Reformer methanol steam

The catalytic combustor provides heat for the endothermic reforming reaction and the vaporization of liquid fuel. The endothermic reforming reaction is carried out in a parallel flow-type micro-channel of the reformer unit. It is well known that the methanol steam reforming reaction for hydrogen production over the Cu/ZnO/AbOs catalyst involves the following reactions [10]. Eq. (1) is the algebraic summation of Eqs. (2) and (3). 

In this study, we developed microchannel PrOx reactor to control CO outlet concentrations less than 10 ppm from methanol steam reformer for PEMFC applications. The reactor was developed based on our previous studies on methanol steam reformer [5] and the basic technologies on microchaimel reactor including design of microchaimel plate, fabrication process and catalyst coating method were applied to the present PrOx reactor. The fabricated PrOx reactor was tested and evaluated on its CO removal performance. 

A miniature methanol steam reformer for polymer electrolyte fuel cell... 

Fig. 4 shows the evolution of temperature in the methanol steam reformer combined with a combustion plate equipped with a gas distributor. In this case hydrogen was used as a fuel for start-up at room temperature. As the reformer temperature reached near 300°C in about 5 min, methanol/water vapor was introduced to the reformer. It can be clearly seen that temperature within the reformer became relatively uniform after 25 min of operation. 

Fig. 4. Evolution of temperature in the methanol steam reformer during the startup and steady-state operation...

Pfeifer, P., Fichtner, M., Schubert, K., Liauw, M. a., Emig, G., Micro-structured catalysts for methanol-steam reforming, in Ehrfeld, W. (Ed.), Microreaction Techndogy 3rd Intematiorud Conference on Microreaction Technology, Proc. of IMRET 3, pp. 372-382, Springer-Verlag, Berlin (2000). 

P., Detailed characterization of various porous alumina based catalyst coatings within microchannels and their testingfor methanol steam reforming, Chem. Eng. Res. Des., special issue on Chemical Reaction Engineering (2003) submitted for publication. 

Lin, Y.M. and M.H. Rei, Study on the hydrogen production from methanol steam reforming in supported palladium membrane reactor, Catal. Today, 67, 77-84, 2001b. 

Jacobs, G., Patterson, P.M., Graham, U.M., Crawford, A.C., Dozier, A., and Davis, B.H. 2005. Catalytic links among the water-gas shift, water-assisted formic acid decomposition, and methanol steam reforming reactions over Pt-promoted thoria. J. Catal. 235 79. 

Mann, Thurgood, and coworkers—Langmuir-Hinshelwood kinetic model for methanol steam reforming and WGS over Cu/Zn. Mann et al.335 published a complex Langmuir-Hinshelwood model for CuO/ZnO catalysts based on what one would encounter for a methanol steam reformer (MSR) for fuel cell applications. The water-gas shift rate, containing all MSR terms, was determined to be ... 

It is worthy to note that numerous researchers have recently observed high catalytic activity for methanol steam reforming over Pd/Zn and Pt/Zn catalysts,528-534 and it would seem that these catalysts likely have potential for low temperature water-gas shift activity. 

Figure 3 in Ref. 217, reproduced on the right, shows SIMS spectra from a CuO/Ce02/ y-Al2 03 catalyst before and after a methanol steam reforming reaction. Assign the main peaks in the spectra, and provide an interpretation for the changes seen in the catalyst after reaction. 

Due to methanol s corrosivity and its affinity for water, it cannot be readily distributed in today s fuel infrastructure. Methanol burns with a nearly invisible flame. Available luminosity additives won t reform in the low-temperature methanol steam reformers. Methanol is more acutely toxic than gasoline. Additives that are likely to be needed for safety and health reasons will impact the fuel processor s performance and cost. 

Logistic fuels, such as jet and diesel fuels, are readily available, but a compact and effective way to remove sulfur from these fuels is needed for portable hydrogen production. Consequently, for most portable applications, it is likely that sulfur-free fuels, such as methanol, will be used. An additional advantage of methanol is that it is easier to activate at low temperatures than other hydrocarbons. Therefore, a portable hydrogen production unit based on methanol steam reforming would be simpler and less costly than other alternatives. Methanol can also be considered an energy carrier as an alternative to liquefied natural gas... 

Figure 23. Methanol—steam reformers, heat exchangers, combustor, and selective oxidation reactors the body materiai was stainless steel. ...

The next step in the processor development will be to integrate the palladium alloy membrane with the methanol steam reformer reactor. The researchers anticipate that the addition of the palladium membrane will improve the reactor performance due to in-situ hydrogen removal. 

Table 5. Methanol Steam Reforming Reactor Performance ...

The steam reforming of DME has been demonstrated to occur through a pair of reactions in series, where the first reaction is DME hydration followed by methanol steam reforming to produce a hydrogen-ridi stream, as expressed in Equations 6.17 and 6.18, respectively ... 

DME hydration occurs over acid catalysts, whereas the methanol steam reforming reaction proceeds over metal catalysts. Consequently, DME steam reforming requires a multi-component catalyst. Two approaches have been proposed in the literature (a) physical mixtures of a DME hydrolysis catalyst and a methanol steam reforming catalyst (b) supported catalysts that combine the DME hydrolysis and methanol steam reforming components into a single catalyst. 

DME hydrolysis is an equilibrium-limited reaction and is considered as the rate-limiting step of overall DME steam reforming. The equilibrium conversion of hydration of DME is low at low temperatures (e.g. about 20% at 275 °C). However, when methanol formed in the first step is rapidly converted into H2 and CO2 by methanol steam reforming catalysts, high DME conversion is expected. Therefore, enhancement of DME hydrolysis is an important factor to obtain high reforming conversion. 

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