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Progress in the Field of Converting Methanol into Light Olefins over the ZSM-5 Zeolite Catalyst
Technical progress in the field of conversion of methanol into ethylene and propylene over the ZSM-5 catalyst was summarized. The economical analysis of the technology, the mechanism of chemical reaction and reaction kinetics were introduced. The factors including the effect of the operating conditions,the influence of catalyst preparation conditions and modification of ZSM-5 zeolite on the reaction and coke formation were also discussed....
2020-07-08 21:52:19浏览：29
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Simultaneous operation of dibenzothiophene hydrodesulfurization and methanol reforming reactions ove
In the current study simultaneous reactions of hydrodesulfurization (HDS) of dibenzothiophene (DBT) and reforming of methanol in a micro-autoclave reactor were studied over bi-metallic ( Co-Mo/Al2O3 and Ni-Mo/Al2O3 ) and tri-metallic ( Pd-Co-Mo/Al2O3 and Pd-Ni-Mo/Al2O3 ) catalyst systems which were prepared by incipient impregnation method.In situ hydrogen utilization and low Pd loadings were the major targets of this study.For comparison purpose,catalytic activity was separately determined for both the methanol reforming and HDS of DBT reactions as well.Ni based catalysts were confirmed with better activity than Co ones for both the reactions with Pd promoted ones ranking at the top i.e.Pd-Ni-Mo/Al2O3 ＞ Ni-Mo/Al2O3 ＞ Pd-Co-Mo/Al2O3＞ Co-Mo/Al2O3 where Pd-Ni-Mo/Al2O3 showed 91％ DBT conversion at 380 ℃ and 12 h reaction time.Some of the selected organic additives on catalytic activity were tested for their effect toward HDS reaction which was unique with close relation to their chemical nature.Reaction products were quantitatively and qualitatively analyzed via HPLC and GC-MS techniques respectively which helped in elucidating reaction mechanism....
2020-07-08 21:52:19浏览：49
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Solvent effects on Pt-Ru/C catalyst for methanol electro-oxidation
Alloying degree,particle size and the level of dispersion are the key structural parameters of Pt-Ru/C catalyst in fuel cells. Solvent(s) used in the preparation process can affect the particle size and alloying degree of the object substance,which lead to a great positive impact on its properties. In this work,three types of solvents and their mixtures were used in preparation of the Pt-Ru/C catalysts by chemical reduction of metal precursors with sodium borohydride at room temperature. The structure of the catalysts was characterized by X-ray diffraction (XRD) and Transmission electron microscopy (TEM). The catalytic activity and stability for methanol electro-oxidation were studied by Cyclic Voltammetry (CV) and Chronoamperometry (CA). Pt-Ru/C catalyst prepared in H_2O or binary solvents of H_2O and isopropanol had large particle size and low alloying degree leading to low catalytic activity and less stability in methanol electro-oxidation. When tetrahydrofuran was added to the above solvent systems,Pt-Ru/C catalyst prepared had smaller particle size and higher alloying degree which resulted in better catalytic activity,lower onset and peak potentials,compared with the above catalysts. Moreover,the catalyst prepared in ternary solvents of isopropanol,water and tetrahydrofuran had the smallest particle size,and the high alloying degree and the dispersion kept unchanged. Therefore,this kind of catalyst showed the highest catalytic activity and good stability for methanol electro-oxidation....
2020-07-08 21:52:19浏览：59
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Promoting effect of polyoxyethylene octylphenol ether on Cu/ZnO catalysts for low-temperature methan
Cu/ZnO catalysts were prepared by the co-precipitation method with the addition of OP-10 (polyoxyethylene octyiphenol ether) and were chemically and structurally characterized by means of XRD,BET,H_2-TPR,CO-TPD and N_2O-titration. The effect of OP-10 addition on the activity of Cu/ZnO for the slurry phase methanol synthesis at 150 ℃ was evaluated. The results showed that Cu/ZnO prepared with addition of 8% OP-10 (denoted as C8) exhibited the promoted activity for the methanol synthesis. The conversion of CO and the STY (space time yield) of methanol were 42.5% and 74.6% higher than those of Cu/ZnO prepared without addition of OP-10 (denoted as CO),respectively. The precursor of C8 contained more aurichalcite and rosasite,and the concerted effect of Cu-Zn in C8 was found to be stronger than that in CO. Compared with CO,C8 showed smaller particle size,lower reduction temperature and larger BET and Cu surface areas....
2020-07-08 21:52:19浏览：50
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Preparation and Methanol Decomposition Activity of Ruthenium Supported Ce-Doped Mesoporous TiO2 Oxid
Mesoporous TiO2-CeO2 mixed oxide(m-TiO2-CeO2) were synthesized using n-cetylpyridinium chloride (C16PyCl) as a structure-directing agent under the neutral conditions and room temperature. The synthesized mesoporous samples were characterized by FT-IR, XRD, and N2 adsorption BET methods. The incorporation of Ce3+ ions into the channel wall improves the stability of the mesoporous structure obviously. After ruthenium being loaded by the impregnating method, the Ru particle strongly interacts with the mesoporous mixed supports. Although a part of the particles are possible to block the support pores, the catalytic activity of ruthenium supported on the m-TiO2-CeO2 for methanol decomposition to carbon monoxide and hydrogen is significantly higher than that of ruthenium supported on m-TiO2. A synergistic effect between CeO2 and TiO2 was observed for promoting the catalytic properties of Ru....
2020-07-08 21:52:19浏览：41
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A New Process for Synthesis of Dimethyl Carbonate from Ethylene Carbonate and Methanol without any C
Dimethyl carbonate was synthesized by transesterification reaction between ethylene carbonate and methanol under supercritical conditions without any catalyst. Experimental results showed that the residence time and the molar ratio of methanol to ethylene carbonate all can affect the conversion of ethylene carbonate. When the molar ratio of methanol to ethylene carbonate was 8:1, 81.2 % conversion can be achieved at 9.0 MPa and 250℃ after 8 h....
2020-07-08 21:52:19浏览：78
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Modulation of Electrochemical Oscillations by Specific Adsorption of Cl- during the Electrooxidation
Potential oscillation during the electrocatalytic oxidation of methanol can be modulated by the specific adsorption of Cl- on the platinum electrode, which suppresses the electrocatalytic oxidation of methanol, and makes the cross cycle in the cyclic voltammogram become smaller and finally disappear with the increase of Cl- concentration. The method is also applicable to the electrocatalytic oxidation of other small organic molecules....
2020-07-08 21:52:19浏览：49
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Methanol Tolerant FeTPP-Pt/C Co-catalysts for the Electroreduction of Oxygen
It was found for the first time that iron tetraphenylporphyrin (FeTPP)-Pt/C showed the good activity for the electroreduction of oxygen and methanol tolerant ability. Their perfor- mances were related to the heat-treatment temperature....
2020-07-08 21:52:19浏览：61
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Preparation of nanocrystalline γ-Al2O3 catalyst using different procedures for methanol dehydration
A series of nanocrystalline γ-alumina are synthesized by different procedures, namely, thermal decomposition method (sample A), precipitation method (sample B) and sol-gel method using sucrose and hexadecyltrimethyl ammonium bromide (CTAB) as templates (samples C and D, respectively). Textural and acidic properties of γ-alumina samples are characterized by XRD, N2 adsorption-desorption and NH3-TPD techniques. Vapor-phase dehydration of methanol into dimethyl ether is carried out over these samples. Among them, sample C shows the highest catalytic activity. NH3-TPD analysis reveals that the sample with smaller crystallite size possesses higher concentration of medium acidic sites and consequently higher catalytic activity. Thermal decomposition method leads to decrease in both surface area and moderate acidity, therefore it is the cause of lower catalytic activity....
2020-07-08 21:52:19浏览：63
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Optimization of hydrothermal synthesis of H-ZSM-5 zeolite for dehydration of methanol to dimethyl et
H-ZSM-5 zeolite was synthesized by hydrothermal method.The effects of different synthesis parameters,such as hydrothermal crystallization temperature (170-190 ℃) and Si/Al molar ratio (100-150),on the catalytic performance of the dehydration of methanol to dimethyl ether (DME) over the synthesized H-ZSM-5 zeolite were studied.The catalysts were characterized by N2 adsorption-desorption,XRD,NH3-TPD,TGA/DTA,and SEM techniques.The full factorial design of experiments was applied to the synthesis of H-ZSM-5 zeolite and the effects of synthesis conditions and their interaction on the yield of DME as the response variable were determined.Analysis of variance showed that two variables and their interaction significantly affected the response.According to the experimental results,the optimized catalyst prepared at 170 ℃ with the Si/Al molar ratio of 100 showed the best catalytic performance among the tested H-ZSM-5 zeolite....
2020-07-08 21:52:19浏览：55
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Carbon nanotubes-Nafion composites as Pt-Ru catalyst support for methanol electro-oxidation in acid
Carbon nanotubes-Nafion (CNTs-Nafion) composites were prepared by impregnated CNTs with Nafion in ethanol solution and characterized by FT-IR. Pt-Ru catalysts supported on CNTs-Nafion composites were synthesized by microwave-assisted polyol process. The physical and electrochemical properties of the catalysts were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), CO stripping voltammetry, cyclic voltammetry (CV) and chronoamperometry (CA). The results showed that the Nafion incorporation in CNTs-Nafion composites did not significantly alter the oxygen-containing groups on the CNTs surface. The Pt-Ru catalyst supported on CNTs-Nafion composites with 2 wt% Nafion showed good dispersion and the best CO oxidation and methanol electro-oxidation activities....
2020-07-08 21:52:19浏览：52
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Pt-Ru Catalysts Prepared by a Modified Polyol Process for Direct Methanol Fuel Cells
Supported PtRu/C catalysts used in direct methanol fuel cells (DMFCs) were prepared by a new modified polyol method.Transmission electron microscopy (TEM),X-ray diffraction (XRD) and cyclic voltammograms (CVs) were carried out to characterize the morphology,composition and the electrochemical properties of the PtRu/C catalyst.The results revealed that the PtRu nanoparticles with small average particle size (≈2.5 nm),and highly dispersed on the carbon support.The PtRu/C catalyst exhibited high catalytic activity and anti-poisoned performance than that of the JM PtRu/C.It is imply that the modified polyol method is efficient for PtRu/C catalyst preparation....
2020-07-08 21:52:19浏览：55
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Comparative studies of adsorbed CO and methanol electrooxidation on carbon supported Pt and PtRu cat
Physicochemical characterization of commercial Pt/C and PtRu/C catalysts was carried out by X-ray diffraction,X-ray photoelectron spectroscopy, and transmission electron microscopy. Comparative studies of methanol electrooxidation on carbon supported Pt and PtRu catalysts in acid solution were performed by means of an electrochemical method. The experimental results showed that PtRu/C not only had a higher electrocatalytic activity for the electrocatalytic oxidation of methanol than Pt/C, but also for the electrocatalytic oxidation of adsorbed CO. Alloy formation of Ru with Pt modified not only the characteristics of H2 adsorption on the surface of catalyst but also the characteristics of CO adsorption on the surface of catalyst. The interaction of CH3OH with Ru was a temperature-activated process requiring elevated temperature....
2020-07-08 21:52:19浏览：40
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Study on Highly Active Catalysts and a Once-Through Process for Methanol Synthesis from Syngas
Highly active CNT-promoted co-precipitated Cu-ZnO-Al2O3 catalysts, symbolized asCuiZnjAlk-x%CNTs, were prepared, and their catalytic activity for once-through methanol synthesis fromsyngas was investigated. The results illustrated that, under the reaction conditions (at 493 K, 5.0 MPa, thevolume ratio of H2/CO/CO2/N2＝ 62/30/5/3, GHSV＝ 4000 h-1), the observed single-pass CO-conversionand methanol-STY over a Cu6Zn3Al1-12.5%CNTs catalyst reached 64% and 1210 mg/(h@g), which wasabout 68% and 66% higher than those (38% and 730 mg/(h@g)) over the corresponding CNT-free catalyst,Cu6Zn3Al1, respectively. The characteristic studies of the catalysts revealed that appropriate incorporationof a minor amount of the CNTs into the CuiZnjAlk brought about little change in the apparent activationenergy of the methanol synthesis reaction, however, led to a considerable increase in the catalyst's active Cusurface area and pronouncedly enhanced the stationary-state concentration of active hydrogen-adspecieson the surface of the functioning catalyst, which would be favorable to increasing the rate of the CO hydro-genation reactions. Moreover, the operation temperature for methanol synthesis over the CNT-promotedcatalysts can be 10-20 degrees lower than that over the corresponding CNT-free contrast system, whichwould contribute considerably to an increase in equilibrium CO-conversion and CH3OH-yield....
2020-07-08 21:52:19浏览：58
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Synthesis of nanocrystalline γ-Al2O3 by sol-gel and precipitation methods for methanol dehydration t
The capability of sol-gel and conventional precipitation techniques for the synthesis of nanocrystalline γ-alumina was investigated.These catalysts were used for vapor-phase dehydration of methanol to dimethyl ether in a fixed-bed reactor under the same operating conditions (T= 300℃,P=1 bar,LHSV = 2.8,11.7,26.1 h-1)and characterized by means of N2 adsorption-desorption,NH3-TPD,XRD,TGA and SEM techniques.According to the experimental results,the catalysts prepared using sol-gel method in non-aqueous medium showed better performance compared with those prepared by other methods....
2020-07-08 21:52:19浏览：77
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