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1.
Park Joo-Hyoung Cho Hyun Ju Park Sang Jun Nam In-Sik Yeo Gwon Koo Kil Jeong Ki Youn Young Kee 《Topics in Catalysis》2007,42(1-4):61-64
Co/Pt/Ba/γ-Al2O3, Co/Ba/γ-Al2O3, Pt/Ba/γ-Al2O3, Co/Pt/γ-Al2O3, Ba/γ-Al2O3, Pt/γ-Al2O3, and Co/γ-Al2O3 type catalysts were prepared by a conventional impregnation method, and their NO
x
storage capacities were evaluated by colorimetric assay. Co-containing catalysts had a higher NO
x
storage capacity than that of Co-free counterparts. The role of each component, especially Co, for the catalysts prepared
was investigated by using in-situ FTIR. The high NO
x
storage for Co-containing catalysts including Co/Ba/γ-Al2O3 and Co/Pt/Ba/γ-Al2O3 is mainly due to the formation of Co3O4 on the catalyst surface identified by XAFS. 相似文献
2.
Deactivation and coke formation on palladium and platinum catalysts in vegetable oil hydrogenation 总被引:1,自引:0,他引:1
Jonas Edvardsson Petri Rautanen Anders Littorin Mikael Larsson 《Journal of the American Oil Chemists' Society》2001,78(3):319-327
Deactivation of palladium and platinum catalysts due to coke formation was studied during hydrogenation of methyl esters of
sunflower oil. The supported metal catalysts were prepared by impregnating γ-alumina with either palladium or platinum salts,
and by impregnating α-alumina with palladium salt. The catalysts were reused for several batch experiments. The Pd/γ-Al2O3 catalyst lost more than 50% of its initial activity after four batch experiments, while the other catalysts did not deactivate.
Samples of used catalysts were cleaned from remaining oil by repeated extractions with methanol, and the amount of coke formed
on the catalysts was studied by temperature-programmed oxidation. The deactivation of the catalyst is a function of both the
metal and the support. The amount of coke increased on the Pd/γ-Al2O3 catalyst with repeated use, but the amount of coke remained approximately constant for the Pt/γ-Al2O3 catalyst. Virtually no coke was detected on the Pd/α-Al2O3 catalyst. The formation of coke on Pd/α-Al2O3 may be slower than on the Pd/γ-Al2O3 owing to the carrier’s smaller surface area and less acidic character. The absence of deactivation for the Pt/γ-Al2O3 catalyst may be explained by slower formation of coke precursors on platinum compared to palladium. 相似文献
3.
Characterization of supported Pd-Cu bimetallic catalysts by SEM, EDXS, AES and catalytic selectivity measurements 总被引:2,自引:0,他引:2
Pd-Cu/γ-Al2O3 bimetallic catalysts were prepared according to different impregnation sequences of γ-Al2O3 and characterized by XRD, SEM, EDXS and AES. The catalysts were tested for the selective hydrogenation of aqueous nitrate
solutions to nitrogen. The reaction selectivity was found to be dependent on the catalyst preparation procedures, which affect
the spatial distribution of metallic copper and palladium phases. A catalyst prepared by impregnating γ -Al2O3 with copper followed by palladium gives higher selectivity to nitrogen than a catalyst prepared by impregnating the support
with palladium followed by copper. The AES examination shows that in the catalyst exhibiting a higher nitrogen production
yield, a reaction zone for the liquid-phase nitrate reduction is located in the interior of particles and covered by a layer
of Pd atoms.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Seung-Soo Kim Jinsoo Kim Hwaung Lee Byung-Ki Na Hyung Keun Song 《Korean Journal of Chemical Engineering》2005,22(4):585-590
Spherical nanostructured γ-Al2O3 granules were prepared by combining the modified Yoldas process and oil-drop method, followed by the Pt impregnation inside
mesopores of the granules by incipient wetness method. Prepared Pt/γ-Al2O3 catalysts were reduced by novel method using plasma, which was named plasma assisted reduction (PAR), and then used for methane
conversion in dielectric-barrier discharge (DBD). The effect of Pt loading, calcination temperature on methane conversion,
and selectivities and yields of products were investigated. Prepared Pt/γ-Al2O3 catalysts were successfully reduced by PAR. The main products of methane conversion were the light alkanes such as C2H6, C3H8 and C4H10 when the catalytic plasma reaction was carried out with Pt/γ-Al2O3 catalyst. Methane conversion was in the range of 38–40% depending on Pt loading and calcination temperature. The highest
yield of C2H6 was 12.7% with 1 wt% Pt/γ-Al2O3 catalysts after calcinations at 500 ‡C. 相似文献
5.
A catalyst for NOx storage/reduction was prepared to improve the activity of Ba–Pt/γ-Al2O3 by replacing Ba with a mixture of Ba and Mg. The catalyst was prepared by impregnating Pt and then co-impregnating Ba and
Mg (Mg:Ba molar ratio = 1) on commercial γ-Al2O3. The tests have been carried out in the presence of CO2 at temperatures between 200 and 400 °C in order to understand the role of both the feed and various alkaline-earth metals.
The storage capacity of the two catalysts was different like the mechanism in the reduction process. 相似文献
6.
Neetha A. Khan Luis E. Murillo Yuying Shu Jingguang G. Chen 《Catalysis Letters》2005,105(3-4):233-238
The low-temperature self-hydrogenation (disproportionation) of cyclohexene was used as a probe reaction to correlate the reactivity
of Co/Pt(111) bimetallic surfaces with supported Co/Pt/γ-Al2O3 catalysts. Temperature-programmed desorption (TPD) experiments show that cyclohexene undergoes self-hydrogenation on the
~1 ML Co/Pt(111) surface at ~219 K, which does not occur on either pure Pt(111) or a thick Co film on Pt(111). Supported catalysts
with a 1:1 atomic ratio of Co:Pt were synthesized on a high surface area γ-Al2O3 to verify the bimetallic effect on the self-hydrogenation of cyclohexene. EXAFS experiments confirmed the presence of Co–Pt
bonds in the catalyst. Using FTIR in a batch reactor configuration, the bimetallic catalyst showed a higher activity toward
the self-hydrogenation of cyclohexene at room temperature than either Pt/γ-Al2O3 or Co/γ-Al2O3 catalysts. The comparison of Co/Pt(111) and Co/Pt/γ-Al2O3 provided an excellent example of correlating the self-hydrogenation activity of cyclohexene on bimetallic model surfaces
and supported catalysts. 相似文献
7.
Hydrodesulfurization of dibenzothiophene over supported and unsupported molybdenum carbide catalysts
Hea Kyung Park Du Soung Kim Kyung Lim Kim 《Korean Journal of Chemical Engineering》1998,15(6):625-630
A series of γ-Al2O3 supported molybdenum carbides [carbided Mo/γ-Al2O3 (MCS), Co-Mo/γ-Al2O3 (CMCS), and Ni-Mo/γ-Al2O3 (NMCS)] and unsupported molybdenum carbide (MCUS) were prepared by the temperature-programmed carburization of their corresponding
molybdenum nitrides with 20 % CH4/H2. XRD and SEM studies show that unsupported molybdenum carbide catalyst possesses a typical crystalline Mo2C (FCC structure), while supported molybdenum carbide catalysts possess highly dispersed surface molybdenum carbide species
on an alumina oxide support. The results of dibenzothiophene (DBT) hydrodesulfurization over molybdenum carbide catalysts
show that the reactivity is strongly dependent on the type of catalyst. Supported molybdenum carbide catalysts possess a higher
reactivity than the unsupported molybdenum carbide catalyst. In addition, Co or Ni promoted, supported molybdenum carbide
catalyst possesses a higher reactivity than the unpromoted, supported molybdenum carbide catalyst. The reactivity, which is
also dependent on the reaction conditions, increases with increasing reaction temperature and pressure and contact time. The
CO uptakes of the molybdenum carbide catalysts correlate well with overall activity (total rate) for DBT hydrodesulfurization.
The major reaction product is biphenyl, with cyclohexylbenzene next in abundance regardless of the type of catalysts and reaction
conditions. It was also found that the molybdenum carbide catalysts exhibit stable initial reactivity due to the stable and
weak acidic characteristics of these catalysts. 相似文献
8.
Pt/γ- Al2O3, Co/γ- Al2O3 and Pt- Co/γ- Al2O3 with different Pt : Co atomic ratios have been prepared with a total metal content of 10 wt% and characterised by hydrogen
chemisorption. The activities of the prereduced catalysts were studied for the reaction of cyclohexanol at 523 K and WHSV
of 4.82 and 7.7 h-1. The Pt-Co/γ-Al2O3 catalyst with 1 : 1 Pt : Co atomic ratio shows typical high metal dispersion and cyclohexanone selectivity.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
Eun-Yong Ko Eun Duck Park Kyung Won Seo Hyun Chul Lee Doohwan Lee Soonho Kim 《Catalysis Letters》2006,110(3-4):275-279
The preferential CO oxidation (PROX) in the presence of excess hydrogen was studied over Pt–Ni/γ-Al2O3. CO chemisorption, X-ray diffraction, transmission electron microscopy, energy dispersive X-ray spectroscopy and temperature-programmed
reduction were conducted to characterize active catalysts. The co-impregnated Pt–Ni/γ-Al2O3 was superior to Pt/Ni/γ-Al2O3 and Ni/Pt/γ-Al2O3 prepared by a sequential impregnation of each component on alumina support. The PROX activity was affected by the reductive
pretreatment condition. The pre-reduction was essential for the low-temperature PROX activity. As the reduction temperature
increased above 423 K, the CO2 selectivity decreased and the atomic percent of Ni in the bimetallic phase of Pt–Ni increased. This catalyst exhibited the
high CO conversion even in the presence of 2% H2O and 20% CO2 over a wide reaction temperature. The bimetallic phase of Pt–Ni seems to give rise to high catalytic activity for the PROX
in H2-rich stream. 相似文献
10.
Guida Sun Cuiqing Li Zhijun Zhou Fengyan Li 《Frontiers of Chemical Engineering in China》2008,2(2):155-164
Supported tungsten phosphide catalysts were prepared by temperature-programmed reduction of their precursors (supported phospho-tungstate
catalysts) in H2 and characterized by X-ray diffraction (XRD), BET, temperature-programmed desorption of ammonia (NH3-TPD) and X-ray photoelectron spectroscopy (XPS). The reduction-phosphiding processes of the precursors were investigated
by thermogravimetry and differential thermal analysis (TG-DTA) and the suitable phosphiding temperatures were defined. The
hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) activities of the catalysts were tested by using thiophene, pyridine,
dibenzothiophene, carbazole and diesel oil as the feedstock. The TiO2, γ-Al2O3 supports and the Ni, Co promoters could remarkably increase and stabilize active W species on the catalyst surface. A suitable
amount of Ni (3%–5%), Co (5%–7%) and V (1%–3%) could increase dispersivity of the W species and the BET surface area of the
WP/γ-Al2O3 catalyst. The WP/γ-Al2O3 catalyst possesses much higher thiophene HDS and carbazole HDN activities and the WP/TiO2 catalyst has much higher dibenzothiophene (DBT) HDS and pyridine HDN activities. The Ni, Co and V can obviously promote the
HDS activity and inhibit the HDN activity of the WP/γ-Al2O3 catalyst. The G-Ni5 catalyst possesses a much higher diesel oil HDS activity than the sulphided industrial NiW/γ-Al2O3 catalyst. In general, a support or promoter in the WP/γ-Al2O3 catalyst which can increase the amount and dispersivity of the active W species can promote its HDS and HDN activities. 相似文献
11.
Hongbin Ma Shufen Li Boyang Wang Ruihong Wang Songjiang Tian 《Journal of the American Oil Chemists' Society》2008,85(3):263-270
The heterogeneous base catalyst, γ-Al2O3 loaded with KOH and K (K/KOH/γ-Al2O3) was first prepared and used in the transesterification of rapeseed oil with methanol to produce biodiesel. The prepared
catalyst was characterized by X-ray diffraction, scanning electron microscopy, Brunauer–Emmett–Teller method, infrared spectroscopy
and X-ray photoelectron spectroscopy. It was found that when γ-Al2O3 is loaded with KOH and K, the Al–O–K species is produced, resulting in an increase in the catalytic activity. The impacts
of catalyst preparation conditions on the catalytic activities of K/KOH/γ-Al2O3 were investigated. The results demonstrate that the catalyst K/KOH/γ-Al2O3 has high catalytic activity when the added amounts of KOH and K are 20 and 7.5 wt% respectively. The transesterification
of rapeseed oil to biodiesel with the prepared heterogeneous base catalyst was optimized. It was found that the yield of biodiesel
can reach as high as 84.52% after 1 h reaction at 60°C, with a 9:1 molar ratio of methanol to oil, a catalyst amount of 4 wt%,
and a stirring rate of 270 g. 相似文献
12.
Zhixin Yu Øyvind Borg De Chen Bjørn Christian Enger Vidar Frøseth Erling Rytter Hanne Wigum Anders Holmen 《Catalysis Letters》2006,109(1-2):43-47
Platelet and fishbone carbon nanofibers (CNFs) have been used as supports for cobalt Fischer–Tropsch catalysts. The activity
and selectivity of the CNF supported catalysts have been studied at 483 K, 20 bar, and H2/CO = 2.1, and compared with corresponding activity and selectivity for α-Al2O3 and γ-Al2O3 supported cobalt catalysts. The platelet CNF supported catalyst has demonstrated high activity and high selectivity to C5+ hydrocarbons, with activity comparable with Co/γ-Al2O3 and selectivity comparable with Co/α-Al2O3. 相似文献
13.
Nano-crystalline Ceria Catalysts for the Abatement of Polycyclic Aromatic Hydrocarbons 总被引:2,自引:0,他引:2
Nano-crystalline cerium oxide catalysts have been prepared by precipitation and evaluated for the total catalytic oxidation
of naphthalene, which is a polycyclic aromatic hydrocarbon (PAH). Ceria synthesised by precipitation with urea was the most
active catalyst for oxidation of naphthalene to carbon dioxide. The urea precipitated CeO2 demonstrated over 90% naphthalene conversion to carbon dioxide at 175°C (100 ppm naphthalene, GHSV=25,000 h−1), whilst ceria precipitated via a carbonate only gave 90% conversion at 275°C. Comparison with known high activity total
oxidation catalysts, Mn2O3 and 0.5% Pt/γ-Al2O3, showed that the urea precipitated CeO2 was a more effective catalyst for naphthalene total oxidation. At temperatures below those required to achieve catalytic
activity the adsorption capacity of urea precipitated ceria for naphthalene was considerably greater than any of the other
catalysts examined. The high adsorption capacity of the material provides the advantage that it can be used as a combined
catalyst and adsorbent to remove PAHs from waste streams. 相似文献
14.
Zinfer R. Ismagilov Mikhail A. Kerzhentsev Vladimir A. Sazonov Lidia T. Tsykoza Nadezhda V. Shikina Vadim V. Kuznetsov Vladimir A. Ushakov Sergey V. Mishanin Nikolay G. Kozhukhar Gennaro Russo Olaf Deutschmann 《Korean Journal of Chemical Engineering》2003,20(3):461-467
Catalytic burners for fuel cell power plant reformers are alternatives to conventional flame burners. Their application is
expected to provide uniform temperatures in the reformer, efficient use of low-calorific gaseous by products and reduction
of pollutant emissions. For testing in the burners, a series of spherical Pd/CeO2/Al2O3 catalysts were prepared. An optimum concentration of ceria providing the highest thermal stability of catalysts was determined.
An effect of catalyst activation in the reaction mixture-1% methane in air was observed. A series of Mn containing oxide catalysts
on spherical γ-Al2O3 or (γ+Χ)-Al2O3, both pure and doped with La, Ce and Mg oxides were prepared. The catalysts were characterized by chemical analysis, X-ray
phase analysis, BET surface area and activity measurements in methane oxidation. A batch of Mn-Mg-La-Al-O catalyst was prepared
for further long-term testing in a model reformer with a catalytic burner. A model reformer with a catalytic burner was designed
and fabricated for testing in the composition of the bench-scale Fuel Cell Power Plant. Preliminary testing of this catalyst
showed that it provided complete methane combustion at the specified operational temperatures over 900 °C. 相似文献
15.
《Journal of Industrial and Engineering Chemistry》2014,20(6):4421-4428
This research includes synthesis of nano-sized γ-Al2O3 catalyst for methanol dehydration reaction to produce DME. A co-precipitation method with four precipitants including sodium carbonate, sodium bicarbonate, ammonium carbonate and ammonium bicarbonate was used for this purpose. The catalysts were characterized by XRD, FTIR, NH3-TPD, SEM, TEM and N2 adsorption–desorption techniques. In order to investigate the catalyst activity, they were used in the fixed bed micro reactor for methanol dehydration reaction at different operating conditions. Also, a commercial γ-Al2O3 nanocatalyst was utilized for comparison purposes. The catalyst prepared by ammonium carbonate showed the highest yield of DME in comparison with other ones. 相似文献
16.
γ-Al2O3-supported alkaline earth metal oxide samples with different MgO, CaO, SrO and BaO loadings have been prepared by impregnating
γ-Al2O3 with alkaline earth metal nitrate solutions and then calcining at 773 K and 1,023 K. The resultant samples have been characterized
by XRD, EDS coupled with SEM, CO2-TPD and BET. After preparation of the γ-Al2O3-supported alkaline earth metal oxide samples and impregnation with the liquid catalyst LCPs30, supplied by Axens, the catalytic
performance of these catalysts was evaluated in the mercaptan oxidation reaction. Results showed that magnesium base oxide
is formed at 773 K and base oxides of calcium, barium and strontium are formed at 1,023 K. Catalysts with higher mole ratios
have higher conversions and the basicity increases with increasing base oxide loading in the samples. Furthermore, the conversion
of mercaptans increases with increasing atomic number of the alkaline earth metal, excluding MgO, which has the highest conversion
compared to the other base oxides. 相似文献
17.
The hydrocracking and hydrodesulfurization (HDS) of n-heptane containing 0.2 mole% dibenzothiophene (DBT) were performed simultaneously
using NiPtMo catalysts supported on HZSM-5, LaY and γ-Al2O3 in a high pressure fixed bed reactor. Molybdenum played an important role in both hydrocracking and hydrodesulfurization
(HDS). We found that the sulfur compound, dibenzothiophene (DBT). in the reactant was adsorbed on a molybdenum site and converted
to hydrogen sulfide so that the active sites of the catalysts for hydrocracking were less poisoned by DBT and the conversion
of n-heptane over molybdenum impregnated catalyst was higher than that over molybdenum-free catalyst. The crystal structures
of the molybdenum supported on the zeolite and γ-Al2O3 were mainly MoO2.5 (OH)0.5[021] and MoO3[210] respectively as shown by XRD analysis. The structure of MoO2.5(OH)0.5 was easily reduced to MoS2[003] during the reaction. After the reaction of 100 hours over the catalyst supported on γ-Al2O3 the crystal structure of MoO3[210] partially changed to MoO3[300] and the structure of MoS2[003] was not observed. Because of the reactant shape selectivity of zeolite, the acid and the metal sites in the intracrystalline
of the catalysts supported on zeolites were less poisoned by DBT. Therefore, both hydrocracking and HDS using n-heptane containing
0.2 mole% of DBT were successfully demonstrated over the prepared catalysts. 相似文献
18.
Jeong Gil Seo Min Hye Youn Sunyoung Park Joohyung Lee Sang Hee Lee Howon Lee In Kyu Song 《Korean Journal of Chemical Engineering》2008,25(1):95-98
An Al2O3-ZrO2 support was prepared by grafting a zirconium precursor onto the surface of commercial γ-Al2O3. A physical mixture of Al2O3-ZrO2 was also prepared for the purpose of comparison. Ni/Al2O3-ZrO2 catalysts were then prepared by an impregnation method, and were applied to the hydrogen production by steam reforming of
liquefied natural gas (LNG). The effect ZrO2 and preparation method of Al2O3-ZrO2 on the performance of supported nickel catalysts in the steam reforming of LNG was investigated. The Al2O3-ZrO2 prepared by a grafting method was more efficient as a support for nickel catalyst than the physical mixture of Al2O3-ZrO2 in the hydrogen production by steam reforming of LNG. The well-developed tetragonal phase of ZrO2 and the high dispersion of ZrO2 on the surface of γ-Al2O3 were responsible for the enhanced catalytic performance of Ni/Al2O3-ZrO2 prepared by way of a grafting method. 相似文献
19.
New catalysts for olefin metathesis are obtained upon interaction between rhenium trisacetylacetonate and -Al2O3 surface. After high temperature treatment in flows of O2 and N2 and addition of organometallic compound as a cocatalyst the activity of the resulting catalyst exceeds that of known Re/Al2O3 catalysts prepared by impregnation. The catalysts exhibit maximal activity at a cocatalyst surface concentration of 3 × 10–7 mol/m2. Further increase of the cocatalyst concentration leads to deactivation. 相似文献
20.
Øyvind Borg Edd A. Blekkan Sigrid Eri Duncan Akporiaye Bente Vigerust Erling Rytter Anders Holmen 《Topics in Catalysis》2007,45(1-4):39-43
The effect of calcination temperature and atmosphere on the properties of γ-Al2O3 supported cobalt Fischer-Tropsch catalysts has been investigated. One common precursor for all the catalysts was prepared
by incipient wetness impregnation of γ-Al2O3 with an aqueous solution of cobalt nitrate hexahydrate. It was subjected to four different calcination atmospheres (air/50%
steam: 30 mL/min, air: 30 mL/min, air: 50 mL/min, N2: 30 mL/min) and eight different calcination temperatures (range: 473–723 K), making the total number of samples 32. Both
the post calcination nitrogen content and the cobalt dispersion were measured. The results demonstrated that in order to maximise
the cobalt dispersion, it is necessary to use low calcination temperatures and remove the precursor decomposition products
(NO, NO2, H2O) efficiently. The Fischer-Tropsch synthesis performance of two catalysts calcined at the same temperature, but at different
air flow rates was evaluated. No significant effect of the air flow rate was found on the turnover frequency or C5+ selectivity, but a high flow rate resulted in 30% higher activity per gram catalyst. 相似文献