged the application area of the solid acid.     

Sulfonic acid-functionalized core-shell Fe_3O_4@carbon microspheres as magnetically recyclable solid acid catalysts

Green and recyclable solid acid catalysts are in urgent demand as a substitute for conventional liquid mineral acids.In this work,a series of novel sulfonic acid-functionalized core-shell Fe_3 O_4@carbon microspheres(Fe_3 O_4@C-SO_3 H) have been designed and synthesized as an efficient and recyclable heterogeneous acid catalyst.For the synthesis,core-shell Fe_3 O_4@RF(resorcinol-formaldehyde) microspheres with tunable shell thickness were achieved by interfacial polymerization on magnetic Fe_3 O_4 microspheres.After high-temperature carbonization,the microspheres were eventually treated by surface sulfonation,re sulting in Fe_3 O_4@C-x-SO_3 H(x stands for carbonization temperature) microspheres with abundant surface SO_3 H groups.The obtained microspheres possess uniform core-shell structure,partially-graphitized carbon skeletons,superparamagnetic property,high magnetization saturation value of 10.6 emu/g,and rich SO_3 H groups.The surface acid amounts can be adju sted in the range of 0.59-1.04 mmol/g via sulfonation treatment of carbon shells with different graphitization degrees.The magnetic Fe_3 O_4@C-x-SO_3 H microspheres were utilized as a solid acid catalyst for the acetalization reaction between benzaldehyde and ethylene glycol,demonstrating high selectivity(97%) to benzaldehyde ethylene glycol acetal.More importantly,by applying an external magnetic field,the catalysts can be easily separated from the heterogeneous reaction solutions,which later show well preserved catalytic activity even after 9 cycles,revealing good recyclability and high stability.     

Ultra high density carbon fiber derived from isotactic polypropylene fiber without skin-core structure

Polypropylene (PP)-based carbon fibers were prepared by sulfonation process of isotactic PP fibers with concentrated sulfuric acid, followed by stress-less carbonization under nitrogen atmosphere. The stabilization behaviors of PP fiber under different sulfonation temperatures and time were discussed. The carbonization behavior of the stabilized PP fibers under different carbonization temperatures, as well as the mechanical performance of the obtained carbon fibers were investigated. The results indicated that linear PP molecule were effectively converted into thermally stable structure at higher temperature (≥130°C) in short time (2 h) through sulfonation-desulfonation reaction, among which ordered graphite structure has been formed prior to the carbonization process. Meanwhile, the carbon fibers were considerably densified by increasing the sulfonation temperature and carbonization temperature, and a bulk density of 1.96 g/cm³ was achieved. Moreover, the temperature and time of the sulfonation process as well as the temperature of the carbonization process were regulated, and carbon fibers with tensile strength of 262.3 MPa was obtained, which was superior to that of 208.1 MPa for the linear low density polyethylene-based carbon fibers reported previously. Isotactic PP was proved to be a promising candidate to develop carbon fibers with tunable graphite structure and mechanical performance.     

椰壳炭磺酸催化剂制备及其对杯[4]芳烃合成反应的催化应用

以废弃椰壳为原料,经炭化和磺化制得新型固体磺酸催化剂,用于催化各种芳醛与间苯二酚的缩合反应,以较高收率(49%～95%)制得一系列杯[4]芳烃化合物,产物结构经IR、1H NMR和MS测试技术表征得以确证。     

磺酸基团功能化的碳-硅介孔复合材料的制备及其在生物柴油绿色合成中的应用(英文)

利用化学浸渍法将蔗糖负载到 SBA-15 介孔材料孔道内部, 高温炭化形成的多聚苯环经发烟硫酸气相磺化处理后, 得到磺酸基团功能化的新型碳-硅介孔复合材料. 发烟硫酸气相磺化处理是该材料合成的关键步骤. X 射线衍射、扫描电镜和氮气吸附结果表明, 碳-硅介孔复合材料经磺酸化处理保持了高度有序的介孔结构. 热重、傅里叶变换的红外光谱及吡啶吸附红外光谱结果证明, 磺酸功能基团成功的嫁接于碳-硅介孔复合材料孔道的内表面, 反应活性中心为 Br?nsted 酸, 酸密度在 0.09~0.70 mmol/g 可以有效调变. 当碳负载量为 35% 时, 该复合材料在生物柴油的绿色合成中显示出最优的催化性能, 且可重复使用 3 次以上.     

分级有序多孔磺化碳催化果糖转化制5-羟甲基糠醛

采用双模板自组装、炭化、氢氟酸蚀刻和磺化等手段制备了具有分级有序多孔结构的磺化碳(SCHOP),并分别在500、600和700℃考察了炭化温度对分级有序多孔碳微观结构的影响;以催化果糖脱水制备5-羟甲基糠醛(5-HMF)为探针反应,评价了SCHOP的催化效果。结果表明,500℃焙烧所制备的SCHOP具有最高的催化活性。SEM、TEM和N2吸附-脱附表明,所制备的催化剂具有规整的分级有序孔结构,但过高的炭化温度会降低炭材料微观结构的有序性;FT-IR、EDS和-SO3H含量测定表明,通过磺化可在碳基体上有效引入磺酸基,炭化温度过高会降低炭材料的芳香性,不利于磺酸基的引入。130℃下反应20 min,果糖的转化率和5-HMF的收率分别高达96.1%和93.4%,表明SCHOP是一种高效固体酸催化剂。     

Sulfonated carbon catalyzed oxidation of aldehydes to carboxylic acids by hydrogen peroxide

Sulfonated carbon as a strong and stable solid acid catalyst exhibited excellent catalytic performance in various acid-catalyzed reactions. Here, sulfonated carbon, as catalyst for oxidation reaction, was prepared via the carbonization of starch followed by sulfonation with concentrated sulfuric acid. N₂ physisorption, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray fluorescence and acid-base titration were used to characterize the obtained materials. The catalytic activity of sulfonated carbon was studied in the oxidation of aldehydes to carboxylic acids using 30 wt% H₂O₂ as oxidant. This oxidation protocol works well for various aldehydes including aromatic and aliphatic aldehydes. The sulfonated carbon can be recycled for three times without obvious loss of activity.     

One-pot synthesis of a novel catalyst with strong acid sites based on carbon/silica composite

A novel catalyst with strong acid sites based on carbon/silica composite has been synthesized through one-pot hydrothermal carbonization of hydroxyethylsulfonic acid, glucose and tetraethyl orthosilicate (TEOS). The novel solid acid showed an acidity of 2.1 mmol/g, much higher than that of traditional solid acids such as Nafion and Amberlyst-15 (0.8 mmol/g). The catalytic activity of the solid acid was investigated in the acetalization and dimerization of α-methylstyrene. The results showed that the novel solid acid was very efficient for both hydrophilic and hydrophobic acid-catalyzed reactions. Because of the high acidity and catalytic activity the novel solid acid based on carbon/silica composite is a promising catalyst for the processes in green chemistry.     

C/粉煤灰复合吸附材料的制备及表征

以粉煤灰和蔗糖为原料,浓硫酸为炭化剂,制备了一种新型的C/粉煤灰复合吸附材料。 采用X光电子能谱、红外吸收光谱、场发射扫描电子显微镜、X射线衍射及N2气吸附实验对所制备复合材料进行了表征。 结果表明,粉煤灰表面被类石墨态炭纳米颗粒所包裹,复合材料表面密集分布着大量的介孔,Brunauer-Emmett-Teller(BET)比表面积SBET=5.4 m2/g,并且在该复合材料表面含有丰富的-SO3H、-COOH和-OH等含氧官能团。 考察了所制备的复合材料对典型阳离子型染料亚甲基蓝及重金属离子的吸附能力,结果表明,该复合材料具有优异的吸附性能,其对亚甲基蓝的吸附能力达到活性炭的83.7%,对典型重金属离子的吸附能力优于市售活性炭。 所制备复合材料可作为活性炭的一种替代品,用于水中有机染料和重金属离子的吸附处理。     

多孔炭材料在纤维素催化转化中的应用

生物质作为自然界唯一可再生的有机碳资源,其利用受到了越来越多的关注。特别是随着能源和环境危机的日益加重,将生物质中非可食用部分催化转化为燃料及具有高附加值的化学品被认为是高效、环保、原子经济的绿色过程。同时,多孔炭材料具有丰富的孔道结构、优异的水热稳定性和大比表面积,是生物质催化转化反应中最常用的载体材料之一。兼之炭材料表面极性、亲疏水性的可调变性,及对酸碱溶剂的反应惰性,也使其无论在学术研究还是在工业应用中都具有特殊的优势。另外,随着纳米炭材料科学的飞速发展,合成孔径、形貌、及表面官能团可控的介孔炭和具有多级孔道结构的多孔炭材料成为可能,将其应用到纤维素催化转化过程中,对深入理解孔道结构、表面官能团对纤维素转化的作用,揭示催化反应作用机制,指导炭基催化剂的设计合成,均具有重要意义。在本综述中,我们首先对纤维素转化中多孔炭的孔道结构和表面官能团性质的独特作用进行了阐述。由于商业活性炭的孔径一般在微孔尺度,但纤维素及可溶低聚糖的分子体积较大,因而其在活性炭中的传质受到了极大的限制。通过模板法获得的介孔炭材料,可实现孔径在2–10 nm的可控合成,大大提高了反应物的扩散速率,使之能与催化活性位有效接触。但孔道过于狭长,在反应过程中堵塞的可能性增高,进而导致催化剂失活;因此,在介孔孔道的基础上,建立互通的多级孔道结构对反应物、中间物、和产物的扩散,及催化活性的保持更为有利。另一方面,炭材料表面的含氧官能团不仅具有加强1,4-糖苷键吸附的作用,还可以作为酸性活性中心催化水解反应的进行;尤其是在传统的水相纤维素催化转化过程中,亲水表面对多孔炭催化剂与反应物的接触非常有利。本文以纤维素水解及纤维素水解加氢反应为例,展开讨论了多孔炭作为固体酸及双功能催化剂载体的应用。在水解反应中,纤维素首先在热水中降解为可溶低聚糖,之后再与活性炭表面官能团反应;其中多孔炭的比表面积、酸量、及酸强度均是促进水解发生的正向因素。在水解加氢反应中,炭载贵金属催化剂作为最常用的加氢催化剂,可获得以六元醇为主的纤维素转化产物。除了加氢作用之外,贵金属小颗粒被证实可以通过氢溢流作用提供水解所需的H+,同时,正价的贵金属也可促进反应过程中的氢转移。另一方面,由于钨物种可催化逆羟醛缩合反应的发生,因此在反应体系中引入钨物种时,水解加氢的主要产物由六元醇变为乙二醇。需要特别指出的是,在纤维素催化水解加氢的过程中,多孔炭材料作为载体同样具有非常重要的作用：一方面,三维介孔的孔道结构不仅有利于反应物、产物的扩散,也有利于加氢金属催化剂的分散,进而提高金属的催化加氢能力;另一方面,当炭材料的表面化学性质改变时,也会影响产物的选择性分布,例如当炭表面显碱性时,由于异构化作用,丙二醇成为主要产物。本文最后,我们列举了一些新型多孔炭材料,包括杂原子改性的多孔炭材料和金属氧化物-炭复合多孔材料的合成方法及其在纤维素催化转化乃至生物质转化中的潜在应用。     

通过聚苯的磺化和碳化制备酸性树脂-碳复合材料

用浓硫酸在170℃下处理聚苯,发生了磺化和碳化过程,生成了一种酸性树脂-碳复合材料.其比表面积为14 m2/g,与磺酸基相关的强酸量为1.2 mmol/g,氨吸附量热测定的起始吸附热较高,表明表面磺酸基没有形成焦硫酸根;部分磺酸基在400℃以上才开始分解,表现出很高的热稳定性.该强酸性复合材料在异戊烯与甲醇醚化生成甲基...     

Conjugate Addition of Indole to α,β‐Unsaturated Ketones Catalyzed by Lewis Acid Immobilized on a Biorenewable Support

Sulfonated carbonaceous solid acid was prepared straightforwardly from household granulated sucrose through a one‐pot carbonization—sulfonation process. The performance of this solid Brønsted acid was tested by the 1,1‐diacylation of aldehydes. Lewis acid, such as indium chloride, was supported on sucrose‐derived carbonaceous solid acid through anion metathesis and successfully applied to the conjugate addition of indole to α,β‐unsaturated ketones.     

基于纤维素的固体酸催化剂的制备及其催化高酸值废油脂生产生物柴油

以廉价的纤维素为原料,经不完全炭化和磺化制得含高密度(1.69 mmol/g) SO3H基团的固体酸催化剂Cellulose-SO3H.结果表明,该催化剂适宜的制备条件为:在400℃炭化15h,再在150℃磺化15h.所得催化剂在油酸与甲醇的酯化反应中表现出明显高于其它几种典型固体酸催化剂(铌酸,Amberlyst- ...     

Efficient synthesis and sulfonation of ordered mesoporous carbon materials

Ordered mesoporous carbons (OMCs) with hexagonal structure were efficiently synthesized via cooperative self-assembly of phenol/formaldehyde resol and surfactant F127 under acidic aqueous conditions. Induced by HCl, a gel phase mainly containing phenol/formaldehyde resol and F127 was obtained within several hours. X-ray diffraction (XRD), transmission electron microscope (TEM) and nitrogen adsorption isotherms indicated that the synthesized samples possess 2-D hexagonal mesostructure. The influence of the synthesis conditions, including acid concentration and mass ratio of resol to F127, was investigated. When the acid concentration was fixed in the range of 0.6-2.0 M and the mass ratio of resol to F127 in the range of 3.5-4.0, highly ordered mesoporous carbon could be synthesized. The synthesized OMCs could be easily sulfonated in concentrated sulfuric acid at elevated temperature. The results indicate that the mesostructural stability and the content of the surface sulfonic acid (SO(3)H) groups depend mainly on the pyrolysis temperature of the OMCs and the sulfonation temperature, suggesting that the combination of pyrolysis and sulfonation temperature is essential for developing OMCs with high densities of SO(3)H groups.     

Hydrothermal Carbon Enriched with Oxygenated Groups from Biomass Glucose as an Efficient Carbocatalyst

Metal‐free carbocatalysts enriched with specific oxygenated groups with different morphology and size were synthesized from glucose by hydrothermal carbonization, in which cheap and widely available biomass could be converted into functionalized carbon using an environmentally benign process. The hydroxy‐ and carbonyl‐enriched hydrothermal carbon (HTC) could be used in nitrobenzene reduction, and higher conversion was obtained on the sphere morphology with smaller size. In the Beckmann rearrangement of cyclohexanone oxime, carboxyl‐enriched HTC exhibited superior performance compared with conventional solid acid (such as HY and HZSM‐5), on which the strong acid sites and weak Lewis acid sites lead to high selectivity for the side product. Although the intrinsic acidity of carbon is weak, the carboxyl‐enriched carbon was used in weak Brønsted acid‐catalyzed reactions, such as the Beckmann rearrangement.     

Optimization and Characterization of Mesoporous Sulfonated Carbon Catalyst and Its Application in Modeling and Optimization of Acetin Production

In this study, an optimized mesoporous sulfonated carbon (OMSC) catalyst derived from palm kernel shell biomass was developed using template carbonization and subsequent sulfonation under different temperatures and time conditions. The OMSC catalyst was characterized using acid-base titration, elemental analysis, XRD, Raman, FTIR, XPS, TPD-NH₃, TGA-DTA, SEM, and N₂ adsorption–desorption analysis to reveal its properties. Results proved that the OMSC catalyst is mesoporous and amorphous in structure with improved textural, acidic, and thermal properties. Both FTIR and XPS confirmed the presence of -SO₃H, -OH, and -COOH functional groups on the surface of the catalyst. The OMSC catalyst was found to be efficient in catalyzing glycerol conversion to acetin via an acetylation reaction with acetic acid within a short period of 3 h. Response surface methodology (RSM), based on a two-level, three-factor, face-centered central composite design, was used to optimize the reaction conditions. The results showed that the optimized temperature, glycerol-to-acetic acid mole ratio, and catalyst load were 126 °C, 1:10.4, and 0.45 g, respectively. Under these optimum conditions, 97% glycerol conversion (GC) and selectivities of 4.9, 27.8, and 66.5% monoacetin (MA), diacetin (DA), and triacetin (TA), respectively, were achieved and found to be close to the predicted values. Statistical analysis showed that the regression model, as well as the model terms, were significant with the predicted R² in reasonable agreement with the adjusted R² (<0.2). The OMSC catalyst maintained excellent performance in GC for the five reaction cycles. The selectivity to TA, the most valuable product, was not stable until the fourth cycle, attributable to the leaching of the acid sites.     

Spherical hollow mesoporous silica supported phosphotungstic acid as a promising catalyst for α-arylstyrenes synthesis via Friedel-Crafts alkenylation

This work presents a scalable approach for preparing spherical hollow mesoporous silica with high surface area/pore volume, serving as outstanding support for supported phosphotungstic acid catalyst with much superior catalytic performance to the one on previously reported spherical mesoporous silica toward diverse transformations, ascribed to the strengthened mass transfer and the enlarged exposure degree of acidic sites to reactants those resulting from unique hollow and mesoporous morphology.     

新型有序介孔磺酸化酚醛树脂FDU-16-SO3H的合成与酸催化性能

通过氯磺酸磺化有序介孔酚醛树脂(FDU-16)制备了新型有序介孔固体酸催化剂FDU-16-SO₃H. X射线衍射(XRD)、氮气吸附以及透射电镜(TEM)等表征结果表明, 经过磺化后的固体酸催化剂依然保持了高度有序性, 大量的磺酸根基团存在于材料的骨架之中. 在酯化反应和酰基化反应中, 这种新型有序介孔固体酸催化剂表现出比工业树脂和磺酸化介孔二氧化硅等材料更高的催化活性, 这主要归因于它具有较大的比表面积、较强的酸性以及骨架的疏水性.     

Highly ordered three dimensional macroporous carbon spheres and their acid catalytic properties

Highly ordered three dimensional macroporous carbon spheres bearing sulfonic acid groups (MPCS-SO₃H) were prepared by incomplete carbonization of glucose in silica crystal bead template, followed by sulfonation and removal of the template. The composition and porous structure of the obtained carbon spheres were investigated by physical adsorption of nitrogen, scanning electron microscopy, energy dispersive X-ray spectroscopy, and transmission electron microscopy techniques. While the Fourier-transform infrared spectroscopy was used to characterize the functional groups on the surface of carbon spheres. The catalytic properties of the MPCS-SO₃H were evaluated by esterification of ethanol with acetic acid, indicating that MPCS-SO₃H possess remarkable catalytic performance (high stability and acid catalytic ability) for the esterification.