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.

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.

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.

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

Thermodynamic Investigation of Acetic Acid Steam Reforming for Hydrogen Production

2012 ◽  
Vol 550-553 ◽  
pp. 2801-2804
Author(s):  
Peng Fu ◽  
Sen Meng An ◽  
Wei Ming Yi ◽  
Xue Yuan Bai
Keyword(s):  
Carbon Monoxide ◽  
Acetic Acid ◽  
Hydrogen Production ◽  
Steam Reforming ◽  
Operating Conditions ◽  
Negative Effects ◽  
Minimization Method ◽  
Gibbs Free Energy Minimization ◽  
Methane Selectivity ◽  
Increasing Temperature

The thermodynamics of acetic acid steam reforming (AASR) for hydrogen production were simulated using a Gibbs free energy minimization method to study the influences of pressure, temperature and water to acetic acid molar feed ratios (WAFR) on the AASR. On the basis of the equilibrium calculations, the optimal operating conditions obtained were 700-800 oC, 1bar and WAFR = 6-10. At these conditions, the yield and selectivity of hydrogen were maximized and the formation of methane and coke was almost inhibited. Higher pressures had negative effects on the yields and selectivities of hydrogen and carbon monoxide. With increasing temperature from 300 to 1000 oC, the selectivity for hydrogen and carbon monoxide increased significantly along with a reduction in methane selectivity. Increase in the WAFR led to the increase in hydrogen selectivity and the decrease in carbon monoxide selectivity.

scholarly journals Elementary Flux Mode Analysis of Acetyl-CoA Pathway in Carboxydothermus hydrogenoformans Z-2901

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Rajadurai Chinnasamy Perumal ◽  
Ashok Selvaraj ◽  
Gopal Ramesh Kumar
Keyword(s):  
Carbon Monoxide ◽  
Hydrogen Production ◽  
Gene Knockout ◽  
Mode Analysis ◽  
Hydrogen Yield ◽  
Acetyl Coa ◽  
Elementary Flux Mode ◽  
Acetyl Coa Pathway ◽  
Carboxydothermus Hydrogenoformans ◽  
Flux Mode

Carboxydothermus hydrogenoformans is a carboxydotrophic hydrogenogenic bacterium species that produces hydrogen molecule by utilizing carbon monoxide (CO) or pyruvate as a carbon source. To investigate the underlying biochemical mechanism of hydrogen production, an elementary mode analysis of acetyl-CoA pathway was performed to determine the intermediate fluxes by combining linear programming (LP) method available in CellNetAnalyzer software. We hypothesized that addition of enzymes necessary for carbon monoxide fixation and pyruvate dissimilation would enhance the theoretical yield of hydrogen. An in silico gene knockout of pyk, pykC, and mdh genes of modeled acetyl-CoA pathway allows the maximum theoretical hydrogen yield of 47.62 mmol/gCDW/h for 1 mole of carbon monoxide (CO) uptake. The obtained hydrogen yield is comparatively two times greater than the previous experimental data. Therefore, it could be concluded that this elementary flux mode analysis is a crucial way to achieve efficient hydrogen production through acetyl-CoA pathway and act as a model for strain improvement.

scholarly journals Thermodynamic Analysis of the Hydrogen Production from Ethanol: First and Second Laws Approaches

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Yannay Casas-Ledón ◽  
Luis E. Arteaga-Perez ◽  
Mayra C. Morales-Perez ◽  
Luis M. Peralta-Suárez
Keyword(s):  
Hydrogen Production ◽  
Thermodynamic Analysis ◽  
Direct Method ◽  
Positive Influence ◽  
State Equation ◽  
Molar Ratio ◽  
Ethanol Conversion ◽  
Hydrogen Yield ◽  
System Quality ◽  
Ethanol Steam

A thermodynamic analysis of hydrogen production from ethanol steam reforming (ESR) is carried out in the present paper. The influence of reactants molar ratio feed into the reforming stage (), temperature (573 to 1173 K) and pressure ( atm) over equilibrium compositions is studied. The direct method employed to analyze the system is the minimization of Gibbs free energy (MGFE) in conjunction with Lee-Kesler state equation, using the Kay mixing rules. The temperature and reactants molar ratio showed a positive influence on the hydrogen yield; ethanol conversion is 100% for the whole interval analyzed while the pressure affected greatly the hydrogen production. The carbon deposition exhibits a maximum value at temperatures around 773 K, and three reactions are proposed to describe the solid carbon formation in a wide temperature range based on thermodynamics and experimental predictions. The conditioning stages (mixing, vaporization, and heating) are studied in addition to the reaction to analyze the system quality by means of an exergetic method applying the 2nd law of thermodynamic.

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