纤维素快速降解并催化转化为5-羟甲基糠醛

采用类似室温离子液体的低温氯化锌熔盐为反应介质,在稀酸的催化下纤维素可快速降解为葡萄糖,而后通过补充二甲亚砜与不同的氯化物金属盐催化剂,可以实现葡萄糖转化为5-羟甲基糠醛, 并研究了其降解过程中的分子机制,探讨了不同金属催化剂的影响,最终得到的HMF的最大产率为53%．     

木质素催化转化制取苯、甲苯和二甲苯

对HZSM-5、HY和MCM-22三种催化剂进行了比较, 其中HZSM-5催化裂解木质素制备苯、甲苯和二甲苯(BTX)的结果最优．确定了木质素催化裂解的最佳反应条件,包括反应温度、载气流速、催化剂/木质素配比．当反应温度为550～600 oC,载气流速为300 mL/min,催化剂/木质素配比为2时,使用HZSM-5催化裂解制备BTX的最高C产率和芳香选择性分别可达25.3%和90.9%。     

水相生物油选择性加氢-催化裂解制取烯烃和芳香烃的试验研究

本文在气相流动反应器中采用ZSM-5催化剂对水相选择性加氢生物油进行了催化裂解试验研究。主要考察了反应温度、质量空速、油分压和原料油组分含量对产物产率和选择性的影响。结果表明,选择性加氢生物油转化为石油化工用品（烯烃和芳香烃）的最优工况为:反应温度,600℃;质量空速,11.7 h^-1;油分压,6693 Pa;油组分含量,12 5%。在此工况下,石油化工用品达到最高碳产率76 0%,其中烯烃57 6%,芳香烃18.4%。烯烃和芳香烃的产率及其主要成分的选择性可以根据市场的需求通过调节反应条件来改变。     

三维金属有机骨架/石墨烯水凝胶均相降解纤维素为小分子酸的研究

通过在三维还原氧化石墨烯孔径中原位生长ZIF-8纳米粒子,制备了三维金属有机骨架/石墨烯催化剂.这种ZIF-8/rGO纳米复合材料同时具有介孔和微孔,并且拥有高比表面积和大量催化位点,是生物质转化的理想催化剂.将纤维素溶解于氢氧化钠水溶液中,在水热条件下,使用这种催化剂,纤维素可以被充分降解转化.纤维素转化率可以达到100%,其主要产物是甲酸,产率最高可达93.66%.催化剂还可以被回收,重复使用依然具有很好的催化效果.     

生物质气经由二甲醚两步法制备低碳烯烃

制备出NiSAPO-34及NiSAPO-34/HZSM-5催化剂,考察了其对二甲醚催化转化制备低碳烯烃的性能．利用Cu/Zn/Al/HZSM-5和筛选出的2%NiSAPO-34/HZSM-5催化剂进行生物质气经由二甲醚两步法制备低碳烯烃的实验, 结果表明在SAPO-34上添加2%的Ni不改变其结构, 但降低了酸中心数量, 并生成了较强的酸中心． 添加少量具有稳定酸中心的HZSM-5, 该催化剂的活性提高到3 h以上, 反应进行2 h获得了最高的低碳烯烃选择性为90.8%． 当把该催化剂应用到两步催化转化过程的第二个反应器中, 其高催化活性可达5 h以上． 当以低氢碳比生物质气(H₂/CO/CO₂/N₂/CH₄=41.5/26.9/14.2/14.6/2.89)作为原料时,经两步转化,低碳烯烃的收率达到84.6 g/m³_syngas．     

含吡咯基亚胺配体钐金属配合物催化合成胍产物

稀土钐金属配合物[2-(2,4,6-Me3C6H2NCH)C4H3N]3Sm (THF)催化芳胺与N,N′-二环己基碳二亚胺反应,得到一系列的胍产物.研究了不同条件下钐金属配合物催化芳胺与N,N′-二环己基碳二亚胺反应的催化活性,探讨了温度、溶剂、反应时间和催化剂用量等因素对催化效果的影响.结果表明,该配合物具有良好的催化活性,在优化条件下均以高于85％的产率得到了相应的胍产物.     

纤维素和甲醇共催化热解制备对二甲苯（英文）

本文对纤维素和甲醇在不同金属氧化物改性的ZSM5催化剂作用下共催化快速热解实现一步制备可再生对二甲苯的过程进行了研究.结果表明,镧改性的ZSM5催化剂是生产生物基对二甲苯的有效催化剂.对二甲苯的选择性和产率主要由催化剂酸性、反应温度和甲醇含量决定.在20%La_2O_3-ZSM5(80)催化剂作用下,纤维素与33wt%甲醇共催化快速热解获得对二甲苯的最高收率和对二甲苯/二甲苯的最高比率分别为14.5 C-mol%和86.8%.本文详细研究了催化热解过程中催化剂的失活,基于产物的分析和催化剂的表征提出了由纤维素制备对二甲苯的可能反应途径.     

用低温电催化重整方法和CoZnAl催化剂进行低温生物油重整制氢

利用电化学催化重整方法和CoZnAl催化剂实现了高效的生物油重整制氢过程．研究了电流强度对氢气产率、碳转化率以及产物分布的影响．结果表明,通过催化剂的电流对氢气产量和碳转化率都有明显的促进作用,在500 oC低温重整条件下氢气产率和碳转化率分别达到大约70%和85%．此外,用XRD、XPS、TGA和BET研究了电流对催化剂的结构和性能的影响．结果表明,通电催化床中热电子对生物油中含氧有机物的重整反应起着重要的促进作用．     

二氧化硅改性分子筛催化生物质基多元醇制备对二甲苯

本文证明了在二氧化硅改性的分子筛催化作用下,生物质基多元醇(如山梨醇、木糖醇、赤藓糖醇、甘油和乙二醇)可以经过催化裂解、烷基化和异构化等反应,生成高附加值的化学品(对二甲苯).与HZSM-5分子筛催化剂相比,二氧化硅改性的分子筛降低了分子筛催化剂的外表面酸和孔径,从而显著的提高对甲苯的选择性和产率.本文详细讨论了催化剂、甲醇添加剂、反应温度和不同类型多元醇原料对对二甲苯选择性和产率的影响.甲醇的添加促进多元醇催化裂解中的烷基化反应,提高了二甲苯的产率.在15%SiO_2/HZSM-5催化剂作用下,对二甲苯的产率最高可达到10.9 C-mol%,对二甲苯在二甲苯中选择性达到91.1%.本文通过研究相关重要反应和催化剂特性,揭示了生物质基多元醇催化裂解制备对二甲苯的反应路径.     

纤维素和甲醇共催化热解制备对二甲苯

本文对纤维素和甲醇在不同金属氧化物改性的ZSM5催化剂作用下共催化快速热解实现一步制备可再生对二甲苯的过程进行了研究. 结果表明，镧改性的ZSM5催化剂是生产生物基对二甲苯的有效催化剂. 对二甲苯的选择性和产率主要由催化剂酸性、反应温度和甲醇含量决定. 在20%La₂O₃-ZSM5(80)催化剂作用下，纤维素与33wt%甲醇共催化快速热解获得对二甲苯的最高收率和对二甲苯/二甲苯的最高比率分别为14.5 C-mol%和86.8%. 本文详细研究了催化热解过程中催化剂的失活，基于产物的分析和催化剂的表征提出了由纤维素制备对二甲苯的可能反应途径.     

Sulfonated reduced graphene oxide as a highly efficient catalyst for direct amidation of carboxylic acids with amines using ultrasonic irradiation

Sulfonated reduced graphene oxide nanosheets (rGO-SO₃H) were prepared by grafting sulfonic acid-containing aryl radicals onto chemically reduced graphene oxide (rGO) under sonochemical conditions. rGO-SO₃H catalyst was characterized by Fourier-transform infrared (FT-IR) spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray photoelectron spectroscopy (XPS). rGO-SO₃H catalyst was successfully applied as a reusable solid acid catalyst for the direct amidation of carboxylic acids with amines into the corresponding amides under ultrasonic irradiation. The direct sonochemical amidation of carboxylic acid takes place under mild conditions affording in good to high yields (56–95%) the corresponding amides in short reaction times.     

合成Pb(OH)2/rGO催化剂用于催化转化糖为乳酸

Pb²⁺离子可以作为高效的催化剂用于降解糖为乳酸, 但是为了降低暴露Pb²⁺离子于环境中的风险,最好的办法是把铅固定在一个固体催化剂上．报道了一个简单的制备Pb(PbO₂)/石墨烯复合固体催化剂的方法,可以得到石墨烯负载的纳米铅催化剂,铅颗粒的尺寸在2～5 nm．获得的催化剂可以在水中用于降解葡萄糖、果糖甚至纤维素,产物主要为乳酸．对于果糖、乳酸的产率为58.7% (433 K,2.5 MPa N₂);当直接使用纤维素为原料,无额外酸、碱催化剂时,乳酸的产率可以达到31.7%.     

Acid functionalized,highly dispersed carbonaceous spheres: an effective solid acid for hydrolysis of polysaccharides

Highly dispersed carbonaceous spheres with sulfonic acid groups were successfully prepared from glucose by hydrothermal method. Transmission electron microscopy (TEM) showed the as-synthesized carbonaceous materials were uniform, spherical in shape with an average diameter of about 450 nm. Fourier transform infrared (FT-IR) proved that –SO₃H, –COOH, OH groups were grafted on the surface of the carbonaceous spheres during the sulfonation. Interestingly, the functionalized carbonaceous spheres exhibited high dispersibility in the polar solvent due to the hydrophilic groups on the surface. The mechanism of the formation for the carbonaceous spheres was also discussed based on the analysis of structure and composition. At last, the functionalized carbonaceous spheres were employed as solid acid to hydrolyze starch and cellulose. By comparison, the as-synthesized catalyst showed considerable high yield of glucose.     

水-四氢呋喃混合溶剂中硫酸氢钠催化生物质转化制备5-羟甲基糠醛及糠醛

报道了在水-四氢呋喃组成的混合溶剂中,采用硫酸氢钠催化各种生物质原料(玉米芯、玉米秸秆、麦秆、稻秆和甘蔗渣)制备重要的生物质基平台化学品5-羟甲基糠醛和糠醛的研究. 考察了反应温度(160～200 oC)、反应时间(30～120 min)、水与四氢呋喃的溶剂比例(1:1～1:10)和原料质量分数(2.4wt%～11.1wt%)等反应工艺的影响.在优化的工艺条件下(190 oC, 90 min, 10:1 THF:H₂O),转化玉米芯得到了47mol%的HMF和56mol%的糠醛. 此外,原料中的木质素也被有效地转化为有机溶木质素.     

Post-modified acid-base bifunctional MIL-101(Cr) for one-pot deacetalization-Knoevenagel reaction

A novel and convenient approach for the construction of the bifunctional MIL-101 material bearing sulfonic acid and amino groups was established via the post-synthetic modification. This material possesses high BET surface area (1446 m²/g) and large pore volume (0.77 cm³/g). Significantly, this material could serve as a bifunctional heterogeneous catalyst and was initially employed for one-pot deacetalization-Knoevenagel reaction, exhibiting excellent catalytic performance (yield 99.74%). More importantly, it can be easily recovered and reused at least three times. Finally, our proposed catalytic mechanism indicated that amino and the sulfonic acid groups played a synergistic effect on this one-pot deacetalization-Knoevenagel reaction.     

The use of acids,niobium oxide,and zeolite catalysts for esterification reactions

We have evaluated the influence of alcohol/fatty acid molar ratio (methanol or ethanol), water and catalyst concentrations and temperature by the esterification of palm fatty acids by heterogeneous acid catalysts (varying types, forms, and particle size). Polynaphtalene sulfonic acid (PSA) and niobium oxide (Nb₂O₅) presented better performance than zeolite catalysts. Reaction with methanol presented higher conversion than with ethanol. The experimental design showed that the most relevant variable is the catalyst concentration and all interactions become important in process. A heterogeneous kinetic model was proposed and applied to experimental data. One of the models was adequate for methanol reaction, whereas the homogeneous model was more appropriate for ethanol reaction. Copyright © 2009 John Wiley & Sons, Ltd.     

Rapid esterification of fatty acid using dicationic acidic ionic liquid catalyst via ultrasonic-assisted method

Biodiesel production via esterification/transesterification reactions can be catalyzed by homogenous or heterogeneous catalysts. Development of heterogeneous catalysts for biodiesel production is highly advantageous due to the ease of product purification and of catalyst recyclability. In this current work, a novel acidic [DABCODBS][CF₃SO₃]₂ dicationic ionic liquid (DIL) was used as heterogeneous catalyst to produce biodiesel using oleic acid as model oil. The esterification was conducted under ultrasonic irradiation (20 kHz) using a 14 mm ultrasonic horn transducer operated at various duty cycles. It was observed that the duty cycle, amplitude, methanol to oil molar ratio, catalyst amount and reaction temperature were the major factors that greatly impact the necessary reaction time to lead to a high yield of biodiesel. The reaction conditions were optimized with the aid of Response Surface Methodology (RSM) designed according to the Quadratic model of the Box Behnken method. The optimum conditions were found to be at catalyst amount of 0.64 mol%, methanol to oil ratio of 14.3:1, temperature of 59 °C, reaction time of 83 min and amplitude of 60% in continuous mode. The results showed that the oleic acid was successfully converted into esters with conversion value of 93.20% together with significant reduction of reaction time from 7 h (using mechanical stirring) to 83 min (using ultrasonication). The results also showed that the acidic DIL catalyst we designed purposely was efficient to catalyze the ultrasonic-assisted esterification yielding high conversion of oleic acid to methyl oleate on short times. The DIL was also recycled and reused for at least five times without significant reduction in performance. Overall, the procedure offers advantages including short reaction time, good yield, operational simplicity and environmentally benign characteristics.     

Ultrasound assisted synthesis of performic acid in a continuous flow microstructured reactor

The present work establishes in depth study of ultrasound assisted preparation of performic acid (PFA) in a continuous flow microstructured reactor. The influence of various parameters viz. formic acid: hydrogen peroxide molar ratio, flow rate, temperature and catalyst loading on the PFA formation were studied in a continuous flow microstructured reactor. In a continuous microstructured reactor in the presence of ultrasonic irradiation, the formation of PFA was found to be dependent on the molar ratio of formic acid: hydrogen peroxide, flow rate of reactants, temperature and catalyst loading (Amberlite IR-120H). The optimized parameter values are 1:1 M ratio, 50 mL/h, 40 °C and 471 mg/cm³ respectively. Further, the performance of Amberlite IR-120H catalyst was evaluated for three successive cycles in continuous microstructured reactor. The performance of catalyst was found to be decreased with the usage of the catalyst and is attributed to neutralization of the sulfonic acid groups, catalyst shrinkage, or loss in pore sites. The experimental results revealed that, for an ultrasound assisted synthesis of PFA in continuous microstructured reactor the observed reaction time was even less than 10 min. The observed intensification in the PFA synthesis process can be attributed to the intense collapse of the cavities formed at low temperature during ultrasonic irradiations, which further improved the heat and mass transfer rates with the formation of H₂O₂ during the reaction. The combined use of ultrasound and a continuous flow microstructured reactor has proved beneficial process of performic acid synthesis.