新型苯选择加氢制环己烯非晶态催化剂Ru-Fe-B/ZrO2的制备及其可调变性

采用化学还原法制备了一种新型高活性和高选择性苯选择加氢制环己烯的Ru-Fe-B/ZrO2纳米非晶态合金催化剂,并利用透射电镜、选区电子衍射、X射线衍射和N2物理吸附仪等手段对催化剂进行了表征.重点研究了Ru-Fe-B/ZrO2催化剂活性和选择性的可调变性,及还原剂NaBH4浓度和洗涤后滤液的pH值对其催化性能的影响.结果表明,在新型Ru-Fe-B/ZrO2催化剂上,当苯转化54%时,环己烯选择性高达80%,同时环己烯选择性随苯转化率升高而缓慢下降.向反应浆液中添加酸性或碱性物质可以调变催化剂的活性和选择性,同时催化剂制备工艺和性能具有很好的可重复性.Ru-Fe-B/ZrO2催化剂融合了纳米和非晶材料的特性,这是其对苯选择加氢制环己烯表现出高活性和高选择性的主要原因.     

MCM-41负载钴催化H_2O_2氧化四氢萘合成α-四氢萘酮

比较了醋酸溶液中过渡金属(Fe、Co、Ni、Ce、Cu、La、Zr或Cr)掺杂MCM-41催化过氧化氢氧化四氢萘合成α-四氢萘酮的转化率和选择性,发现其中Co/MCM-41的催化活性最好。探讨了Co/MCM-41作催化剂时反应温度、反应时间、催化剂用量等对四氢萘氧化的转化率和形成四氢萘酮选择性的影响,确定了较优的反应条件:m(四氢萘)∶m(催化剂)=12.5∶1;反应温度T=383 K,反应时间8 h。四氢萘的转化率达94.7%,α-四氢萘酮的选择性达到70.3%。在反应体系中,Co/MCM-41是一种固体非均相催化剂。催化剂Co/MCM-41可回收重复使用3次,催化活性基本不变。     

N-羟基-N-苯基-2-吡啶甲酰胺钴配合物的合成及均相催化乙苯的氧化反应

近年来,在催化氧化反应领域,人们一直试图用价廉易得的氧作氧化剂,在较温和的条件下催化烃类氧化,以得到价值更高的含氧化合物．研究新的活化分子氧的高活性催化剂成为化学家追求的重要目标之一［１～４］．在各类催化剂中,金属卟啉类［５,６］和金属席夫碱类［...     

焦磷酸盐-磷酸盐复合催化剂高效催化乳酸脱水制丙烯酸

利用沉淀法制得焦磷酸盐与磷酸盐在浆状态下复配制备成复合催化剂,并用于催化乳酸脱水制丙烯酸.实验发现催化剂的组成对乳酸的转化率及丙烯酸的选择性有着重要的影响,当磷酸盐/焦磷酸盐质量比在30∶70～50∶50范围内,可以获得较高的乳酸的转化率和丙烯酸的选择性.催化反应条件如反应温度,乳酸进料浓度,液空速也被详细地进行了考察.此外,考察了该复合催化剂的稳定性.当催化剂连续运行56 h后,乳酸的转化率保持在96%以上,丙烯酸的选择性也高达57%.为了进一步揭示催化剂的结构与催化性能之间的关系,利用X射线粉末衍射、热重、扫描电镜和傅立叶红外等对催化剂进行了表征.     

Synthesis of dypnone by solvent free self condensation of acetophenone over nano-crystalline sulfated zirconia catalyst

Nano-crystalline sulfated zirconia catalyst, prepared by two-step sol–gel method, has been studied for the solvent free self condensation of acetophenone to dypnone. The influence of calcination temperature on the structural, textural and catalytic activity of sulfated zirconia has been analyzed. The surface acidity along with the structural and textural features of the catalyst influenced its activity. The conversion of acetophenone was found to be effected by the variation in the reaction and calcination temperature, however, the dypnone selectivity was not affected much. The catalyst calcined at 650 °C, showed maximum dypnone selectivity of 92% with 68.2% acetophenone conversion at 170 °C after 7 h. The catalyst was reused up to five cycles with marginal decrease in acetophenone conversion, however, without losing its selectivity for dypnone.     

2-羟基-1,4-萘醌的合成及铁卟啉-氧催化中间体形成平衡常数的测定

铁卟啉催化剂;羟基萘醌;2-羟基-1;4-萘醌的合成及铁卟啉-氧催化中间体形成平衡常数的测定     

固体酸催化剂催化酯化反应研究：Ⅰ.催化剂的制备及性能

酯化反应是基本有机化学中的一个重要反应,传统上使用的浓H_2SO_4催化剂常常引起一些严重问题.如:设备腐蚀严重,引起副反应及产生大量难以处理的含酸残液等.近年来,采用各种分子筛,氧化物及超强酸等作为该过程的催化剂的研究工作多见报道,这些工作无疑具有重要意义,但主要问题在于低温催化活性不高.     

锆对低温液相合成甲醇Cu-Cr催化剂性能的影响

Cu-Cr and Cu-Cr-Zr catalysts for the low temperature methanol synthesis slurry phase, with the surface area of 77.9 and 113.2 m2/g respectively, were prepared by the co precipitation approach. The activity and selectivity of these catalysts were evaluated in a stainless steel autoclave at 5.5 MPa and at different temperatures of 383 and 423 K separately. It was found that the activity of Cu-Cr-Zr catalyst was obviously higher than that of Cu-Cr catalyst, whereas the methanol selectivity of Cu-Cr-Zr catalyst was a little lower. The concentration of sodium compounds in the solution after reaction was also measured. The results showed that the concentration of sodium formate after reaction is much lower than that before reaction, which is quite different from the observations from the Cu-Cr catalyst previously. This implies that the conversion of sodium methoxide to sodium formate has been completely suppressed in the presence of zirconia in Cu-Cr-Zr catalyst. This finding is more beneficial to improve the performance of Cu-Cr catalyst and to increase the life of catalyst system as well.     

Carvone epoxidation by system “hydrogen peroxide-[Mn2L2O3][PF6]2 (L = 1,4,7-trimethyl-1,4,7-triazacyclononane)-carboxylic acid”: a combinatorial approach to the process optimization?

Summary Epoxidation of natural terpene (+)-carvone by the system consisting of a catalyst, oxalic acid (co-catalyst) and H₂O₂ (70% aqueous solution; oxidant) was studied and factorial design methods were applied for the optimization of this reaction. A dinuclear manganese(IV) complex [LMn(O)₃MnL](PF₆)₂ (L = 1,4,7-trimethyl-1,4,7-triazacyclononane) was used as a catalyst, and acetonitrile was employed as a solvent. An analysis by methods of the complete 2⁴ factorial design showed that an increase in the catalyst concentration gives a strong positive effect on the carvone conversion and selectivity. Hydrogen peroxide has a smaller positive effect on the conversion, but at high concentration, H₂O₂ leads to some decrease in the selectivity. An increase in the oxalic acid concentration has a beneficial effect on the conversion, but does not affect the selectivity.     

Mn/ Re/Cu体系催化剂催化甲醇一步合成二甲氧基甲烷的研究

以ReO_x/CuO为催化剂,将甲醇选择性氧化一步合成二甲氧基甲烷（DMM）。考察了不同催化剂、反应温度以及Mn作为助剂对反应的影响。并利用XRD、程序升温脱附(NH₃-TPD)和程序升温还原(H₂-TPR)等手段对该催化剂进行了表征。结果表明,在一定的温度范围内,较高的反应温度有利于提高甲醇的转化率和DMM选择性;少量的Mn（2%）作为结构型助剂加入催化剂,通过改善催化剂表面分散度以及酸碱性,可以提高甲醇的转化率以及DMM的选择性;在非临氧条件下,催化剂表面的晶格氧可以参与反应,将甲醇氧化并最终得到DMM。     

低浓度煤层气在发烟硫酸中液相部分氧化的催化剂研究

在发烟硫酸溶液中,对低浓度煤层气液相部分氧化的催化剂进行了筛选,考察了硫酸盐化合物系列、过渡金属化合物系列、碘化合物系列对低浓度煤层气液相部分氧化的催化活性,对筛选出的碘催化剂进行了催化剂加入量的考察,并对碘催化剂的催化机理进行了讨论。结果表明,碘单质的催化效果最好,低浓度煤层气中甲烷转化率可达79.69%,甲烷选择性可达83.74%。在对碘催化剂加入量的考察中发现,随着碘催化剂加入量的增加,低浓度煤层气的转化率先增加,达到最大值以后,再逐渐减小。根据甲烷在发烟硫酸溶液中液相部分氧化的反应机理,提出低浓度煤层气在发烟硫酸溶液中液相部分氧化的反应机理属于亲电反应机理。     

NOx—Catalyzed Gas—Phase Activation of Methane： the Formation of Hydrogen

NOx-catalyzed oxidation of methane without a solid catalyst was investigated, and a hydrogen selectivity of 27% was obtained with an overall methane conversion of 34% and a free O2 concentration of 1.7% at 700℃.     

笼状烃金刚烷的新合成方法

笼状烃金刚烷的新合成方法米镇涛郭建维邱立勤（天津大学化工学院天津３０００７２）关键词金刚烷，沸石，催化异构金刚烷（三环［３．３．１．１［３，７］癸烷）是一种周正对称、非常稳定的笼状烃，是由１０个碳原子和１６个氢原子构成的环状四面体碳氢化合物，基本骨...     

用于F—T合成的超细粒子催化剂及其制备化学

为提高F-T过程的汽油收率,本研究开发了一种新型工艺过程,即由合成气先转化为低碳烯烃,再将烯烃在HZSM-5分子筛上转化为高辛烷值汽油。利用超细粒子并选用适当的助剂提高了F-T过程的反应活性,选择性和热稳定性。考察了几种前躯物及助剂Mn,Zn,Mg对F-T合成的影响。由实验结果确认采用Fe/Mn草酸复盐作前躯物,经超细化处理后制得的8805催化剂活性高,选择性好,几项主要指标均已超过国内外同类催化剂水平。     

Liquid Phase Isomerization of α-Pinene. Study of the Reaction on Sulfated ZrO2

The -pinene isomerization reaction was studied on sulfated zirconium oxide catalyst for different experimental conditions. The catalysts are active for producing camphene when they present Brönsted acidity and when zirconium oxide crystallizes in the tetragonal phase. The -pinene conversion and its selectivity to camphene can be optimised by proper selection of operating conditions such as temperature, catalyst concentration and reaction time. The use of this catalyst in the appropriate conditions can result in selectivity to camphene of about 70%.     

常压下合成对硝基苯甲醚

以对硝基氯苯、甲醇和氢氧化钠为原料,用苄基三乙基氯化铵作相转移催化剂,在常压下合成了对硝基苯甲醚。对催化剂的选择及用量、原料配比,反应时间和反应温度对转化率的影响进行了讨论。在最佳反应条件下对硝基氯苯的转化率＞９９％,对硝基苯甲醚的收率为９１％,纯度为９８．５％     

High-Performance Supported Ru Catalysts for the Aqueous-Phase Hydrogenation of Levulinic Acid to γ-Valerolactone

γ-Valerolactone (GVL) can be obtained by efficient hydrogenation of levulinic acid using ruthenium-based catalysts in an aqueous medium. This paper reports an in-depth study on the activity and selectivity of Ru catalysts supported on zirconia-alumina, focusing on the effect of Ru concentration (0.5, 1.5 and 3 wt. % of Ru) and the selection of operational reaction variables. The results showed that the activity strongly depends on the number and oxidation state of the supported ruthenium particles. The most active catalyst, Ru3/ZA, presented the highest number of nanometric particles of zerovalent Ru and the highest number of acid sites. This catalyst gave ca. 100 % selectivity towards GVL, at high conversion of levulinic acid (over 99 %) under the best operating conditions evaluated (120 °C, 3 MPa H₂ pressure, 1 h of reaction, and 0.1 g of catalyst). In addition, this catalyst kept high levels of conversion and selectivity after successive reuse cycles.     

Effect of oxygen on the activity of a Pd-Fe/a-Al2O3catalyst for CO coupling to diethyl oxalate

The effect of oxygen on the activity and selectivity of a Pd-Fe/a-Al₂O₃ catalyst for CO coupling to diethyl oxalate (DEO) was studied in the range of 105 - 120^oC. The results showed that the conversion of CO and the STY (Space Time Yield) of DEO increased with increasing oxygen concentration from 5 to 10 mol% and reaction temperature, but the selectivity to DEO decreased. The role of oxygen in CO coupling is discussed on the basis of the experimental results in the present work and the XPS characterization of the catalysts. It was also found that the activity and selectivity of the catalyst could be fully recovered after removing O₂ from the reaction system.     

Design and synthesis of the honeycomb PtSnNa/ZSM-5 monolithic catalyst for propane dehydrogenation

A novel PtSnNa/ZSM-5 monolithic catalyst was designed and synthesized for the propane dehydrogenation reaction, which was a significant transformation in industry. Experimental results showed that although the propane conversion and the propylene selectivity gradually fell down along with the reaction time, the descent speed of the PtSnNa/ZSM-5 monolithic catalyst was slower than that of the granule catalyst and the propane conversion and propylene selectivity of the reaction with monolithic catalyst still remained at a high level after 12 hr. The monolithic catalyst had regular pore structure that facilitated the separation of the product from the catalyst and reduced the limitation on internal and external diffusion and mass transfer, and led to the high catalytic activity and stability. The catalyst could be easily fabricated and was of highly industrial application potential.     

One-step synthesis of solid sulfonic acid catalyst and its application in the acetalization of glycerol: crystal structure of cis-5-hydroxy-2-phenyl-1,3-dioxane trimer

A one-pot method was employed to immobilize sulfonic acid onto silica obtained from rice husk ash using 3-(mercaptopropyl)trimethoxysilane to form a solid catalyst denoted as RHASO₃H. BET measurements of the catalyst showed the surface area to be 340 m² g^?1 with the average pore volume of 0.24 mL g^?1 and the pore diameter of 2.9 nm. Acidity test of cation exchange capacity and pyridine adsorption studies revealed the presence of Br?nsted acid sites on the catalyst surface. The catalyst was used in the acetalization reaction of glycerol with benzaldehyde. Under optimized conditions, the reaction showed the maximum conversion of 78 % after 8 h with 67 % selectivity towards the five membered ring isomer. Variation in the glycerol concentration had a significant effect on the reactants conversion. A single crystal X-ray study of one of the products proved the existence of a unique trimer formed by hydrogen bonding by the six-membered cis-isomer. The catalyst was several times recycled without any loss of its catalytic activity.