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1.
Yejin Lee Hoda Shafaghat Jae-kon Kim Jong-Ki Jeon Sang-Chul Jung In-Gu Lee Young-Kwon Park 《Korean Journal of Chemical Engineering》2017,34(8):2180-2187
Tungstated zirconia (WO3/ZrO2 with WO3 loadings of 9.9 (WZ9.9), 15.5 (WZ15.5), and 15.7 wt% (WZ15.7)) and Amberlyst (15, 35, 36, 39 and 45) catalysts were employed to upgrade pyrolysis bio-oil of acacia sawdust through an esterification reaction using methanol at atmospheric pressure and room temperature or 80 °C. The upgrading efficiency was evaluated by measuring the total acid number (TAN) and viscosity. The viscosity and TAN of the resulting upgraded bio-oil were found to be dependent on the calcination temperature of the WO3/ZrO2 catalysts. At room temperature, the largest decrease in viscosity and TAN of the bio-oil and methanol mixture was obtained using WZ9.9 tungstated zirconia calcined at 900 °C. An increase in reaction temperature to 80 °C improved the flowability and TAN of the methanol-added bio-oil using WZ9.9 activated at 900 °C. The product distribution of the bio-oil upgraded using methanol revealed esterification to be the dominant reaction pathway under the reaction conditions of this study. When the ether extracted bio-oil was upgraded at 80 °C using methanol over catalysts, the Amberlyst catalysts were found more effective than tungstated zirconia catalysts in enhancing the esterification reaction and reducing TAN. 相似文献
2.
Joseph A. Singh Ang Cao Julia Schumann Tao Wang Jens K. Nørskov Frank Abild-Pedersen Stacey F. Bent 《Catalysis Letters》2018,148(12):3583-3591
Methanol is an important chemical compound which is used both as a fuel and as a platform molecule in chemical production. Synthesizing methanol, as well as dimethyl ether, directly from carbon dioxide and hydrogen produced using renewable electricity would be a major step forward in enabling an environmentally sustainable economy. We utilize density functional theory combined with microkinetic modeling to understand the methanol synthesis reaction mechanism on a model CoGa catalyst. A series of catalysts with varying Ga content are synthesized and experimentally tested for catalytic performance. The performance of these catalysts is sensitive to the Co:Ga ratio, whereby increased Ga content results in increased methanol and dimethyl ether selectivity and increased Co content results in increased selectivity towards methane. We find that the most active catalysts have up to 95% CO-free selectivity towards methanol and dimethyl ether during CO2 hydrogenation and are comparable in performance to a commercial CuZn catalyst. Using in situ DRIFTS we experimentally verify the presence of a surface formate intermediate during CO2 hydrogenation in support of our theoretical calculations. 相似文献
Graphical Abstract
3.
Hye-Won Lim Hye Jin Jun Myung-June Park Hyo-Sik Kim Jong Wook Bae Kyoung-Su Ha Ho-Jeong Chae Ki-Won Jun 《Korean Journal of Chemical Engineering》2010,27(6):1760-1767
A kinetics model that takes the synergetic effect of carbon dioxide fraction on the methanol production rate into account
is applied to the development of a mathematical model for the bench-scale reactor. A comparison between the simulation results
and the experimental data corroborates the validity of the model. Several optimization strategies are suggested to maximize
the methanol yield, among which the utilization of piecewise trajectories for wall temperature along the reactor axis as well
as the optimal CO2 fraction at the inlet of the reactor is found to be the best strategy in the sense of methanol production per unit amount
of the feed, in such a way that the optimization strategy considers the variation of the reaction temperature in the reactor
and maximizes the synergetic effect on the production rate by the addition of carbon dioxide. 相似文献
4.
Abstract
Ce X Zr1−X O2 catalysts with different cerium content (X) (X = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0) were prepared by a sol–gel method for use in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Among these catalysts, Ce0.6Zr0.4O2 was found to show the best catalytic performance. In order to enhance the acidity and basicity of Ce0.6Zr0.4O2 catalyst, Ga2O3 was supported on Ce0.6Zr0.4O2 (XGa2O3/Ce0.6Zr0.4O2 (X = 1, 5, 10, and 15)) by an incipient wetness impregnation method with a variation of Ga2O3 content (X, wt%). Effect of acidity and basicity of Ga2O3/Ce0.6Zr0.4O2 on the catalytic performance in the direct synthesis of dimethyl carbonate was investigated using NH3-TPD and CO2-TPD experiments. Experimental results revealed that both acidity and basicity of the catalysts played a key role in determining the catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. Large acidity and basicity of the catalyst facilitated the formation of dimethyl carbonate. The amount of dimethyl carbonate produced over XGa2O3/Ce0.6Zr0.4O2 catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, 5Ga2O3/Ce0.6Zr0.4O2, which retained the largest acidity and basicity, showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. 相似文献5.
G. Blanco-Brieva M. Montiel-Argaiz F. Desmedt P. Miquel J. M. Campos-Martin J. L. G. Fierro 《Topics in Catalysis》2017,60(15-16):1151-1155
Three catalysts consisting of palladium supported on functionalized silica with different acid groups (namely aryl sulfonic, alkyl phosphonic and alkyl carboxylic groups) were prepared and tested in the direct synthesis of hydrogen peroxide in neutral methanol medium at an overall pressure of 5.0 MPa. These catalysts can produce hydrogen peroxide. In addition, the activity results indicated correlations among the acid strength of the acidic group on the supports, the proportion of high binding energy palladium species and the selectivity for hydrogen peroxide. 相似文献
6.
The structure of glasses in the x(0.16GaCh2 · 0.84GeCh2) · (1 − x)(SbCh1.5) (Ch = S, Se) system has been investigated using Raman scattering. The structure of glasses is interpreted as a superposition
of the following structural units: Ge(Ga)Ch4/2, Ch3/2Ge(Ga)-Ge(Ga)Ch3/2, SbCh3/2, and -Ch-Ch-, where Ch = S and Se. The change in the fraction of the corresponding structural units with a change in the
glass composition has been analyzed. 相似文献
7.
Ce
X
Zr1−X
O2 catalysts with different cerium content (X) (X=0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1.0) were prepared by a sol-gel method. Among
these catalysts, Ce0.6Zr0.4O2 showed the best catalytic performance in the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. To
see the effect of acidity and basicity of transition metal oxide/Ce0.6Zr0.4O2 catalysts on the catalytic performance in the direct synthesis of dimethyl carbonate, MO/Ce0.6Zr0.4O2 (MO=Ga2O3, La2O3, Ni2O3, Fe2O3, Y2O3, Co3O4, and Al2O3) catalysts were prepared by an incipient wetness impregnation method. NH3-TPD and CO2-TPD experiments were carried out to measure acidity and basicity of the supported catalysts, respectively. Experimental results
revealed that both acidity and basicity of the catalysts played a key role in determining the catalytic performance in the
direct synthesis of dimethyl carbonate from methanol and carbon dioxide. The amount of dimethyl carbonate produced over MO/Ce0.6Zr0.4O2 catalysts increased with increasing both acidity and basicity of the catalysts. Among the catalysts tested, Ga2O3/Ce0.6Zr0.4O2, which had the largest acidity and basicity, exhibited the best catalytic performance in the direct synthesis of dimethyl
carbonate from methanol and carbon dioxide. 相似文献
8.
S. F. Tikhov Yu. N. Bespalko V. A. Sadykov A. N. Salanov S. I. Reshetnikov 《Combustion, Explosion, and Shock Waves》2016,52(5):535-543
The activity of plates of CuO/Al2O3/FeAlO/FeAl structured cermet catalysts is compared by varying their alumina content. The catalysts were prepared by impregnation of cermet supports obtained by mechanochemical activation of powder mixtures of an alumina precursor [20–50% (wt.)], iron, and aluminum, followed by hydrothermal treatment and calcination. It is shown that increasing the content of the alumina precursor (product of thermal activation of gibbsite) increases the specific surface area of the support and the mesopore and macropore volumes and reduces its mechanical strength. The content of the active component (CuO) also increases, resulting in an increase in the specific activity of catalyst despite a reduction in the effectiveness of using the active component. The activity of catalysts with a moderate concentration of alumina is sufficient to initiate methane oxidation. 相似文献
9.
Zhou-wen Fang Di Wen Zhi-hao Wang Xiang-li Long 《Korean Journal of Chemical Engineering》2018,35(11):2172-2184
The production of isophthalic acid (IPA) from the oxidation of m-xylene (MX) by air is catalyzed by H3PW12O40 (HPW) loaded on carbon and cobalt. We used H2O2 solution to oxidize the carbon to improve the catalytic activity of HPW@C catalyst. Experiments reveal that the best carbon sample is obtained by calcining the carbon at 700 °C for 4 h after being impregnated in the 3.75% H2O2 solution at 40 °C for 7 h. The surface characterization displays that the H2O2 modification leads to an increase in the acidic groups and a reduction in the basic groups on the carbon surface. The catalytic capability of the HPW@C catalyst depends on its surface chemical characteristics and physical property. The acidic groups play a more important part than the physical property. The MX conversion after 180 min reaction acquired by the HPW@C catalysts prepared from the activated carbon modified in the best condition is 3.81% over that obtained by the HPW@C catalysts prepared from the original carbon. The IPA produced by the former is 46.2% over that produced by the latter. 相似文献
10.
In the present study, we synthesized biodiesel from soybean oil through a transesterification reaction catalyzed by lithium carbonate. Under the optimal reaction conditions of methanol/oil molar ratio 32:1, 12 % (wt/wt oil) catalyst amount, and a reaction temperature of 65 °C for 2 h, there was a 97.2 % conversion to biodiesel from soybean oil. The present study also evaluated the effects of methanol/oil ratio, catalyst amount, and reaction time on conversion. The catalytic activity of solid base catalysts was insensitive to exposure to air prior to use in the transesterification reaction. Results from ICP-OES exhibited non-significant leaching of the Li2CO3 active species into the reaction medium, and reusability of the catalyst was tested successfully in ten subsequent cycles. Free fatty acid in the feedstock for biodiesel production should not be higher than 0.12 % to afford a product that passes the EN biodiesel standard. Product quality, ester content, free glycerol, total glycerol, density, flash point, sulfur content, kinematic viscosity, copper corrosion, cetane number, iodine value, and acid value fulfilled ASTM and EN standards. Commercially available Li2CO3 is suitable for direct use in biodiesel production without further drying or thermal pretreatment, avoiding the usual solid catalyst need for activation at high temperature. 相似文献
11.
Simona Ostachaviciute Jonas Baltrušaitis Eugenijus Valatka 《Journal of Applied Electrochemistry》2010,40(7):1337-1347
Thin films of bare and Se-containing tungsten trioxide (WO3) on AISI304-type stainless steel were prepared by electrochemical deposition using peroxy-tungstate solutions. The obtained
films were characterized by X-ray diffraction, photoelectron spectroscopy, scanning electron microscopy, thermal and photovoltammetry
analyses. The oxidation of methylene blue, phenol, and methanol was used to evaluate the photoelectrocatalytic activity of
the prepared films. It has been established that the incident photon-to-current efficiency (IPCE) in 0.1-M K2SO4 decreases as the concentration of methylene blue and phenol increases. On the contrary, the IPCE values increase with the
increase in initial concentration of methanol. The bulk electrolysis experiments revealed that the prepared films are stable
and can be used for photoelectrochemical oxidation of methanol. 相似文献
12.
L. Colmenares E. Guerrini Z. Jusys K. S. Nagabhushana E. Dinjus S. Behrens W. Habicht H. Bönnemann R. J. Behm 《Journal of Applied Electrochemistry》2007,37(12):1413-1427
The activity, selectivity, and methanol tolerance of novel, carbon supported high-metal loading (40 wt.%) Pt/C and Pt3Me/C (Me = Ni, Co) catalysts for the O2 reduction reaction (ORR) were evaluated in model studies under defined mass transport and diffusion conditions, by rotating
(ring) disk and by differential electrochemical mass spectrometry. The catalysts were synthesized by the organometallic route,
via deposition of pre-formed Pt and Pt3Me pre-cursors followed by their decomposition into metal nanoparticles. Characteristic properties such as particle sizes,
particle composition and phase formation, and active surface area, were determined by transmission electron microscopy, energy
dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. For comparison, commercial Pt/C catalysts
(20 and 40 wt.%, E-Tek, Somerset, NJ, USA) were investigated as well, allowing to evaluate Pt loading effects and, by comparison
with the pre-cursor-based catalyst with their much smaller particle sizes (1.7 nm diameter), also particle size effects. Kinetic
parameters for the ORR were evaluated; the ORR activities of the bimetallic catalysts and of the synthesized Pt/C catalyst
were comparable and similar to that of the high-loading commercial Pt/C catalyst; at typical cathode operation potentials
H2O2 formation is negligible for the synthesized catalysts. Due to their lower methanol oxidation activity the bimetallic catalysts
show an improved methanol tolerance compared to the commercial Pt/C catalysts. The results indicate that the use of very small
particle sizes is a possible way to achieve reasonably good ORR activities at an improved methanol tolerance at DMFC cathode
relevant conditions. 相似文献
13.
Yang Yu Zhoufeng Bian Fujiao Song Juan Wang Qin Zhong Sibudjing Kawi 《Topics in Catalysis》2018,61(15-17):1514-1527
Herein, we studied the influence of calcination temperature (500–800 °C) of Ni/CeO2 and Ni/Ce0.8Zr0.2O2 catalysts on the specific surface area, pore volume, crystalline size, lattice parameter, chemical bonding and oxidation states, nickel dispersion and CH4/CO production rate in CO2 methanation. In general, the catalytic performance revealed that Zr doping catalysts could increase the CH4 production rate. Combined with the production rate and the characterizations results, we found that the combination of nickel dispersion, peak area of CO2–TPD and OII/(OII + OI)) play the critical role in increasing the CH4 production rate. It is well to be mentioned that the CO production rate is strongly influenced by the nickel dispersion. Furthermore, the in-situ DRIFTS confirmed that the CO originates from the decomposition of H-assisted formate species. 相似文献
14.
I. R. Il’yasov M. V. Nazarov A. I. Laskin A. A. Lamberov A. Sh. Bikmurzin V. M. Shatilov I. F. Nazmieva 《Catalysis in Industry》2011,3(1):96-101
The influence of the structural and electronic characteristics of nonpromoted and cobalt-promoted Pd catalysts on their adsorption
and catalytic properties is studied. It is shown that the conversion of vinylacetylene depends on the dispersion of palladium
for both types of catalysts synthesized from acetate and acetylacetonate complexes. The palladium acetylacetonate catalysts
have a higher palladium dispersion than the samples obtained from acetate complex solutions, thus leading to a higher conversion
of vinylacetylene. It is established that the selectivity of vinylacetylene conversion into 1,3-butadiene on palladium acetate
and acetylacetonate catalysts depends on the state of the 3d orbitals of surface Pd atoms. The palladium acetate catalysts are characterized by a higher electron density on the 3d orbital in comparison with the acetylacetonate samples, thus producing higher selectivities of vinylacetylene conversion
into 1,3-butadiene. The introduction of cobalt into Pd/δ-Al2O3 catalyst synthesized from acetylacetonate complex leads to the formation of bimetallic Pd-Co particles, in which Pd atoms
have higher electron density than those in the nonpromoted Pd/δ-Al2O3 catalyst, due probably to the donation of electron density from promoter atoms, with a resulting decline in the adsorption
ability of bimetallic particles with regard to 1,3-butadiene and hydrogen. As a consequence, the selectivity of vinylacetylene
conversion into 1,3-butadiene increases. Requirements for the size, dispersion, and electronic characteristics of the active
component in the catalysts for the selective hydrogenation of vinylacetylene are formulated, and two techniques for their
synthesis are proposed. 相似文献
15.
O. V. Artamonova O. V. Almjasheva I. Ya. Mittova S. S. Lavrushina V. V. Gusarov 《Glass Physics and Chemistry》2005,31(2):236-239
The hydrothermal synthesis of nanocrystals in the ZrO2-In2O3-H2O system is investigated kinetically. The presence of indium hydroxide results in an increase in the dehydration temperature of this system. The size of nanocrystals is equal to 20–30 nm and virtually does not depend on the temperature and time of hydrothermal treatment or on the type of crystalline modification of ZrO2. An increase in the synthesis temperature leads to an increase in the fraction of the monoclinic zirconia modification.Original Russian Text Copyright © 2005 by Fizika i Khimiya Stekla, Artamonova, Almjasheva, Mittova, Lavrushina, Gusarov. 相似文献
16.
Bi3Mo2Fe1P x oxide catalysts were prepared by a co-precipitation method and the influence of phosphorous content on the catalytic performance in the oxidative dehydrogenation of 1-butene was investigated. The addition of phosphorous up to 0.4mole ratio to Bi3Mo2Fe1 oxide catalyst led to an increase in the catalytic performance; however, a higher phosphorous content (above P=0.4) led to a decrease of conversion. Of the tested catalysts, Bi3Mo2Fe1P0.4 oxide catalyst exhibited the highest catalytic performance. Characterization results showed that the catalytic performance was related to the quantity of a π-allylic intermediate, facile desorption behavior of adsorbed intermediates and ability for re-oxidation of catalysts. 相似文献
17.
Minwoo Lee Bora Ye Bora Jeong Hye-yeon Chun Duck Hyun Lee Sam-sik Park Heesoo Lee Hong-Dae Kim 《Korean Journal of Chemical Engineering》2018,35(10):1988-1993
We present a reduced-graphene-oxide (rGO)-supported V2O5-WO3-TiO2 (VWTi) catalysts for the efficient selective catalytic reduction of NOx. The rGO support provides well-dispersed functional sites for the nucleation of nanoparticles, allowing the formation of VWTi catalysts with high specific surface areas. The dispersion of the nanoparticles, as observed by transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS), confirmed the uniform dispersion of the particles on the rGO surface. Detailed Fourier-transform infrared (FT-IR) and NH3 temperature-programmed desorption (NH3-TPD) analyses indicated that the high density of acidic sites provided by the rGO is key to the observed enhancement of NOx removal efficiency, and the rGO-supported catalysts exhibit improved NOx removal efficiencies with smaller amounts of V2O5 and WO3 compared with the commercially available V2O5-WO3-TiO2 catalysts. 相似文献
18.
Xin An Jinlu Li Yizan Zuo Qiang Zhang Dezheng Wang Jinfu Wang 《Catalysis Letters》2007,118(3-4):264-269
A series of Cu/Zn/Al/Zr CO2 hydrogenation to methanol catalysts containing different ratios of Al/Zr were prepared using a co-precipitation procedure.
SEM, TEM, and XRD characterization showed that all the catalysts comprised crystallites in a fibrous structure and their Cu/Zn
crystallite dispersions were better than that of a commercial (COM) catalyst. It is suggested that the high dispersion and
stability of the Cu/Zn crystallites due to the fibrous structure enhanced CO2 hydrogenation, and the added Zr component further improved the catalyst. A 5% Zr addition gave a methanol space time yield
80% higher than that on the COM catalyst. 相似文献
19.
The catalytic oxidation of hydrogen sulfide (H2S) to elemental sulfur was studied over CeO2-TiO2 catalysts. The synthesized catalysts were characterized by various techniques such as X-ray diffraction, BET, X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of ammonia, and scanning electron microscopy (SEM). Catalytic performance studies of the CeO2-TiO2 catalysts showed that H2S was successfully converted to elemental sulfur without considerable emission of sulfur dioxide. CeO2-TiO2 catalysts with Ce/Ti=1/5 and 1/3 exhibited the highest H2S conversion, possibly due to the uniform dispersion of metal oxides, high surface area, and high amount of acid sites. 相似文献
20.
A. L. Lapidus V. S. Budtsov T. E. Cooley O. L. Eliseev L. A. Tishkova 《Solid Fuel Chemistry》2007,41(1):28-30
The effect of promotion of Co catalysts with noble metals on their activity and selectivity in the synthesis of hydrocarbons from CO and H2 has been studied. Platinum at a content of (0.05–0.10)% has been found to be best promoter. 相似文献