Hydrogenation of ethylene on a Co-Mo/Al2O3 catalyst under transient conditions

1986 ◽  
Vol 51 (12) ◽  
pp. 2760-2769
Author(s):  
Jana Samková ◽  
Karel Klusáček ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Total Concentration ◽  
Ethylene Hydrogenation ◽  
Response Curves ◽  
Feed Composition ◽  
Rate Determining Step ◽  
Al2o3 Catalyst ◽  
Adsorbed Ethylene ◽  
Hydrogenation Of Ethylene

Hydrogenation of ethylene on a Co-Mo/Al2O3 catalyst at 353 K and atmospheric pressure has been studied. The unsteady-state method was used, in which reactor feed-rate and feed-composition were changed in a defined way. The analysis of transient response curves proved negligible adsorption of hydrogen and ethane and confirmed the reaction mechanism of ethylene hydrogenation which involves reaction of adsorbed ethylene with hydrogen from gas phase in the rate determining step. Combined stationary and transient experimental data were used to calculate kinetic parameters: rate constant of ethylene hydrogenation, total concentration of active sites on the catalyst surface and equilibrium adsorption coefficient of ethylene.

Kinetics of the catalytic hydrodesulphurization reaction system; hydrogenation of ethylene and butene

1980 ◽  
Vol 45 (10) ◽  
pp. 2742-2750 ◽  
Author(s):  
Pavel Fott ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Flow Reactor ◽  
Reaction System ◽  
Circulation Flow ◽  
Kinetic Description ◽  
Molybdenum Catalyst ◽  
Cobalt Molybdenum Catalyst ◽  
Kinetics Of ◽  
Hydrogenation Of Ethylene

Hydrogenation has been studied of ethylene and butene in a circulation flow reactor on a cobalt-molybdenum catalyst at 360 °C and atmospheric pressure. The effect has been investigated of simultaneous hydrodesulphurization of thiophene on the hydrogenation. The results have confirmed that different active sites for hydrogenation and hydrodesulphurization must be considered in the kinetic description of simultaneous hydrogenation of ethylene and hydrodesulphurization of thiophene. For isolated hydrogenation of ethylene and butene the absence of hydrogen sulphide in the reaction mixture considerably enhances the hydrogenation activity of the catalyst due to the change of its state.

Chemisorption of oxygen and hydrogenation of ethylene on sulphided Co-Mo/Al2O3 catalyst. Effect of activation process

1989 ◽  
Vol 54 (8) ◽  
pp. 2069-2082 ◽  
Author(s):  
Hana Zahradníková ◽  
Ludvík Beránek
Keyword(s):  
Active Sites ◽  
Room Temperature ◽  
Dynamic Method ◽  
Activation Process ◽  
Subsequent Reduction ◽  
Oxygen Chemisorption ◽  
Hydrogenation Reactions ◽  
Catalyst Effect ◽  
Al2o3 Catalyst ◽  
Hydrogenation Of Ethylene

Oxygen chemisorption by pulse dynamic method at room temperature and the activity for ethylene hydrogenation at 300 °C in a flow regime were determined for Co-Mo/Al2O3 catalyst CHEROX 36-01 sulphided by a H2S/H2 (1:10) mixture at 400 °C. The measurements were carried out either immediately after sulphidation or after subsequent reduction of the sulphided catalyst by hydrogen. The chemisorption of oxygen was measured both prior to and after the catalytic reaction. In addition, the reactivation of the catalyst was examined after its passivation by oxygen chemisorption. The reactivation was effected either by resulphidation or by reduction with hydrogen at 400 °C, on repeated reactivation also by combination of both procedures, variables being the time of activation and reactivation steps. The results are discussed from the standpoint of the structure and interrelation between active sites for oxygen chemisorption and catalytic, especially hydrogenation reactions. Formation of coordinately unsaturated sites and SH groups is emphasized. The reasons of possible failures in correlations between chemisorption capacity for oxygen and catalytic activity are mentioned.

Effect of the pretreatment conditions on the activity of an industrial Co-Mo/Al2O3 catalyst

1983 ◽  
Vol 48 (3) ◽  
pp. 691-697 ◽  
Author(s):  
Lachezar Petrov ◽  
Chavdar Vladov ◽  
Dimitar Shopov ◽  
Věnceslava Friebová ◽  
Ludvík Beránek
Keyword(s):  
Catalytic Activity ◽  
Atmospheric Pressure ◽  
Ethylene Hydrogenation ◽  
Kinetic Methods ◽  
Pretreatment Temperature ◽  
Pretreatment Conditions ◽  
Al2o3 Catalyst ◽  
Active Centres

The processes of reduction and sulphidation of an industrial Co-Mo/Al2O3 catalyst have been studied by means of gravimetric and kinetic methods at atmospheric pressure. The effect of the pretreatment temperature on the catalytic activity for ethylene hydrogenation and thiophene hydrodesulphurization has been studied. Two types of active centres, for hydrogenation and for hydrodesulphurization, have been characterized on the basis of their different properties.

Kinetics of the reduction of nitrogen oxide and dinitrogen oxide by ammonia on a V2O5/Al2O3 catalyst in the absence of oxygen

1986 ◽  
Vol 51 (11) ◽  
pp. 2528-2536 ◽  
Author(s):  
Milan Čížek ◽  
Vladimír Pour
Keyword(s):  
Nitrogen Oxide ◽  
Oxidation State ◽  
Atmospheric Pressure ◽  
Surface Reaction ◽  
Reduction Of No ◽  
Rate Determining Step ◽  
Langmuir Hinshelwood Mechanism ◽  
Temperature Ranges ◽  
Kinetics Of ◽  
Al2o3 Catalyst

The kinetics of the reduction of NO and N2O by ammonia on a V2O5/Al2O3 catalyst (15 mass % V2O5) have been measured over the temperature range 300-480 °C at atmospheric pressure. The presence of water vapour in the reaction mixture retards the reduction rates of both NO and N2O. The oxidation state of vanadium does not change within the concentration and temperature ranges investigated. From the results for the reaction kinetics and the oxidation state of vanadium it is concluded that the reduction of NO and N2O by ammonia occurs by the associative Langmuir-Hinshelwood mechanism with the surface reaction as the rate-determining step.

Catalytic Neutralization of Naphthenic Acid from Petroleum Crude Oil by Using Cerium Oxide Catalyst and 2- Methylimidazole in Polyethylene Glycol

2020 ◽  
Vol 13 ◽  
Author(s):  
Norshahidatul Akmar Mohd Shohaimi ◽  
Norfakhriah Jelani ◽  
Ahmad Zamani Ab Halim ◽  
Nor Hakimin Abdullah ◽  
Nurasmat Mohd Shukri
Keyword(s):  
Polyethylene Glycol ◽  
Crude Oil ◽  
Cerium Oxide ◽  
Active Sites ◽  
Naphthenic Acid ◽  
Naphthenic Acids ◽  
Catalyst Loading ◽  
High Concentration ◽  
Oil Refineries ◽  
Al2o3 Catalyst

: The presence of relatively high naphthenic acid in crude oil may contribute to the major corrosion in oil pipelines and distillation units in crude oil refineries. Thus, high concentration Naphthenic Acids crude oil is considered tobe of low quality and is marketed at lower prices. In order to overcome this problem, neutralization method had been developed to reduce the TAN value in crude oil. In this study, crude oil from Petronas Penapisan Melaka was investigated. The parameters studied were reagent concentration, catalyst loading, calcination temperature and reusability of the potential catalyst. Basic chemical used were 2- methylimidazole in polyethylene glycol (PEG 600) with concentration 100, 500 and 1000 ppm. Cerium oxide-based catalysts supported onto alumina prepared with different calcination temperatures. The catalyst was characterized by using Brunauer-Emmett-Teller (BET), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetry Analysis-Differential Thermal Gravity (TGA-DTG) to study physical properties of the catalyst. The Ce/Al2O3 catalyst calcined at 1000°C was the best catalyst due to larger surface area formation which lead to increment of active sites thus will boost the catalytic activity. The result showed that the Ce/Al2O3 catalyst meet Petronas requirement as the TAN value reduced to 0.6 mgKOH/g from original TAN value of 4.22 mgKOH/g. The best reduction of TAN was achieved by using catalyst loading of 0.39% and reagent of 1000 ppm.

Kinetics of the catalytic hydrodesulphurization reaction system; hydrogenolysis of thiophene

1980 ◽  
Vol 45 (10) ◽  
pp. 2728-2741 ◽  
Author(s):  
Pavel Fott ◽  
Petr Schneider
Keyword(s):  
Atmospheric Pressure ◽  
Active Sites ◽  
Flow Reactor ◽  
Kinetic Equations ◽  
Reaction System ◽  
Reaction Products ◽  
Molybdenum Catalyst ◽  
Cobalt Molybdenum Catalyst ◽  
Kinetics Of ◽  
Reaction Schemes

Kinetics have been studied of the reaction system taking place during the reaction of thiophene on the cobalt-molybdenum catalyst in a gradientless circulation flow reactor at 360 °C and atmospheric pressure. Butane has been found present in a small amount in the reaction products even at very low conversion. In view of this, consecutive and parallel-consecutive (triangular) reaction schemes have been proposed. In the former scheme the appearance of butane is accounted for by rate of desorption of butene being comparable with the rate of its hydrogenation. According to the latter scheme part of the butane originates from thiophene via a different route than through hydrogenation of butene. Analysis of the kinetic data has revealed that the reaction of thiophene should be considered to take place on other active sites than that of butene. Kinetic equations derived on this assumption for the consecutive and the triangular reaction schemes correlate experimental data with acceptable accuracy.

scholarly journals Heterogeneous Catalytic Synthesis of 2-Methylbenzimidazole from 2-Nitroaniline and Ethanol Over Mg Modified Cu-Pd/γ-Al2O3

Catalysts ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Feng Feng ◽  
Yaqin Deng ◽  
Zheng Cheng ◽  
Xiaoliang Xu ◽  
Qunfeng Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Hydrogen Transfer ◽  
High Efficiency ◽  
Simple Procedure ◽  
Direct Synthesis ◽  
Reaction System ◽  
Simple Method ◽  
Heterogeneous Catalytic ◽  
Coupled Reaction ◽  
Al2o3 Catalyst

The direct synthesis of benzimidazoles from 2-nitroaniline and ethanol over Cu-Pd/γ-Al2O3 catalysts has the advantages of requiring easily available starting materials, having high efficiency, and a simple procedure. The modification by Mg of the Cu-Pd/γ-Al2O3 catalyst could improve the catalytic activity significantly. The addition of Mg to the Cu-Pd/γ-Al2O3 catalyst could maintain and promote the formation of CuPd alloy active sites. Meanwhile, the basicity of the support was enhanced appropriately by Mg, which generated more basic sites (Al-Oδ−) to accelerate the dehydrogenation of alcohol and increased the rate of the whole coupled reaction. The 2-nitroaniline was completely converted over Cu-Pd/(Mg)γ-Al2O3 after reacting for six hours, and the yield of 2-methylbenzimidazole was 98.8%. The results of this work provide a simple method to develop a more efficient catalyst for the “alcohol-dehydrogenation, hydrogen transfer and hydrogenation” coupled reaction system.

scholarly journals Influence of incorporating a small amount of silica on the catalytic performance of a MoO3/Al2O3 catalyst in ethanol oxidative dehydrogenation

2018 ◽  
Vol 16 (6) ◽  
Author(s):  
Aline Villarreal ◽  
Gabriella Garbarino ◽  
Paola Riani ◽  
Aida Gutiérrez Alejandre ◽  
Jorge Ramírez ◽  
...  
Keyword(s):  
Oxidative Dehydrogenation ◽  
Active Sites ◽  
Catalytic Performance ◽  
Redox Behavior ◽  
Acid Base ◽  
Pure Alumina ◽  
Molybdenum Catalyst ◽  
Al2o3 Catalyst ◽  
Dehydrogenation Of Ethanol

The influence of incorporating a small amount of silica on the catalytic performance of MoO3/Al2O3 catalyst was studied. Molybdenum supported on pure alumina and 5% SiO2-Al2O3 supports were synthesized. The catalysts were characterized by XRD, Raman, UV-Vis and IR spectroscopies, FE-SEM microscopy, and their activity was evaluated in the oxidative dehydrogenation of ethanol to acetaldehyde. Molybdenum supported on pure alumina gives a 74% yield to acetaldehyde (at 573 K) due to the generation of oxy-dehydrogenation active sites by molybdenum and to the decrement of the alumina dehydration sites. For the molybdenum catalyst supported on silica-containing alumina, the molybdenum species were displaced from the strongest alumina’s acid-base couples, located on nanoparticles edges, corners and defects, to weaker ones located on plane faces causing the rise of weakly bonded species with less active redox behavior.  

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