Thermodynamic Analysis of the Absorption Enhanced Autothermal Reforming of Ethanol

2013 ◽  
Vol 16 (3) ◽  
pp. 229-237 ◽  
Author(s):  
Virginia Collins-Martínez ◽  
Miguel A. Escobedo Bretado ◽  
Jesús Salinas Gutiérrez ◽  
Miguel Meléndez Zaragoza ◽  
Vanessa. G. Guzmán ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Thermodynamic Analysis ◽  
Hydrogen Concentration ◽  
Autothermal Reforming ◽  
Operating Conditions ◽  
Co2 Absorption ◽  
Carbon Formation ◽  
High Hydrogen ◽  
Molar Ratios ◽  
Co2 Absorbent

Thermodynamic analysis of the absorption enhanced autothermal reforming of ethanol using CaO as CO2 absorbent and O2 in the feed was performed to determine favorable operating conditions to produce a high hydrogen ratio (HR, mols H2-produced/EtOH-feed) and hydrogen concentration in gas product. Steam/Ethanol (S/EtOH) and oxygen/ethanol (O2/EtOH) feed molar ratios were varied in order to find autothermal (?H ? 0) and carbon free operating conditions at 300-900°C and CaO as CO2 absorbent at 1 atm. Carbon formation analysis used S/EtOH = 1.75-2.8, while for hydrogen production varied from stoichiometric; 3:1 to 6.5:1, and O2/ETOH from 0 to 1.0. Results indicate no carbon formation at S/EtOH ? stoichiometric. The absorption enhanced autothermal reforming of ethanol using CaO, O2/EtOH = 0.33, S/EtOH = 6.5 and 600°C, produced an autothermal system with 98% H2 and only a reduction of 9.8% in HR and with respect to the CO2 absorption reforming without O2 feed.

Thermodynamic Analysis of the Absorption Enhanced Steam Reforming of Biofuel Model Compounds

2013 ◽  
Vol 16 (3) ◽  
pp. 239-251 ◽  
Author(s):  
Virginia Collins-Martínez ◽  
Miguel A. Escobedo Bretado ◽  
Jesús Salinas Gutiérrez ◽  
Miguel Meléndez Zaragoza ◽  
Alejandro López Ortiz
Keyword(s):  
Thermodynamic Analysis ◽  
Steam Reforming ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Carbon Formation ◽  
Model Compounds ◽  
High Hydrogen ◽  
Co2 Absorbent

Thermodynamic analysis of the steam reforming of biofuel model compounds using CaO, and Na2ZrO3, as CO2 absorbents was performed to determine favorable operating conditions to produce a high hydrogen ratio (HR, molsH2 produced/molsHC fed) and concentration (%H2) gas product. Biofuel compounds (HC’s) used were: 2,4-dimethylphenol (DMP), furfural (FUR) and vanillin (VAI). Equilibrium product compositions were studied at 300-850°C, steam to hydrocarbon molar ratio (S/HC) and CO2 absorbent at 1 atm. S/HC varied from stoichiometric; 15:1 (DMP), 13:1 (VAI) and 8:1 (FUR) to twice and trice their stoichiometric values, respectively. At stoichiometric S/HC ratios results indicate significant carbon formation with conventional reforming at T < 600°C, with no carbon formation using absorbents with any of the HC’s. The use of a CO2 absorbent resulted in an increase in HR and H2 purity of about 3 and 30% higher, respectively. The order from high to low HR was: VA>DMP>FUR.

Autothermal Reforming of Ethanol for Hydrogen Production: Thermodynamic Analysis

2013 ◽  
Vol 415 ◽  
pp. 658-665 ◽  
Author(s):  
Nawadee Srisiriwat ◽  
Chananchai Wutthithanyawat
Keyword(s):  
Carbon Monoxide ◽  
Hydrogen Production ◽  
Thermodynamic Analysis ◽  
Equilibrium Composition ◽  
Product Distribution ◽  
Autothermal Reforming ◽  
Hydrogen Yield ◽  
Molar Ratios ◽  
Carbon Monoxide Formation ◽  
Gibbs Free Energy Minimization

This work presents the autothermal reforming (ATR), or called oxidative steam reforming (OSR), of ethanol for hydrogen production. A thermodynamic analysis of product distribution for ATR from ethanol has been performed by using the method of Gibbs free energy minimization. The effect of steam-to-carbon (S:C) and air-to-carbon (A:C) molar ratios under adiabatic temperature of ATR reactor on chemical equilibrium composition of hydrogen rich stream is investigated. An increase of S:C ratio increases an efficiency of hydrogen production while carbon monoxide formation decreases but, however, more energy consumption for preheating reactants is also needed. An increase of A:C ratio in the range between 0 and 1.75 causes an increase of hydrogen yield but at greater A:C ratio, a decrease of hydrogen production and more water formation can be found. The results of the thermodynamic equilibrium show that the predicted hydrogen composition in the reaction of fuel-water-air system at constant temperature is higher than that obtained from experiment in both the absence and presence of catalysts in the OSR reaction when the temperature is fixed at 700 °C. The predicted carbon monoxide is lower than that obtained from the results of non-catalytic reaction but higher than that attained from the presence of catalyst in process.

Hydrogen Production via Catalytic Autothermal Reforming of Desulfurized Jet-A Fuel

2016 ◽  
Author(s):  
Shuyang Zhang ◽  
Xiaoxin Wang ◽  
Peiwen Li
Keyword(s):  
Energy Efficiency ◽  
Hydrogen Production ◽  
Hydrogen Storage ◽  
Coke Formation ◽  
Autothermal Reforming ◽  
Operating Conditions ◽  
Hydrogen Yield ◽  
Fuel Conversion ◽  
Optimal Operating ◽  
Reaction Equilibrium

On-board hydrogen production via catalytic autothermal reforming is beneficial to vehicles using fuel cells because it eliminates the challenges of hydrogen storage. As the primary fuel for both civilian and military air flight application, Jet-A fuel (after desulfurization) was reformed for making hydrogen-rich fuels in this study using an in-house-made Rh/NiO/K-La-Ce-Al-OX ATR catalyst under various operating conditions. Based on the preliminary thermodynamic analysis of reaction equilibrium, important parameters such as ratios of H2O/C and O2/C were selected, in the range of 1.1–2.5 and 0.5–1.0, respectively. The optimal operating conditions were experimentally obtained at the reactor’s temperature of 696.2 °C, which gave H2O/C = 2.5 and O2/C = 0.5, and the obtained fuel conversion percentage, hydrogen yield (can be large than 1 from definition), and energy efficiency were 88.66%, 143.84%, and 64.74%, respectively. In addition, a discussion of the concentration variation of CO and CO2 at different H2O/C, as well as the analysis of fuel conversion profile, leads to the finding of effective approaches for suppression of coke formation.

scholarly journals Hydrogen Production From Palmitic Acid Through Autothermal Reforming: Thermodynamic Analysis

2015 ◽  
Vol 19 (4) ◽  
pp. 153-165 ◽  
Author(s):  
Tawiwan Kangsadan ◽  
Thanarak Srisurat ◽  
Pattaraporn Kim ◽  
Navadol Laosiripojana ◽  
Sunisa Jindasuwan ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Palmitic Acid ◽  
Thermodynamic Analysis ◽  
Autothermal Reforming

CFD Modeling of Methane Autothermal Reforming in a Catalytic Microreactor

2007 ◽  
Vol 5 (1) ◽  
Author(s):  
Ali Fazeli ◽  
Mohsen Behnam
Keyword(s):  
Fuel Cell ◽  
Hydrogen Production ◽  
Hot Spot ◽  
Three Dimensional ◽  
Reaction Rates ◽  
Autothermal Reforming ◽  
Cfd Modeling ◽  
Air Distribution ◽  
Total Oxidation ◽  
High Hydrogen

Producing hydrogen from natural gas for a mini scale fuel cell is a new challenge for researchers. Therefore, modeling of hydrogen production microreactors should be helpful for designing and developing new microreactors. Experimental sensing of velocity, concentration, temperature and reaction rates in numerous points of the microreactor is impracticable. A microreactor in special geometry was considered for hydrogen production and a CFD model was developed in order to incorporate the mechanism of autothermal reforming. This mechanism includes three main reactions and Langmuir-Hinshelwood type kinetic rates. A three dimensional reformer model was developed to simulate the reactive laminar flow model of this microreactor. Effects of styles of feed entrance, air to fuel ratio and adding water to methane were studied. This model shows that there are hot spots near the entrance of the microreactor where the total oxidation of methane occurs and air distribution along the microreactor is a good solution for hot spot problems. The model shows that air distribution is good for fuel cell application because of high hydrogen production and low CO content in the outlet.

Thermodynamic Analysis of Hydrogen Production from Ethanol in Supercritical Water Oxidation

2011 ◽  
Vol 110-116 ◽  
pp. 77-82
Author(s):  
Nawadee Srisiriwat
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Hydrogen Production ◽  
Thermodynamic Analysis ◽  
Supercritical Water ◽  
Water Oxidation ◽  
Equilibrium Composition ◽  
Operating Conditions ◽  
Molar Ratio ◽  
Hydrogen Yield

A thermodynamic analysis was performed for hydrogen production from ethanol reforming and oxidation in supercritical water (SCW) conditions. The minimization of Gibbs free energy was used to calculate the equilibrium composition to investigate the effect of operating conditions, pressure, temperature, H2O2:EtOH molar ratio and H2O:EtOH molar ratio, on product yields. The theoretical results indicated that the yields of hydrogen and carbon monoxide decreased as the pressure increased but a H2/CO ratio at atmospheric pressure was lower than that at SCW conditions. High temperatures increased the efficiency of hydrogen production although the amount of carbon monoxide also increased. The presence of oxygen led to great decreases in methane oxidized to carbon dioxide and water. The spending of some hydrogen oxidized to water resulting in a lower hydrogen yield. High H2O:EtOH ratios increased the yields of hydrogen and carbon dioxide but decreased the methane and carbon monoxide production. It is possible to conclude that high temperature, high H2O:EtOH ratio and low addition of oxygen should lead to best results in the SCWO of ethanol.

scholarly journals THERMODYNAMIC ANALYSIS OF AUTOTHERMAL REFORMING OF METHANE VIA ENTROPY MAXIMIZATION: HYDROGEN PRODUCTION

2015 ◽  
Author(s):  
T. L. de SOUZA ◽  
C. C. R. S. ROSSI ◽  
C. G. ALONSO ◽  
R. GUIRARDELLO ◽  
V. F. CABRAL ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Thermodynamic Analysis ◽  
Autothermal Reforming ◽  
Entropy Maximization
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