Hydrolysis of mechanically pre-treated cellulose catalyzed by solid acid SO_4~(2-)-TiO_2 in water–ethanol solvent

An efficient catalyst SO_4~(2-)-TiO_2(ST) from industrial metatitanic acid has been successfully prepared to catalyze hydrolysis of ball-milling cellulose. The results show that the highest catalytic efficiency is obtained for ST calcined at 450 °C(ST-450) with the yield of 21.8% glucose, 13.0% 5-HMF and 4.2% furfural at 200 °C for30 min. The ball milling of cellulose and solid acid catalyst significantly enhances the cellulose hydrolysis. The high Lewis to Br?nsted acid sites ratio for ST-450 induced by bidentate ligands between SO_4~(2-)and TiO_2 benefits high organics yield, and high total acid sites contribute to the high cellulose conversion. The large pore volume of0.29 cm~3·g~(-1) and appropriate pore size of 7.35 nm of ST-450 also contribute to the high performance. High reaction temperature over 200 °C exhibits negative effect on glucose and 5-HMF yield due to undesired side reactions, while furfural product is stable in the reaction system. The bidentate ligands between SO_4~(2-)and TiO_2 are considered as active acid sites for cellulose hydrolysis in water–ethanol solvents.     

Postsynthetic acid modification of amino-tagged metal-organic frameworks: Structure-functionrelationship for catalytic 5-hydroxymethylfurfural synthesis

Developing an efficient and selective catalyst for the dehydration of fructose to 5-hydroxymethylfurfural (HMF) is significant for biomass conversion. Herein, a metal-organic framework (MOF) with acidity and strong hydrophobicity is first reported by the condensation of amino-tagged MOFs with mercapto carboxylic acids and subsequent oxidation. The hydrophobic acidic MOFs possess acid densities ranging from 0.2-1.0 mmol·g^-1, H₂O contact angles of 114°-125°, and specific surface areas above 260 m²·g^-1. Compared to the methyl sulfo-functionalized MOF, the benzene sulfo-functionalized MOF with a strong hydrophobicity shows much higher activity and selectivity for the conversion of fructose to 5-hydroxymethylfurfural. In particular, 2.99% (mass) UiO-PhSO₃H shows the best catalytic performance with a 90.4% HMF yield due to its suitable hydrophobicity and abundant acidic sites. Moreover, the catalyst shows great stability after recycling for 5 runs. This work provides an interesting design strategy for the preparation of hydrophobic acidic MOFs and shows the powerful synergistic effect of acidity and hydrophobicity.     

Functionalized metal–organic frameworks with strong acidity and hydrophobicity as an efficient catalyst for the production of 5-hydroxymethylfurfural

In the dehydration of fructose to 5-hydroxymethyl furfural(HMF), in situ produced water weakens the acid strength of the catalyst and causes the rehydration of HMF, causing unsatisfactory catalytic activity and selectivity. In this work, a class of benzenesulfonic acid-grafted metal–organic frameworks with strong acidity and hydrophobicity is obtained by the direct sulfonation method using 4-chlorobenzenesulfonic acid as sulfonating agent. The resultant MOFs have a specific surface area of greater than 250 m~2·g~(-1), acid density above 1.0 mmol·g~(-1), and water contact angle up to 129°. The hydrophobic MOF-Ph SO_3 H exhibits both higher catalytic activity and selectivity than MOF-SO_3 H in the HMF synthesis due to its better hydrophobicity and olephilicity. Moreover, the catalyst has a high recycled stability. At last, fructose is completely converted, and 98.0% yield of HMF is obtained under 120 °C in a DMSO solvent system. The successful preparation of the hydrophobic acidic MOF provides a novel hydrophobic catalyst for the synthesis of HMF.     

硝酸胶溶剂对CuO/HZSM-5成型催化剂性能的影响

催化剂CuO/HZSM-5在氧化亚氮(N₂O)催化分解领域有着重要地位,完成对催化剂成型条件的探索是其工业实际应用的重要步骤。在CuO/HZSM-5成型过程中,胶溶剂的用量对成型催化剂的机械强度,催化活性以及其他物化性质有重要的影响。通过机械强度测定、活性评价、X射线衍射分析(XRD)、孔结构分析、氨气程序升温吸附脱附分析(NH₃-TPD)、氢气程序升温还原分析(H₂-TPR)等手段对催化剂性能进行分析。机械强度测定与NH₃-TPD分析结果显示,胶溶剂用量对成型催化剂机械强度和酸量影响较大,胶溶剂用量为体积分数2%时,机械强度最高为135.8 N·cm^-1,而催化剂酸量在胶溶剂用量为体积分数7%时最高。XRD与孔结构分析结果显示胶溶剂用量由0增长至体积分数7%,催化剂的孔容积改变幅度较小,但比表面积由277 cm²·g^-1增至293 cm²·g^-1,HZSM-5的特征峰变化较小。活性评价与H₂-TPR分析结果显示,胶溶剂用量为0的催化剂与添加胶溶剂后的成型催化剂,N₂O完全分解的温度提高幅度最大为20 ℃,活性下降,且H₂-TPR中还原峰提高幅度最大为27 ℃,可还原性变差。而胶溶剂用量由体积分数2%提高至7%,成型催化剂CuO/HZSM-5的催化活性以及可还原性差异较小。     

Au基MOFs双功能催化剂的制备及其催化CO2与苯胺/H2反应性能

以UiO-66(Zr)、MIL-100(Fe)、MIL-100(Cr)、MIL-101(Cr)、NH 2-MIL-101(Al)为载体,Au为活性组分,制备Au/UiO-66(Zr)、Au/MIL-100(Fe)、Au/MIL-100(Cr)、Au/MIL-101(Cr)、Au/NH 2-MIL-101(Al)双功能催化剂。采用XRD、BET、NH 3-TPD、HRTEM等表征催化剂的结构,在釜式反应器中评价催化剂对CO 2与苯胺/H 2反应生成N-甲基苯胺与N,N-二甲基苯胺的N-甲基化反应性能,考察反应条件对催化剂催化性能的影响。结果表明,催化剂的XRD特征衍射峰与相应MOFs的模拟特征峰基本一致;负载Au后催化剂仍具有高的比表面积和大的孔容、孔径;不同MOFs负载Au的催化剂具有不同的酸强度和酸量;Au纳米粒子的分散性很好,粒径为(3~7)nm。制备的催化剂均具有催化CO2与苯胺/H2的N-甲基化反应性能,其中质量分数2%Au/MIL-101(Cr)催化剂催化性能最好,苯胺转化率为45.26%,N-甲基苯胺和N,N-二甲基苯胺选择性分别为73.50%和26.50%,重复使用性能优异。     

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。     

缺陷UiO-66对水中塑化剂的吸附

金属有机骨架材料（metal-organic frameworks,MOFs）是一种具有骨架结构的新型多孔材料。本研究合成了金属有机框架化合物UiO-66和有缺陷的UiO-66（UiO-66-1）,并研究了其作为吸附剂吸附塑化剂邻苯二甲酸二甲酯（DMP）的性能及其吸附动力学,最后通过拟合吸附等温线和吸附动力学模型拟合了吸附剂的最大吸附量和最快吸附时间。实验结果表明,UiO-66-1对DMP有更好的吸附性能,在5~10min内快速达到吸附平衡,pH在3~10吸附率仍可保持稳定;分析测试结果表明,引入缺陷的UiO-66-1的比表面积比UiO-66大,达到了1438m²/g,孔容为0.58cm³/g,晶体的尺寸也明显增大,吸附量增大了近一倍,最大吸附量可达到404mg/g,且循环利用率高;通过吸附等温线模型和吸附动力学模型的拟合研究表明,UiO-66-1的吸附过程比较符合Langmuir模型和拟二级动力学模型。     

Ca-γ-Al2O3耦合酸溶液催化葡萄糖制5-HMF

针对以葡萄糖为原料制备5-羟甲基糠醛（5-HMF）的问题,开发了CaO杂化的γ-Al₂O₃球形颗粒[Ca-γ-Al₂O₃,粒径1.8（±0.1） mm]耦合酸溶液制备过程,采用XRD与BET对Ca-γ-Al₂O₃球形颗粒进行了表征,研究了CaO杂化量、溶剂酸浓度、溶剂中二甲基亚砜（DMSO）与水的比例、催化剂用量、反应温度与时间对反应效果的影响,并评价了Ca-γ-Al₂O₃的操作稳定性,探讨了催化机理。实验结果表明：CaO的杂化（杂化量10%）对颗粒的孔结构影响相对较小,且在Ca-γ-Al₂O₃上分布较为均匀。在0.05 mol·L^-1酸浓度、V（DMSO）/V（H₂O）=3∶1、葡萄糖与催化剂比例为2∶1（125 mg∶63 mg）、反应温度140℃与反应时间3 h下,以Ca （5%）-γ-Al₂O₃为催化剂,葡萄糖转化率为100%,5-HMF收率最高为58.6％。此外,Ca-γ-Al₂O₃循环操作（未煅烧）5次后,5-HMF收率略有降低至55％左右,同时杂化负载方式使得CaO在酸性溶液中的泄露较低,表明Ca-γ-Al₂O₃具有良好的操作稳定性。催化剂机理分析表明,Ca-γ-Al₂O₃具有良好的葡萄糖异构化能力,CaO的杂化可提高催化剂与葡萄糖的相互作用,果糖脱水过程主要依赖于酸溶液的催化。     

Structured hierarchical Mn-Co mixed oxides supported on silicalite-1 foam catalyst for catalytic combustion

Silicalite-1 (S1) foam was functionalized by supporting manganese-cobalt (Mn-Co) mixed oxides to develop the structured hierarchical catalyst (Mn-Co@S1F) for catalytic combustion for the first time. The self-supporting S1 foam with hierarchical porosity was prepared via hydrothermal synthesis with polyurethane (PU) foam as the template. Subsequently, Mn-Co oxide nano sheets were uniformly grown on the surface of S1 foams under hydrothermal conditions to prepare the structured hierarchical catalyst with specific surface area of 354 m²·g^-1, micropore volume of 0.141 cm³·g^-1 and total pore volume of 0.217 cm³·g^-1, as well as a good capacity to adsorb toluene (1.7 mmol·g^-1 at p/p₀ = 0.99). Comparative catalytic combustion of toluene of over developed structured catalyst Mn-Co@S1F was performed against the control catalysts of bulk Mn-Co@S1 (i.e., the crushed Mn-Co@S1F) and unsupported Mn-Co oxides (i.e., Mn-Co). Mn-Co@S1F exhibited comparatively the best catalytic performance, that is, complete and stable toluene conversion at 248 °C over 65 h due to the synergy between Mn-Co oxides and S1 foam, which provided a large number of oxygen vacancies, high redox capacity. In addition, the hierarchical porous structure also improved the accessibility of active sites and facilitated the global mass transfer across the catalyst bed, being beneficial to the catalysis and catalyst longevity.     

过氧化氢氧化再生纤维素及其阻燃、吸附性能

以过氧化氢氧化再生纤维素(GC)制备羧基再生纤维素(OGC),表征OGC结构变化及其对阻燃和吸附性能影响机理。通过碱泡预处理能有效提高GC比表面积,增加反应效率,获得羧基含量达15.6%的OGC。FT-IR和¹³C NMR表征结果说明OGC葡萄糖基环上的C₆位伯羟基能被选择性氧化成羧基。随着羧基含量的提高,OGC无定形部分溶解而提高其结晶度,晶型则无显著变化,OGC的热分解温度下降,但是成炭率显著提高。当添加6.25%OGC为成炭剂用于环氧树脂膨胀型阻燃时,氧指数达到27.2,阻燃等级为V0。以火焰原子吸收分光光度法测定结果表明,当羧基含量为15.6%,OGC对铅和铜离子吸附量分别提高14倍和3.5倍,其原因在于氧化改性能显著提高OGC的比表面积和容积率,增加吸附容量。研究结果说明以过氧化氢氧化制备的OGC在阻燃成炭剂以及金属离子吸附领域中具有良好的应用前景。     

One Step Preparation of Sulfonated Solid Catalyst and Its Effect in Esterification Reaction

A carbon-based sulfonated catalyst was prepared by direct sulfonation and carbonization （in moderate conditions：200 ＆#176;C, 12 h） of red liquor solids, a by-product of paper-making process. The prepared sulfonated cata-lyst （SC） had aromatic structure, composed of carbon enriched inner core, and oxygen-containing （SO3H, COOH, OH） groups enriched surface. The SO3H, COOH, OH groups amounted to 0.74 mmol·g^-1, 0.78 mmol·g^-1, 2.18 mmol·g^-1, respectively. The fresh SC showed much higher catalytic activity than that of the traditional solid acid catalysts （strong^-acid 732 cation exchange resin, hydrogen type zeolite socony mobile-five （HZSM-5）, sulfated zir-conia） in esterification of oleic acid. SC was deactivated during the reactions, through the mechanisms of leaching of sulfonated species and formation of sulfonate esters. Two regeneration methods were developed, and the catalytic activity can be mostly regenerated by regeneration Method 1 and be fully regenerated by regeneration Method 2, respectively.     

Defective NH2-UiO-66 (Zr) effectively converting CO2 into cyclic carbonate under ambient pressure,solvent-free and co-catalyst-free conditions

In this study, a series of metal–organic frameworks (MOFs) NH₂-UiO-66-xHAc catalysts were synthesized by solvothermal method using acetic acid (HAc) as a modulator, and were applied to the cycloaddition of CO₂ and epichlorohydrin (EPIC) under ambient pressure. Influences of the modulation by HAc on morphologies and structures of the MOFs are demonstrated via PXRD, FESEM, FTIR, N₂ adsorption–desorption, XPS and ¹H NMR characterizations. The results show that the MOFs containing mesoporous pores can be prepared by adjusting the concentration of HAc. By optimizing the amount of HAc added, the specific surface area of NH₂-UiO-66-8HAc is as high as 879.17 m²·g^-1, which is 28.3% higher than that of the original MOFs. And the evaluation of catalytic performance showed that HAc modulation enhanced the activity of NH₂-UiO-66-xHAc under mild conditions. The exposure of Lewis acid sites, increased specific surface area and porosity via the modulation of HAc defective ligand can be supposed the key factors to determine the enhanced catalytic activities. In addition, considering the influence of gas concentration on the reaction, the concept of TOP (Turnover of Pressure, defined as the mass of conversions of a unit mass catalyst under unit pressure and unit time) was first proposed in this article.     

Ce修饰Na Y分子筛负载PdO纳米晶催化剂用于苯的催化氧化反应

以CeO_2修饰多孔NaY分子筛作为载体,采用高温液相还原法制备纳米晶PdO催化剂,用于低浓度苯催化氧化反应。采用XRD、N2吸附-脱附、透射电镜-能谱(HRTEM-EDS)、H2程序升温还原(H_2-TPR)、O_2程序升温脱附(O_2-TPD)和程序升温表面反应(TPSR)等对载体和催化剂进行表征。结果表明,NaY分子筛结构稳定,比表面积651 m~2·g~(-1)和孔容0. 326 cm~3·g~(-1),纳米晶PdO能够较均匀地分散在NaY载体上,颗粒尺寸约(3～5) nm。加入一定量CeO_2后,Pd O以较小的纳米晶颗粒形式分散在CeO_2周围,活性组分与助剂协同作用促进了催化剂中晶格氧的流动性,明显改善了0. 2%Pd/NaY的氧化性能。0. 2%Pd/8%Ce/NaY表现出最佳催化活性和良好稳定性,250℃可完全催化降解1000×10~(-6)的苯,并且230℃连续反应100 h,催化剂转化率稳定在86%。     

葡萄糖基多孔碳材料对CO2/CH4的分离性能

以淀粉糖（主要成分为葡萄糖）为碳前体,制备了一系列多孔碳材料（C-GLCs-800）,对其进行孔隙结构分析,并应用FT-IR、SEM、TGA对其进行了表征,测定了材料在288、298和308 K下的CO₂和CH₄吸附等温线,根据IAST理论预测了材料对CO₂/CH₄二元体系的吸附选择性。实验结果显示,活化条件对材料的孔隙结构有明显影响,随着KOH/C质量比的增加,所制备的C-GLCs-800比表面积和总孔容先增加后降低。其中C-GLC-800-4的BET比表面积高达3153 m²·g^-1,总孔容为2.056 cm³·g^-1。C-GLC-800-2的窄微孔（V_d<1 nm,孔容0.3538 cm³·g^-1）含量最高,为30.63%。C-GLC-800-2在298 K和10⁵ Pa下对CO₂吸附量高达3.96 mmol·g^-1,明显高于许多传统吸附材料和MOFs材料在相同条件下对CO₂的吸附容量。应用Clausiuse-Clapeyron方程计算了CO₂和CH₄在材料上的吸附热,应用IAST理论计算了CO₂/CH₄的吸附选择性,结果显示C-GLC-800-2对CO₂/CH₄的吸附选择性为8.35。     

纤维素基生物质多孔炭的制备及其超级电容器性能研究

以棉纤维素为原料,采用硝酸盐、尿素、纤维素共混后热裂解的方法制备分级多孔炭HPC样品,通过改变煅烧温度和KOH活化处理对多孔炭比表面积及孔结构进行调控。对比三个不同温度煅烧活化处理后样品的循环伏安曲线、恒电流充放电曲线、比容量等电化学参数,结果表明,4AC@HPC800样品作为超级电容器工作电极具有优良的电化学性能,其比表面积高达2433.8 m²·g^-1,在1 A·g^-1的电流密度下比容量高达234.7 F·g^-1,在大电流密度10 A·g^-1时依然有207.6 F·g^-1的比容量,具有良好的倍率性能;电极在2 A·g^-1的电流密度下循环10000次后依然有196.1 F·g^-1的比容量,表明其具有长时工作的特性。     

废轮胎热解炭低温催化焦油重整制备富氢气体的研究

以全钢型废旧轮胎为原料，通过热解、活化、浸渍、焙烧的流程制备了三种热解炭催化剂，分别为轮胎热解炭（Raw char）、轮胎热解活性炭（AC）和负载Zn的活性炭（Zn/AC）。采用N₂吸/脱附、SEM、EDS、XRD等表征方法对催化剂进行了一系列表征和分析，发现CO₂/H₂O活化可显著提高催化剂BET比表面积，最高可达380 m²·g^-1，有效改善催化剂表面结构性质，同时浸渍法使催化剂表面负载大量ZnO活性位。对三种催化剂在纤维素热解焦油重整制氢过程中的催化性能进行了研究，发现Raw char（600℃）具有最佳催化效果，相较于空白组（500℃），热解气中H₂体积分数提高了12.4%，达到19.3%，其次为Zn/AC（500℃）组的17.8%，实现了低温下催化纤维素焦油热解制得高产率H₂。     

生物质转化制5-羟甲基糠醛的酸催化研究新进展

5-羟甲基糠醛（5-HMF）是一种重要的平台化合物,可转化为一系列重要有机化工原料、医药中间体、农药产品等。本文综述了近5年来国内外以纤维素、淀粉、菊糖、蔗糖、果糖、葡萄糖和农林废物等生物质为原料,在不同酸催化下制备5-羟甲基糠醛的一些特色工作,分析比较了不同酸催化反应体系的优缺点,并建议在制备5-HMF的过程中应加强催化材料的绿色设计、催化剂循环利用的工程研究和农林副产物的复合催化液化工艺的探索,以促进生物质制备5-HMF工业技术的发展。     

纤维素基生物质多孔炭的制备及其超级电容器性能研究

以棉纤维素为原料,采用硝酸盐、尿素、纤维素共混后热裂解的方法制备分级多孔炭HPC样品,通过改变煅烧温度和KOH活化处理对多孔炭比表面积及孔结构进行调控。对比三个不同温度煅烧活化处理后样品的循环伏安曲线、恒电流充放电曲线、比容量等电化学参数,结果表明,4AC@HPC800样品作为超级电容器工作电极具有优良的电化学性能,其比表面积高达2433.8 m²·g^-1,在1 A·g^-1的电流密度下比容量高达234.7 F·g^-1,在大电流密度10 A·g^-1时依然有207.6 F·g^-1的比容量,具有良好的倍率性能;电极在2 A·g^-1的电流密度下循环10000次后依然有196.1 F·g^-1的比容量,表明其具有长时工作的特性。     

机械化学法合成金属有机骨架材料HKUST-1及其吸附苯性能

金属有机骨架材料是一类新兴纳米多孔功能材料,研究出一种绿色环保的制备和活化金属有机骨架材料方法对于其工业应用具有重要的意义。应用机械化学法合成金属有机骨架材料(HKUST-1),并提出采用乙醇对所合成的材料进行活化和纯化,讨论不同溶剂(氯仿、乙醇)活化对合成的HKUST-1的孔隙结构和吸附性能的影响。研究结果表明:相对于传统水热法合成时间(24 h),无溶剂机械化学法反应时间缩短为30 min;活化溶剂对HKUST-1的比表面积和孔结构有较大的影响,乙醇比氯仿更容易置换出HKUST-1孔道中残留的前驱物,增大材料的比表面积,乙醇活化得到的HKUST-1比表面积高达1442.7 m²·g^-1。在298 K、8 kPa条件下,乙醇活化得到的HKUST-1对苯的吸附容量高达6.90 mmol·g^-1,比氯仿活化和水热法合成的HKUST-1对苯的吸附量高约25%,而且高于同等温度压力条件下活性炭、碳分子筛、沸石等常规吸附剂对苯的平衡吸附量。     

Synthesis of silica powder with high pore volume by skeleton reinforcement

In this paper, a method composed of gelation of basic skeleton (first step) and skeleton reinforcement process (second step) was introduced to synthesize silica powder with high pore volume through the reaction between water glass and sulfuric acid. No organic solvents were involved in the entire preparation process and the final product was collected by spray drying. The effect of concentration of base solution, gelation point pH value and skeleton reinforcement time on the BET specific surface area and pore volume of the prepared silica powder were investigated intensively. The results show that, a basic skeleton with good dispersibility and high porosity was obtained when the concentration of base solution was 0.1 mol·L^-1 and the gelation pH value reached 6.5. Then the basic skeleton grew into a more uniform porous structure after 30 min skeleton reinforcement. Under these optimum conditions, silica powder prepared by skeleton reinforcement method had a BET specific surface area of 358.0 m²·g^-1, and its pore volume reached 2.18 cm³·g^-1, which was much higher than that of prepared by skeleton-free method (1.62 cm³·g^-1) and by direct gelation method (0.31 cm³·g^-1).