ZnCl_2溶液中微波辅助SnCl_4催化纤维素制备5-HMF

将纤维素溶解在ZnCl_2溶液中,以SnCl_4为催化剂,微波下使纤维素降解成5-羟甲基糠醛(5-HMF)。实验考察了微波功率、纤维素的质量、ZnCl_2溶液浓度、反应时间及催化剂与纤维素物质的量比等对5-HMF产率的影响。结果表明,以SnCl_4为催化剂,在优化条件:1.0 g纤维素溶解在100 m L 70%ZnCl_2溶液中,微波功率为420 W,降解反应9 min,SnCl_4与纤维素物质的量比2∶1下,5-HMF的产率达到39.4%。     

Rapid conversion of cellulose to 5-hydroxymethylfurfural using single and combined metal chloride catalysts in ionic liquid

Direct conversion of cellulose into 5-hydroxymethylfurfural(HMF) was performed by using single or combined metal chloride catalysts in 1-ethyl-3-methylimidazolium chloride(Cl) ionic liquid.Our study demonstrated formation of 2-furyl hydroxymethyl ketone(FHMK),and furfural(FF) simultaneously with the formation of HMF.Various reaction parameters were addressed to optimize yields of furan derivatives produced from cellulose by varying reaction temperature,time,and the type of metal chloride catalyst.Catalytic reaction by using FeCl3 resulted in 59.9% total yield of furan derivatives(HMF,FHMK,and FF) from cellulose.CrCl3 was the most effective catalyst for selective conversion of cellulose into HMF(35.6%) with less concentrations of FHMK,and FF.Improving the yields of furans produced from cellulose could be achieved via reactions catalyzed by different combinations of two metal chlorides.Further optimization was carried out to produce total furans yield 75.9% by using FeCl3/CuCl2 combination.CrCl3/CuCl2 was the most selective combination to convert cellulose into HMF(39.9%) with total yield(63.8%) of furans produced from the reaction.The temperature and time of the catalytic reaction played an important role in cellulose conversion,and the yields of products.Increasing the reaction temperature could enhance the cellulose conversion and HMF yield for short reaction time intervals(5~20 min).     

Oxidative Dehydrogenation of 1-Butene to 1,3-Butadiene Using CO2 over Cr-SiO2 Catalysts Prepared by Sol-gel Method

A series of Cr-SiO₂ catalysts with a Cr content(mass fraction) ranging from 0.5% to 9% was prepared by a sol-gel method. The catalysts were characterized by XRD, N₂ adsorption, EDX elemental mapping, Raman spectroscopy, UV-Vis spectroscopy, XPS and H₂-TPR, and their catalytic behavior in the dehydrogenation of 1-butene to 1,3-butadiene(BD) using CO₂ as a soft oxidant was studied. The initial BD yield is well correlated with the amount of Cr⁶⁺ in the fresh catalysts. The highest BD yield of ca. 34% is achieved on the catalysts with 5%-9% Cr at 600℃ and weight hourly space velocity(WHSV) of 4.5 g·g_cat^-1·h^-1. The promoting effect of CO₂ on the BD yield was observed, which can be attributed to the reaction coupling between a simple dehydrogenation of 1-butene and the reverse water-gas shift reaction as well as regaining the oxidation state(lattice oxygen) of reduced Cr³⁺ species due to the mild oxidation ability of CO₂. The Cr-SiO₂ catalyst exhibits higher BD yield than the Cr catalyst supported on SBA-15, which is attributed to the higher amount of Cr⁶⁺ present on the former catalyst.     

离子液体中树脂催化转化果糖为5-羟甲基糠醛

开发了以离子液体1-丁基-3-甲基咪唑氯盐([BMIM]Cl)为溶剂, 固体酸离子交换树脂NKC-9为催化剂转化果糖为5-羟甲基糠醛的绿色工艺. 在此催化体系中, 100 ℃下反应10 min时5-HMF的产率达到78.0%, 其反应时间远远小于已有文献报道的长达数小时的反应时间. 在此催化体系中, 果糖起始浓度的增加对5-HMF产率影响不大, 因而此工艺同样适用于处理高浓度的果糖溶液. 离子液体[BMIM]Cl和树脂组成的催化体系可以循环使用, 经过9次重复使用后仍能保持稳定的催化活性.     

钯-高分子载体催化剂对糠醛加氢液相反应的研究

以弱碱性苯乙烯系阴离子交换树脂[D392,-NH₂,D382,-NHCH₃,D301R,-NH(CH₃)₂],强碱性苯乙烯系阴离子交换树脂[201×7DVB,-NH⁺(CH₃)₃]和弱碱性环氧系阴离子交换树脂(701,-NH₂)为载体制备了3种钯-高分子载体催化剂.考察了反应条件、高分子载体的种类、钯含量和催化剂用量对糠醛催化加氢生成四氢糠醇反应及催化性能的影响.在体积分数为50%的乙醇-水溶液和水中对糠醛常压液相加氢反应,钯-高分子载体(阴离子交换树脂D392,-NH₂,D382,-NHCH₃)催化剂均可使糠醛的加氢反应转化率达100%,生成四氢糠醇的选择性达98%以上,而用金属钯为催化剂的转化率达70%以上,选择性达97%以上.同时用XPS分析了高分子载体催化剂的结构与催化加氢反应性能的关系.     

Reactions of 2-phenylpyrrole with bromobenzoylacetylene on metal oxides active surfaces

The solvent-free interaction of 2-phenylpyrrole with bromobenzoylacetylene (room temperature) upon their grinding with solid metal oxides (MgO, CaO, ZnO, BaO, Al₂O₃, TiO₂, ZrO₂) and salts (CaCO₃, ZrSiO₄) leads to either the cross-coupling product or the adduct of pyrrole addition to the riple bond of acetylene. The ethynylation is accompanied by the formation of intermediate and side products: E-2-(1-bromo-2-benzoylethenyl)-5-phenylpyrrole and 1,1-di(5-phenylpyrrol-2-yl)-2-benzoylethene. The activity of the metal oxides in the ethynylation reaction falls in the order (in the brackets, the content of 2-benzoylethynyl-5-phenylpyrrole in the reaction mixture is given): ZnO (81%), BaO (73%), Al₂O₃ (71%), MgO (69%), CaO (50%). The oxides, SiO₂, TiO₂, ZrO₂, and the salts, CaCO₃ and ZrSiO₄, are inactive in the ethynylation reaction affording only the intermediate adduct, with ZrO₂ the isolated yield of the bromoethenylpyrrole reaching 60%. ESR monitoring shows the reaction to start from one electron transfer from pyrrole to acetylene mediated by the oxide surface. The adduct is readily converted on Al₂O₃ to 2-(benzoylethynyl)-5-phenylpyrrole crystallized mostly as cis-rotamer (X-ray data).     

由N-酰基-a-氨基酸合成5(4H)-噁唑酮的新方法

在碳酸钾、丙酮的水溶液中由N-酰基四氢噻唑-2-硫酮进行氨基酸解得到10种N-酰基-α-氨基酸Ⅰ_a-j发现在三聚氯氰及三乙胺存在下,由N-酰基-α-氨基酸环合成8种饱和5(4H)-噁唑酮Ⅱ_a-h的新方法,进而在硫酸铁催化下得到10种不饱和5(4H)-噁唑酮衍生物Ⅲ_a-j     

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。     

2-甲硫基-4-羟基-5-嘧啶甲酸乙酯的工艺优化

以S-甲基异硫脲半硫酸盐和乙氧基亚甲基丙二酸二乙酯为主要原料,乙醇为溶剂,合成出2-甲硫基-4-羟基-5-嘧啶甲酸乙酯,研究了2-甲硫基-4-羟基-5-嘧啶甲酸乙酯的工艺优化,考察了投料比、反应温度、反应时间等因素对产率的影响。 获得较好的反应条件:n(C₂H₆N₂S·1/2H₂SO₄):n(C₁₀H₁₆O₅):n(NaOH)=1.2:1:1.8,在室温下缓慢滴加NaOH溶液,搅拌反应6 h,酸化得白色固体产物,产率为81.1%。产物结构经熔点测定仪、¹H NMR、ESI-MS、FT-IR等技术手段得到验证。     

高被引文章

A Cu₃(BTC)₂ (copper(Ⅱ) benzene 1, 3, 5-tricarboxylate) metal organic framework (MOF) catalyst was successfully prepared through an electrochemical route and used for selective catalytic reduction of nitrogen oxide (NO_x) with NH₃ for the first time. After systematically optimizing the reaction conditions such as solvents, voltage, electrolyte concentration, and reaction time, pure Cu₃(BTC)₂ with high crystallinity was obtained in 97.2% yield. The physicochemical properties of the catalyst were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Raman spectroscopy, in situ Fourier transform infrared (FTIR) spectroscopy, temperature-programmed desorption (TPD), and X-ray photoelectron spectroscopy (XPS). TGA results indicated that the framework was stable up to 310℃. The catalytic activity of Cu₃(BTC)₂ was evaluated using NO conversion as a model reaction. The Cu₃(BTC)₂ activation temperature significantly affected the catalytic activity. The Cu₃(BTC)₂ sample activated at 240℃ had the best catalytic activity and gave NO conversion of 90% at 220-280℃. A reaction mechanism was proposed based on the in situ FTIR spectroscopy results.