scholarly journals Kinetic Study on Overall Reaction Rate with Ceramics-filled Anaerobic Fixed-bed Reactor

1990 ◽  
Vol 13 (4) ◽  
pp. 235-244,225
Author(s):  
Tadao KASAKURA ◽  
Mitsuo KAWASE
Keyword(s):  
Kinetic Study ◽  
Reaction Rate ◽  
Fixed Bed ◽  
Fixed Bed Reactor

scholarly journals Thermochemical Heat Storage in a Lab-Scale Indirectly Operated CaO/Ca(OH)2 Reactor—Numerical Modeling and Model Validation through Inverse Parameter Estimation

2021 ◽  
Vol 11 (2) ◽  
pp. 682
Author(s):  
Gabriele Seitz ◽  
Farid Mohammadi ◽  
Holger Class
Keyword(s):  
Numerical Model ◽  
Gas Flow ◽  
Reaction Rate ◽  
Heat Storage ◽  
Bulk Material ◽  
Fixed Bed ◽  
Experimental Results ◽  
Fixed Bed Reactor ◽  
Thermochemical Heat Storage ◽  
Speed Up

Calcium oxide/Calcium hydroxide can be utilized as a reaction system for thermochemical heat storage. It features a high storage capacity, is cheap, and does not involve major environmental concerns. Operationally, different fixed-bed reactor concepts can be distinguished; direct reactor are characterized by gas flow through the reactive bulk material, while in indirect reactors, the heat-carrying gas flow is separated from the bulk material. This study puts a focus on the indirectly operated fixed-bed reactor setup. The fluxes of the reaction fluid and the heat-carrying flow are decoupled in order to overcome limitations due to heat conduction in the reactive bulk material. The fixed bed represents a porous medium where Darcy-type flow conditions can be assumed. Here, a numerical model for such a reactor concept is presented, which has been implemented in the software DuMux. An attempt to calibrate and validate it with experimental results from the literature is discussed in detail. This allows for the identification of a deficient insulation of the experimental setup. Accordingly, heat-loss mechanisms are included in the model. However, it can be shown that heat losses alone are not sufficient to explain the experimental results. It is evident that another effect plays a role here. Using Bayesian inference, this effect is identified as the reaction rate decreasing with progressing conversion of reactive material. The calibrated model reveals that more heat is lost over the reactor surface than transported in the heat transfer channel, which causes a considerable speed-up of the discharge reaction. An observed deceleration of the reaction rate at progressed conversion is attributed to the presence of agglomerates of the bulk material in the fixed bed. This retardation is represented phenomenologically by mofifying the reaction kinetics. After the calibration, the model is validated with a second set of experimental results. To speed up the calculations for the calibration, the numerical model is replaced by a surrogate model based on Polynomial Chaos Expansion and Principal Component Analysis.

scholarly journals Solution Combustion Synthesis of Fe2O3-Based Catalyst for Ammonia Synthesis

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1027
Author(s):  
Binxiang Cai ◽  
Huazhang Liu ◽  
Wenfeng Han
Keyword(s):  
Combustion Synthesis ◽  
Reaction Rate ◽  
Ammonia Synthesis ◽  
Fixed Bed ◽  
Solution Combustion Synthesis ◽  
Fixed Bed Reactor ◽  
High Dispersion ◽  
Synthesis Reaction ◽  
Solution Combustion ◽  
Metal Nitrates

Fe2O3-based catalysts were prepared by solution combustion synthesis (SCS) with metal nitrates (Fe, K, Al, Ca) as the precursors and glycine as the fuel. The activities of catalysts were evaluated in terms of ammonia synthesis reaction rate in a fixed bed reactor similar to the industrial reactors. The results indicate that the precursor of catalyst prepared by SCS is Fe2O3 which facilitates the high dispersion of promoters to provide high activity. The catalysts exhibit higher activity for ammonia synthesis than that of traditional catalysts, and the reaction rate reaches 138.5 mmol g−1 h−1. Fe2O3 prepared by SCS could be favorable precursor for ammonia synthesis catalyst. The present study provides a pathway to prepare catalyst for ammonia synthesis.

A kinetic study of gaseous potassium capture by coal minerals in a high temperature fixed-bed reactor

Fuel ◽  
2008 ◽  
Vol 87 (15-16) ◽  
pp. 3304-3312 ◽  
Author(s):  
Yuanjing Zheng ◽  
Peter Arendt Jensen ◽  
Anker Degn Jensen
Keyword(s):  
High Temperature ◽  
Kinetic Study ◽  
Fixed Bed ◽  
Fixed Bed Reactor

Kinetics of the Reaction Between Solid Active Sodium Carbonate of the Second Generation and the Gaseous Sulfur Dioxide

1996 ◽  
Vol 61 (8) ◽  
pp. 1141-1157 ◽  
Author(s):  
Květoslava Stejskalová ◽  
Zdeněk Bastl ◽  
Karel Mocek
Keyword(s):  
Sulfur Dioxide ◽  
Kinetic Study ◽  
Sodium Carbonate ◽  
Reaction Rate ◽  
Second Generation ◽  
Surface Composition ◽  
Fixed Bed Reactor ◽  
Active Sodium ◽  
Before And After ◽  
Gaseous Sulfur

The results are presented of a detailed experimental kinetic study of the heterogeneous reaction between gaseous sulfur dioxide and the solid active sodium carbonate of the second generation which has been prepared by a controlled thermal dehydration of higher hydrates of the sodium carbonate. The measurements have been carried out in an all-glass kinetic apparatus with an integral fixed-bed reactor. The reaction course was studied in dependence on genesis and nature of the active sodium carbonate, on temperature and on composition of the gas phase. The reaction rate is significantly affected by presence of the water vapour which acts as a gaseous catalyst. Experimental data have been treated by using the model proposed by Erdos (Collect. Czech. Chem. Commun. 32, 1653 (1967), and the values of the effective reaction rate constants have been computed. The kinetic study of active sodium carbonate of the second generation has been completed by the determination of microstructure (SEM) of solid samples before and after reaction, and by determining the solid surface composition before and after reaction by means of electronic spectra (ESCA).

Comparative study of catalytic conversion of glycerol, a by-product of transesterification, to cyclic hydrocarbons using MCM-22, ZSM-5 and alumina

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Sandeep Kumar ◽  
Dinesh Kumar ◽  
Neeru Anand ◽  
Vinay Shah
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Fixed Bed ◽  
Liquid Product ◽  
Value Added ◽  
Fixed Bed Reactor ◽  
High Yield ◽  
Esterification Reaction ◽  
Glycerol Conversion ◽  
Ms Analysis

Abstract Recently chemical consumption has increased due to the growth of human population and industrialization. Depleting fuel reserves and increase in chemicals rise has led and researcher to focus on alternative bio based chemicals. Glycerol which is produced as a major byproduct from the trans-esterification reaction of fatty acids for producing biodiesel has been used in this work for conversion to value added products. Conversion of glycerol in presence of alumina, MCM-22 (pure silica based mesoporous catalyst) and ZSM-5 (Si-Al based catalyst) is investigated at different temperature and catalyst weight in a fixed bed reactor. The conversion of glycerol was found to be maximum in presence of alumina whereas maximum liquid products were obtained with ZSM-5. GC/MS analysis confirmed the production of Furan compounds in higher fraction with both alumina as well as ZSM-5 showing the importance of acid sites for the glycerol conversion to higher hydrocarbons. The GC/MS analysis of liquid product obtained in presence of catalyst was also observed with high area% of unconverted glycerol. The order is as follow 54% (MCM-22) > 44% (ZSM-5) > 42.2% (Alumina). For the investigation of the conversion for varying catalyst weight (0–3 g with 0.5 g weight difference), reaction temperature were varied between 450 and 550 °C. Different values of n = 0, 1, 2 etc. were used for the fitting of the respective plot. A change in reaction rate and the rate constant indicated that with the change of temperature, reaction rate was increased. The rate constant value obtained between 0.09 and 0.12 h−1. In all cases 450 °C and catalyst weight of 2.5 g was obtained as optimum for higher liquid yield. TGA analysis of spent catalyst also showed that alumina give high yield (∼50% by weight) of coke as compared to ZSM-5 and MCM-22.

A 2-D observer to estimate the reaction rate in a stopped flow fixed bed reactor for gas phase olefin polymerization

AIChE Journal ◽  
2014 ◽  
Vol 60 (10) ◽  
pp. 3511-3523 ◽  
Author(s):  
Barbara Browning ◽  
Nida Sheibat-Othman ◽  
Isabelle Pitault ◽  
Timothy F. L. McKenna
Keyword(s):  
Gas Phase ◽  
Reaction Rate ◽  
Olefin Polymerization ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
Stopped Flow
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