Study of Complex Reactions under Rapid Deactivation -- Improvements in the Reaction Equipment and in the Methodology for Kinetic Calculation

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Diana Mier ◽  
Andrés Tomás Aguayo ◽  
Alaitz Atutxa ◽  
Ana G Gayubo ◽  
Javier Bilbao
Keyword(s):  
Data Analysis ◽  
Kinetic Equation ◽  
Kinetic Model ◽  
Technological Development ◽  
Kinetic Modelling ◽  
Past History ◽  
Accurate Determination ◽  
Process Conditions ◽  
Product Analysis ◽  
Simulation And Optimization

The technological development of catalytic processes under rapid deactivation requires the rigorous calculation of the deactivation kinetic equation in order to be useful in the simulation and optimization of industrial processes. Accordingly, suitable equipment for reaction and product analysis and a rigorous methodology for kinetic data analysis are required. These aspects are approached in this paper using the transformation of methanol into olefins on a SAPO-18 as the model reaction. In this reaction, deactivation is rapid and there is also an initiation period depending on process conditions. The correct use of gas chromatography allows for improving the collection of experimental data of composition with time-on-stream, given that, on the one hand, it minimizes the time required for analysis (4 min), and on the other, a better homogenization of the reaction product sample is achieved, which allows for a more accurate determination of the composition corresponding to a given time-on-stream. Furthermore, the rigorous kinetic modelling of deactivation requires a data analysis methodology that considers the past history of the catalyst and an activity to be defined based on a rigorous physical meaning. Accordingly, the concept of the integrated kinetic model has been used in this paper, whose basis is the calculation of kinetic parameters by simultaneously solving the zero time-on-stream kinetic model and the kinetic equation for deactivation.

scholarly journals Amperometric Biosensors Based on Direct Electron Transfer Enzymes

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4525
Author(s):  
Franziska Schachinger ◽  
Hucheng Chang ◽  
Stefan Scheiblbrandner ◽  
Roland Ludwig
Keyword(s):  
Electron Transfer ◽  
Electrode Materials ◽  
Direct Electron Transfer ◽  
Accurate Determination ◽  
Direct Electrochemistry ◽  
Product Analysis ◽  
Amperometric Biosensors ◽  
Chemical Surface ◽  
Fusion Enzymes ◽  
Cost Efficient

The accurate determination of analyte concentrations with selective, fast, and robust methods is the key for process control, product analysis, environmental compliance, and medical applications. Enzyme-based biosensors meet these requirements to a high degree and can be operated with simple, cost efficient, and easy to use devices. This review focuses on enzymes capable of direct electron transfer (DET) to electrodes and also the electrode materials which can enable or enhance the DET type bioelectrocatalysis. It presents amperometric biosensors for the quantification of important medical, technical, and environmental analytes and it carves out the requirements for enzymes and electrode materials in DET-based third generation biosensors. This review critically surveys enzymes and biosensors for which DET has been reported. Single- or multi-cofactor enzymes featuring copper centers, hemes, FAD, FMN, or PQQ as prosthetic groups as well as fusion enzymes are presented. Nanomaterials, nanostructured electrodes, chemical surface modifications, and protein immobilization strategies are reviewed for their ability to support direct electrochemistry of enzymes. The combination of both biosensor elements—enzymes and electrodes—is evaluated by comparison of substrate specificity, current density, sensitivity, and the range of detection.

Kinetic modelling of the photocatalytic inactivation of bacteria

2010 ◽  
Vol 61 (6) ◽  
pp. 1547-1553 ◽  
Author(s):  
Javier Marugán ◽  
Rafael van Grieken ◽  
Alberto E. Cassano ◽  
Orlando M. Alfano
Keyword(s):  
Kinetic Model ◽  
Kinetic Parameters ◽  
Catalyst Concentration ◽  
Kinetic Modelling ◽  
Kinetic Constant ◽  
Water Disinfection ◽  
Radiation Absorption ◽  
Simple Modification ◽  
Model Based ◽  
Photocatalytic Inactivation

This work analyzes the kinetic modelling of the photocatalytic inactivation of E. coli in water using different types of kinetic models; from an empirical equation to an intrinsic kinetic model including explicit radiation absorption effects. Simple empirical equations lead to lower fitting errors, but require a total of 12 parameters to reproduce the results of four inactivation curves when the catalyst concentration was increased. Moreover, these parameters have no physical meaning and cannot be extrapolated to different experimental conditions. The use of a pseudo-mechanistic model based on a simplified reaction mechanism reduces the number of required kinetic parameters to 6, being the kinetic constant the only parameter that depends on the catalyst concentration. Finally, a simple modification of a kinetic model based on the intrinsic mechanism of photocatalytic reactions including explicit radiation absorption effects achieved the fitting of all the experiments with only three parameters. The main advantage of this approach is that the kinetic parameters estimated for the model become independent of the irradiation form, as well as the reactor size and its geometrical configuration, providing the necessary information for scaling-up and design of commercial-scale photoreactors for water disinfection.

scholarly journals Effect of Pressure, H2/CO Ratio and Reduction Conditions on Co–Mn/CNT Bimetallic Catalyst Performance in Fischer–Tropsch Reaction

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 698
Author(s):  
Omid Akbarzadeh ◽  
Noor Asmawati Mohd Zabidi ◽  
Guangxin Wang ◽  
Amir Kordijazi ◽  
Hamed Sadabadi ◽  
...  
Keyword(s):  
Performance Test ◽  
Bimetallic Catalyst ◽  
Fixed Bed ◽  
Tropsch Synthesis ◽  
Process Conditions ◽  
Gravimetric Analysis ◽  
Product Analysis ◽  
Fischer Tropsch ◽  
Fischer Tropsch Synthesis ◽  
Strong Electrostatic Adsorption

The effects of process conditions on Fischer–Tropsch Synthesis (FTS) product distributions were studied using a fixed-bed microreactor and a Co–Mn/CNT catalyst. Cobalt and Manganese, supported on Carbon Nanotubes (CNT) catalyst were prepared by a Strong Electrostatic Adsorption (SEA) method. CNT supports were initially acid and thermally treated in order to functionalize support to uptake more Co clusters. Catalyst samples were characterized by Transmitted Electron Microscope (TEM), particle size analyzer, and Thermal Gravimetric Analysis (TGA). TEM images showed catalyst metal particle intake on CNT support with different Co and Mn loading percentage. Performance test of Co–Mn/CNT in Fischer–Tropsch synthesis (FTS) was carried out in a fixed-bed micro-reactor at different pressures (from 1 atm to 25 atm), H2/CO ratio (0.5–2.5), and reduction temperature and duration. The reactor was connected to the online Gas Chromatograph (GC) for product analysis. It was found that the reaction conditions have the dominant effect on product selectivity. Cobalt catalyst supported on acid and thermal pre-treated CNT at optimum reaction condition resulted in CO conversion of 58.7% and C5+ selectivity of 59.1%.

Simulation and Experimental Research on Vehicle Ride Comfort and Suspension Parameters Optimisation

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Z. Ding ◽  
Z. Lei
Keyword(s):  
Kinetic Model ◽  
Ride Comfort ◽  
Physical And Mental Health ◽  
Vehicle Model ◽  
Simulation And Optimization ◽  
Suspension Systems ◽  
Passenger Vehicles ◽  
Suspension Parameters ◽  
Vehicle Technology ◽  
Test Verification

With the development of vehicle technology and the improvement of living standards, people’s ride comfort requirements for vehicle are also increasing. Especially for commercial passenger vehicles, the ride comfort is related to physical and mental health of passengers. Since the suspension is a major chassis system that affects the ride comfort of vehicle, so for how to make the vehicle to maintain good ride in a variety of driving conditions, the design and improvement of suspension are essential. The research content of this paper is simulating and optimizing the suspension parameters based on kinetic model of vehicle. First, a kinetic model of vehicle for minibus system is established. Then, test verification is carried out for the ride comfort of vehicle model. The results show that the established vehicle model can be used for simulation and optimization of front and rear suspension systems through the application of genetic algorithm.

Employing Simulated Data to Illustrate an Important Cause of the ‘Steepling’ Effect in Breath Alcohol Analysis

1994 ◽  
Vol 34 (4) ◽  
pp. 321-323 ◽  
Author(s):  
Rod G. Gullberg
Keyword(s):  
Kinetic Model ◽  
Data Collection ◽  
Nonlinear Regression ◽  
Kinetic Modelling ◽  
Analytical Data ◽  
Simulated Data ◽  
Breath Alcohol ◽  
Random Samples ◽  
The Mean ◽  
Over Time

The ‘steepling’ effect (large excursions in analytical data over time) is a debated issue in forensic breath alcohol analysis with various explanations being postulated. Simulated breath alcohol data was generated according to a hypothetical kinetic model where single random samples as well as means of duplicate random samples were plotted with respect to time at 0.2 hour intervals. In addition, the simulated data was compared when both two or more digit treatment was employed. Results showed the occurrence of significant noise or ‘steepling’ when single, two-digit breath alcohol samples were employed as compared to a four-digit mean computed from three-digit duplicates. The magnitude of variability was quantified by means of nonlinear regression resulting in the residual sum of squares (RSS) = 0.00202 for the single analysis and RSS = 0.00053 for the mean of duplicates. The method of data collection and treatment appears to contribute significantly to the ‘steepling’ phenomenon. Intuitively, replicate analyses reduce variability and allow for more accurate kinetic modelling employing breath alcohol analysis.

Constituent Particles and Dispersoids in an Al-Mn-Fe-Si Alloy Studied in Three-Dimensions by Serial Sectioning

2013 ◽  
Vol 765 ◽  
pp. 451-455 ◽  
Author(s):  
Liam Dwyer ◽  
Joseph Robson ◽  
Joao Quinta da Fonseca ◽  
Nicolas Kamp ◽  
Teruo Hashimoto ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Three Dimensions ◽  
Process Conditions ◽  
Second Phase ◽  
Serial Sectioning ◽  
3 Dimensional ◽  
Intermetallic Particles ◽  
Second Phase Particles ◽  
Proper Consideration

Second phase particles in wrought aluminium alloys are crucial in controlling recrystallization and texture. In Al-Mn-Fe-Si (3xxx) alloys, the size, spacing, and distribution of both large constituent particles and small dispersoids are manipulated by heat treatment to obtain the required final microstructure and texture for operations such as can-making. Understanding how these particles evolve as a function of process conditions is thus critical to optimize alloy performance. In this study, a novel 3-dimensional technique involving serial sectioning in the scanning electron microscope (SEM) has been used to analyse the intermetallic particles found in an as-cast and homogenized Al-Mn-Fe-Si alloy. This has allowed an accurate determination of the size and shape of the constituent particles and dispersoids derived from a 3-dimensional dataset. It is demonstrated that a proper consideration of the 3-dimensional microstructure reveals important features that are not obvious from 2-dimensional sections alone.

Experimental determination of friction coefficients between thermoplastics and rapid tooled injection mold materials

2005 ◽  
Vol 11 (3) ◽  
pp. 167-173 ◽  
Author(s):  
Mary E. Kinsella ◽  
Blaine Lilly ◽  
Benjamin E. Gardner ◽  
Nick J. Jacobs
Keyword(s):  
Injection Molding ◽  
Accurate Determination ◽  
Rapid Tooling ◽  
Injection Molding Process ◽  
Process Conditions ◽  
Molding Process ◽  
Friction Coefficients ◽  
Content Type ◽  
Temperature Conditions

PurposeTo determine static friction coefficients between rapid tooled materials and thermoplastic materials to better understand ejection force requirements for the injection molding process using rapid‐tooled mold inserts.Design/methodology/approachStatic coefficients of friction were determined for semi‐crystalline high‐density polyethylene (HDPE) and amorphous high‐impact polystyrene (HIPS) against two rapid tooling materials, sintered steel with bronze (LaserForm ST‐100) and stereolithography resin (SL5170), and against P‐20 mold steel. Friction tests, using the ASTM D 1894 standard, were run for all material pairs at room temperature, at typical part ejection temperatures, and at ejection temperatures preceded by processing temperatures. The tests at high temperature were designed to simulate injection molding process conditions.FindingsThe friction coefficients for HDPE were similar on P‐20 Steel, LaserForm ST‐100, and SL5170 Resin at all temperature conditions. The HIPS coefficients, however, varied significantly among tooling materials in heated tests. Both polymers showed highest coefficients on SL5170 Resin at all temperature conditions. Friction coefficients were especially high for HIPS on the SL5170 Resin tooling material.Research limitations/implicationsApplications of these findings must consider that elevated temperature tests more closely simulated the injection‐molding environment, but did not exactly duplicate it.Practical implicationsThe data obtained from these tests allow for more accurate determination of friction conditions and ejection forces, which can improve future design of injection molds using rapid tooling technologies.Originality/valueThis work provides previously unavailable friction data for two common thermoplastics against two rapid tooling materials and one steel tooling material, and under conditions that more closely simulate the injection‐molding environment.

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