scholarly journals THE KINETICS AND MECHANISM OF THE SELECTIVE OXIDATIVE DEHYDROGENATION REACTİON OF METHYLCYCLOPENTANE

2021 ◽  
pp. 12-20
Author(s):  
A.M. Aliyev ◽  
◽  
M.Y. Abbasov ◽  
M.G. Aliyeva ◽  
G.A. Alizade ◽  
...  
Keyword(s):  
Oxidative Dehydrogenation ◽  
Surface Preparation ◽  
Catalyst Layer ◽  
Active Phase ◽  
Structure Study ◽  
Catalytic Layer ◽  
Catalyst Activation ◽  
Heterogeneous Catalytic ◽  
Structured Catalyst ◽  
Key Steps

The oxidative dehydrogenation of alicyclic diene hydrocarbons refers to scarcely studied heterogeneous catalytic reactions which proceed with the participation of oxygen. The dehydrogenation of methylcyclopentane is an endothermic reaction. To improve the reaction kinetics, this research was to develop a structured catalyst by conductive metals (Cu, Zn, Co, Cr) support which could hold an adherent catalytic layer. The active phase was impregnated onto these support metals and the developed catalyst was tested for the dehydrogenation of methylcyclopentane. The catalyst preparation involved three main key steps which were support oxidative reaction, loading of active particles on the catalyst surface, preparation of an active catalyst layer on the surface finally bringing the catalyst into the active phase. Different types of catalyst activation and deactivation mechanisms stability have been studied in this investigation. The advantage of this works, the oxidative dehydrogenation of methylcyclopentane is that it occurs at the expense of oxygen in the air. The zeolite structure study helped identify the effect of the combination of catalysts, and adsorption of metals on clinoptilolite and dispersion on the selectivity of the catalyst particles. Numerical values of the kinetic parameters were calculated

scholarly journals THE SOLVING OF THE PROBLEM IN THE WORKING ZONE. THE NUMERICAL CALCULATION OF THE MODEL OF THE NIZHNEKAMSK REACTOR FOR THE STYRENE PRODUCTION (PART-3)

2021 ◽  
pp. 6-13
Author(s):  
V. N. Koleskin ◽  
A. A. Yunusov ◽  
A. A. Yunusova ◽  
P. G. Shtern ◽  
A. V. Lukyanova ◽  
...  
Keyword(s):  
Large Scale ◽  
Industrial Process ◽  
Catalyst Layer ◽  
Catalytic Layer ◽  
Working Zone ◽  
Heterogeneous Catalytic ◽  
Developed Surface ◽  
Heterogeneous Catalytic Processes ◽  
Granular Layers ◽  
Granular Catalyst

Heterogeneous catalytic processes conducted in axial or radial type reactors with a still catalytic layer are some of the most important elements of the chemical technology. The attention of scientists and manufacturers to the investigation and application of these contact units deals with the following advantages: a highly developed surface of a phase separation, a possibility to provide a high flow velocity and hence to decrease sizes and a material consumption, a construction simplicity and a reliability of an exploit. Improving an operation of contact units may be achieved by refining present technologies, catalysts, disperse system structures and by creating new ones. Nevertheless, in some cases large scale hydrodynamic heterogeneities in a working zone of the unit cancel out efforts to increase an efficiency of chemical, heat/mass transfer and other processes. The exploration of reasons of the hydrodynamic heterogeneities formation requires an investigation of liquid and gas motion physics features in granular layers. A practice of a chemical reactors exploitation reveals that technical and economical indicators of an industrial process are as a rule lower than the calculated ones, derived on a stage of the process design. Now it can be considered proven that one of the reasons affecting the reactor output is the heterogeneity of a reagents flow in a granular catalyst layer. The article deals with a mathematical modeling of an incompressible liquid flow in flat and radial contact units with the still granular layer and a creation of numerical realization methods for the model We propose a cycle of articles dealt with a model of a real reactor that consists of three parts: a distributing manifold, a collecting manifold and a working zone, where the still layer of a granular catalyst is loaded. An input and an output are made with a Z-shaped scheme. We consider processes and their equations in each reactor zone in detail.

scholarly journals Enhanced catalytic ozonation of ibuprofen using a 3D structured catalyst with MnO2 nanosheets on carbon microfibers

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guhankumar Ponnusamy ◽  
Hajar Farzaneh ◽  
Yongfeng Tong ◽  
Jenny Lawler ◽  
Zhaoyang Liu ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Active Sites ◽  
Low Cost ◽  
Three Dimensional ◽  
Industrial Applications ◽  
Catalytic Ozonation ◽  
Heterogeneous Catalytic ◽  
Structured Catalyst ◽  
Dimensional Network ◽  
Carbon Microfibers

AbstractHeterogeneous catalytic ozonation is an effective approach to degrade refractory organic pollutants in water. However, ozonation catalysts with combined merits of high activity, good reusability and low cost for practical industrial applications are still rare. This study aims to develop an efficient, stable and economic ozonation catalyst for the degradation of Ibuprofen, a pharmaceutical compound frequently detected as a refractory pollutant in treated wastewaters. The novel three-dimensional network-structured catalyst, comprising of δ-MnO2 nanosheets grown on woven carbon microfibers (MnO2 nanosheets/carbon microfiber), was synthesized via a facile hydrothermal approach. Catalytic ozonation performance of Ibuprofen removal in water using the new catalyst proves a significant enhancement, where Ibuprofen removal efficiency of close to 90% was achieved with a catalyst loading of 1% (w/v). In contrast, conventional ozonation was only able to achieve 65% removal efficiency under the same operating condition. The enhanced performance with the new catalyst could be attributed to its significantly increased available surface active sites and improved mass transfer of reaction media, as a result of the special surface and structure properties of this new three-dimensional network-structured catalyst. Moreover, the new catalyst displays excellent stability and reusability for ibuprofen degradation over successive reaction cycles. The facile synthesis method and low-cost materials render the new catalyst high potential for industrial scaling up. With the combined advantages of high efficiency, high stability, and low cost, this study sheds new light for industrial applications of ozonation catalysts.

scholarly journals Role of CO2 During Oxidative Dehydrogenation of Propane Over Bulk and Activated-Carbon Supported Cerium and Vanadium Based Catalysts

2021 ◽  
Author(s):  
Petar Djinović ◽  
Janez Zavašnik ◽  
Janvit Teržan ◽  
Ivan Jerman
Keyword(s):  
Catalytic Activity ◽  
Activated Carbon ◽  
Oxidative Dehydrogenation ◽  
Active Phase ◽  
Lattice Oxygen ◽  
Chemisorbed Oxygen ◽  
Catalytically Active ◽  
Temperature Programmed ◽  
Propane Cracking

AbstractCeO2, V2O5 and CeVO4 were synthesised as bulk oxides, or deposited over activated carbon, characterized by XRD, HRTEM, CO2-TPO, C3H8-TPR, DRIFTS and Raman techniques and tested in propane oxidative dehydrogenation using CO2. Complete oxidation of propane to CO and CO2 is favoured by lattice oxygen of CeO2. The temperature programmed experiments show the ~ 4 nm AC supported CeO2 crystallites become more susceptible to reduction by propane, but less prone to re-oxidation with CO2 compared to bulk CeO2. Catalytic activity of CeVO4/AC catalysts requires a 1–2 nm amorphous CeVO4 layer. During reaction, the amorphous CeVO4 layer crystallises and several atomic layers of carbon cover the CeVO4 surface, resulting in deactivation. During reaction, V2O5 is irreversibly reduced to V2O3. The lattice oxygen in bulk V2O5 favours catalytic activity and propene selectivity. Bulk V2O3 promotes only propane cracking with no propene selectivity. In VOx/AC materials, vanadium carbide is the catalytically active phase. Propane dehydrogenation over VC proceeds via chemisorbed oxygen species originating from the dissociated CO2. Graphic Abstract

scholarly journals Ultrathin Washcoat and Very Low Loading Monolithic Catalyst with Outstanding Activity and Stability in Dry Reforming of Methane

Nanomaterials ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 445 ◽  
Author(s):  
Fazia Agueniou ◽  
Hilario Vidal ◽  
María Pilar Yeste ◽  
Juan C. Hernández-Garrido ◽  
Miguel A. Cauqui ◽  
...  
Keyword(s):  
Thermodynamic Limit ◽  
Catalyst Layer ◽  
Active Phase ◽  
Dry Reforming ◽  
Redox Properties ◽  
Dry Reforming Of Methane ◽  
Alumina Catalyst ◽  
Monolithic Catalyst ◽  
Prolonged Time ◽  
Zro2 Catalyst

A Ni/CeO2/ZrO2 catalyst with improved redox properties has been washcoated onto a honeycomb cordierite monolith in the form of a nonconventional alumina-catalyst layer, just a few nanometers thick. In spite of the very low active phase loading, the monolith depicts outstanding performance in dry reforming of methane, both in terms of activity, with values reaching the thermodynamic limit already at 750 °C, even under extreme Weight Hourly Space Velocities (WHSV 115–346 L·g−1·h−1), as well as in terms of stability during prolonged Time on Stream (TOS 24–48 h).

Tar-Polyurethane Joint Coating for the Three-Layer Polyethylene Pipeline Coating

1996 ◽  
Author(s):  
Robert H. Rogers
Keyword(s):  
Cathodic Protection ◽  
Surface Preparation ◽  
Spray Coating ◽  
Field Trials ◽  
Localized Corrosion ◽  
Preparation Technique ◽  
Coating System ◽  
Actual Field ◽  
History Of Use ◽  
Key Steps

This article describes a new joint coating system implemented by Bechtel for a major international, 48 inch diameter gas pipeline. Despite the long history of use as a pipe and valve coating, the new implementation is the industry’s first significant use of a thermoset hot spray coating applied to field weld areas of pipe, mill coated with a three layer polyethylene system. In the laboratory and in field trials, the coating demonstrated integrity, was applied much quicker than the traditional heat shrink sleeve, and eliminated several application contingencies. Laboratory investigations undertaken in Houston, Texas and Lyon, France were key steps in selecting the 100% solids tar-polyurethane coating. Additionally, the testing assisted in developing the surface preparation technique, and demonstrating the coating’s ability to adhere to the polyethylene coating as well as the steel pipe. Serious localized corrosion, and cathodic protection shielding associated with other joint coatings are less probable with the new joint coating system. Actual field cathodic protection testing indicated very low current consumption for the completed pipeline. The efficient joint coating operation contributed to setting new construction records.

NEW POSSIBILITIES OF LOW-TEMPERATURE GENERATION OF ACTIVE CENTERS DURING HETEROGENEOUS-HOMOGENEOUS ACTIVATION OF PROPANE ON SILICA GEL SURFACE, MODIFIED WITH ZnO BY THE SOL-GEL AND CHEICAL TRANSPORT REACTION METHODS

2021 ◽  
Vol 55 (1 (254)) ◽  
pp. 1-6
Author(s):  
Tatevik O. Kamalyan ◽  
Petros S. Gukasyan ◽  
Samvel M. Vardapetyan ◽  
Oleg A. Kamalyan
Keyword(s):  
Silica Gel ◽  
Sol Gel ◽  
Kinetic Method ◽  
Active Phase ◽  
Active Centers ◽  
Chemical Transport Reaction ◽  
Transport Reaction ◽  
Heterogeneous Catalytic ◽  
Surface Modified ◽  
The Given

By the example of heterogeneous catalytic oxidation of propane the process of peroxide radicals transfer from the surface of catalysts into the reactor volume is studied. For comparison ZnO/SiO2 contacts obtained by depositing the active phase on the silica surface by sol-gel and chemical transport reaction (CTR) were used. It was established that for the case both the temperature of the radicals transfer from the surface to the volume and the value of the activation energy are lower than in the case. It was shown that the modification of the silica gel surface with zinc oxide by the CTR method is more effective as compared with the sol-gel method. It is established that in both cases the active phase of the catalyst exhibits paramagnetic properties. On the basis of the given, semi-artificial kinetic method of radical detachment, the obligatory mechanism of activation failed.

The role of active phase in Ce modified BiMo catalysts for oxidative dehydrogenation of 1-butene

2016 ◽  
Vol 264 ◽  
pp. 180-184 ◽  
Author(s):  
Chao Wan ◽  
Dang-guo Cheng ◽  
Fengqiu Chen ◽  
Xiaoli Zhan
Keyword(s):  
Oxidative Dehydrogenation ◽  
Active Phase
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