共查询到20条相似文献,搜索用时 46 毫秒
1.
S. I. Sulima V. G. Bakun R. E. Yakovenko N. P. Shabel’skaya A. N. Saliev G. B. Narochnyi A. P. Savost’yanov 《Kinetics and Catalysis》2018,59(2):218-228
The physico-chemical characteristics and microstructure of cobalt silica gel catalysts with an Al2O3 additive (up to 10%) for the synthesis of hydrocarbons by the Fischer–Tropsch method are studied using a set of methods including X-ray diffraction, BET, IR spectroscopy, and temperature-programmed reduction of H2, as well as scanning and transmission electron microscopy. Phases with a spinel structure, Со3О4, CoAl2O4, and solid solutions on their basis are identified in the samples. The addition of Al2O3 changes the degree of heterogeneity and the orientation of the cobalt crystallites in the oxide and reduced forms of the catalysts. Addition of 1% Al2O3 stabilizes Со3О4 in the spinel form with a structure close to the normal one and promotes the formation of cobalt with a unimodal distribution of particles with an average size of 8 nm. The catalyst is characterized by maximum activity and selectivity with respect to C5+ carbons. 相似文献
2.
The activity and stability of aluminum-palladium catalysts in the hydrogenation of aromatic hydrocarbons mixed with thiophene were studied. The catalysts were obtained by impregnation of γ-A2O3 with aqueous solutions of salts of palladium complexes. Preliminary sulfiding followed by oxidative activation of Pd/Al2O3 catalysts were found to favor the formation of such palladium state on the surface at which the hydrogenation of aromatic hydrocarbons in the presence of sulfur-containing impurities proceeds without a noticeable change in the activity with time. IR spectroscopy showed that the palladium metal surface fragments forming CO complexes with a characteristic absorption band at 1998 cm–1 are resistant to poisoning with sulfur-containing compounds in the hydrogenation of aromatic hydrocarbons. 相似文献
3.
Najmeh Bashiri Sayed Javid Royaee Morteza Sohrabi 《Research on Chemical Intermediates》2018,44(1):217-229
Global warming, fossil fuel depletion and fuel price increases have motivated scientists to search for methods for the storage and reduction of the amount of greenhouse gases, especially CO2. The hydrogenation process has been introduced as an emerging method of CO2 capture and convertion into value-added products. In this study, new types of catalysts are introduced for CO2 hydrogenation and are compared based on catalytic activity and product selectivity. The physical properties of the samples are specified using BET. Iron catalysts supported on γ-Al2O3 with different metal promoters (X = Ni, K, Mn, Cu) are prepared through the impregnation method. Moreover, Fe–Ni catalysts supported on HZSM5-Al2O3 and Ce–Al2O3 are synthesized. Samples are reduced by pure H2 and involved in hydrogenation reaction in a fixed bed reactor (H2/CO2 = 3, total pressure = 10 MPa, temperature = 523 K, GHSV = 2000, 1250 nml/min). All catalysts provide high conversion in hydrogenation reactions and the results illustrate that the selectivity of light hydrocarbons is higher than that of methane and CO. It is found that Ni has a promoting effect on the conversion fluctuations throughout the reaction with 66.13% conversion. Using combined supported catalysts leads to enhancing catalytic performance. When Fe–Ni/γ–Al2O3—HZSM5 is utilized, CO2 conversion is 81.66% and the stability of the Fe–Ni catalyst supported on Al2O3 and Ce–Al2O3 furthey improves. 相似文献
4.
Gold catalysts with loadings ranging from 0.5 to 7.0 wt% on a ZnO/Al2O3 support were prepared by the deposition–precipitation method (Au/ZnO/Al2O3) with ammonium bicarbonate as the precipitation agent and were evaluated for performance in CO oxidation. These catalysts
were characterized by inductively coupled plasma-atom emission spectrometry, temperature programmed reduction, and scanning
transmission electron microscopy. The catalytic activity for CO oxidation was measured using a flow reactor under atmospheric
pressure. Catalytic activity was found to be strongly dependent on the reduction property of oxygen adsorbed on the gold surface,
which related to gold particle size. Higher catalytic activity was found when the gold particles had an average diameter of
3–5 nm; in this range, gold catalysts were more active than the Pt/ZnO/Al2O3 catalyst in CO oxidation. Au/ZnO/Al2O3 catalyst with small amount of ZnO is more active than Au/Al2O3 catalyst due to higher dispersion of gold particles. 相似文献
5.
Sheng-Li Chen Haitao Wang Guimei Yuan Zhiqing Wang Zhi Cai 《Transition Metal Chemistry》2011,36(4):441-445
Macro-/mesoporous Al2O3 supports were prepared by using monodisperse polystyrene (PS) microspheres as a template. The pore volume and BET surface
area of the Al2O3 supports increased considerably with increasing amounts of the PS microspheres; further investigation showed that PS template
only increased the volume of macro-pores but did not change the volume of meso-pores or micro-pores. Macro-/mesoporous Re2O7/Al2O3 metathesis catalysts were prepared through loading Re2O7 onto the as-prepared macro-/mesoporous Al2O3 supports, and their catalytic performance was tested in a fixed-bed tubular reactor using the metathesis of normal butylenes
as a probe reaction. The results showed that the prepared macro-/mesoporous Re2O7/Al2O3 catalyst had high activity with consistent selectivity; propylene and pentene accounted for more than 90 wt% of the metathesis
products, while the amount of ethylene plus hexane was less than 10 wt%, the majority of which was hexane. These Re2O7/Al2O3 catalysts had not only higher activity, but also longer working life span and higher tolerance to carbon residues than conventional
Re2O7/Al2O3 catalysts. 相似文献
6.
Catalytic performance of gallia-supported iridium catalysts in the reaction of selective hydrogenation of crotonaldehyde in the gas phase was studied and compared to that of platinum and ruthenium catalysts. The best catalytic properties in terms of the selectivity to crotyl alcohol are shown by 5 wt % Pt/α-Ga2O3 and 5 wt % Ir/α-Ga2O3 catalysts prepared from nonchlorine precursors: Pt(acac)2 and Ir(acac)3, but for the 5 wt % Pt/α-Ga2O3 a very high selectivity of 75% at the high conversion (ca. 60%) is observed. A high selectivity of galia-supported iridium and platinum catalysts was explained by the surface reducibility of gallium oxide leading to covering (decoration) of platinum and iridium by gallium suboxides and the promoting effect of gallium. 相似文献
7.
Liquid-phase reduction NO
3
−
using monometallic and bimetallic catalysts (5% Rh/Al2O3, 5% Rh-0.5% Cu/Al2O3, 5% Rh-1.5% Cu/Al2O3, 5% Rh-5% Cu/Al2O3 and a physical mixture of 5% Rh/Al2O3 and 1.5% Cu/Al2O3) was studied in a slurry reactor operating at atmospheric pressure. Kinetic measurements were performed for a low concentration
of nitrate (0.4 × 10−3−3.2 × 10−3 mol dm−3) and the temperature range 293–313 K. From the experimental data, it was found that the reduction of nitrate is first order
with respect to nitrate. On the basis of the rate constants, the apparent activation energy was established using a graphic
method.
Published in Russian in Kinetika i Kataliz, 2007, Vol. 48, No. 6, pp. 881–886.
This article was submitted by the authors in English. 相似文献
8.
Ying Tang Feiqin Chang Rui Zhou Bo Shen Qitong Cheng 《Russian Journal of Applied Chemistry》2016,89(12):2066-2071
Biodiesel containing almost no glycerol has been produced by coupling reaction carried out over K2CO3 supported by calcium oxide as solid base catalysts. The solid base catalysts synthesized by wet impregnation exhibit an exceedingly high activity in biodiesel production. It was found that the reaction time required for the highest yield of biodiesel, 99.2%, can be shortened to 30 min over K2CO3/Al2O3 under the optimum reaction conditions: 8: 1: 1 molar ratio of methanol/DMC/oil, 30 wt % K2CO3/Al2O3 catalyst, and 65°C reaction temperature. Solid basic catalysts examined in the study were characterized by BET surface area, XRD, CO2-TPD, and SEM techniques. The strong interaction between K2CO3 and the support yields a new basic active site, which can be probably responsible for the high activity of K2CO3/Al2O3. 相似文献
9.
Esneyder Puello-Polo Edgar Marquez J. L. Brito 《Journal of Sol-Gel Science and Technology》2018,88(1):90-99
The effect of Nb as a support modifier on the NiMo6/Al2O3–Nb2O5(x) (x?=?0, 1, 4, and 8?wt% Nb) catalysts was studied. The supports were prepared by one-pot coprecipitation from soluble precursors. The XRF analysis of the catalysts showed that the contents of Mo and Ni increased slightly with the presence of Nb. Micropore area and pore volume augmented importantly with Nb content, resulting in pore diameters between 5.3 and 9.3?nm. XPS analysis showed that the presence of Nb decreases the active metal–support interaction, improving the Mo and Ni sulfidation degree. The Raman spectra of sulfided catalysts suggested an increase in the number of layers of MoS2 in the presence of Nb. Generally, the thiophene HDS activity at normal pressure of sulfided NiMo6/Al2O3–Nb2O5(8) was greater than that of the sulfided catalysts with x?=?0, 1, and 4?wt% Nb, which can be attributed to the Nb promotion that would have an effect on the type of active site (Brønsted or Lewis acidic sites), since the number of sites by CO chemisorption for sulfided NiMo6/Al2O3–Nb2O5(x) did not show correlation with the catalytic activity. The high-pressure HDS activity of dibenzothiophene was also greater in the presence of Nb, and the hydrogenation route was preferred for the Nb-promoted solid, while the unpromoted one showed a larger yield of direct desulfurization products. 相似文献
10.
G. V. Pankina P. A. Chernavskii A. Yu. Krylova V. V. Lunin 《Kinetics and Catalysis》2007,48(4):567-571
The physicochemical properties of Co-supported catalysts were studied, and the particle size of Co in Co/MgO/Al2O3 and Co-0.2% Ru/MgO/Al2O3 catalysts for the Fischer-Tropsch synthesis (FTS) was estimated using a magnetic method. It was found that a considerable fraction of superparamagnetic Co particles, which increase selectivity for C5+ hydrocarbons and decrease the yield of methane in the FTS, was present in a ruthenium-containing catalyst along with single-domain ferromagnetic particles. In this case, the catalyst activity increased by a factor of 10. 相似文献
11.
A. Kirilin P. Mäki-Arvela K. Kordas A. -R. Leino A. Shchukarev D. Boström J. -P. Mikkola L. M. Kustov T. O. Salmi D. Yu. Murzin 《Kinetics and Catalysis》2011,52(1):72-76
One-pot synthesis of R-1-phenyethylacetate at 70°C was investigated using three different catalysts simultaneously, namely a bimetallic PdZn/Al2O3 as a hydrogenation catalyst, an immobilized lipase as an acylation catalyst and Ru/Al2O3 as a racemization catalyst. The most active bimetallic catalyst was PdZn/Al2O3 calcined at 300°C and reduced at 400°C, whereas the most selective although less active catalyst was the one being calcined
and reduced at 500°C. The highest selectivity to R-1-phenylethyl acetate over this catalyst was 32 at 48% conversion. Ru/Al2O3 was confirmed to have a positive effect on the formation of the desired product, although it was not very active in the racemization
during one-pot synthesis. 相似文献
12.
Ag/Al2O3 is a promising catalyst for the selective catalytic reduction (SCR) by hydrocarbons (HC) of NO
x
in both laboratory and diesel engine bench tests. New developments of the HC-SCR of NO
x
over a Ag/Al2O3 catalyst are reviewed, including the efficiencies and sulfur tolerances of different Ag/Al2O3-reductant systems for the SCR of NO
x
; the low-temperature activity improvement of H2-assisted HC-SCR of NO
x
over Ag/Al2O3; and the application of a Ag/Al2O3-ethanol SCR system with a heavy-duty diesel engine. The discussions are focused on the reaction mechanisms of different Ag/Al2O3-reductant systems and H2-assisted HC-SCR of NO
x
over Ag/Al2O3. A SO2-resistant surface structure in situ synthesized on Ag/Al2O3 by using ethanol as a reductant is proposed based on the study of the sulfate formation. These results provide new insight
into the design of a high-efficiency NO
x
reduction system. The diesel engine bench test results showed that a Ag/Al2O3-ethanol system is promising for catalytic cleaning of NO
x
in diesel exhaust. 相似文献
13.
A series of Pd/Al2O3–ZrO2 catalysts were prepared to be used in methane oxidation. The effect of the addition order of metal alkoxides on the texture,
structure and catalytic properties of the solids is studied. The control of the preparation parameters is achieved via sol
gel way as an attractive route of the preparation of these catalysts. N2 physisorption, XRD, Scanning Electronic Microscopy (SEM) and H2 chemisorption are the main techniques used to characterize the prepared Pd/Al2O3–ZrO2 catalysts. Textural analysis reveals the mesoporosity of all the catalysts independently of the addition order of alkoxides
while surface area is more pronounced when the aluminium alkoxide is added before or with the zirconium precursor. XRD patterns
show the development of the zirconia tetragonal phase for all the catalysts. Better metallic dispersion is obtained when aluminium
alkoxide is added first which can be justified by the high homogeneity observed on the corresponding catalyst as revealed
by SEM technique. 相似文献
14.
M. S. Nikulshina A. V. Mozhaev P. P. Minaev M. Fournier C. Lancelot P. Blanchard E. Payen C. Lamonier P. A. Nikulshin 《Russian Journal of Applied Chemistry》2017,90(7):1122-1129
Trimetallic NiMoW/Al2O3 catalyst was prepared using mixed H4SiMo3W9O40 heteropoly acid of Keggin structure and nickel citrate. Bimetallic NiMo/Al2O3 and NiW/Al2O3 catalysts based on H4SiMo12O40 and H4SiW12O40, respectively, were synthesized as reference samples. The use of mixed H4SiMo3W9O40 heteropoly acid as an oxide precursor allows the tungsten sulfidation degree and the degree of promotion of active phase particles to be increased. The hydrodesulfurization activity is enhanced as compared to NiW/Al2O3 catalyst. The synergistic enhancement of the activity of the NiMo3W9/Al2O3 catalyst relative to the bimetallic analogs is probably caused by formation of new mixed promoted active sites for direct desulfurization. 相似文献
15.
Qiang Chen Shaohua Zheng Shikuan Yang Wei Li Xiaoyun Song Bingqiang Cao 《Journal of Sol-Gel Science and Technology》2012,61(3):501-508
Monodispersed and hydrophobic ZnO/Al2O3 composite nanoparticles are prepared by a nonhydrolytic sol–gel method. ZnCl2 and AlCl3 are dissolved in acetone and used as precursors. Oleic acid is adopted as an oxygen donor. The tribology properties of the
prepared ZnO/Al2O3 composite nanoparticles are studied by the four-ball friction and thrust ring friction test. It is demonstrated that the
average friction coefficient and the wear scar diameter are reduced by 37.5 and 26.2%, respectively, in comparison with pure
lubricating oil. Moreover, the ZnO/Al2O3 composite nanoparticles bear the merits of ZnO and Al2O3 when used as lubricant additives, exhibiting both excellent antifriction and antiwear behaviors simultaneously. The ZnO/Al2O3 composite nanoparticles improve the lubrication effect not only by turning the sliding friction into rolling friction, but
also forming a hard Al2O3 protective film onto the thrust-ring surface containing ZnO/Al2O3 nanoparticles, which have much potentiality in industrial applications. 相似文献
16.
A presulphided treatment was applied to the oxidic Ni-Mo-Zn/Al2O3 catalyst (nickel catalyst) in order to avoid thermal run-away during initiation of the hydrogenation of pyrolysis gasoline. The physico-chemical properties of the prepared oxidic nickel catalyst, the reduced and passivated (RP) nickel catalyst and the sulphided (RPS) nickel catalyst were characterised using N2 adsorption-desorption, X-ray diffraction, temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The TPR results showed that the reducibility of the RP Ni-Mo-Zn/Al2O3 catalyst was improved over the oxidic nickel catalyst. The XPS spectra confirmed the binding energy of the RPS nickel catalyst to be higher than that of the oxidic nickel catalyst. The catalytic performance was evaluated on a fixed-bed reactor (reaction temperature between 30 °C and 70°C, at 2.8 MPa of total pressure and weight hourly space velocity of 2.0 h?1, the volume of H2/pyrogasoline = 200: 1). The rising temperature of the RPS nickel catalyst was almost 20°C lower than that of the oxidic nickel catalyst during the initial stage of the hydrogenation reaction. The results indicated that the RPS nickel catalyst exhibited better stability than the oxidic nickel catalyst during the start-up period, thereby providing a better selectivity in long-term operation. 相似文献
17.
Ji In Park Jae-Sun Jung Young Su Noh Kwan-Young Lee Dong Ju Moon 《Research on Chemical Intermediates》2018,44(6):3813-3822
Higher alcohol has been considered as a potential fuel additive. Higher alcohol, including C2–C4 alcohol was synthesized by catalytic conversion of syngas (with a ratio of CO/H2?=?1) derived from natural gas over modified Cu/ZnO/Al2O3 catalyst. Modified Cu/ZnO/Al2O3 catalysts promoted by alkali metal (Li) for higher alcohol synthesis (HAS) were prepared at different pH (6, 6.5, 7, 8, and 9) by co-precipitation to control Cu surface area and characterized by N2 physisorption, XRD, SEM, H2-TPR and TPD. The HAS reaction was carried out under a pressure of 45 bar, GHSV of 4000 h?1, ratio of H2/CO?=?1, and temperature ranges of 240 and 280 °C. It was found that the malachite phase of copper causes the size of copper to be small, which is suitable for methanol synthesis. Methanol and HAS share a common catalytic active site and intermediate. It was also found that the productivity to higher alcohol was correlated with Cu surface area. 相似文献
18.
Summary A series of Al2O3-SnO2 catalysts with Al2O3 to SnO2 molar ratio of 1:1, 1:0.5, 1:0.2 and 1:0.1 were synthesized by sol-gel technique and characterized by thermal analysis and FTIR. In the case of binary gels - addition of tin component leads to better crosslinking than in pure alumina gel and as a result to a much uniform texture structure. 相似文献
19.
Xiao-dong Tang Hai Lu Jing-jing Li Lu Chen 《Russian Journal of Applied Chemistry》2016,89(12):2043-2049
Desulfurization performance was evaluated by an adsorption model or real oil (diesel and kerosene) at low temperature using nanocrystalline NiO/Al2O3-1 adsorbent in static equipment. The properties of the NiO/Al2O3 adsorbent samples were characterized by BET surface areas, transmission electron microscopy, FTIR spectra, and TG-DTG curves. Desulfurization experimental results indicated that the desulfurization efficiency for kerosene is much higher than that for diesel due to the π-electronic interaction and S–M bonds with NiO/Al2O3-1 adsorbent. Also, a performance of adsorbent regeneration was kept well for multiple cycles. 相似文献
20.
M. D. Smolikov K. V. Kazantsev E. V. Zatolokina D. I. Kir’yanov E. A. Paukshtis A. S. Belyi 《Kinetics and Catalysis》2010,51(4):584-594
The state of surface Pt atoms in the Pt/SO4/ZrO2/Al2O3 catalyst and the effect of the state of platinum on its adsorption and catalytic properties in the reaction of n-hexane isomerization were studied. The Pt-X/Al2O3 alumina-platinum catalysts modified with various halogens (X = Br, Cl, and F) and their mechanical mixtures with the SO4/ZrO2/Al2O3 superacid catalyst were used in this study. With the use of IR spectroscopy (COads), oxygen chemisorption, and oxygen-hydrogen titration, it was found that ionic platinum species were present on the reduced
form of the catalysts. These species can adsorb to three hydrogen atoms per each surface platinum atom. The specific properties
of ionic platinum manifested themselves in the formation of a hydride form of adsorbed hydrogen. It is believed that the catalytic
activity and operational stability of the superacid system based on sulfated zirconium dioxide were due to the participation
of ionic and metallic platinum in the activation of hydrogen for the reaction of n-hexane isomerization. 相似文献