Fig. 1. SEM micrographs of fracture profiles of inverted beaded SiC monoliths after heating at 1200 °C for 6 h in air with (a) 7.2 μm pores (inset: an optical micrograph of the whole SiC porous monolith); (b) 2.2 μm pores; and (c) 0.75 μm pores. The black spots are the windows that connect adjacent pores in these close packed structures. The bits of debris are due to cutting of the samples before SEM analysis.

Fig. 2. Polymer removal and sintering temperature sequence used to obtain high-density, nonporous alumina housings and lids. The heating and cooling rates were optimized to avoid cracking and deformation in the final alumina structures.

Fig. 3. (a) Optical and SEM (inset) micrographs of a high-density alumina housing with five microchannels (400 μm×150 μm×1 mm) in negative relief, obtained via gel-casting. Optical micrographs of (b) alumina lid and (c) assembled ceramic microreactor comprised of an alumina housing structure with five SiC porous monoliths (see Fig. 1), an alumina lid, and alumina inlet and outlet tubes.

Fig. 4. NH₃ conversion using Ru-coated SiC porous monoliths (volume = 0.55 mm³) as a function of temperature for different NH₃ flow rates measured from 450 to 1000 °C. The conversion values were obtained for integrated ceramic microreactors comprised of SiC catalytic monoliths with (a) 7.2 μm pores; (b) 2.2 μm pores; and (c) 0.75 μm pores. All data are fitted with the design equation for first-order kinetics in a PFR, assuming constant temperature and a constant pressure gradient across the reactor. (- - -) indicates the equilibrium conversion of NH₃ as a function of temperature.

Fig. 5. Arrhenius plot of integral turnover frequencies for decomposition of NH₃ in integrated ceramic microreactors comprised of Ru-covered SiC monoliths with 7.2- and 2.2-μm pores. The lines connecting the data points are added to guide the eye.

Catalyst loading and dispersion data for Ru-covered SiC porous monoliths with pore diameters of 7.2, 2.2, and 0.75 μm

Observed first-order reaction rate constants k^′ at different temperatures for SiC porous monoliths with pore diameters of 7.2 and 2.2 μm