(769g) Influence of Microwave Band Irradiation On Catalytic Reforming Systems Operating Under Deleterious Conditions

In catalyst systems microwave radiation has been shown to
increase reaction rates, lower the bulk temperature at which reactions occur,
and assist in the desorption of sulfur. 
Past research into zeolite and catalytic systems has examined the
effects of microwaves on adsorbate equilibriums with
the goal of altering equilibrium states. 
Despite beneficial effects, the large-scale application of microwaves in
adsorption and catalytic systems has remained limited.  Significant gaps exist in the
understanding of microwave interactions in complex catalytic systems.

The present study on Ni-based reforming catalysts examines
the influence of irradiation in the microwave band (2.45GHz, λ=12.1cm) on
carbon deposition. Catalytic reforming of hydrocarbon fuels is frequently
plagued by catalyst deactivation via carbon deposition, sulfur poisoning, and
oxidation of metal surface sites. To probe interactions with electromagnetic
radiation a model catalyst system was chosen consisting of cordierite monolith
to minimize internal field attenuation, washcoated
with a Ni/Ce_0.75Zr_0.25O­₂ catalyst.  Autothermal reforming of a mixture of
propane and ethylene was used in this study with O/C and H₂O/C ratios
chosen to create reaction conditions where significant deactivation due to
carbon deposition would be expected. 
Experiments were performed in a single mode
microwave cavity varying the source power from 0-900Watts with continuous
monitoring of the effluent using an electron ionization mass spectrometer.  The results of microwave band catalyst
irradiation on: (i) Carbon deposition and morphology,
and (ii) changes in the product distributions and fuel conversion are
discussed.