Autothermal Reforming of Ethanol for Hydrogen Production: Steady State Modeling

2013 ◽  
Vol 415 ◽  
pp. 651-657 ◽  
Author(s):  
Chananchai Wutthithanyawat ◽  
Nawadee Srisiriwat
Keyword(s):  
Steady State ◽  
Fuel Cell ◽  
Hydrogen Production ◽  
Autothermal Reforming ◽  
Adiabatic Temperature ◽  
Efficient Production ◽  
Operating Condition ◽  
Molar Ratios ◽  
Fuel Cell Application ◽  
Production Of Hydrogen

As increasing hydrogen demand for fuel cell application is expected in the near future, the efficient production of hydrogen is vital enabling technology for commercialization of fuel cell for residences and automobiles. Among different technologies of hydrogen production, autothermal reforming is considered to be thermally self-sustaining that the external heat source is not required. In this work, a steady state modeling of autothermal reforming of ethanol for hydrogen production has been performed. Because the operating condition at adiabatic temperature is designed for autothermal reformer, the estimated function of adiabatic temperature as function of steam-to-carbon (S:C) and air-to-carbon (A:C) molar ratios can be determined. At autothermal condition, the effect of S:C and A:C ratios on the product distributions of hydrogen rich stream is thermodynamically investigated. At fixed reactor pressure of 1 bar and preheat temperature of 200 °C, the favorable operating condition for the autothermal reforming of ethanol is found to be a S:C ratio of 2.0 and an A:C ratio of 1.75 at adiabatic temperature of 639 °C.

Numerical Simulation of an Axisymmetric Ethanol Reforming Reactor for Hydrogen Fuel Cell Applications

2006 ◽  
Author(s):  
Gregory A. Buck ◽  
Hiroyuki Obara
Keyword(s):  
Fuel Cell ◽  
Hydrogen Production ◽  
Autothermal Reforming ◽  
Great Promise ◽  
Hydrogen Fuel Cell ◽  
Hydrogen Fuel ◽  
Gaseous State ◽  
Ethanol Reforming ◽  
Wide Range ◽  
Production Of Hydrogen

Hydrogen fuel cell technology is currently capable of providing adequate power for a wide range of stationary and mobile applications. Nonetheless, the sustainability of this technology rests upon the production of hydrogen from renewable resources. Among the techniques under current study, the chemical reforming of alcohols and other bio-hydrocarbon fuels, appears to offer great promise. In the so called autothermal reforming process, a suitable combination of total and partial oxidation supports hydrogen production from ethanol with no external addition of energy required. Furthermore, the autothermal reforming process conducted in a well insulated reactor, produces temperatures that promote additional hydrogen production through the endothermic steam reforming and the water-gas shift reactions, which may be catalyzed or uncatalyzed, with the added benefit of lowered carbon monoxide concentrations. In this study, an adiabatic ethanol reforming reactor was simulated assuming the reactants to be air (21% O2 and 79% N2) and ethanol (C2H5OH) and the products to be H2O, CO2, CO and H2, with all constituents taken to be in the gaseous state. The air was introduced uniformly through a ring around the side of the reactor and the gaseous ethanol was injected into the center of one end, with products withdrawn from the center of the opposite end, to create an axisymmetric flow field. The gas flows within the reactor were assumed to be turbulent, and the chemical kinetics of a simple four reaction system was assumed to be controlled by turbulent mixing processes. Air and fuel flow rates into the reactor were varied to obtain six different levels of oxidation (air-fuel ratios) while maintaining the same total gaseous mass flow out of the reactor. The numerical results for the reacting flow show that hydrogen production is maximized when the air-fuel ratio on a mass basis is held at approximately 2.8. These findings are in qualitative agreement with observations from previous experimental studies.

scholarly journals Hydrogen production from water electrolysis: role of catalysts

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Shan Wang ◽  
Aolin Lu ◽  
Chuan-Jian Zhong
Keyword(s):  
Hydrogen Production ◽  
Water Splitting ◽  
Noble Metal ◽  
Active Sites ◽  
Current Knowledge ◽  
Low Cost ◽  
Critical Role ◽  
Water Electrolysis ◽  
Efficient Production ◽  
Production Of Hydrogen

AbstractAs a promising substitute for fossil fuels, hydrogen has emerged as a clean and renewable energy. A key challenge is the efficient production of hydrogen to meet the commercial-scale demand of hydrogen. Water splitting electrolysis is a promising pathway to achieve the efficient hydrogen production in terms of energy conversion and storage in which catalysis or electrocatalysis plays a critical role. The development of active, stable, and low-cost catalysts or electrocatalysts is an essential prerequisite for achieving the desired electrocatalytic hydrogen production from water splitting for practical use, which constitutes the central focus of this review. It will start with an introduction of the water splitting performance evaluation of various electrocatalysts in terms of activity, stability, and efficiency. This will be followed by outlining current knowledge on the two half-cell reactions, hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), in terms of reaction mechanisms in alkaline and acidic media. Recent advances in the design and preparation of nanostructured noble-metal and non-noble metal-based electrocatalysts will be discussed. New strategies and insights in exploring the synergistic structure, morphology, composition, and active sites of the nanostructured electrocatalysts for increasing the electrocatalytic activity and stability in HER and OER will be highlighted. Finally, future challenges and perspectives in the design of active and robust electrocatalysts for HER and OER towards efficient production of hydrogen from water splitting electrolysis will also be outlined.

Thermodynamic study of hydrogen production from crude glycerol autothermal reforming for fuel cell applications

2010 ◽  
Vol 35 (13) ◽  
pp. 6617-6623 ◽  
Author(s):  
Suthida Authayanun ◽  
Amornchai Arpornwichanop ◽  
Woranee Paengjuntuek ◽  
Suttichai Assabumrungrat
Keyword(s):  
Fuel Cell ◽  
Hydrogen Production ◽  
Crude Glycerol ◽  
Autothermal Reforming ◽  
Thermodynamic Study

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.

Internal Reforming SOFC System for Flexible Coproduction of Hydrogen and Power

2005 ◽  
Author(s):  
Kas Hemmes ◽  
Anish Patil ◽  
Nico Woudstra
Keyword(s):  
Fuel Cell ◽  
Hydrogen Production ◽  
Natural Gas ◽  
Total System ◽  
Flow Sheet ◽  
Content Increase ◽  
Fuel Utilization ◽  
Production Mode ◽  
Internal Reforming ◽  
Production Of Hydrogen

In the framework of the project Greening of Gas, in which the feasibility of mixing hydrogen into the natural gas network in the NL is studied, we are exploring alternative hydrogen production methods. Fuel cells are usually only seen as devices that convert hydrogen into power and heat. It is less well known that these electrochemical energy converters can produce hydrogen, or form an essential component in systems for co-production of hydrogen and power. Co-production of hydrogen and power from NG in an Internal reforming fuel cell (IR FC) is worked out by flow sheet calculations on an Internal reforming Solid Oxide fuel cell (IR-SOFC) system. It is shown that the system can operate in a wide range of fuel utilization values at least from 60% representing highest hydrogen production mode to 95% corresponding to ‘normal’ fuel cell operation mode. For the atmospheric pressure system studied here hydrogen and CO content increase up to 22.6 and 13.5 % respectively at a fuel utilization of 60%. Total system efficiency (power + H2/CO) is increasing significantly at lower fuel utilization and can reach 94 %. Our study confirms that the calculations of Vollmar et al1) on an IR-SOFC stack also hold for a complete FC system. Notably that paradoxically a system with the same fuel cell stack when switched to hydrogen production mode can yield more power in addition to the H2 and CO produced. This is because the hydrogen production mode allows for operation at high current and power densities. The same system can double its power output (e.g. from 1.26 MW to 2.5 MW) while simultaneously increasing the H2 /CO output to 3.1MW). Economics of these systems is greatly improved. These systems can also be considered for hydrogen production for the purpose of mixing it with natural gas in the natural gas grid in order to reduce CO2 emissions at the end users, because of the ability to adopt the system rapidly to fluctuations in natural gas/hydrogen demand.

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.

Nickel Multi-walled Carbon Nanotube Composite Electrode for Hydrogen Generation

2012 ◽  
Vol 1387 ◽  
Author(s):  
Nitin Kalra ◽  
Kalathur Santhanam ◽  
David Olney
Keyword(s):  
Carbon Nanotube ◽  
Hydrogen Production ◽  
Large Scale ◽  
Coulombic Efficiency ◽  
Superior Performance ◽  
Efficient Production ◽  
Scale Production ◽  
Production Of Hydrogen ◽  
Carbon Nanotube Composite ◽  
Decomposition Of Water

ABSTRACTThe electrochemical decomposition of water is an attractive method, however, the performance of the electrodes and efficiencies are of great concern in its large scale production. In this context, we wish to report here the superior performance of Ni-multiwalled carbon nanotube composite as cathode in the decomposition of water. The current voltage curves recorded with this electrode in different media showed a significant electrocatalysis in the reduction of hydrogen ion; the background electrolysis is shifted in the anodic direction. The nanocomposite composition has been found to be crucial in the efficient production of hydrogen. A coulombic efficiency of about 68% has been obtained at this electrode with a hydrogen production rate of 130L/m2 d. This electrode is more efficient than the 316L stainless steel (composition in percentage: C 0.019, Cr 17.3, Mo 2.04, Ni 11.3, Mn 1.04, N 0.041, Fe bulk) cathode that produces 10 ml/h at an area of 20 cm2 (5L/m2.h) (2). The results obtained with different electrolytes, performance variation with electrode composition, and current densities will be presented. The trials carried out using solar panel instead of DC power source showed similar hydrogen production rates and efficiencies.

A Spatially Resolved Physical Model for Dynamic Modeling of a Novel Hybrid Reformer-Electrolyzer-Purifier (REP) for Production of Hydrogen

2017 ◽  
Author(s):  
Derek McVay ◽  
Li Zhao ◽  
Jack Brouwer ◽  
Fred Jahnke ◽  
Matt Lambrech
Keyword(s):  
Experimental Data ◽  
Carbon Dioxide ◽  
Steady State ◽  
Fuel Cell ◽  
Physical Model ◽  
Physical Models ◽  
Co2 Removal ◽  
Molten Carbonate ◽  
Spatially Resolved ◽  
Production Of Hydrogen

A molten carbonate electrolysis cell (MCEC) is capable of separating carbon dioxide from methane reformate while simultaneously electrolyzing water. Methane reformate, for this study, primarily consists of carbon dioxide, hydrogen, methane, and a high percentage of water. Carbon dioxide is required for the operation of a MCEC since a carbonate ion is formed and travels from the reformate channel to the sweep gas channel. In this study, a spatially resolved physical model was developed to simulate an MCEC in a novel hybrid reformer electrolyzer purifier (REP) configuration for high purity hydrogen production from methane and water. REP effectively acts as an electrochemical CO2 purifier of hydrogen. In order to evaluate the performance of REP, a dynamic MCEC stack model was developed based upon previous high temperature molten carbonate fuel cell modeling studies carried out at the National Fuel Cell Research Center at the University of California, Irvine. The current model is capable of capturing both steady state performance and transient behavior of an MCEC stack using established physical models originating from first principals. The model was first verified with REP experimental data at steady state which included spatial temperature profiles. Preliminary results show good agreement with experimental data in terms of spatial distribution of temperature, current density, voltage, and power. The combined effect of steam methane reformation (SMR) and water electrolysis with electrochemical CO2 removal results in 96% dry-basis hydrogen at the cathode outlet of the MCEC. Experimental measurements reported 98% dry-basis hydrogen at the cathode outlet.

Hydrogen production for fuel cell application via thermo-chemical technique: An analytical evaluation

2021 ◽  
Vol 47 ◽  
pp. 101413
Author(s):  
Peyman Maghsoudi ◽  
Amirreza Kaabinejadian ◽  
Mohammad Mehdi Homayounpour ◽  
Mehdi Bidabadi
Keyword(s):  
Fuel Cell ◽  
Hydrogen Production ◽  
Analytical Evaluation ◽  
Fuel Cell Application ◽  
Chemical Technique

Production of Hydrogen by Autothermal Reforming of Propane over Ni/δ-Al2O3

2006 ◽  
Vol 6 (11) ◽  
pp. 3396-3398 ◽  
Author(s):  
Hae Ri Lee ◽  
Kwi Yeon Lee ◽  
Nam Cook Park ◽  
Jae Soon Shin ◽  
Dong Ju Moon ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Chemical Reduction ◽  
Autothermal Reforming ◽  
Production Of Hydrogen ◽  
Reduction Methods ◽  
Better Than ◽  
Water Alcohol

The performance of Ni/δ-Al2O3 catalyst in propane autothermal reforming (ATR) for hydrogen production was investigated in the present study. The catalysts were characterized using XRD, TEM, and SEM. The activity of the Ni/δ-Al2O3 catalyst manufactured by the water-alcohol method was better than those of the catalysts manufactured by the impregnation and chemical reduction methods. The Ni/δ-Al2O3 catalysts were modified by the addition of promoters such as Mg, La, Ce, and Co, in order to improve their stability and yield. Hydrogen production was the largest for the Ni-Co-CeO2/Al2O3 catalyst.

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