International Journal of Hydrogen Energy 32 (2007) 1429 – 1436 www.elsevier.com/locate/ijhydene
Diesel fuel processor for hydrogen production for 5 kW fuel cell application D. Sopeña a,∗ , A. Melgar a , Y. Briceño a , R.M. Navarro b , M.C. Álvarez-Galván b , F. Rosa c a Fundación CIDAUT. Parque Tecnológico de Boecillo, P. 209, 47151 Boecillo (Valladolid), Spain b Instituto de Catálisis y Petroquímica (CSIC), C/ Marie Curie 2, Cantoblanco (Madrid), Spain c Instituto Nacional de Técnica Aeroespacial, Carretera San Juan del Puerto-Matalascañas, km 33, 21130 Mazagón-Moguer (Huelva), Spain
Available online 26 December 2006
Abstract The present paper describes a diesel fuel processor designed to produce hydrogen to feed a PEM fuel cell of 5 kW. The fuel processor includes three reactors in series: (1) oxidative steam reforming reactor; (2) one-step water gas shift reactor; and (3) a preferential oxidation reactor. The design of the system was accomplished by means of a one-dimensional model. A specific study of the fuel-air mixing chamber was carried out with Fluent 䉸 by taking into account fuel evaporation and cool flame processes. The assembly of the installation allowed the characterisation of each component and the control of each working parameter. The first experimental results obtained in the reformer system using decaline and diesel fuels demonstrate the feasibility of the design to produce hydrogen suitable to feed a PEM fuel cell. 䉷 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. Keywords: Fuel processor; Diesel fuel; Hydrogen production; Oxidative reforming; Reformer
1. Introduction Nowadays, there is a growing interest in hydrogen technologies because fuel cell is one of the most promising technologies for electric generation converting directly, by means of electrochemical process, chemical energy of hydrogen into electric energy. Hydrogen is one of the most abundant elements on earth, but its main drawback is that it is always found combined forming water, hydrocarbons,… . Fossil fuel reforming by means of catalytic processes [1,2] is currently the most used method for hydrogen production and it will continue to be, until hydrogen production using renewable energies could be economically feasible. Among fossil fuels that can be reformed, natural gas is the most used for hydrogen generation in large-scale or in residential sector whereas reforming of liquid fuels (gasoline, diesel fuel, methanol,…) appears suitable for transportation purposes (on-board reforming) or for small energy generators in isolated zones taking into account the higher energy density of liquid fuels which favours storage in reduced volumes, and whose distribution infrastructure is well established. ∗ Corresponding author. Tel.: +34 983 54 80 35; fax: +34 983 54 80 62.
E-mail address:
[email protected] (D. Sopeña). URL: http://www.cidaut.es.
Among liquid fuels to be reformed, diesel fuel is an interesting option owing to its low price, availability, ease of handling and high-energy density. In general, the conversion of hydrocarbon fuels to hydrogen can be carried out by three main reaction processes [3], namely, steam reforming (SR), partial oxidation (POX) and the combination of the previous processes in oxidative steam reforming (OSR). The main characteristics of each of the aforementioned processes are summarised in Table 1. Among the reforming processes, the oxidative reforming was the technology selected to perform the primary diesel reforming because it offers simpler design, lower temperature of operation and more dynamic response to work under varying loads. Oxidative reforming process combines the endothermic SR reaction with the exothermic POX reaction, allowing the control of the heat effects of the reaction adjusting the feed proportions of fuel, air and steam [4–7]. Depending on the design and operating conditions of the reformer (temperature, O2 /C and H2 O/C ratios), the H2 -rich effluent gas contains 5.10 vol% of carbon monoxide. This carbon monoxide must be converted to additional hydrogen in order to increase the efficiency of the reforming process [8–10]. For this purpose, a water gas shift (WGS) reactor was integrated after the primary reformer unit. Under adiabatic conditions, CO conversion by WGS reforming is
0360-3199/$ - see front matter 䉷 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2006.10.046
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Table 1 Characteristics of the main reforming processes used for liquid hydrocarbons Steam reforming (SR) Reaction: Cn Hm + 2nH2 O ⇔ nCO2 + (2n + m/2)H2 Reaction temperature = 750 ◦ C H ◦ = 1280 kJ/mol (for gasoline case)
% vol of hydrogen = 55 Slow start-up. Needs external heating system
Partial oxidation reforming (POX) Reaction: Cn Hm + n/2(O2 + 3.76N2 ) ⇔ nCO + m/2H2 + n/2 · 3.76N2 Reaction temperature = 1100 ◦ C H ◦ = −659 kJ/mol (for gasoline case)
% vol of hydrogen = 28 Quick and easy start-up
Oxidative steam reforming (OSR) Reaction: Cn Hm + a · n(O2 + 3.76N2 ) + b · nH2 O ⇔ pCO + qCO2 + rH2 + sH2 O + a · n · 3.76N2 where a = O2 /C ratio and b = H2 O/C ratio % vol of hydrogen = 35.40 Reaction temperature = 850.900 ◦ C H ◦ ≈ 0 kJ/mol O2 /C = 0.3.0.5, H2 O/C = 2.3
thermodynamically limited achieving after the shift step a minimum CO concentration of 0.5.1 vol%. For applications with proton-exchange membrane fuel-cell (PEMFC), to avoid the rapid deactivation of electro-catalysts in the fuel cell, this CO concentration must be reduced to less than 20 ppm. There are three available major technologies such as methanation, Pd membranes and preferential oxidation (PROX) to decrease CO concentration to levels below 20 ppm. However, taking into account the difficulties associated with both the methanation (CO2 accompanying CO) and the severity of operation with Pd membrane separation, the approach undertaken in this work was the CO clean-up stage by catalytic selective oxidation process [11]. Accordingly, this paper describes in a condensed manner some developments of a large project entitled “Development and construction of a 5 kW diesel reformer”, jointly developed by the National Institute for Aerospace Technology (INTA), the Institute of Catalysis and Petrochemistry (ICP-CSIC), the Association of Research and Industrial Cooperation of Andalucia (AICIA) and the Research and Development Center in Transport and Energy (CIDAUT) with the objective to build up a prototype able to evaluate the design of catalysts, reactors and auxiliary systems required to convert the diesel fuel into a hydrogen gas stream that fulfil specifications to feed a PEMFC system. 2. Experimental 2.1. System description The fuel processor design was done considering a hydrogen production to feed a 5 kWe PEM fuel cell taking into account a stack efficiency of 0.4 and a stoichiometric excess of H2 of 1.55 (specifications given by fuel cell manufacturer). With these values together with the data obtained at laboratory scale at ICP-CSIC related to the optimal O2 /C and H2 O/C ratios (between 0.3–0.8 and 2–5, respectively), the maximum flow rates of reactants were calculated. Flow rates of 2.64 l/h of diesel fuel, 8.44 Nm3 /h of air and 11.44 Nm3 /h of steam were fixed as design values. The scale-up of the system from laboratory
data obtained at ICP-CSIC was carried out by means of a onedimensional model [12,13] that allows the simulation of the behaviour of reactors (using thermodynamic and kinetic data) as well as heat exchangers (HE) (with heat transfer equations). The results provided by these simulations allowed to determine the size of the reactors, the HE and the temperature evolution throughout the different units of the reformer. The individual behaviour of catalysts developed for each unit was studied by ICP-CSIC using reactors at a laboratory scale. These studies allowed a fast screening of catalysts activities and the determination of both optimal operating conditions and catalyst stability under working conditions. From these studies, different catalyst formulations to be used in the reformer were selected: Pt supported on modified alumina with improved thermal and coke resistance as catalyst for the oxidative reforming unit, Pt deposited on mixed CeO2 .TiO2 as catalyst for the one-step WGS unit and highly dispersed Pt on bare alumina as catalyst formulation loaded in the PROX unit. By scaling-up laboratory data, volumes of catalysts of 2.61, 3.16 and 11.25 l were calculated for the oxidative reforming reactor, WGS reactor and PROX reactor, respectively. These volumes of catalysts imply a gas hourly space velocities, at maximum flow rates, of 12 710, 14 230 and 2850 h−1 , respectively. In Fig. 1, the operational diagram of the system is presented. The scheme of the reformer shows the following individual units connected in series: (i) preheating-mixing diesel/air/water chamber; (ii) oxidative reforming unit (OSR); (iii) desulphuriser unit; (iv) WGS unit; (v) PROX unit; and (vi) water condenser units. Reactor axial temperature profiles were followed with six thermocouples equidistantly distributed along the reactor axis. HE were placed between the different reactors with the objective to adapt the input temperature in each reactor to the design temperature. The molar composition of the gas streams at the exit of each reactor was monitored by an on-line gas chromatograph (VARIAN CP-4900 Micro Gas Chromatograph) equipped with a TC detector and programmed to operate under highsensitivity conditions. Fig. 2 shows the picture of the assembly of the aforementioned elements integrating the reformer prototype.
D. Sopeña et al. / International Journal of Hydrogen Energy 32 (2007) 1429 – 1436
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STEAM
H2
MIXING CHAMBER
N2 HEATER
AIR
OSR
DIESEL FUEL
H.E. 1 H.E. DESULPHURIZER
REFRIGERATION WATER
EXHAUST
H.E. 2 WGS REACTOR
CONDENSER
H.E. 3 H.E. PROX REACTOR
REFRIGERATION WATER
CONDENSER
EXIT TO FUEL CELL
Fig. 1. Scheme of the reformer prototype developed at CIDAUT.
OSR Desulphurizer WGS Reactor PrOx Reactor
Vaporiser
Heat released, Heat loss
Cool Flame
Electrical Heater Mixing Chamber
Heat released
Heatloss
Fig. 2. Pictures showing the front and back sides of the reformer prototype.
T0
2.2. Preparation of fuel–air–water feed mixture The formation of the diesel–air–steam mixture is essential as it determines the quality of the reforming process. This mixture must be highly homogenised to prevent the appearance of hot spots and coking on catalyst surfaces during oxidative reforming process. An alternative to evaporation/mixing process is the cool flame process that offers the possibility to evaporate the liquid hydrocarbons free of residues. The cool flame process allows the achievement of a stable temperature, which helps in the mixing and homogenisation because the heat released during the exothermic reforming reactions assists in the vaporisation and break-up of the heaviest fractions of the hydrocarbons. Cool flames start when a liquid hydrocarbon is vaporised in a preheated air current [6,14]. Fig. 3 shows the heat released and the heat loss during the diesel–air–steam mixture at different temperatures. From this figure it can be observed
T1
T2
Temperature
Fig. 3. Heat variations in the fuel–air mixing chamber as function of mixture temperature.
that the diesel–air–steam mixture in the interval from T0 to T1 provokes heat loss, while the heat released when heating the mixture above T1 exceeds the heat loss and provokes a temperature increase up to T2 . At this point, heat released and heat loss are equilibrated and cool flame is established. In the case of diesel fuel, the cool flame regime begins at 300 ◦ C and may be stable until temperatures close to 480 ◦ C. 2.3. Operational sequence The start up sequence of the reformer prototype is carried out in two steps including drying and catalysts activation by reduction. Drying step includes the heating of the reactors and
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lines (at 150.200 ◦ C) under nitrogen flow to remove residual water in the system. Subsequently, catalysts in the different reactors are reduced under H2 /N2 mixtures (10% vol in H2 ) to complete the reduction of platinum active phases (2 h at 350 ◦ C for the OSR catalyst, 2 h at 250 ◦ C for the WGS catalyst and 2 h at 200 ◦ C in the case of the PROX catalyst). After that, each reactor is heated up under a low flow of nitrogen to the process temperatures: 800.850 ◦ C for oxidative reforming reactor, 450 ◦ C for the desulphuriser, 290 ◦ C for the WGS reactor and 170 ◦ C for the PROX reactor. Once all the reactors have reached the process temperature, steam, air and diesel fuel are introduced in the OSR reactor. Air and steam flow rates are carefully adjusted by keeping constant the O2 /C and H2 O/C ratios (0.5 and 3.5 for diesel fuel, respectively). Specific control strategies have been developed to face up to anomalous situations during reformer operation (variations in flow rates, reactor temperatures, catalysts deactivation,…). For that reason every parameter of the system (flow rates, pressures and temperatures) can be controlled and monitored by means of a control system. The control system allows the modification of the parameters and process values of each one of the PIDs that control components (pumps, electrovalves), temperatures or input flow rates to correct anomalous situations during reforming operation.
3. Results Previously to the description of the results, it could be remarked that the developed prototype can be considered as a facility for testing and characterising the different components of the reformer (reactors, HE, condensers), either in isolated or coupled ways under different working conditions, rather than an integrated reformer. 3.1. Preparation of fuel–air–water feed mixture Fig. 4 presents the simulations by FLUENT of the fuel vaporisation that takes place in the mixing chamber. The figure shows the diesel vaporisation in microdroplets at different time intervals along its advance through the mixing chamber. Different tests were done to validate the mixing process simulations studying different diesel fuel feed and mixing temperatures. Fig. 5 displays temperature profiles along the OSR reactor for different cases: (i) decaline without cool flame; (ii) decaline with cool flame; and (iii) diesel fuel with cool flame. In these three cases the fuel flow rate was 1 l/h and the O2 /C ratio for decaline was 0.35 and 0.5 for diesel fuel. The H2 O/C ratio was near to three for both cases. From this figure, different cool flame temperature for decaline (about 435 ◦ C) and
Fig. 4. Frames of the simulation by fluent of diesel fuel vaporisation in the mixing chamber.
1000
800
800
700
600
600
T OSR 4
1433
T OSR3
T OSR5
400
Temperature, °C
Temperature, °C
D. Sopeña et al. / International Journal of Hydrogen Energy 32 (2007) 1429 – 1436
Decaline Decaline-cool flame
200
Diesel-cool flame 0 0
200
400 Length, mm
6 00
T OSR6
T OSR2
500 400
T OSR 1
T MC T HE
300
800
WITHOUT COOL FLAME
200
WITH COOL FLAME
Fig. 5. Temperature profiles through the primary reformer for different fuels with and without cool flame. H2
50
480.500 ◦ C)
3.2. Primary reforming with decaline The first characterisation studies of the OSR reactor were conducted using a Ni-based catalyst and decaline as fuel to avoid the damage of the catalyst to be used with diesel fuel in the first tests. Different experimental tests were carried out to determine the thermal reactor response and to know the effect of H2 O/C and O2 /C ratios on the product selectivity for reforming reactions. The data obtained from these tests were compared with equivalent data obtained at a laboratory scale (ICP-CSIC test unit) with the objective of comparing the performances of the reforming reactor design used in the prototype and the laboratory reactor. Table 2 and Fig. 7 show experimental results obtained in the oxidative reforming of decaline at different O2 /C and H2 O/C ratios. Fig. 7 shows a decrease in hydrogen concentration with the increase in the O2 /C ratio. This observation may be due to the dilution effect of nitrogen gas in the inlet flow. The CO2 concentration in product gas stream also decreases with the
40 Gas composition,%
diesel fuel (between are observed. Temperatures in the first part of the OSR reactor rise considerably by the cool flame process because this process enhances fuel vaporisation and mixture homogenisation. Fig. 5 also shows differences in temperatures at which diesel fuel and decaline reforming were produced (around 850 ◦ C for diesel fuel whereas for decaline is around 650 ◦ C). It could be remarked that there is a first POX zone at the beginning of the catalytic bed where higher temperatures than the rest of the reactor are reached (typically around 1000 ◦ C as shown in [9]). As no thermocouple was placed in this region, these temperatures are not shown in the graph. It has been mentioned above that the cool flame produced in the mixing chamber helps to keep stable the temperature profile in the primary reformer reactor (OSR) in spite of the variations that can happen upstream. This is clearly shown in Fig. 6 where the oscillations in temperature in the upper part of the OSR reactor (TOSR1, TOSR2 and TOSR3) produced by oscillations in the steam flow are buffered by the cool flame, due to the equilibrium state that this phenomenon involves.
N2
30
CO2
20
10 0 27800
CO CH4
28000
28200
28400
28600
Time, s
Fig. 6. Evolution with time-on-stream of temperatures and product composition after diesel reforming (diesel flow = 1 l/h, O2 /C = 0.33 and H2 O/C = 4).
increase in the O2 /C ratio in the feed. This tendency is contrary to what it was expected, because higher O2 /C ratios should imply higher CO2 concentrations due to the higher oxidation conditions. This anomalous behaviour can be due to the nonadiabatic process of the reactor and/or because the mixture is not as homogeneous as it could be expected. On examining the influence of H2 O/C ratio on product selectivities, the data summarised in Table 2 indicate that there is not a clear influence over the reforming stream composition. Other tests were carried out in order to study the influence of the space velocity on the selectivity of reforming products. In Fig. 8, the reforming gas compositions obtained at different decaline flow rates (from 0.7 to 1.7 l/h) are presented. From data in Fig. 8 it is clear that for decaline flow rates higher than 1.5 l/h, a loss in hydrogen production occurs as a consequence of the higher selectivity to hydrogen-containing products (methane, ethane and ethylene). Comparing the data obtained in the reformer prototype with that obtained at laboratory scale, the ratio between the H2 produced (in Nm3 /h) per mass of catalyst in the reformer is similar in both scales. This result can be taken as conclusive that the design of the primary reformer is valid as it allows to simulate
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Table 2 Outlet gas concentrations in the decaline oxidative reforming at different O2 /C and H2 O/C ratios (decaline flow = 1 l/h) O2 /C
Test Test Test Test Test Test Test Test Test Test
1 2 3 4 5 6 7 8 9 ICP
H2 O/C
0.35 0.35 0.38 0.4 0.45 0.36 0.35 0.35 0.35 0.5
% vol
3.5 3.5 4 4 4 4 4 4 4 3
H2
N2
CO
CO2
CH4
45.7 44.5 41.5 40.8 39.8 47 46.9 46.7 45.9 39.1
31.2 33.1 36.9 38.2 39.8 30.3 29.5 29.7 32.0 42.0
8.1 7.1 4.6 4.7 5.2 5.9 5.2 5.8 5.0 5.1
14.5 15.1 16.4 16.1 15 16.6 17.2 16.8 17.1 13.2
0.5 0.2 0.1 0.1 0.1 0.2 0.2 0.1 0.3 0.1
800
H2
T OSR 6 T OSR 2
700
N2
CO2 CO CH4 0.36
T OSR 3 T OSR5
600
T OSR4 T OSR 1
500
T MC T HE
400
0.38
0.4
0.42
0.44
0.46
O2/C ratio
300
Fig. 7. Outlet gas concentrations after decaline reforming for different O2 /C feed ratios (decaline flow = 1 l/h, H2 O/C = 3.5.4).
50
H2
3.3. Primary reforming with diesel fuel Similarly to the previous study, OSR reactor was also characterised for the reforming of a low-content sulphur diesel fuel (less than 34 ppm of sulphur) at 850 ◦ C for various O2 /C and H2 O/C feed ratios. Experimental results are presented in Table 3 and Fig. 9. These results indicate that the increase in the O2 /C ratio provokes an increase in N2 and CO2 concentrations with a subsequent decrease in H2 and CO concentrations. In this case, the tendency regarding the CO2 increase with the increase in O2 /C ratio is fulfilled. The reformer performance increases with decreasing of the O2 /C ratio due to the increase of H2 concentration at the outlet. Concerning the influence of H2 O/C ratio, the outlet gas composition does not change significantly with the increase of the H2 O/C ratio, as it was also observed with decaline feed. For this reason, future reforming operation will be carried out with the lowest H2 O/C ratio, though it must be kept always higher than 3. This is necessary for cool flame stabilization. The observed catalytic trends when O2 /C and H2 O/C ratios
Gas composition, %
40
the laboratory conditions in which mass and thermal diffusion were minimised.
4 N N2 2
30
3
DIESEL FLOW (10 x l/h)
20
CO CO22
10
CO CO
ETHYLENE
24000
26000
2 1
Diesel flow (l/h)
50 45 40 35 30 25 20 15 10 5 0 0.34
Temperature, ºC
Dry gas concentration, % vol
Last test corresponds to ICP-CSIC laboratory microreactor.
CH CH4 4
0 18000
20000
22000 Time, s
Fig. 8. Gas composition and temperature in primary reformer during decaline reforming at different decaline flow rates (O2 /C=0.35.0.4 and H2 O/C=3.5).
are changed agree with the results from the small-scale tests accomplished in ICP-CSIC facilities and also from other literature reports [7,9]. From these studies, oxidative reforming of diesel fuel at 850 ◦ C and feed ratios of H2 O/C/O2 = 3/1/0.5 led to improved hydrogen production. Stability of the reaction system was studied over times on stream of 10 h of oxidative reforming of a commercial diesel fuel (15 ppm S) under the above operation conditions. Fig. 10 shows the variations in the reforming products as function of
D. Sopeña et al. / International Journal of Hydrogen Energy 32 (2007) 1429 – 1436
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Table 3 Outlet gas concentrations in the diesel oxidative reforming at different O2 /C and H2 O/C ratios (diesel flow = 1 l/h, T = 850 ◦ C) O2 /C
Test Test Test Test
2 3 4 ICP
0.5 0.5 0.55 0.48
H2 O/C
% vol
3.2 3 3 3.2
Efficiency
H2
N2
CO
CO2
CH4
36.52 38.5 36.1 37.5
42.3 39.5 44.3 42.7
7.6 8.2 5.1 6.7
13.5 13.6 14.6 13.1
0.001 0.001 0.001 0.001
0.853 0.845 0.789 0.875
Last test corresponds to ICP-CSIC laboratory microreactor.
T OSR 6
N2
900
40 H2
30
Temperature, ºC
Dry gas concentration, % vol
50
20 CO2 10
CO
700
T OSR5 T OSR4 T OSR 3 T OSR 2
T OSR 1
T MC
500
CH4 0 0.47
0.49
0.51 O2 /C ratio
0.53
T HE
0.55
300
Fig. 9. Outlet gas composition from diesel reforming at different O2 /C feed ratios. (T = 850 ◦ C, diesel flow = 1 l/h and H2 O/C = 3.3.5).
N2
40 Gas composition, %
time on stream. From this figure it is evident that a stable hydrocarbon conversion is maintained during the reaction time selected for this purpose. Finally the comparison between results obtained in the reformer prototype with results obtained at laboratory scale confirms the validity of the design previously observed in the case of decaline studies.
50
30
H2
20
CO2 CO
10
4. Conclusions An experimental system to obtain hydrogen to produce 5 kW of electric power in a PEM fuel cell has been developed. Working parameters (feed flows and temperatures), control strategies and PIDs of the whole reformer system have been tuned. Compositions and temperatures at the output of the OSR reactor have been obtained and validated with laboratory results from ICP-CSIC and other literature works. For decaline feed, optimum values of O2 /C and H2 O/C ratios (0.35 and 3, respectively) and hydrocarbon feed (1.5 l/h) have been obtained. In the case of diesel fuel, operational feed ratios of O2 /C = 0.5 and H2 O/C = 3 resulted in an improvement of hydrogen production from diesel reforming. For both hydrocarbon feeds, H2 production rates per mass of catalyst were similar to those reached at a laboratory scale have been obtained, thus confirming the validity of the design of the primary reformer reactor. Tasks regarding the development of thermal integration, reduction of starting time, autonomy, design size reduction and increase of the produced hydrogen are currently in progress.
0 29000
CH4
29500
30000 30500 Time, s
ETHYLENE
31000
31500
Fig. 10. Evolution of reformer gas composition and temperature with time on stream (diesel flow = 1 l/h, O2 /C = 0.5 and H2 O/C = 3.5).
Acknowledgments This work has been partially funded by INTA thanks to a specific agreement between INTA, CIDAUT, ICP-CSIC and AICIA.
References [1] Brown LF. A survey of processes for producing hydrogen fuel from different sources for automotive-propulsion fuel cells. Report from Los Alamos National Laboratory; 1996.
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[2] Pereira C, Bae JM, Ahmed S, Krumpelt M. Liquid fuel reformer development: autothermal reforming of diesel fuel. Hydrogen Program Technical Review. California, 2000. [3] Westerholm R, Petterson LJ. Multi-fuel reformers for automotive fuel cell applications. Stockholm: KFB-Meddelande, 1999. p. 29. [4] Cheekatamarla PK, Lane AM. Catalytic autothermal reforming of diesel fuel for hydrogen generation in fuel cells. I. Activity tests and sulphur poisoning. J Power Sources 2005;152:256–63. [5] Liu DJ, Kaun TD, Liao HK, Ahmed S. Characterization of kilowattscale autothermal reformer for production of hydrogen from heavy hydrocarbons. Int J Hydrogen Energy 2004;29:1035–46. [6] Hartmann L, Lucka K, Köhne H. Mixture preparation by cool flames for diesel-reforming technologies. J Power Sources 2003;118: 286–97. [7] Palm C, Cremer P, Peters R, Stolten D. Small-scale testing of a precious metal catalyst in the autothermal reforming of various hydrocarbon feeds. J Power Sources 2002;106:231–7.
[8] Ghenciu AF. Review of fuel processing catalyst for hydrogen production in PEM fuel cell systems. Solid State Mat Sci 2006;6:389–99. [9] Podolski WF, Kim YG. Modelling the water-gas shift reaction. Ind Eng Chem Process Res Dev 1974;4(13):415–21. [10] Rase H.F. in: Chemical reactor design for process plants, volume two: case studies and design data. New York: Wiley; 1977. [11] Kahlich MJ, Gasteiger HA. Kinetics of the selective CO oxidation in H2 -rich gas on Pt/Al2 O3 . J Catal 1997;171(1):93–105. [12] Sopeña D, Horrillo A, Briceño Y, Rosa F. Model of a diesel fuel processor that feeds a 5 kW PEM fuel cell. Preprints of XVI national congress of mechanical engineers, Leon, 2004. [13] Tinaut FV, Sopeña D, Briceño Y, Rosa, F. Simulation model to design a diesel autothermal fuel processor prototype. Preprints of 15th world hydrogen energy conference, Yokohama, 2004. [14] Naidja A, Krishna CR, Butcher T, Mahajan D. Cool flame partial oxidation and its role in combustion and reforming of fuel for fuel cell system. Prog Energy Combust Sci 2003;29:155–91.
