共查询到20条相似文献,搜索用时 15 毫秒
1.
Wataru Ninomiya Yasuhiko Tanabe Ken-Ichiro Sotowa Toshiya Yasukawa Shigeru Sugiyama 《Research on Chemical Intermediates》2008,34(8-9):663-668
Dehydrogenation of decalin to naphthalene through tetralin and that of dicyclohexyl to biphenyl through phenylcyclohexane with Pt/C and Pd/C was investigated mainly under the liquid film state, in which the catalyst was just wet but not suspended and covered with a thin film of liquid substrate. To improve the catalytic activities, the effects of the addition of tellurium into Pd/C were investigated to reveal that the combination of tellurium, palladium and conjugated systems produced during the dehydrogenation of cycloalkames was important to the improvement of the activities. 相似文献
2.
Selective hydrogenation of citral over Au-based bimetallic catalysts in supercritical carbon dioxide
Selective hydrogenation of citral was investigated over Au-based bimetallic catalysts in the environmentally benign supercritical carbon dioxide (scCO2) medium. The catalytic performances were different in citral hydrogenation when Pd or Ru was mixed (physically and chemically) with Au. Compared with the corresponding monometallic catalyst, the total conversion and the selectivity to citronellal (CAL) were significantly enhanced over TiO2 supported Pd and Au bimetallic catalysts (physically and chemically mixed); however, the conversion and selectivity did not change when Ru was physically mixed with Au catalyst compared to the monometallic Ru/TiO2, and the chemically mixed Ru-Au/TiO2 catalyst did not show any activity. The effect of CO2 pressure on the conversion of citral and product selectivity was significantly different over the Au/TiO2, Pd-Au/TiO2, and Pd/TiO2 catalysts. It was assumed to be ascribed to the difference in the interactions between Au, Pd nanoparticles and CO2 under different CO2 pressures. 相似文献
3.
Norihito Hiyoshi Chandrashekhar V. Rode Osamu Sato Masayuki Shirai 《Research on Chemical Intermediates》2008,34(8-9):767-770
The hydrogenation behavior of tetralin in the presence and absence of benzothiophene was studied over a charcoal-supported rhodium catalyst in supercritical carbon dioxide solvent. The catalyst activity, as well ascis-decalin selectivity, decreased in the presence of benzothiophene. 相似文献
4.
Shaobin Wang Kazuhisa Murata Takashi Hayakawa Satoshi Hamakawa Kunio Suzuki 《Reaction Kinetics and Catalysis Letters》1999,68(2):265-270
Several metal oxides supported on sulfated zirconia catalysts were tested for the oxidative dehydrogenation of ethane into
ethylene by carbon dioxide. It is found that the catalytic behavior of supported oxide catalysts differ depending on the nature
of metal oxides. Chromium oxide-sulfated zirconia exhibits the highest ethane conversion and medium level of ethylene selectivity,
producing 38% ethylene yield at 50% ethane conversion at 650°C. 相似文献
5.
Selective hydrogenation with supported metal catalysts widely used in the production of fine chemicals and pharmaceuticals often faces a trade-off between activity and selectivity, mainly due to the inability to adjust one factor of the active sites without affecting other factors. In order to solve this bottleneck problem, the modulation of the microenvironment of active sites has attracted more and more attention, inspired by the collaborative catalytic mode of enzymes. In this perspective, we aim to summarize recent advances in the regulation of the microenvironment surrounding supported metal nanoparticles (NPs) using porous materials enriched with organic functional groups. Insights on how the microenvironment induces the enrichment, oriented adsorption and activation of substrates through non-covalent interaction and thus determines the hydrogenation activity and selectivity will be particularly discussed. Finally, a brief summary will be provided, and challenges together with a perspective in microenvironment engineering will be proposed.Insights on microenvironment engineering for metal nanoparticles using porous materials enriched with organic groups and how it determines the hydrogenation performance through non-covalent interaction are highlighted. 相似文献
6.
Liquid phase hydrogenation of phenol over Pt/C catalysts was investigated under conventional conditions and supercritical carbon dioxide (scCO2). The equivalent ration of hydrogen to phenol shows a significant effect on the product selectivity. Hydrogenation of phenol in different solvents was also studied, the experimental results show that polarity of solvents influences the yield of cyclohexanone remarkably, scCO2 has the highest one. Catalytic hydrogenation of phenol in scCO2 or sub-scCO2 was emphatically researched. The result is that near the critical point of CO2 phenol has higher reaction activity than that of normal organic solvents, cyclohexanone has 47% in yield and 87% in selectivity. 相似文献
7.
Hongqing Chen Hao Yu Yong Tang Minqiang Pan Guangxing Yang Feng Peng Hongjuan Wang Jian Yang 《天然气化学杂志》2009,18(2):191-198
Hydrogen was produced over noble metal (Ir, Ru, Rh, Pd) catalysts supported on various oxides, including γ-Al2O3, CeO2, ZrO2 and La2O3, via the autothermal reforming reaction of ethanol (ATRE) and oxidative reforming reaction of ethanol (OSRE). The conversion of ethanol and selectivites for hydrogen and byproducts such as methane, ethylene and acetaldehyde were studied. It was found that lanthana alone possessed considerable activity for the ATRE reaction, which could be used as a functional support for ATRE catalysts. It was demonstrated that Ir/La2O3 prevented the formation of methane, and Rh/La2O3 encumbered the production of ethylene and acetaldehyde. ATRE reaction was carried out over La2O3-supported catalysts (Ir/La2O3) with good stability on stream, high conversion, and excellent hydrogen selectivity approaching thermodynamic limit under autothermal condition. Typically, 3.4 H2 molecules can be extracted from a pair of ethanol and water molecules over Ir(5wt%)/La2O3. The results presented in this paper indicate that Ir/La2O3 can be used as a promising catalyst for hydrogen production via ATRE reaction from renewable ethanol. 相似文献
8.
Hydrogen production via autothermal reforming of ethanol over noble metal catalysts supported on oxides
下载免费PDF全文
![点击此处可从《天然气化学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Hongqing Chen Hao Yu Yong Tang Minqiang Pan Guangxing Yang Feng Peng Hongjuan Wang Jian Yang 《天然气化学杂志》2009,18(2)
Hydrogen was produced over noble metal (Ir, Ru, Rh, Pd) catalysts supported on various oxides, including γ-Al2O3, CeO2, ZrO2 and La2O3, via the autothermai reforming reaction of ethanol (ATRE) and oxidative reforming reaction of ethanol (OSRE). The conversion of ethanol and selectivites for hydrogen and byproducts such as methane, ethylene and acetaldehyde were studied. It was found that lanthana alone possessed considerable activity for the ATRE reaction, which could be used as a functional support for ATRE catalysts. It was demonstrated that Ir/La2O3 prevented the formation of methane, and Rh/La2O3 encumbered the production of ethylene and acetaldehyde. ATRE reaction was carried out over La2O3-supported catalysts (Ir/La2O3) with good stability on stream, high conversion, and excellent hydrogen selectivity approaching thermodynamic limit under autothermal condition. Typically, 3.4 H2 molecules can be extracted from a pair of ethanol and water molecules over Ir(5wt%)/La2O3. The results presented in this paper indicate that Ir/La2O3 can be used as a promising catalyst for hydrogen production via ATRE reaction from renewable ethanol. 相似文献
9.
采用浸渍法制备了一系列MTiO3(M=Mg、Ca、Sr、Ba)钙钛矿型氧化物负载的Ni催化剂(Ni的负载量为5%,质量分数),通过XRD、氮吸附、H2-TPR、CO2-TPD、XPS和TG等技术对催化剂进行了表征,对其甲烷二氧化碳重整反应的催化性能进行了研究。结果表明,M为不同碱土金属时,催化剂上金属载体相互作用、活性组分的表面原子浓度以及催化剂晶格氧的流动性都发生了变化。Ni/CaTiO3催化剂上金属载体相互作用较强,还原出的活性组分Ni的含量较多,晶格氧流动性较高,因而具有较好的催化性能。SrTiO3载体颗粒粒径较大,Ni/SrTiO3催化剂上Ni的分散度不高,金属载体的相互作用较弱,表面Ni原子相对含量较低,晶格氧的流动性较差,其甲烷二氧化碳重整反应活性也最低。 相似文献
10.
P. Staiti S. Galvagno P. Antonucci A. Rositani P. Vitarelli 《Reaction Kinetics and Catalysis Letters》1984,26(1-2):111-116
Partial hydrogenation of benzene to cyclohexene has been studied on Pt/Nylon 66, Pt/MgO and Pt/TiO2. An effect of the support on the selectivity to cyclohexene was observed, Pt/Nylon showing the highest selectivity, followed by Pt/MgO and Pt/TiO2. An interaction of platinum with the more basic supports (Nylon, MgO) and a pretreatment under oxidizing conditions, results in a higher selectivity to cyclohexene.
Pt/ 66, Pt/MgO PtTiO2. , Pt/, Pt/MgO Pt/T,O2. (, MgO) .相似文献
11.
Langer R Diskin-Posner Y Leitus G Shimon LJ Ben-David Y Milstein D 《Angewandte Chemie (International ed. in English)》2011,50(42):9948-9952
A highly active iron catalyst for the hydrogenation of carbon dioxide and bicarbonates works under remarkably low pressures and achieves activities similar to some of the best noble metal catalysts. A mechanism is proposed involving the direct attack of an iron trans-dihydride on carbon dioxide, followed by ligand exchange and dihydrogen coordination. 相似文献
12.
A fluorinated trisphenylphosphine ligand was reacted with [(COD)CIRh]2 (COD = cyclooctadiene) and [(COD)2Rh]+BArF− {BArF = tetrakis[(3,5-bistrifluoromethyl)phenyl]borate} to synthesize new fluorinated derivatives of the well-known Wilkinson
catalyst as {[P(Ph(CF3)2)3]3RhBArF}, {[P(Ph)3]3RhBArF} and {[P(Ph(CF3)2)3]3RhCl}. BArF anion was used to synthesize cationic complexes. All the synthesized complexes were tested and found to be soluble
in supercritical carbon dioxide (scCO2) media. The catalytic activities of the rhodium complexes were examined for hydrogenation of styrene in scCO2. The catalysts showed different activities between 47.9–77.4%. The most effective result among the synthesized Rh-catalysts
was obtained with a conversion of 77.4% corresponding to {[P(Ph(CF3)2)3]3RhBArF} under the reaction conditions of 343K temperature and 123 bar pressure after 8 h in scCO2 (molar ratio of substrate to catalyst = 500). 相似文献
13.
A charcoal-supported rhodium catalyst was highly active for the ring hydrogenation of phenol and cresols under supercritical carbon dioxide. 相似文献
14.
Transforming nonselective into chemoselective metal catalysts for the hydrogenation of substituted nitroaromatics 总被引:1,自引:0,他引:1
Corma A Serna P Concepción P Calvino JJ 《Journal of the American Chemical Society》2008,130(27):8748-8753
It is generally accepted that good hydrogenation noble and nonnoble metal catalysts such as Pt, Ru, or Ni are not chemoselective for hydrogenation of nitro groups in substituted aromatic molecules. We have found that it is possible to transform nonchemoselective into highly chemoselective metal catalysts by controlling the coordination of metal surface atoms while introducing a cooperative effect between the metal and a properly selected support. Thus, highly chemoselective and general hydrogenation Pt, Ru, and Ni catalysts can be prepared by generating nanosized crystals of the metals on the surface of a TiO 2 support and decorating the exposed (111) and (100) crystal faces by means of a simple catalyst activation procedure. By doing this, it has been possible to change the relative rate for hydrogenating competitive groups present in the molecule by almost 2 orders of magnitude, increasing the chemoselectivity from less than 1% to more than 95%. 相似文献
15.
Summary The dehydrogenation of isobutane to isobutene in the presence of carbon dioxide was carried out over supported vanadium oxide
catalysts. The influence of the support on the catalytic performance was investigated. The isobutane conversion and isobutene
selectivity in the presence of carbon dioxide were compared with the results obtained during the dehydrogenation reaction
in the presence of helium (inert gas). The catalysts were characterized by temperature-programmed techniques (TPR, TPD-NH3, TPD-CO2). 相似文献
16.
N. Lingaiah N. Seshu Babu Rajesh Gopinath P. Siva Sankara Reddy P. S. Sai Prasad 《Catalysis Surveys from Asia》2006,10(1):29-39
The use of supported Pd catalysts, with low and high metal content, for the hydrodechlorination of chlorobenzene is presented in this article. Application of microwave irradiation during preparation of catalysts resulted in the synthesis of large Pd particles at moderate temperatures. The nature of the support played a key role in the formation of cationic Pd species. The extent of interaction of the Pd species with the support, the nature of metal precursor, particularly the residual chlorine on the surface were found to significantly affect the activity of the catalysts. In the case of bimetallic catalysts also microwave heating resulted in creation of bigger particles of Pd compared to those observed in conventionally heated catalysts. Besides, it minimized alloy formation as a result of which the activity of the catalysts in hydrodechlorination was found to be higher compared to that observed on conventionally prepared catalysts. Contrary to the general observation that low dispersed Pd catalysts are preferable for high stability, by means of the deposition-precipitation method adopted for catalyst preparation it was demonstrated that even highly dispersed (low Pd containing) catalysts can exhibit comparable activity and stability. An analysis of the nature of Pd species and its role in the stability of the catalysts is presented.IICT communication No. 051224 相似文献
17.
Carbon-supported noble metals are tailored for hydrodesulfurization reaction by adding iron, in such a manner that undesirable hydrogenation reactions are prevented without decrease of the catalytic activity.
, , , .相似文献
18.
Two composite supports with a mixed inorganic–organic structure were synthesized: BTAl and UTAl. Hydrophilic–hydrophobic dual properties of the supports were suitable for preparing egg-shell-supported metal catalysts for selective hydrogenation reactions. The catalysts were characterized by ICP, XRD, OM, TEM, EPMA, XPS and TGA. Their mechanical resistance was assessed. Activity and selectivity were tested with the hydrogenation of 2,3-butanedione (diacetyl) to 3-hydroxy-2-butanoneacetoin (acetoin). The same order of increasing metal particle size was found for the two tested supports: Pt < Ru < Pd. The XPS analysis showed that the metal/composite catalysts reduced in H2 at 503 K had two kinds of active sites: reduced (Me°) and electron-deficient (Me+). It was rationalized that the hydrogen bond cleavage was performed on the Me° active sites, while reactant adsorption occurred on the Me+ sites. The differences in activity and selectivity between the composite catalysts were attributed to electronic effects on the different metals and to different adsorptive properties of the different polymers. The high selectivity to acetoin was attributed to the preferential adsorption of diacetyl as compared to the adsorption of acetoin. The BTAl catalysts were slightly more active and selective than the UTAl ones. This was attributed to electronic effects caused by remnant organic groups on the composite supports (urethane or biphenyl on UTAl or BTAl, respectively). Pd-BTAl was the most active and selective catalyst, a fact related to electronic effects of both palladium and the support. 相似文献
19.
20.
Commercially available polystyrene supported amine and phosphine resins facilitate palladium-mediated Heck and Suzuki reactions in supercritical carbon dioxide (scCO2). 相似文献