This work consist of an experimental study a Fuel Processor for PEM fuel cells and is divided in two parts. In the first part Autothermal Reforming (ATR) of JP8 fuel is presented. The ATR was tested during catalyst light-off to gain insight into the transient properties of with a catalytic wall reactor; next a monolith reactor was tested for catalyst durability and thermal cycles. Durability tests were conducted with sulfurized and desulfurized JP8 fuel, exhibiting distinct deactivation patterns. An 80 hour durability test with the desulfurized fuel was conducted, during which H₂ yield dropped from 32% to 28%, and CO to CO₂ selectivity increased, while fuel conversion was approximately constant, suggesting steam reforming and water gas shift activity loss. A 380-hour durability test with sulfurized fuel has exhibited an initial steep activity loss upon which the activity leveled off. A 120 start/stop cycle test was conducted, showing limited activity loss.

In the second part Preferential Oxidation of CO on Pt/Al ₂O₃ is presented. First an experimental investigation was conducted. Next mathematical models were developed and employed to elucidate experimental data. A comparison between PROX and rWGS reactors identified two regimes. In the high temperature regime rWGS and PROX results overlap, suggesting that the rWGS reaction is responsible for the CO conversion drop in PROX operation. An axial test was conducted revealed that the CO concentration exhibits a maximum along the axial direction. Heat and mass transfer effects were investigated by testing two substrates: monolith and wire-screens. Results show that screens exhibit a higher conversion and selectivity towards CO oxidation. An analysis using a kinetic- transport model has shown that concentration gradients between catalyst wall and bulk gas are expected in the upstream portion of the reactor, where CO and H₂ compete for O₂. In order to understand the the intermediate temperature regime a microkinetic model was developed. The model determined that these two regimes are the expression of a switch in rate limiting step. This switch is also reflected in a shift in surface coverages. With increasing temperature, the microkinetic model shows that CO coverage decreases while H* increases, until the CO conversion peak is achieved. After the peak, H* surface coverage decreases again, indicating the onset of the rWGS reaction which is a net H* sink.