scholarly journals ASPECTOS ENERGÉTICOS E ELETRÔNICOS DA ZEÓLITA H-ZSM-5 NA AÇÃO CATALÍTICA DA REAÇÃO DE DESIDRATAÇÃO DE ÁLCOOIS

2020 ◽  
Author(s):  
Gustavo Gomes de Sousa ◽  
José Roberto dos Santos Politi
Keyword(s):  
Reaction Mechanism ◽  
Fossil Fuels ◽  
Acid Catalysis ◽  
High Efficiency ◽  
Dehydration Process ◽  
Dehydration Reaction ◽  
Alcohol Dehydration ◽  
Catalytic Behavior ◽  
Zeolite Cavity ◽  
Computational Methodology

Due to the growth of ecological concerns and the need to reduce dependence on fossil fuels, the dehydration of alcohols by acid catalysis has been used for the production of various hydrocarbons. Inside this theme, the H-ZSM-5 zeolite has been widely used as a catalyst for this reaction because its high efficiency. Thus, in order to understand the catalyzed reaction mechanism of the alcohol dehydration reaction, this work used the computational methodology ONIOM to study the catalytic behavior of the H-ZSM-5. It was modeled the dehydration reaction process for several alcohols (ethanol, propanol, isopropanol, butanol and 2-butanol) by modeling these alcohols within the zeolite cavity. The study was divided into 3 stages: the adsorption and protonation of alcohols by zeolite, the description of the hydroxyl outlet, and the formation of the double bond. The analysis of the results indicates that the first stage of the reaction occurs with the contact of alcohol with the zeolite cavity, where acid hydrogen promotes the protonation of alcohols, occurring differently for each alcohol. The dehydration process occurs, preferably, via E2 type elimination mechanisms. However, the profile of the energy curves indicates that for larger alcohols, the mechanism is intermediate between the elimination mechanisms E2 with some features of E1 (E2[E1]). Therefore, the zeolite converts alcohols to hydrocarbons in a specific way. Primary, lower-chain alcohols follow E2 mechanism, while secondary and longer-chain alcohols react by a slightly different mechanism, namely E2[E1].

scholarly journals FATTY ACID ESTERIFICATION: EFFECTS OF UNSATURATION AND SYNTHESIS WITH THERMAL HEATING VIA ULTRASON AND MICROWAVES

2018 ◽  
Vol 15 (30) ◽  
pp. 447-462
Author(s):  
M. C. de M. SOUZA ◽  
L. DI SOUZA ◽  
V. P. da S. Caldeira ◽  
A. G. D. SANTOS ◽  
B. ADILSON
Keyword(s):  
Fatty Acids ◽  
Oleic Acid ◽  
Fatty Acid ◽  
Energy Demand ◽  
Fossil Fuels ◽  
Acid Catalysis ◽  
Thermal Heating ◽  
Ultrasonic Methods ◽  
Homogeneous Acid ◽  
Acid Esterification

With the increasing selective energy demand, fossil fuels are becoming scarce and environmentally incorrect, a viable alternative to this problem being the production of biodiesel. However, the esterification and transesterification reactions used are slow, expensive and ecologically incorrect because they produce polluting waste. Thus, it is necessary to develop techniques, reagents and equipment that make them fast, cheap and environmentally friendly. This work evaluated the performance of the thermal heating, microwave and ultrasonic methods in the esterification efficiency of oleic and stearic fatty acids via homogeneous acid catalysis. The efficiency of the reaction was certificated with the variables: time, yield and conversion and the biodiesel characterization were done with TG / DTG, FTIR and NMR. Conversions were determined by TG and 1H NMR and the yield by gravimetry. The results showed conversion with all methods with differences in the analyzed variables. The yields decrease in the microwave order (52%) conduction (33%) ultrasound (30%) for reactions with oleic acid and are practically the same (22, 22 and 20), independently of the stearic acid. Among the methods used, the most efficient is the microwave, because it has a higher yield in the case of oleic acid and reducing the reaction time.

scholarly journals Direct Carbon Fuel Cell-Cleaner and Efficient Future Power Generation Technology

2019 ◽  
Vol 6 (1) ◽  
pp. 14-30
Author(s):  
Uzair Ibrahim ◽  
Ahsan Ayub
Keyword(s):  
Carbon Dioxide ◽  
Fuel Cell ◽  
Fossil Fuels ◽  
High Efficiency ◽  
Thermal Power ◽  
Gaseous State ◽  
Thermal Plant ◽  
Direct Carbon Fuel Cell ◽  
Pure Carbon ◽  
Pure Carbon Dioxide

Increasing greenhouse effect due to the burning of fossil fuels has stirred the attention of researchers towards cleaner and efficient technologies. Direct carbon fuel cell (DCFC) is one such emerging technology that could generate electricity from solid carbon like coal and biogas in a more efficient and environmental-friendly way. The mechanism involves electrochemical oxidation of carbon to produce energy and highly pure carbon dioxide. Due to higher purity, the produced carbon dioxide can be captured easily to avoid its release in the environment. The carbon dioxide is produced in a gaseous state while the fuel used is in a solid state. Due to different phases, all of the fuel can be recovered from the cell and can be reused, ensuring complete (100%) fuel utilization with no fuel losses. Moreover, DCFC operates at a temperature lower than conventional fuel cells. The electric efficiency of a DCFC is around 80% which is nearly double the efficiency of coal thermal plant. In addition, DCFC produces pure carbon dioxide as compared to the thermal power plant which reduces the cost of CO2 separation and dumping. In different types of DCFCs, molten carbon fuel cell is considered to be superior due to its low operating temperature and high efficiency. This paper provides a comprehensive review of the direct carbon fuel cell technology and recent advances in this field. The paper is focused on the fundamentals of fuel cell, history, operating principle, its types, applications, future challenges, and development.

Graphite Electrodes for Hydrogen Production by Acid Electrolysis

2020 ◽  
Vol 1012 ◽  
pp. 158-163
Author(s):  
Oliveira Marilei de Fátima ◽  
Mazur Viviane Teleginski ◽  
Virtuozo Fernanda ◽  
Junior Valter Anzolin de Souza
Keyword(s):  
Hydrogen Production ◽  
Fossil Fuels ◽  
High Efficiency ◽  
Low Cost ◽  
Electric Energy ◽  
Gas Production ◽  
Hydrogen Fuel Cells ◽  
Graphite Electrodes ◽  
Alkaline Electrolysis ◽  
Selection Of

Nowadays, humanity has become aware of the consequences that the use of fossil fuels entails, and the latest developments in the energy sector are leading to a diversification of energy resources. In this context, researching on alternative forms of producing electric energy is being conducted. At the transportation level, a possible solution for this matter may lie in hydrogen fuel cells. The electrolysis of water is one of the possible processes for hydrogen production, but the reaction to break the water molecule requires a great amount of energy and this is precisely the biggest issue involving this process. In this work, low cost electrodes of 254 stainless steel and electrolytic graphite were used for hydrogen production, allowing high efficiency and reduced oxidation during the process. The selection of these materials allows to obtain a high corrosion resistance electrolytic pair, by replacing the high cost platinum electrode usually employed in the alkaline electrolysis process. The formic acid of biomass origin was used as an electrolyte. It was observed that the developed reactor have no energy losses through heat and it was possible to obtain approximately 82% conversion efficiency in the gas production process.

scholarly journals EXERGY-BASED INVESTIGATION OF A COAL-FIRED ALLAM CYCLE

2019 ◽  
Vol 137 ◽  
pp. 01018 ◽  
Author(s):  
Jing Luo ◽  
Ogechi Emelogu ◽  
Tatiana Morosuk ◽  
George Tsatsaronis
Keyword(s):  
Fossil Fuels ◽  
Coal Gasification ◽  
High Efficiency ◽  
Cycle Performance ◽  
Energetic Efficiency ◽  
Component Level ◽  
Lower Efficiency ◽  
Heating Value ◽  
Lower Heating Value ◽  
Lower Heating

Allam cycle is a novel cycle that capitalizes on the unique thermodynamic properties of supercritical CO2 and the advantages of oxy-combustion for power generation. It is a high-pressure supercritical carbon dioxide cycle designed to combust fossil fuels such as natural gas or syngas (from coal gasification systems) with complete CO2 separation at a high-efficiency and zero atmospheric emissions. This semi-closed cycle produces sequestration-ready/pipeline quality CO2 by-product, and thus eliminates the need for additional CO2-capture system. The Coal-fueled Allam cycle is targeted to deliver between 51-52% net efficiency (lower heating value) for coal gasification. In this study, the expected energetic efficiency is verified by simulating the system in Ebsilon professional software and the result showed that the net efficiency of the simulated coal-fired plant is 30.7%, which is significantly lower than the targeted value. The lower efficiency maybe as a result of the missing heat integration in the system, the high power demand of the oxidant compressor and CO2 compressors. And an exergy analysis based on published cycle data is employed, to investigate the cycle performance, identify the sources of the cycle’s thermodynamic inefficiencies at the component level; a sensitivity analysis is also performed to study the effects of selected thermodynamic parameters on the overall performance of the coal-fired Allam cycle.

Solar Upgrading of Fuels for Generation of Electricity

2001 ◽  
Vol 123 (2) ◽  
pp. 160-163 ◽  
Author(s):  
Rainer Tamme ◽  
Reiner Buck ◽  
Michael Epstein ◽  
Uriyel Fisher ◽  
Chemi Sugarmen
Keyword(s):  
Gas Turbines ◽  
Large Scale ◽  
Fossil Fuels ◽  
High Efficiency ◽  
Combined Cycle ◽  
Test Facility ◽  
Small Scale ◽  
Start Up ◽  
Efficiency Conversion ◽  
Solar Field

This paper presents a novel process comprising solar upgrading of hydrocarbons by steam reforming in solar specific receiver-reactors and utilizing the upgraded, hydrogen-rich fuel in high efficiency conversion systems, such as gas turbines or fuel cells. In comparison to conventionally heated processes about 30% of fuel can be saved with respect to the same specific output. Such processes can be used in small scale as a stand-alone system for off-grid markets as well as in large scale to be operated in connection with conventional combined-cycle plants. The complete reforming process will be demonstrated in the SOLASYS project, supported by the European Commission in the JOULE/THERMIE framework. The project has been started in June 1998. The SOLASYS plant is designed for 300 kWel output, it consists of the solar field, the solar reformer and a gas turbine, adjusted to operate with the reformed gas. The SOLASYS plant will be operated at the experimental solar test facility of the Weizmann Institute of Science in Israel. Start-up of the pilot plant is scheduled in April 2001. The midterm goal is to replace fossil fuels by renewable or non-conventional feedstock in order to increase the share of renewable energy and to establish processes with only minor or no CO2 emission. Examples might be upgrading of bio-gas from municipal solid waste as well as upgrading of weak gas resources.

scholarly journals Design 2-Speed Transmission for Compact Electric Vehicle Using Dual Brake System

2019 ◽  
Vol 9 (9) ◽  
pp. 1793
Author(s):  
Jae-Oh Han ◽  
Jae-Won Shin ◽  
Jae-Chang Kim ◽  
Se-Hoon Oh
Keyword(s):  
Automobile Industry ◽  
Alternative Fuels ◽  
Fossil Fuels ◽  
High Efficiency ◽  
Bending Strength ◽  
Combustion Engine ◽  
High Reliability ◽  
Environmentally Friendly ◽  
Drive System ◽  
The Government

Mega trends in the global automotive industry are environmentally friendly. As laws and regulations tighten at the government level, the automobile industry is striving to develop a drive system that can operate without using fossil fuels, instead of developing an internal combustion engine using fossil fuels. Environmentally-friendly energy is attracting attention as an alternative to solve the problems of air pollution and fossil fuel depletion. Electricity is attracting the most attention among environmentally-friendly alternative fuels. In addition, research on the development of a high-efficiency and high-reliability advanced electric automobile drive system are actively being carried out. In this study, a two-speed transmission for electric vehicles is developed using environmentally-friendly fuel. The 1st and the 2nd planetary gear modules were integrated, the ring gear and the carrier gear were shared, and the dual disc brake was used to design a mechanism for fixing each sun and shifting gear. Such a structure can improve shift energy efficiency compared to that of conventional transmissions. It was judged that the structure was suitable for an electric car using a limited power supply. Each gear was designed by calculating bending strength and surface durability.

Hydrolysis of Ketene Catalyzed by Formic Acid: Modification of Reaction Mechanism, Energetics, and Kinetics with Organic Acid Catalysis

2015 ◽  
Vol 119 (19) ◽  
pp. 4347-4357 ◽  
Author(s):  
Matthew K. Louie ◽  
Joseph S. Francisco ◽  
Marco Verdicchio ◽  
Stephen J. Klippenstein ◽  
Amitabha Sinha
Keyword(s):  
Reaction Mechanism ◽  
Formic Acid ◽  
Organic Acid ◽  
Acid Catalysis ◽  
Acid Modification ◽  
Hydrolysis Of

scholarly journals Highly Selective Synthesis of Chlorophenols under Microwave Irradiation

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Yawen Xiong ◽  
Hongdong Duan ◽  
Xia Meng ◽  
Zhaoyun Ding ◽  
Weichun Feng
Keyword(s):  
Reaction Mechanism ◽  
Reaction Time ◽  
Hydrochloric Acid ◽  
Microwave Irradiation ◽  
High Efficiency ◽  
Selective Synthesis ◽  
Conversion Rates ◽  
Electron Donating Groups ◽  
Electron Transfers ◽  
Excellent Selectivity

Oxychlorination of various phenols is finished in 60 minutes with high efficiency and perfect selectivity under microwave irradiation. These reactions adopt copper(II) chloride (CuCl2) as the catalyst and hydrochloric acid as chlorine source instead of expensive and toxic ones. Oxychlorination of phenols substituted with electron donating groups (methyl, methoxyl, isopropyl, etc.) atortho-andmeta-positions is accomplished with higher conversion rates, lower reaction time, and excellent selectivity. A proposed reaction mechanism is deduced; one electron transfers from CuCl2to phenol followed by the formation of tautomeric radical that can be rapidly captured by chlorine atom and converts intopara-substituted product.

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