Autothermal Hydrogen Generation From Methanol in a Ceramic Microchannel Network

Thermally-integrated minichannel networks have been widely investigated for multi-stage reforming of hydrocarbon fuels to hydrogen gas, as part of an overall portable-power system, where two or more of processes are coupled to maximize overall thermal efficiency. Hydrogen gas has been identified as a promising alternative fuel for portable chemistry in light of its relative abundance and emission-free combustion. Compact, multifunctional reactors have been developed for portable-power systems to produce hydrogen on-site for utilization by proton-exchange membrane (PEM) or solid-oxide fuel cells (SOFC's) in portable electronics devices and automotive applications^1-3.

Our research group is developing a new class of ceramic microchannel reactor, combining the benefits of precision machining and ceramics extrusion. An extruded ceramic microchannel network is combined with a precision-machined distributor to realize complex distribution patterns which allow integration of two or more processes within a monolithic unit. This novel technique presents the following advantages; (i) ease of catalyst introduction, (ii) Selectable wall thermal conductivities by appropriate ceramics selection, enabling high temperature operation⁴, (iii) Two-dimensional distribution patterns, capable of coupling three or more processes in parallel for heat exchange, and (iv) reversible packaging.

This work presents the design and fabrication of a ceramic minichannel network, interfaced with brass distributors in order to evaluate the thermal integration issues of a new class of versatile, scalable, integrated ceramic minichannel network. This novel device will be tested for: i) coupled fuel combustion and reforming (two-process coupling), and ii) coupled fuel vaporization, fuel combustion and fuel steam reforming (three-process coupling). Detail thermal and reaction experiments will be performed to demonstrate the potential of this compact minichannel device for hydrogen production.

¹Terazaki, T.; Nomura, M.; Takeyama, K.; Nakamura, O.; Yamamoto, T. Development of Multi-Layered Microreactor with Methanol Reformer for Small PEMFC. Journal of Power Sources 2005, 145, 691.

²Han, J.; I.-S. Kim; K.-S. Choi. Purifier-Integrated Methanol Reformer for Fuel Cell Vehicles. J. Power Sources. 2000, 86(1-2), 223.

³Deshmukh, S.R.; Vlachos, D.G. Effect of Flow Configuration on the Operation of Coupled Combustor/Reformer Microdevices for Hydrogen Production. Chem. Eng. Sci. 2005, 60, 5718.

⁴Moreno, A., K. Murphy and B.A. Wilhite, “Parametric Study of Solid-Phase Axial Heat Conduction in Thermally Integrated Microchannel Networks,” Ind. Eng. Chem. Res., 47, 9040-9054 (2008).