scholarly journals Promoters for Improvement of the Catalyst Performance in Methane Valorization Processes

2021 ◽  
Vol 23 (3) ◽  
pp. 147
Author(s):  
I.Z. Ismagilov ◽  
A.V. Vosmerikov ◽  
L.L. Korobitsyna ◽  
E.V. Matus ◽  
M.A. Kerzhentsev ◽  
...  
Keyword(s):  
High Efficiency ◽  
Catalyst Activity ◽  
Operation Mode ◽  
Coke Formation ◽  
Product Yield ◽  
Carbon Accumulation ◽  
Stable Operation ◽  
Coke Content ◽  
Methane Dehydroaromatization ◽  
Long Time

In this work, the introduction of modifying additives in the composition of catalysts is considered as an effective mode of improving functional characteristics of materials for two processes of methane conversion into valuable products – methane dehydroaromatization (DHA of CH4) into benzene and hydrogen and autothermal reforming of methane (ATR of CH4) into synthesis gas. The effect of type and content of promoters on the structural and electronic state of the active component as well as catalyst activity and stability against deactivation is discussed. For DHA of CH4 the operation mode of additives M = Ag, Ni, Fe in the composition of Mo-M/ZSM-5 catalysts was elucidated and correlated with the product yield and coke content. It was shown that when Ag serves as a promoter, the duration of the catalyst stable operation is enhanced due to a decrease in the rate of the coke formation. In the case of Ni and Fe additives, the Ni-Мо and Fe-Mo alloys are formed that retain the catalytic activity for a long time in spite of the carbon accumulation. For ATR of CH4, the influence of M = Pd, Pt, Re, Mo, Sn in the composition of Ni-M catalysts supported on La2O3 or Ce0.5Zr0.5O2/Al2O3 was elucidated. It was demonstrated that for Ni-M/La2O3 catalysts, Pd is a more efficient promoter that improves the reducibility of Ni cations and increases the content of active Nio centers. In the case of Ni-M/Ce0.5Zr0.5O2/Al2O3 samples, Re is considered the best promoter due to the formation of an alloy with anti-coking and anti-sintering properties. The use of catalysts with optimal promoter type and its content provides high efficiency of methane valorization processes.

Modeling and Simulation Study of an Industrial Radial Moving Bed Reactor for Propane Dehydrogenation Process

2016 ◽  
Vol 14 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Sim Yee Chin ◽  
Anwaruddin Hisyam ◽  
Haniif Prasetiawan
Keyword(s):  
Flow Reactor ◽  
Catalyst Activity ◽  
Coke Formation ◽  
Plug Flow ◽  
Propane Dehydrogenation ◽  
Propane Conversion ◽  
Reactor Model ◽  
Moving Bed ◽  
Coke Content ◽  
Experimental Values

AbstractAn accurate model is required to optimize the propane dehydrogenation reaction carried out in the radial moving bed reactors (RMBR). The present study modeled the RMBR using a plug flow reactor model incorporated with kinetic models expressed in simple power-law model. Catalyst activity and coke formation were also considered. The model was solved numerically by discretizing the RMBR in axial and radial directions. The optimized kinetic parameters were then used to predict the trends of propane conversion, temperature, catalyst activity and coke content in the RMBR along axial and radial directions. It was found that the predicted activation energies of the propane dehydrogenation, propane cracking and ethylene hydrogenation were in reasonable agreement with the experimental values reported in the literature. The model developed has accurately predicted the reaction temperature profile, conversion profile and catalyst coke content. The deviations of these simulated results from the plant data were less than 5%.

scholarly journals Novel semi-analytical optoelectronic modeling based on homogenization theory for realistic plasmonic polymer solar cells

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zahra Arefinia ◽  
Dip Prakash Samajdar
Keyword(s):  
Solar Cells ◽  
Active Layer ◽  
Analytical Modeling ◽  
High Efficiency ◽  
Polymer Solar Cells ◽  
Scattered Light ◽  
Homogenization Theory ◽  
Computational Time ◽  
Coupled Equations ◽  
Long Time

AbstractNumerical-based simulations of plasmonic polymer solar cells (PSCs) incorporating a disordered array of non-uniform sized plasmonic nanoparticles (NPs) impose a prohibitively long-time and complex computational demand. To surmount this limitation, we present a novel semi-analytical modeling, which dramatically reduces computational time and resource consumption and yet is acceptably accurate. For this purpose, the optical modeling of active layer-incorporated plasmonic metal NPs, which is described by a homogenization theory based on a modified Maxwell–Garnett-Mie theory, is inputted in the electrical modeling based on the coupled equations of Poisson, continuity, and drift–diffusion. Besides, our modeling considers the effects of absorption in the non-active layers, interference induced by electrodes, and scattered light escaping from the PSC. The modeling results satisfactorily reproduce a series of experimental data for photovoltaic parameters of plasmonic PSCs, demonstrating the validity of our modeling approach. According to this, we implement the semi-analytical modeling to propose a new high-efficiency plasmonic PSC based on the PM6:Y6 PSC, having the highest reported power conversion efficiency (PCE) to date. The results show that the incorporation of plasmonic NPs into PM6:Y6 active layer leads to the PCE over 18%.

scholarly journals On Performance of Sparse Fast Fourier Transform Algorithms Using the Aliasing Filter

Electronics ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1117
Author(s):  
Bin Li ◽  
Zhikang Jiang ◽  
Jie Chen
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
High Efficiency ◽  
Theory And Practice ◽  
Long Time ◽  
And Performance ◽  
Binary Tree Search ◽  
The One ◽  
Sparse Fast Fourier Transform ◽  
L1 And L2

Computing the sparse fast Fourier transform (sFFT) has emerged as a critical topic for a long time because of its high efficiency and wide practicability. More than twenty different sFFT algorithms compute discrete Fourier transform (DFT) by their unique methods so far. In order to use them properly, the urgent topic of great concern is how to analyze and evaluate the performance of these algorithms in theory and practice. This paper mainly discusses the technology and performance of sFFT algorithms using the aliasing filter. In the first part, the paper introduces the three frameworks: the one-shot framework based on the compressed sensing (CS) solver, the peeling framework based on the bipartite graph and the iterative framework based on the binary tree search. Then, we obtain the conclusion of the performance of six corresponding algorithms: the sFFT-DT1.0, sFFT-DT2.0, sFFT-DT3.0, FFAST, R-FFAST, and DSFFT algorithms in theory. In the second part, we make two categories of experiments for computing the signals of different SNRs, different lengths, and different sparsities by a standard testing platform and record the run time, the percentage of the signal sampled, and the L0, L1, and L2 errors both in the exactly sparse case and the general sparse case. The results of these performance analyses are our guide to optimize these algorithms and use them selectively.

A New Prediction Model on the Luminance of OLEDs Subjected to Different Reverse Biases for Alleviating Degradation in AMOLED Displays

2014 ◽  
Author(s):  
Paul C.-P. Chao ◽  
Yen-Ping Hsu ◽  
Yung-Hua Kao ◽  
Kuei-Yu Lee
Keyword(s):  
Reverse Bias ◽  
High Efficiency ◽  
Life Time ◽  
Density Currents ◽  
High Brightness ◽  
Light Emitting ◽  
Wide Viewing Angle ◽  
Time Operation ◽  
Long Time ◽  
History Of

Organic light-emitting diodes (OLEDs) have drawn much attention in areas of displays and varied illumination devices due to multiple advantages, such as high brightness, high efficiency, wide viewing angle, and simple structure. However, the long-time degradation of OLED emission is a serious drawback. This degradation was investigated by past works, which pointed out that the degradation was induced by high-density currents through OLED component under the long-time operation [1][2]. Proposed by a past work [3], different reverse biases was imposed on OLED components in display frames to alleviate the long-time degradation on OLEDs. Most recently, along with the reverse bias, new pixel circuits [4][5] for AMOLED displays are designed to alleviate OLED degradation, thus successfully extending OLED life time. However, since emission luminances in different frame times during AMOLED displaying differs significantly for displaying varied images, the OLED degradation evolves in a highly unpredictable fashion. In this study, based on valid theories, the voltage across the OLED is first used as indicator for OLED degradation. Then the relation between the level of OLED degradation, in terms of OLED’s cross voltage, and the history of imposing reverse biases are precisely modeled. With the model, the degradation of the OLED under reverse bias to extend lifetime can be successfully predicted. Based on this model, engineers can then optimize the applied reverse bias on OLEDs to maximize the OLED lifetime for varied display requirement.

scholarly journals Development of COVID-19 vaccines utilizing gene therapy technology

2021 ◽  
Author(s):  
Hironori Nakagami
Keyword(s):  
Viral Vectors ◽  
High Efficiency ◽  
Genetic Disorders ◽  
Rapid Development ◽  
Adenovirus Vector ◽  
Phase 3 ◽  
Double Blind ◽  
Time Period ◽  
Short Period ◽  
Long Time

Abstract There is currently an outbreak of respiratory disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus disease 2019 (COVID-19) is caused by infection with SARS-CoV-2. Individuals with COVID-19 have symptoms that are usually asymptomatic or mild in most initial cases. However, in some cases, moderate and severe symptoms have been observed with pneumonia. Many companies are developing COVID-19 vaccine candidates using different technologies that are classified into four groups (intact target viruses, proteins, viral vectors and nucleic acids). For rapid development, RNA vaccines and adenovirus vector vaccines have been urgently approved, and their injection has already started across the world. These types of vaccine technologies have been developed over more than 20 years using translational research for use against cancer or diseases caused by genetic disorders but the COVID-19 vaccines are the first licensed drugs to prevent infectious diseases using RNA vaccine technology. Although these vaccines are highly effective in preventing COVID-19 for a short period, safety and efficiency evaluations should be continuously monitored over a long time period. As the time of writing, more than 10 projects are now in phase 3 to evaluate the prevention of infection in double-blind studies. Hopefully, several projects may be approved to ensure high-efficiency and safe vaccines.

scholarly journals Electromechanical Modeling and Simulation of Piezoelectric Vibration based Energy Harvester Interfaced with MPPT based Electrical Circuit using Matlab Simulink

2019 ◽  
Vol 8 (2S11) ◽  
pp. 36-40
Keyword(s):  
Energy Harvester ◽  
High Efficiency ◽  
Electrical Circuit ◽  
Vibration Energy Harvester ◽  
Matlab Simulink ◽  
Electromechanical Model ◽  
Wind Vibration ◽  
Long Time ◽  
Piezoelectric Vibration ◽  
High Output

Wind vibration based energy harvester using piezoelectric material has been of great concern to researchers for a long time for low power generation and applications. In this paper, wind generated vibrations are used to develop electromechanical model of piezoelectric vibration energy harvester to generate electrical output using MATLAB simulink and comparision has been drawn between an electromechanical model of piezoelectric harvester interfaced with P&O MPPT based electrical model and without it. It has been found that overall model with MPPT provides high output with high efficiency

An intelligent robot for indoor substation inspection

2020 ◽  
Vol 47 (5) ◽  
pp. 705-712
Author(s):  
Chenjie Wang ◽  
Lu Yin ◽  
Qing Zhao ◽  
Wei Wang ◽  
Chengyuan Li ◽  
...  
Keyword(s):  
Nuclear Power ◽  
High Efficiency ◽  
Sensor Data ◽  
Robotic Arm ◽  
Stable Operation ◽  
Intelligent Robot ◽  
Visual Servo ◽  
Content Type ◽  
Electric Power Supply ◽  
Inspection Robots

Purpose To ensure the safety of electric power supply, it is necessary to inspect substation equipment. With the dramatic increase in the number of substations, especially indoor substations, intelligent robot inspection has become an important development direction. This paper aims to describe the design of a trackless robot with a robotic arm, which is capable of navigating autonomously and inspecting the equipment in a narrow and complex indoor substation. Design/methodology/approach A robust four-wheel platform powered by electric motors is used to carry the robot. By fusing multiple-sensor data and visual markers, the robot achieves autonomous movement based on simultaneous localization and mapping. In addition, to accurately obtain the reading of meters located at height or in a narrow space, the robot is equipped with a newly designed visual servo robotic arm. Findings In practical application, the robot satisfies the requirements of substation inspection, improves work efficiency, saves costs and achieves good results. The robot is also approved by the relevant departments of the State Grid Corporation of China. Practical implications After stable operation in a substation for a period of one year, the robot shows high efficiency and stability, meeting the requirements of indoor substation inspection. Meanwhile, the robot greatly promoted the realization of indoor and outdoor integrated substation automatic inspection, and is expected to be further applied in other industrial inspection sites, including mine, tunnel and nuclear power plant. Originality/value Due to the complex indoor environment, most of the existing inspection robots are only used outdoors, and there are no good trackless inspection robots for use indoors. The proposed robot is a trackless intelligent inspection robot for use in indoor substations. The robot features a number of important modules, including an autonomous localization and navigation module and a visual servo manipulator module, which can be used in narrow spaces or at height.

scholarly journals Reversible Nature of Coke Formation on Mo/ZSM‐5 Methane Dehydroaromatization Catalysts

2019 ◽  
Vol 58 (21) ◽  
pp. 7068-7072 ◽  
Author(s):  
Nikolay Kosinov ◽  
Evgeny A. Uslamin ◽  
Lingqian Meng ◽  
Alexander Parastaev ◽  
Yujie Liu ◽  
...  
Keyword(s):  
Coke Formation ◽  
Methane Dehydroaromatization ◽  
Reversible Nature

The Complex Oxidation Behavior of Pd Combustion Catalysts

2001 ◽  
Vol 7 (S2) ◽  
pp. 1064-1065
Author(s):  
K. Lester ◽  
A.K. Datye
Keyword(s):  
Phase Transformations ◽  
High Temperatures ◽  
Catalytic Combustion ◽  
Catalyst Activity ◽  
Combustion Process ◽  
Reaction Rates ◽  
Stable Operation ◽  
Temperature Combustion ◽  
High Temperature Combustion ◽  
Complex Oxidation

Combustion of natural gas for power generation leads to NOx formation due to the high temperatures encountered. Catalytic combustion allows the entire combustion process to be completed at temperatures where NOx formation can be avoided. The catalyst of choice is supported PdO. As temperature is increased, PdO decomposes to Pd metal with profound effects on catalyst reactivity. Persistent hysteresis in reaction rates have been related to the decomposition of PdO into Pd and its reformation.Understanding and controlling the phase transformations, and the resulting activity variations, is of enormous importance for high temperature combustion catalysts where predictable catalyst activity is necessary for stable operation. Farrauto et al. studied the phase transformations of PdO to Pd using thermogravimetric analysis (TGA). They concluded that while PdO decomposes to Pd at high temperatures during the heating cycle, upon cooling the Pd does not transform to PdO till the temperature drops by several hundred degrees.

A Method of Power Generation From Low Temperature Medium

2002 ◽  
Author(s):  
Qingjun Cai ◽  
Chung-Lung Chen
Keyword(s):  
Waste Heat ◽  
Stable Operation ◽  
Vapor Bubbles ◽  
Power Generator ◽  
New Device ◽  
Heating And Cooling ◽  
Higher Power ◽  
Long Time ◽  
Generating Capacity ◽  
Cooling Tube

For a long time, how to utilize waste heat to generate electricity has been an interesting and challenging field for energy scientists. This paper presents a new method, ferrofluid power generator (FPG), which takes advantage of waste heat or solar energy to generate electricity in a multiple heating and cooling tube with alternate ferrofluid slug and vapor bubble structures. Based on this method, a new device, a thermomagnetic engine (TME) composed of a straight vacuum tube, a current induced coil, and magnet & ferrofluid slugs (MFS), was designed. Experimental results show that the expanding vapor bubbles push MFSs to generate drastic and continuous oscillating movements under the effect of heat. The pulse voltage signals from the induced coil demonstrate that the TME has a practical structure, potentially higher power generating capacity, and a stable operation.

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