固载型杂多酸催化剂研究进展

介绍了固载型杂多酸的制备、表征及其表面作用机理。着重综述了近年来活性炭、SiO2、TiO2、MCM 41分子筛、γ Al2O3、TiO2 Al2O3、阳离子交换树脂、惰性膜、USY 1、ZrO2 SO2 4和TiO2 WO3等各种固载型杂多酸催化剂在国内外的研究和应用情况,并展望了未来的研究方向。     

催化裂化再生器中铂助燃剂催化活性的测定(Ⅰ)——在新助燃剂上CO氧化的反应动力学

研究了催化裂化再生条件下铂助燃剂上ＣＯ氧化反应动力学。在排除了反应管及稀释剂的催化氧化作用后，测定了铂含量为１０－６ｇ／ｇ的国产新助燃剂上的反应动力学数据，得出了在氧过量时一氧化碳和氧的反应级数分别为１和０．５。给出了６６０℃下的反应速度常数值及其置信区间。     

Characterization of bimetallic NaY-supported Pt-Pd catalyst by EXAFS,TEM and TPR

NaY-supported bimetallic Pt-Pd catalysts have been studied by TEM, TPR and EXAFS. Small, randomly mixed particles are formed in the zeolite cages. When the Pt content is increased, a Pt core structure appears and the dispersion increases. Particle diameters are about 1–2 nm for bimetallic samples.     

硝基苯加氢制备对氨基苯酚的工艺要素研究

在稀硫酸介质中,Pt/C催化,硝基苯加氢还原、转位得到目标化合物对氨基苯酚。工艺要素研究表明:硝基苯20mL,氢气压力为1kPa的水封压力,温度85～90℃,十六烷基三甲基溴化铵用量为0.1g,2%Pt/C催化剂0.5g,反应时间为5h时,所得产品质量达到并优于日本JISK4144 1986标准要求。     

High utilization platinum deposition on single-walled carbon nanotubes as catalysts for direct methanol fuel cell

This research aims to enhance the activity of Pt catalysts, thus to lower the loading of Pt metal in fuel cell. Highly dispersed platinum supported on single-walled carbon nanotubes (SWNTs) as catalyst was prepared by ion exchange method. The homemade Pt/SWNTs underwent a repetition of ion exchange and reduction process in order to achieve an increase of the metal loading. For comparison, the similar loading of Pt catalyst supported on carbon nanotubes was prepared by borohydride reduction method. The catalysts were characterized by using energy dispersive analysis of X-ray (EDAX), transmission electron micrograph (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectrum (XPS). Compared with the Pt/SWNTs catalyst prepared by borohydride method, higher Pt utilization was achieved on the SWNTs by ion exchange method. Furthermore, in comparison to the E-TEK 20 wt.% Pt/C catalyst with the support of carbon black, the results from electrochemical measurement indicated that the Pt/SWNTs prepared by ion exchange method displayed a higher catalytic activity for methanol oxidation and higher Pt utilization, while no significant increasing in the catalytic activity of the Pt/SWNTs catalyst obtained by borohydride method.     

Reaction Coupling of Ethylbenzene Dehydrogenation with Nitrobenzene Hydrogenation

The chemical equilibrium for the coupling of ethylbenzene dehydrogenation with nitrobenzene hydrogenation, to produce styrene and aniline simultaneously, has been calculated on the basis of the Soave–Redlich–Kwong equation of state. The dehydrogenation of ethylbenzene in the presence of nitrobenzene over the catalysts -Al₂O₃, ZSM-5, activated carbon and platinum supported on activated carbon has been carried out at 400 °C. The effects of Pt loading and the pretreatment of the catalysts have been investigated. It has been revealed that the conversion of ethylbenzene can be greatly improved by the reaction coupling due to the elimination of the hydrogen produced in the reaction by the hydrogenation of nitrobenzene. Platinum supported on the activated carbon has been suggested as a suitable catalyst. The best results with ethylbenzene conversion of 33.8% and styrene selectivity of 99.2% were obtained over Pt(0.02 wt%)/AC at 400 °C. Moreover, such process is also energetically favored since the necessary process heat to drive the ethylbenzene dehydrogenation can be provided by the coupling with the exothermic nitrobenzene hydrogenation reaction.     

Heterogeneous asymmetric reactions. 23. Enantioselective hydrogenation of ethyl pyruvate over cinchonine- and α-isocinchonine-modified platinum catalysts

The enantioselective hydrogenation of ethyl pyruvate to (S)-ethyl lactate over cinchonine- and -isocinchonine-modified Pt/Al₂O₃ catalysts was studied as a function of modifier concentration and reaction temperature. The maximum enantioselectivities obtained under the applied mild conditions were 89% ee using cinchonine (0.014 mmoldm^–3, 1 bar H₂, 23°C, 6% AcOH in toluene), and 76% ee in the case of -isocinchonine (0.14 mmoldm^–3, 1 bar H₂, –10°C, 6% AcOH in toluene). Since -isocinchonine of rigid structure exists only in anti-open conformation these data provide additional experimental evidence to support the former suggestion concerning the dominating role of anti-open conformation in these cinchona-modified enantioselective hydrogenations.     

气相酯交换法合成碳酸甲丙酯负载型催化剂的研究

考察了负载型金属氧化物催化剂对碳酸二甲酯和丙醇气相酯交换合成碳酸甲丙酯的催化性能,并采用BET、XRD、CO2-TPD方法对催化剂进行了表征.结果表明,TiO2/Al2O3对反应具有较高的催化活性和稳定性.随着TiO2负载量的增加,催化剂的比表面积减小,而催化性能则随Ti负载量的增加先增加后减小,在Ti负载量为5%(wt)时活性达到最高,当Ti负载量低于5%(wt)时,TiO2可能以非晶态形式分散在Al2O3表面,而当Ti负载量高于5%(wt)时,TiO2以微晶的形式存在.CO2-TPD研究表明,负载量的改变对催化剂的碱性影响不明显.     

可伸缩铰支管接头简介

本文指出了埋入地下的刚性管接头连接的管道易出现的问题及为解决这些问题而发明的可伸缩铰支管接头的特点及结构。     

Dehydrogenation of Cyclohexene on Platinum Nanoclusters on a Thin Film of Al2O3/NiAl(100)

Using a scanning-tunneling microscope, reflection high-energy electron diffraction and photoelectron spectra with synchrotron radiation, we investigated the temperature dependence of the dehydrogenation of cyclohexene (C₆H₁₀) adsorbed on Pt nanoclusters supported on an ultra-thin film of Al₂O₃/NiAl(100). The Pt clusters, grown by vapor deposition, are structurally ordered and exhibit a mean diameter 2.2 nm and height 0.4 nm. The progress of dehydrogenation was monitored through the temporal variation of C 1s photoelectron spectra; analysis of these features revealed that the dehydrogenation of cyclohexene with increasing sample temperature occurs as a sequential process beginning around 150 K, a temperature significantly less than that for Pt single-crystal surfaces. The dehydrogenation behavior, particularly the decomposition into elemental carbon, is found to vary with Pt coverage.