Figure 1. Temperature and oxygen mole fraction contour maps in the micro-structured heat-exchanger reactor for hydrogen production by steam methanol reforming.

The nitrogen and steam mole fraction contour maps in the micro-structured heat-exchanger reactor are illustrated in Figure 2 for hydrogen production by steam methanol reforming. The volume of a reaction chamber, unless otherwise indicated, refers to the internal volume where reaction substantially occurs but not adjacent material. Where a catalyst is present, the volume includes at least the catalyst volume and catalyst void fraction. Core volume of a heat exchanger refers to the volume of the adjacent flow paths of the two fluids during the portion that they are adjacent and subject to primary heat transfer and including the volume of any intervening material, such as walls between the adjacent flow paths. The initial composition is representative of a reformate stream generated from steam reforming of isooctane at a 1.5:1 steam to carbon ratio. While a reforming outlet typically has at least these four compounds carbon monoxide, carbon dioxide, steam, and hydrogen, the ratios of the components depend on the type of reforming being performed, such as partial oxidation or steam reforming as well as the operating conditions of the reformer. In addition, additional material may be added to the reformate outlet prior to performing a water gas shift reaction. Accordingly, the inlet stream to a water gas shift reactor might have a carbon monoxide to carbon dioxide molar ratio that ranges from about 2:1 to about 1:5. Typically, the steam to gas ratio, defined as the moles of water divided by the moles of the remaining gas, is between about 0.2 and 0.6. Once the desired reactor temperatures are achieved, methanol and water injection begin and eventually generates the desired heat transfer medium which displaces the starter gas. In the meantime, the reformate exiting the first reactor, although diluted with some starter gas, can still be used in the fuel cell during system startup so long as the carbon monoxide levels are low enough. Alternatively, the diluted reformate could be diverted into the combustor for burning, or dumped to the atmosphere, if desired, until acceptable carbon monoxide levels are achieved. Once the desired operating temperatures are achieved, fresh methanol and water are again injected into the recirculating gas, and normal fuel processor operation resumes. Carbon monoxide output from the fuel processor is controlled over the operating range of the processor by varying the water-methanol ratio, the amount of air added to the reactor, and the speed of the recirculating fan to respectively drive the reaction equilibrium, oxidize the carbon monoxide and maintain the required heat transfer within the processor. Preferably, the heat exchanger is a cross flow exchanger adapted to flow the circulating heat transfer medium through the cold side second conduits in a first direction and the heating fluid through the hot side first conduits in a second direction transverse the first direction. The heating fluid will comprise combustion products exhausted from a combustor fueled by methanol and unused hydrogen exiting the anode compartments of the fuel cell that is fueled by the fuel processor. A variety of reactors can employ the steam reforming catalysts. Examples include fuel cell reactors, steam reformers, and conversion reactors. Instead of the fuel cell, the hydrogen may be transported to one of a storage tank, a refueling station, a hydrocracker, hydrotreater, or to additional hydrogen purifiers. The hydrogen may be employed as a synthesis gas, as a component in hydrogenation reactions, and the like. The alcohol reforming reactor may also be configured by placing the reaction chamber adjacent to a heat exchanger chamber that is comprised of an array of microchannels or a single microchannel. The width of the reaction chamber is dependent on the effective thermal conductivity of the catalyst insert. The higher the effective thermal conductivity of the catalyst insert, the wider the insert to enable rapid heat removal. In another configuration, the reaction chamber may be connected to a fuel tank such that alcohol from the tank can flow directly into the reaction chamber. Although a fuel tank is commonly used, any alcohol fuel source could be used. The liquid fuel stream may flow through a separate vaporizer or be vaporized within a section of the steam-reforming reactor. The alcohol is vaporized in a microchannel vaporizer and preheated in a microchannel preheater. The reformation fuel channel is disposed along the axis on a side of the reformation chamber opposite the combustion chamber. The reformation products channel is disposed outside the reformation fuel channel with respect to the axis and on the side of the reformation chamber opposite the combustion chamber, and the combustion exhaust channel is disposed outside the reformation fuel channel with respect to the axis and on the side of the reformation chamber opposite the combustion chamber.