不同改性组分对Cu-ZnO基催化剂低温甲醇合成性能的影响

通过共沉淀法制备了Al、Zr和Ce改性的Cu-ZnO基低温甲醇合成催化剂,采用氮气物理吸附、H2-TPR、CO2-TPD、N2O滴定、XRD和TEM等技术对其进行了表征,并考察了改性组分和煅烧温度对其在170℃下合成气制甲醇催化性能的影响。结果表明,经Zr改性的Cu-ZnO基催化剂,其低温甲醇合成性能较好;随着煅烧温度的降低,Cu在催化剂表面的分散度逐渐变大、颗粒逐渐变小,所得到的催化剂其活性也较高;其中,未经煅烧的Cu-ZnO/ZrO2催化剂的活性最佳,其甲醇时空产率为106.02 g/(kg·h),选择性达87.04%。     

十元环分子筛在甲醇芳构化反应中催化性能的研究

合成了ZSM-5、ZSM-22、EU-1、MCM-22和ITQ-13具有十元环孔道结构的5种分子筛,研究了分子筛结构、酸性分布等因素对其在甲醇芳构化反应中催化性能的影响。研究表明,不同结构分子筛的形貌、酸性及孔径均存在较大差异,进而影响了其在甲醇制芳烃反应中的催化活性和稳定性。研究的5种分子筛中,ZSM-5表现出最佳的芳构化活性,芳烃收率达34.8%,MCM-22芳烃收率约为21.9%,而其他3种结构的分子筛催化剂基本未表现出甲醇芳构化活性。通过添加具有芳构化性能的Ga物种对ZSM-5和MCM-22进行改性,可显著提升芳烃收率,Ga/ZSM-5上芳烃收率达到40.8%,Ga/MCM-22上芳烃收率可提高到27.1%。另外,采用TG/DTA、GC等方法研究了失活催化剂的积炭情况,发现分子筛结构对积炭量、积炭组成及积炭分布存在显著影响。     

硼掺杂碳化硅负载Pt催化剂的甲醇电催化氧化性能

以硼掺杂碳化硅(B0.1SiC)为载体,采用循环伏安法在B0.1SiC载体上电沉积Pt纳米粒子制备了Pt/B0.1SiC催化剂。利用X射线光电子能谱、X射线衍射、氮气吸附-脱附、扫描电镜及透射电镜等测试方法对催化剂的晶型、表面性质及形貌进行了表征。结果表明,硼原子掺杂进入SiC晶格并取代了Si位点,使B0.1SiC载体的导电性增强;Pt纳米粒子均匀地分布在B0.1SiC载体上,平均粒径为2.7 nm。与相同条件下制备的Pt/SiC催化剂相比,Pt/B0.1SiC具有较大的电化学活性表面积、更高的甲醇催化氧化活性和稳定性。     

Palladium‐Catalyzed Carbonylation of 2‐Bromoanilines with 2‐Formylbenzoic Acid and 2‐Halobenzaldehydes: Efficient Synthesis of Functionalized Isoindolinones

A concise and highly versatile method for the synthesis of functionalized isoindolinones is reported. Various 2‐bromoanilines undergo palladium‐catalyzed carbonylation with 2‐formylbenzoic acid under a convenient and mild procedure to give good to excellent yields of the corresponding isoindolinones. Additionally, 2‐halobenzaldehydes can be applied as substrates in palladium‐catalyzed double‐carbonylation to provide identical compounds in moderate to good yields.     

间接电氧化2-丁酮制备α-羟基缩酮的研究

在板框式循环电解槽中,以KOH为电解质,KI为催化剂,石墨电极分别为阳极和阴极,研究电化学间接氧化2-丁酮合成乙偶姻中间体α-羟基缩酮,讨论电流密度、极板间电解液流速、电解液中2-丁酮浓度、电解温度以及通电量等电解条件对中间体收率和电流效率的影响,经优选工艺条件为：电流密度40 mA·cm^-2,流速6.4 cm·s^-1,2-丁酮浓度1.75 mol·L^-1,电解温度30℃,通电量为1.5 F·moL^-1时,中间体收率可达78.9%,电流效率40.1%. 循环伏安测试结果表明,电解时碘离子在阳极氧化生成碘单质,甲醇在阴极还原生成甲氧基负离子,原料2-丁酮与电解产物反应,并最终生成乙偶姻中间体.     

Palladium‐Catalyzed Enantioselective Heck Carbonylation with a Monodentate Phosphoramidite Ligand: Asymmetric Synthesis of (+)‐Physostigmine, (+)‐Physovenine,and (+)‐Folicanthine

Reported herein is the development of the first enantioselective monodentate ligand assisted Pd‐catalyzed domino Heck carbonylation reaction with CO. The highly enantioselective domino Heck carbonylation of N‐aryl acrylamides and various nucleophiles, including arylboronic acids, anilines, and alcohols, in the presence of CO was achieved. A novel monodentate phosphoramidite ligand, Xida‐Phos, has been developed for this reaction and it displays excellent reactivity and enantioselectivity. The reaction employs readily available starting materials, tolerates a wide range of functional groups, and provides straightforward access to a diverse array of enantioenriched oxindoles having β‐carbonyl‐substituted all‐carbon quaternary stereocenters, thus providing a facile and complementary method for the asymmetric synthesis of bioactive hexahydropyrroloindole and its dimeric alkaloids.     

钌催化的手性苯基/苯并噻唑甲醇的转移氢化合成

以苯基/苯并噻唑甲酮为原料, 手性二胺钌络合物为催化剂, 甲酸钠为氢源, i?PrOH/H₂O(体积比1:1)为溶剂, 在室温(30 ℃)条件下, 通过不对称转移氢化, 合成了一系列手性苯基/苯并噻唑甲醇类化合物, 其对映选择性(e.e.)值高达99%. 此外, 还探讨了其它苯基/氮杂环甲酮的不对称转移氢化. 该方法具有反应条件温和、 催化剂廉价易得及操作简便等优点.     

Pd-Cu/ZrO2催化CO2加氢制甲醇的性能

采用溶胶-凝胶法制备了n(Cu):n(Zr)=1:1、1:2、1:4和1:8的Cu/ZrO₂催化剂。 实验结果表明,当n(Cu):n(Zr)=1:4时,催化剂表现出较高的CO₂转化率(8.0%)和甲醇选择性(59.5%),为了增加CO₂的转化率,提高甲醇选择性,在n(Cu):n(Zr)=1:4的催化剂中添加质量分数1%的Pd,采用浸渍法制备了Pd-Cu/ZrO₂催化剂。 在250 ℃、2 MPa、12000 mL/(g·h)和V(H₂):V(CO₂)=3:1的反应条件下,CO₂转化率和CH₃OH收率相比Cu/ZrO₂催化剂(n(Cu):n(Zr)=1:4)分别提高了40.0%和80.9%。 通过X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、N₂吸附-脱附(BET)、X射线光电子能谱仪(XPS)和程序升温还原化学吸附仪(H₂-TPR)等仪器表征证明Pd的添加提高了催化剂的分散性和比表面积。 催化剂中Pd和Cu之间强相互作用,使Cu2p轨道结合能向低处偏移,还原温度的降低,说明Pd-Cu/ZrO₂催化剂还原能力增强,使得CO₂加氢活性提高。     

CO and methanol adsorption on (2 × 1)Pt(110) and ion‐eroded Pt(111) model catalysts

Methanol adsorption on ion‐sputtered Pt(111) surface exhibiting high concentration of vacancy islands and on (2 × 1)Pt(110) single crystal were investigated by means of photoelectron spectroscopy (PES) and thermal desorption spectroscopy. The measurements showed that methanol adsorbed at low temperature on sputtered Pt(111) and on (2 × 1)Pt(110) surfaces decomposed upon heating. The PES data of methanol adsorption were compared to the data of CO adsorbed on the same Pt single crystal surfaces. In the case of the sputtered Pt(111) surface, the dehydrogenation of H_xCO intermediates is followed by the CO bond breakage. On the (2 × 1)Pt(110) surface, carbon monoxide, as product of methanol decomposition, desorbed molecularly without appearance of any traces of atomic carbon. By comparing both platinum surfaces we conclude that methanol decomposition occurs at higher temperature on sputtered Pt(111) than on (2 × 1)Pt(110). Copyright © 2010 John Wiley & Sons, Ltd.     

介孔氧化铝的制备及其在甲醇脱水制二甲醚反应中的应用

以硝酸铝为铝源,以十六烷基三甲基溴化铵为阳离子模板剂,采用均匀沉淀法成功制得热稳定性较高和高度有序的介孔Al2O3(其比表面积179.8 m2/g,孔径5.4 am,孔体积0.3 cm3/g),并用于甲醇脱水制二甲醚反应中.结果表明,在280℃,液时空速为30 h-1条件下,甲醇转化率为90.2%,二甲醚时空收率最高可...