松木粉制备高比表面积炭基固体酸催化剂

以一种廉价的农林废弃物——松木粉为原料,首先经过炭化和活化处理,制备活性炭,再通过苯磺酸重氮盐还原法处理活性炭引入磺酸基团（—SO3H）,从而制备出具有高比表面积的炭基固体酸催化剂（AC-SO3H）。其比表面积达到1364 m2/g,磺酸基密度为1.36 mmol/g。以乙酸的酯化反应考察了炭基固体酸催化剂的催化活性,并与Amberlyst-15、Nafion NR50以及Nafion SAC-13等几种固体酸催化剂进行了比较。实验结果表明,炭基固体酸催化剂的催化活性仅略低于Amberlyst-15,高于Nafion NR50和Nafion SAC-13,炭基固体酸催化剂的成本也远远低于Nafion NR50和NafionSAC-13。研究结果表明,以松木粉为原料,通过炭化、活化和磺化处理能够得到性能优异且成本低廉的炭基固体酸催化剂。     

新型有序介孔炭基固体酸的制备及其催化双酚A合成

采用软模板法制得具有高度有序介孔孔道结构、高密度-SO₃H基团的新型有序介孔炭基固体酸催化剂。通过N₂吸附-脱附、X射线衍射、透射电镜、EDX能谱以及酸碱滴定等手段对催化剂进行了表征,考察了炭化温度对介孔炭基固体酸催化剂介孔孔道结构、表面酸性以及催化活性的影响。结果表明,500 ℃是最适宜的炭化温度,该炭化温度下制备的催化剂介观有序性较好且酸密度较高。所得的催化剂在丙酮与苯酚缩合生成双酚A的反应中表现出明显高于其它3种固体酸催化剂（001×7,D072,无定型炭基固体磺酸）的活性。可见,有序介孔炭基固体酸是一种高效的新型固体酸催化剂,在双酚A领域具有较好的应用潜力。     

生物柴油合成用木质素固体酸催化剂的制备

采用炭化磺化法,以天然生物质木粉为原料制备了生物质炭基固体酸催化剂,研究了不同树种的生物质木粉对炭基固体酸催化剂的催化酯化性能的影响.比较了4种不同原料制备的炭基同体酸催化剂的催化性能,并进行了表征.结果表明,与其他炭基固体酸催化剂相比,以生物质木粉为原料制备的炭基固体酸催化剂表现出了较高的催化酯化性能.     

实验条件对活性炭基固体酸催化剂制备的影响

以煤基商品活性炭为载体,通过苯磺酸重氮盐还原反应制备活性炭基固体酸催化剂。系统考察了重氮盐制备方法,无水乙醇、蒸馏水、次磷酸的用量等实验条件对炭基固体酸催化剂磺酸密度以及催化活性的影响。研究得到的最优实验条件是,苯磺酸重氮盐无需抽滤处理,重氮盐制备反应时间为45 min、无水乙醇用量为50 mL、不加蒸馏水、次磷酸用量300 mL,该条件下得到的炭催化剂磺酸密度达到1.46 mmol/g,超过目前催化剂磺酸密度的2倍,其对乙酸酯化反应的催化性能比未优化时提高了38%。     

生物质竹屑活性炭磺酸官能化固体酸催化剂的制备

以竹屑为原料,经高温炭化、微波磺化接枝等步骤制备具有酸催化功能的竹屑活性炭磺酸,通过FTIR、TG、DTA对其进行了分析,并测定了其催化性能。结果表明,在炭化温度为560℃、炭化时间为3 h、微波活化时间为30min的最佳条件下,所制得竹屑活性炭磺酸的酸量为0.847 mmol.g-1,酯化催化效果接近于Amerlyst-15磺酸树酯,稳定性好,是一种良好的新型固体酸催化剂。     

秸秆炭基固体酸的一步溶剂热法制备及表征

以秸秆为原料,采用一步溶剂热法制备秸秆炭基固体酸,考察了制备条件对其表面酸浓度的影响,并通过N2吸附-脱附、XRD、FT-IR、SEM、EDS、TGA和DCS等手段对秸秆炭基固体酸进行了表征。结果表明,当2.0 g秸秆与60 m L浓硫酸在温度为200℃条件下反应12 h,所得的秸秆炭基固体酸表面酸浓度达1.01 mmol/g,比表面积和总孔容分别为1 567.4 m2/g和0.75 cm3/g。秸秆炭基固体酸为经过不完全炭化和磺化过程生成的磺酸基负载型芳香族炭结构化合物,在260℃以下具有良好的热稳定性。     

PET在油茶壳炭C⁃SO3H基固体酸催化剂下的液化行为研究

以废弃生物质油茶壳为原料,在经过一系列炭化、磺化后成功制备了一种新型的炭基固体酸催化剂（C-SO₃H）,考察了催化剂制备过程中温度和浓度等因素对催化活性的影响,利用X射线衍射仪、扫描电子显微镜、红外光谱仪和核磁共振波谱仪等对催化剂及其催化废弃聚对苯二甲酸乙二醇酯（PET）的催化效率、催化机理等进行了测定和分析。结果表明,催化剂的最佳制备条件为：浸渍比1∶1、浸渍浓度2 mol/L、炭化温度700 ℃、磺化温度160 ℃;催化PET的最大的转化率和BHET回收率分别为95 %和68 %;催化剂微观呈现无定型炭结构,含有大量的羟基,具有较大的比表面积;醇解反应产物为单体BHET。     

炭基固体酸对芳香酸酯化反应的催化性能研究

通过重氮盐还原反应对活性炭进行磺化处理,制备炭基固体酸催化剂(简称炭催化剂),考察了炭催化剂对苯甲酸、苯乙酸、3-苯丙酸等芳香酸与乙醇的酯化反应的催化活性。结果表明,炭催化剂对苯甲酸的催化活性较低,反应10 h的催化效果仅为硫酸催化剂的6%;炭催化剂对苯乙酸、3-苯丙酸催化活性较高,10 h催化效果达到硫酸的89%。     

木质素磺酸钠制备固体酸催化剂及其催化活性研究

采用炭化磺化法以木质素磺酸钠为原料制备一种固体酸催化剂,并用于纤维素的水解反应,通过扫描电子显微镜(SEM)、X射线衍射分析(XRD)、热重分析(TGA)、傅里叶红外(FTIR)、酸碱滴定进行了表征。考察了炭化温度对固体酸催化剂的表面酸量和催化性能的影响。结果表明,在碳化温度为300℃时制得的催化剂其磺酸基含量高达1.3 mmol/g,对纤维素水解的催化活性优于其他常见的酸催化剂,在180℃反应6 h后,还原糖产量为44.2%。     

木质素磺酸钠制备固体酸催化剂及其催化活性研究

采用炭化磺化法以木质素磺酸钠为原料制备一种固体酸催化剂,并用于纤维素的水解反应,通过扫描电子显微镜(SEM)、X射线衍射分析(XRD)、热重分析(TGA)、傅里叶红外(FTIR)、酸碱滴定进行了表征。考察了炭化温度对固体酸催化剂的表面酸量和催化性能的影响。结果表明,在碳化温度为300℃时制得的催化剂其磺酸基含量高达1.3 mmol/g,对纤维素水解的催化活性优于其他常见的酸催化剂,在180℃反应6 h后,还原糖产量为44.2%。     

Methane Partial Oxidation Using A (La0.6Sr0.4)(Ga0.8Mg0.05Co0.15)O3–δ Membrane

A novel sulfonated carbon composite solid acid was successfully prepared by the pyrolysis of a polymer matrix impregnated with glucose followed by sulfonation. The title catalyst has higher acid site density, better esterification activity of both small and large free fatty acids (acetic acid and palmitic acid), and better reusability than the previously reported carbon-based catalyst prepared by sulfonating pyrolyzed sugar. This catalyst also exhibited higher esterification activity than tungstated zirconia (WZ) and Silica-Supported Nafion (Nafion^®SAC-13). The higher activity of the sulfonated carbon composite solid acid catalyst was clearly due to the presence of a much higher acid site density than any of the other catalysts.     

竹炭碳磺酸的制备及其催化性能

以富含纤维素的天然竹粉为原料,通过硫酸浸渍,炭化和磺化的过程,制备竹炭碳磺酸并将其应用于纤维素水解反应。首先对改性前后的竹粉及其主要成分进行热重分析,发现硫酸能打破竹粉组分之间部分原有的化学键,促进竹粉的热解过程,使竹粉在低温下进行热解与炭化。然后系统地研究浸渍比例、浸渍液浓度、炭化温度和磺化温度等因素对催化剂活性的影响,得到催化剂最优制备条件。最后采用XRD、BET、FT-IR和SEM等方法对竹炭碳磺酸进行表征,结果表明通过合理调控温度能使竹炭磺酸具有良好的孔结构和较高的磺酸量,且磺酸量可能和芳香碳环上的活泼氢数目有关。     

Enhanced esterification of carboxylic acids with ethanol using propylsulfonic acid-functionalized natural rubber/hexagonal mesoporous silica nanocomposites

Propylsulfonic acid-functionalized natural rubber (NR)/hexagonal mesoporous silica (HMS) nanocomposites (NR/HMS-SO₃H) with different acid contents were prepared via an in situ sol–gel process, and then applied as heterogeneous acid catalysts in the esterification of model carboxylic acids and palm fatty acid distillate (PFAD) with ethanol. The NR/HMS-SO₃H composites exhibited a wormhole-like framework with enhanced wall thickness, high mesoporosity, and enhanced hydrophobicity. The NR/HMS-SO₃H composites exhibited a superior catalytic performance compared to a commercial Nafion/silica composite solid acid catalyst (SAC-13) and conventional propylsulfonic acid-functionalized HMS (HMS-SO₃H). The NR/HMS-SO₃H catalyst can be regenerated and reused in the esterification.     

Preparation of a Sulfonated Porous Carbon Catalyst with High Specific Surface Area

A sulfonated (SO₃H-bearing) carbon catalyst with mesoporous structure and high specific surface area is successfully prepared by impregnating the cellulosic precursor (wood powder) with ZnCl₂ prior to activation and sulfonation. The specific surface area of the porous carbon catalyst thus prepared is also found to increase with carbonization temperature to a maximum of 1,560 m² g^?1 at ca. 773 K. Structural analyses reveal that the porous carbon catalysts carbonized at temperatures higher than 723 K contain high densities of micro- and mesopores. The porous carbon catalyst exhibits high catalytic performance for the esterification of acetic acid (343 K), the activity for which is dependent only on the acid density. The porous carbon catalyst also exhibits high catalytic activity for the benzylation of toluene, whereas non-porous sulfonated carbon has very limited activity for this reaction. The activity for the benzylation of toluene is dependent on both the specific surface area and the acid density of the sulfonated porous carbon catalyst.     

Transesterification of triacetin with methanol on Nafion® acid resins

Although homogeneous alkali catalysts (e.g., NaOH) are commonly used to produce biodiesel by transesterification of triglycerides (vegetable oils and animal fats) and methanol, solid acid catalysts, such as acidic resins, are attractive alternatives because they are easy to separate and recover from the product mixture and also show significant activity in the presence of fatty acid impurities, which are common in low-cost feedstocks. To better understand solid acid catalyst performance, a fundamental transesterification kinetic study was carried out using triacetin and methanol on Nafion^® (perfluorinated-based ion-exchange resin) catalysts. In particular, Nafion^® SAC-13 (silica-supported Nafion) and Nafion^® NR50 (unsupported Nafion) were investigated, because both show great promise for biodiesel-forming reactions. The reaction kinetics for a common homogeneous acid catalyst (H₂SO₄) were also determined for comparison. Liquid-phase reaction was performed at 60 °C using a stirred batch reactor. The swelling properties of the resin in solvents of diverse polarity that reflect solutions typically present in a biodiesel synthesis mixture were examined. The initial reaction rate was greatly affected by the extent of swelling of the resin, where, as expected, a greater effect was observed for Nafion^® NR50 than for the highly dispersed Nafion^® SAC-13. The reaction orders for triacetin and methanol on Nafion^® SAC-13 were 0.90 and 0.88, respectively, similar to the reaction orders determined for H₂SO₄ (1.02 and 1.00, respectively). The apparent activation energy for the conversion of triacetin to diacetin was 48.5 kJ/mol for Nafion^® SAC-13, comparable to that for H₂SO₄ (46.1 kJ/mol). Selective poisoning of the Brønsted acid sites on Nafion^® SAC-13 using pyridine before transesterification revealed that only one site was involved in the rate-limiting step. These results suggest that reaction catalyzed by the ion-exchange resin can be considered to follow a mechanism similar to that of the homogeneous catalyzed one, where protonated triglyceride (on the catalyst surface) reaction with methanol is the rate-limiting step.     

生物质碳磺酸的制备及其催化水解纤维素性能

对炭化温度、磺化条件以及不同碳源等因素对生物质碳磺酸的酸量、表面结构及催化纤维素水解活性的影响进行了系统研究,并采用XRD、BET、 FT-IR和SEM等对碳磺酸的微观特征进行了分析,发现合适的炭化温度和炭化程度是制备高酸量碳磺酸的关键,在相同的炭化和磺化条件下,用不同生物质碳源制备得到碳磺酸的酸量接近,微观结构不同对纤维素水解催化活性有一定影响。在本文研究的几种碳磺酸中,具有蜂窝大孔结构的竹炭碳磺酸呈现比较突出的催化活性。将竹粉在400℃炭化3 h,然后在180℃下磺化8 h,得到竹炭碳磺酸的总酸量和磺酸量分别可达5.34和1.25 mmol·g^-1。     

Activity Comparison of Different Solid Acid Catalysts in Etherification of Glycerol with tert-Butyl Alcohol in Flow and Batch Reactors

In the presented work, etherification of glycerol with TBA was investigated in a continuous flow and also in a batch reactor using nine different commercial solid acid catalysts, namely Amberlyst-15, Amberlyst-36, Amberlyst-35, Amberlyst-16, Relite EXC8D, Lewatit K2629, H-Beta, H-Mordenite and Nafion SAC-13. Results proved the advantages of flow reactor to achieve quite high glycerol conversion values in very short residence times, due to efficient contact of reactants with the solid catalyst, which was caused by higher catalyst to reactant ratio within the reactor. Results of batch reactor experiments obtained in the temperature range of 80–200 °C proved the importance of operating temperature on the catalytic performance of these materials. Amberlyst-15, which has the highest Brønsted acidity, gave the highest glycerol conversion at 90–100 °C. However, this material is unstable at temperatures higher than 110 °C. Performances of Amberlyst-36 and Relite EXC8D were the best in the range of 110–150 °C, which started to become unstable at 150 °C. Although the catalytic performance of Nafion-SAC-13 was not as good as Amberlyst type resins at temperatures up to 150 °C, its thermal stability was higher and could be used up to 200 °C. Although Brønsted acidity was the most important property of these materials in the etherification reaction of glycerol, results also proved the importance of diffusion resistance on the observed conversion values, which limited the penetration of glycerol to the active acid sites, especially in the catalysts with smaller pore diameters and at lower temperatures. Increased significance of swelling at higher temperatures, especially with Amberlyst-36 which had lower cross-linking in its structure and less rigidity, contributed to the penetration of the reactants to the active sites. Water produced during the etherification reaction was also shown to cause deactivation of the catalysts by reversible adsorption on the acid sites.