Megapores with spherical-like cells connected through windows and high porosities make up catalyst supports in the form of ceramic foams. These characteristics provide significant benefits for catalytic processes that are limited by mass or heat transport. This study focuses on the manufacture of ceramic foam using a polymeric sponge replica process and polymer foams as a template for catalyst supports, which are industrial waste from the packaging sector. To make ceramic foam catalysts, they were dipped in a catalyst solution, followed by a breakdown stage and a sintering process. Experiments focused on determinants that affect the desired characteristics of ceramic foams, such as the types of polymer foams that affect foam morphology, the rheology of catalyst solution that affects catalyst dispersion, and the polymer decomposition rate that affects catalytic performance during dry reforming of the methane process. The cell architectures of polyurethane and polyvinyl alcohol foams are attractive for catalyst support preparation because they have 98−99% porosity and typical cell sizes of 200 and 50 μm, respectively. The polyurethane performance was superior to the performance of polyvinyl alcohol in terms of higher porosity and better catalytic-solution absorption offering high catalyst active areas. The catalyst prepared from concentrated 10 wt % Ni/Al 2 O 3 −MgO (10NAM) slurry had the highest surface area (59.18 m 2 /g) and the highest metal oxide dispersion (5.65%). These results are relevant to the flow behavior of catalyst slurry which plays a key role in coating the catalyst gel on the polymer template. The thermal decomposition rate used to remove the polymer template from the catalyst structure is proportional to the ceramic foam structure (catalyst support structure). The slow decomposition rate bent and fractured foam-cell struts more than the faster rate. On the other hand, achieving good catalyst dispersion on catalyst supports necessitated a high sintering rate. When sintering was adjusted at a high sintering rate, the metal− particle dispersion was relatively high, around 7.44%, and the surface area of ceramic foam catalysts was 64.61 m 2 /g. Finally, the catalytic behavior toward hydrogen production through the dry reforming of methane using a fixed-bed reactor was evaluated under certain operating conditions.
Fuel cell performance tests for automotive applications include static and dynamic tests, and the dynamic load test is typically carried out to investigate the cell operating performance related to driving behavior in the particular use of fuel cell electric vehicles. The automatic hydrogen flow controller, utilized to regulate the hydrogen flow as a function of time, is one of the imperative apparatuses applied for the dynamic test. The driving behavior generally consists of rapid load fluctuations, several loads running at idle, full power, overload circumstances, start−stop repeats, and cold starting, and these dynamic variations are directly related to the power required for propelling a vehicle and the demand for hydrogen volume fluctuation throughout time. The desired automatic hydrogen flow controller was designed and manufactured for the dynamic performance test via the driving simulation protocol of a heavy-duty vehicle. The main experimental activities were performed to observe the responsibility and accuracy of the invented controller. The relation between the reliability of using the automatic hydrogen flow controller and the performance improvement of fuel cell operation was studied to gain ideas for further fuel cell modification. The hydrogen flow rates controlled by the created flow controller presented a data tolerance of approximately 0.84% which was not significantly different from the theoretical figure based on T-test analysis. The controller reacted to variations in flow rates in as little as 1−2 s, which was acceptable for the dynamic test. Regarding the performance enhancement, this automatic hydrogen flow controller assisted a single cell to generate 16% more power and 33% more energy at 45 mA as a minimum current demand in comparison with the results obtained from a test system using a traditional hydrogen controller with a constant flow rate.
Polypropylene/three-carbon-filler composite bipolar plates (BPs) of direct methanol fuel cell (DMFC) were fabricated by an injection molding. The composite materials were made of polypropylene (PP), carbon black, carbon fiber and graphite. Gas flow channel surfaces on the BPs were subsequently modified by polypyrrole (PPy) using a coating technique in order to improve surface electrical conductivity. This research is a feasibility study to use PPy-coated PP composite as BPs in a DMFC. The surface electrical resistance and performance in a fuel cell containing the composite BPs under DMFC operating conditions were evaluated against conventional graphite BPs. The surface resistance values of PPy-coated PP composites decreased around six orders of magnitude, compared with those values of PP composites. According to the performance results, PPy-coated composite BPs can be used in DMFC if the surface adhesion between a PPy layer and the BP surface was further improved.
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