Highly selective synthesis of 3-methylindole from glycerol and aniline over Cu/NaY modified by K2O

The vapor-phase synthesis of 3-methylindole from glycerol and aniline over Cu/NaY modified by K2O was investigated. The catalysts were characterized by X-ray diffraction （XRD） and the temperature- programmed desorption of ammonia （NH3-TPD）. The effect of the reaction temperature on the activity and selectivity of Cu]NaY-K2O catalyst was also investigated. The results indicated that the addition of K2O to Cu/NaY increased the selectivity of the catalyst remarkably because the amount of middle-strong acid sites decreased clearly. The decrease of the reaction temperature was beneficial for the increase of 3- methylindole selectivity. Over Cu/NaY-K2O, the selectivity of 3-methylindole reached 75% and the yield of the target product was up to 47% at 220 ℃. A probable catalytic mechanism for the synthesis of 3- methylindole from glycerol and aniline was proposed.     

Glucose Isomerization into Fructose Catalyzed by MgO/NaY Catalyst

The MgO/NaY catalysts prepared by impregnation method were used for the conversion of glucose to fructose in water medium.The effects of MgO loading, reaction temperature, glucose concentration and reaction time on the catalytic performance for the reaction were studied.The activity testing results indicated that fructose could be generated effectively by controlling the components of the catalyst and reaction conditions.The maximal fructose yield of 33.8% with the selectivity of 67.3% was achieved over the 10% MgO/NaY catalyst at 100 ℃ for 2 h.Moreover, the catalysts were characterized by XRD, BET, and CO₂-TPD techniques.The structural property of NaY with higher surface area facilitated glucose conversion, and the modulated basicity of the catalyst with MgO addition contributed to the formation of fructose in the tautomerization of aldose to ketose.     

Rh/SiO~2和Rh/NaY催化剂上合成气反应的高压原位 红外光谱研究

采用高压原位FT-IR技术,对比研究了CO加H~2反应条件下Rh/SiO~2和Rh/NaY催化剂表面反应中间物种。在Rh/SiO~2表面上,无论在常压还是在1.0MPa合成气中,只观察到线式和桥式吸附CO。而在常压合成气中,Rh/NaY上不仅存在上述CO吸附物种,而且还有孪生型的Rh(Ⅰ)(CO)~2和少量Rh~6(CO)~1~6;当合成气压力升至1.0MPa后,Rh(Ⅰ)(CO)~2迅速转化成Rh~6(CO)~1~6和在2042cm^-^1产生吸收的单核羰基Rh物种,与此同时催化剂表面还生成了单齿和双齿乙酸根物种;这些在高压下生成的物种在合成气压力重新降回到常压时依然稳定存在。研究Rh/NaY上合成气反应表面物种与H~2的反应行为表明单齿乙酸根很可能是反应的活性中间物。这些结果说明Rh/NaY催化剂在高压合成气中的重构是诱发选择生成乙酸反应的基础。     

Synthesis of propylene carbonate from urea and 1,2-propylene glycol over ZnO/NaY catalyst

Propylene carbonate (PC) was produced from 1,2-propylene glycol (1,2-PG) and urea in a continuous-flow fixed bed reactor over heterogeneous ZnO catalyst supported on NaY. Among different ZnO loadings of ZnO/NaY catalysts, 5 wt% ZnO loadings of ZnO/NaY showed the highest activity. Characterization and reaction results indicated that the catalysts with a balanced strength of acid and base sites performed well for the synthesis of propylene carbonate from urea and 1,2-PG.     

NaY Zeolite Functionalized by Sulfamic Acid/Cu(OAc)2 as a Novel and Reusable Heterogeneous Hybrid Catalyst in Efficient Synthesis of Bis,Tris, and Tetrakis(indolyl)methanes, 3,4‐Dihydropyrimidin‐2(1H)‐ones,and 2‐Aryl‐1H‐benzothiazoles

An efficient acid‐catalyzed synthesis of some bis, tris, and tetrakis(indolyl)methanes, 3,4‐dihydropyrimidin‐2(1H )‐ones, and 2‐aryl‐1H ‐benzothiazoles is reported using NaY zeolite functionalized by sulfamic acid/Cu(OAc )₂ (NaY zeolite‐NHSO₃H /Cu(OAc )₂) in excellent yield. The heterogeneous catalyst has a simple work‐up procedure and could be recycled and reused for six reaction cycles.     

Adaptation of Cu/ZnO/Al_2O_3 to Temperature Change in Methanol Synthesis from CO_2 Hydrogenation

The induction behavior in CO2 hydrogenation was studied by varying the reaction temperature to investigate the adaptation of the Cu/ZnO/Al2O3 catalyst to the temperature change. The results indicated that a used catalyst had a tendency to keep the last running state in new reaction conditions for MeOH formation, and that this tendency was related to the difference in Cu/Cun+ ratio caused by CO2 and CO produced at different reaction temperatures. However, the reverse water-gas shift reaction (RWGS) induced at four temperatures was completely different from that of methanol synthesis. It implied that the two so-called competitive reactions in CO2+H2, RWGS and methanol synthesis, have different active centers.     

MgO/NaY催化糠醛和丙酮合成航空燃料中间体的性能研究

采用"机械混合-焙烧"方法制备了负载型固体碱催化剂MgO/NaY,研究了糠醛与丙酮在水-乙醇体系中的羟醛缩合反应,考察了催化剂负载量、原料配比、反应温度、反应时间等因素对催化剂性能的影响。结果表明,20%MgO/NaY催化剂表现出最佳的催化性能,在85℃条件下反应8 h后,糠醛转化率达到99.6%,亚糠基丙酮(FA)和二亚糠基丙酮(F₂A)选择性分别达到42.2%和57.1%,缩合产物的总收率为98.6%。高温促进反应中间体向产物的转化,有利于提高产物的总选择性。改变糠醛/丙酮的摩尔比可调控两种缩合产物的选择性,较高的糠醛/丙酮摩尔比有利于提高F₂A的选择性,但会降低整体反应速率。重复性评价表明,催化剂具有较好的再生性能。     

Adaptation o Cu／ZnO／Al2O3 to Temperature Change in Methanol Synthesis from CO2 Hydrogenation

The induction behavior in CO2 hydrogenation was studied by varying the reaction temperature to investigate the adaptation of the Cu/ZnO/Al2O3 catalyst to the temperature change,The results indicated that a used catalyst had a tendency to keep the last running state in new reaction conditions for MeOH formation,and that this tendency was related to the difference in Cu/Cu^n ration caused by CO2 and CO produced at different reaction temperatures,However,the reverse water-gas shift reaction (BWGS) induced at four temperatures was completely different from that of methanol synthesis,It implied that the two so-called competitive reactions in CO2 H2,RWGS and methanol synthesis,have different, active centers.     

Adaptation of Cu/ZnO/Al2O3 to Temperature Change in Methanol Synthesis from CO2 Hydrogenation

The induction behavior in CO2 hydrogenation was studied by varying the reaction temperatureto investigate the adaptation of the Cu/ZnO/Al2O3 catalyst to the temperature change. The resultsindicated that a used catalyst had a tendency to keep the last running state in new reaction conditionsfor MeOH formation, and that this tendency was related to the difference in Cu/Cun+ ratio caused byCO2 and CO produced at different reaction temperatures. However, the reverse water-gas shift reaction(RWGS) induced at four temperatures was completely different from that of methanol synthesis. It impliedthat the two so-called competitive reactions in CO2+H2, RWGS and methanol synthesis, have differentactive centers.     

载体对浸渍型Cu/Mn/Mg/K甲醇裂解催化剂的影响

载体对浸渍型Cu/Mn/Mg/K甲醇裂解催化剂的影响;     

Host (Nano Cage NaY)/Guest Mn(II), Co(II), Ni(II) and Cu(II) Complexes of N,N‐Bis(3,5‐Di‐Tert‐Butylsalicyidene)‐2,2‐Dimethyle‐1,3‐Diaminopropane: Synthesis and Catalyst Activity

Mn(II), Co(II), Ni(II) and Cu(II) and N,N‐bis(3,5‐di‐tert‐butylsalicyidene)‐2,2‐dimethyle‐1,3‐diaminopropane complexes have been synthesized in Y zeolite cavity by the reaction of ion‐exchanged metal ions with the flexible ligand molecules. The host‐guest materials obtained have been characterized by elemental analysis, XRD, surface area, pore volume, TGA, FT‐IR and UV‐Vis techniques. Analysis of data indicates that formation of complexes in the pores Y zeolite without affecting the zeolite framework structure. Also, we report the oxidation of cyclohexanol catalyzed by host‐guest catalyst with tert‐buthyl hydrogen peroxide as oxygen donor. The activity of benzyl alcohol oxidation decreases in the series‐[Co(L)]/NaY > [Cu(L)]/NaY > [Mn(L)]/NaY > [Ni(L)]/NaY and the percent of product completely depend to catalyst. Zeolite complexes are stable enough to be reused and are suitable to be utilized as partial oxidation catalysts.     

微乳法制备纳米Ru/NaY催化剂及其催化对苯二酚加氢

采用曲拉通X-100(Triton X-100)/正己醇/正庚烷/RuCl_3·3H_2O水溶液构成微乳液,以水合肼为还原剂,制备了纳米Ru颗粒,再破乳将其负载于NaY分子筛得到M-Ru/NaY催化剂.通过XRD、BET、XPS、SEM、TEM及DSC分析方法对催化剂进行了表征.表征结果表明,M-Ru/NaY催化剂具有金属钌平均粒径小,分布均匀,高度分散等优点.以对苯二酚加氢制1,4-环己二醇为探针反应,对微乳法和传统浸渍法制备的催化剂活性和选择性进行了比较,深入研究了催化剂用量,反应温度,氢气压力对对苯二酚加氢活性的影响及最佳反应时间的确定.实验结果表明,M-Ru/NaY催化剂在反应温度150℃,氢气压力4.0 MPa,m(M-Ru/NaY)∶m(对苯二酚)=0.2∶1,溶剂为异丙醇,此条件下反应30 min,对苯二酚转化率为100%,1,4-环己二醇的选择性高达92.6%.还考察了M-Ru/NaY催化剂的稳定性.最后,探讨了对苯二酚加氢反应路径.     

微波固相法制备ZnCl2/NaY催化剂ZnCl2/NaY在月桂烯Diels-Alder反应中的催化性能

比较了微波固相法、普通加热法和简单混合法制备的ZnCl2/NaY及溶液离子交换法制备的ZnNaY在月桂烯与丙烯醛Diels-Alder反应中的催化性能,发现微波固相法制备的催化剂表现出最高的环加成选择性和区域选择性.通过对微波固相法制备的催化剂中ZnCl2负载量的考察,揭示了微波诱导ZnCl2在NaY分子筛表面形成了不同催化活性中心的特点,分散在分子筛表面的ZnCl2具有更高的催化活性和区域选择性.微波辐射可成功地将ZnCl2固载于NaY分子筛中,当ZnCl2负载量为6.3%时,ZnCl2与NaY分子筛主要发生固态离子交换反应;当ZnCl2负载量达25%时,催化活性提高了3倍,区域选择性提高了1倍以上.而且,以微波固相法制备的ZnCl2/NaY催化剂,其环加成选择性和区域选择性随反应温度的升高而下降.     

Highly dispersed Cu supported on mesoporous Al-KIT-6 for oxidative carbonylation of methanol to dimethyl carbonate

Microporous NaY zeolite is a common support of Cu catalysts for oxidative carbonylation of methanol, but the dispersion of Cu species on NaY is usually subjected to its micropore size. Here, ordered mesoporous KIT-6 was employed as the support for Cu catalyst and Al was incorporated into its framework to increase the surface acidity, which eventually improves the surface exchange capacity and Cu dispersion. The evolution of the state of Cu species on KIT-6 was analyzed combined with control of Cu loading. The physicochemical properties of the supports and corresponding catalysts were characterized by N₂ adsorption–desorption, X-ray diffraction, ammonia temperature programmed desorption, Fourier transform infrared spectra, transmission electron microscopy, hydrogen temperature programmed reduction, and X-ray photoelectron spectroscopy. It was found that mesoporous KIT-6 showed better Cu dispersion than microporous NaY zeolite. Agglomerated CuO, dispersed CuO, and Cu²⁺ are the major Cu species observed on the catalyst surface. The increased surface acidic sites of KIT-6 by Al incorporation promoted the formation of Cu²⁺ and dispersion of CuO. With the increase in Cu loading, the Cu²⁺ content in the catalyst was decreased gradually along with increase in the bulk CuO. It was speculated that some exchanged Cu²⁺ could be transformed into highly dispersed CuO and even bulk CuO after calcination at a high Cu loading. Combined with the catalyst evaluation results, it was deduced that highly dispersed Cu²⁺ and CuO particles play significant roles in catalytic activity. The catalyst Cu/Al-K-10 achieved the highest space time yield of dimethyl carbonate of 135.4 mg/(g·h), which is 2.7 times the Cu/K-10 owing to its more dispersed Cu species. This laid the basis for preparing highly dispersed Cu species on mesoporous silica supports.     

Solvent-free synthesis of propargylamines via A3 coupling reaction and organic pollutant degradation in aqueous condition using Cu/C catalyst

The present report focuses on the efficient and operationally simple synthesis of biomass-derived carbon as support to immobilize copper particles as a catalyst for the one-pot synthesis of propargylamines from furfural via the A³ coupling reaction. This new catalyst showed remarkable catalytic performance leading to a 97% yield within 5 h at 80 °C using 5 mg (0.0022 mmol Cu) of Cu/C catalyst under solvent-free condition. Moreover, nitro-substituted compounds such as 4-nitrophenol (4-NP) are highly toxic and not easily degradable. Hence, a quick and effective method is required to neutralize these toxic compounds. The synthesized active support Cu/C catalyst having various electron-donating groups containing small amounts of Cu plays an essential role in the catalytic reduction of 4-NP (0.1 g). Using only 3 mg (0.0013 mmol Cu) of Cu/C catalyst and NaBH₄ (10 mmol), a 99% yield (100% selectivity) in the aqueous condition at 25 °C was achieved. The catalytic reduction follows the pseudo-first-order kinetics with reaction rate constant of 0.028 s⁻¹. Moreover, results demonstrate that the Cu/C catalyst has superior catalytic activity due to the presence of electron-donating molecules such as O, S, and N atoms, which enable synergistic effect in enhancing the overall catalytic performance. Notably, the recoverability and recyclability of the synthesized catalyst were evaluated for up to four cycles, which confirmed its stability in these cycles.     

超临界甲醇中Ce/Cu/Zn/Al催化木质素制备酚类化合物的研究

采用共沉淀法制备Ce/Cu/Zn/Al催化剂,并将其应用于超临界甲醇中木质素的催化液化.考察单因素条件对木质素转化率和生成酚类的影响,得到最佳反应条件:反应温度320℃,反应时间120 min,催化剂用量150 mg,初始压力2 MPa,木质素的转化率达到67.33%,酚类产率达到30.84%.同时,以苯酚及愈创木酚为模型物,比较有无催化剂对液化产物分布或选择性生成的影响. Ce/Cu/Zn/Al催化剂的加入促进了甲醇的重整及其与模型化合物苯酚、愈创木酚的烷基化反应,从而生成了大量的烷基苯酚.     

助剂对Cu/Cr催化剂上甲醇部分氧化制氢的活性影响

曾研究了Cu/Cr二元催化剂上甲醇部分氧化制氢的反应，发现当Cu/Cr比为6：4时，催化剂的Cu^0比表面积最大，呈现出较好的活性。在Cu/Cr（6：4）催化剂中添加Fe,Zn,Al等8种助剂，考察其对甲醇部分氧化制氢催化性能的影响，并着重研究了Zn助剂的作用。实验结果表明，Zn的引入，有利于催化剂活性的提高。当Zn含量为10％时，催化剂活性最好。XRD表征结果表明，Cu/Cr催化剂的失活与其表面上的Cu物种烧结有关，Zn的引入可明显增强Cu/Cr（6：4）催化剂的热稳定性，提高其寿命。     

Fe2O3改性NaY沸石上吡咯烷亚硝胺的降解

 采用程序升温表面反应（TPSR），NH3－TPD，TG－MS和脉冲催化反应等手段研究了吡咯烷亚硝胺（NPYR）在Fe2O3改性NaY沸石上的催化降解．结果表明，用微波辐射、浸渍或焙烧等不同方法制备的改性沸石对NPYR降解的催化性能各不相同，以浸渍法制备的样品活性最高，但该样品对降解产物NO2的吸附作用较弱．在NPYR的降解反应中，Fe2O3改性NaY沸石上的Fe向沸石外表面迁移和富集，覆盖了沸石表面的铝，使催化剂表现出Fe2O3的性质．     

NH3-SCR反应过程中NH3和NOx在Cu/SAPO-34分子筛催化剂上的吸附特性和作用

通过离子交换法制得Cu/SAPO-34菱沸石分子筛催化剂, 同时研究了NH₃和NO_x (NO和NO₂)在该催化剂上的吸附位、吸附强度、吸附量和吸附速率, 得到了不同反应气氛在Cu/SAPO-34 上的吸附性能及其在NH₃选择性催化还原(NH₃-SCR)反应中的作用. 研究采用瞬态实验、程序升温脱附(TPD)和漫反射傅里叶变换红外光谱(DRIFTS)等方法进行表征实验. 瞬态实验结果表明NH₃是吸附性气体. 程序升温脱附实验和红外漫反射实验结果表明NH₃可以吸附在布朗斯特和路易斯酸性位上形成不同的NH₃物种, 它们显示不同的SCR活性. NH₃在Cu²⁺上的吸附速率最快, 且键强最强. NO_x可以氧化并以硝酸盐/亚硝酸盐的形式吸附在Cu物种上. 最后, 本文讨论了NH₃选择性催化还原反应过程中在Cu物种上的中间物种并推测反应机理.     

红外光谱法研究表面溢出效应

采用红外光谱法, 利用重氢交换反应证明在Pt-NaY/HY体系有氢溢出(spillover)效应发生, 测量了100 ℃和50 ℃时的交换速率。发现在50 ℃时高频羟基的交换速率大于低频羟基。并对溢出机构进行了初步的讨论。