The reaction mechanism of ammonia decomposition to nitrogen
and hydrogen over platinum loaded titanium oxide photocatalyst was
investigated through various reaction tests, as well as ESR and FT-IR
spectroscopies. The photoformed hole on the titanium oxide oxidizes
NH3 to form amide radical (•NH2) and
proton. The amide radicals produce hydrazine (N2H4), and it can be further decomposed to form nitrogen and hydrogen.
On the other hand, the photoformed electron migrates to platinum nanoparticles
through the conduction band of the titanium oxide and reduces the
proton to yield hydrogen. The metals with larger work function, such as platinum, can provide more effective cocatalysts. In this photocatalytic reaction system,
water molecules were essential for the continuous reaction progress.
An in situ FT-IR study clarified that water restricted the accumulation
of inactive byproduct, ammonium ion (NH4
+),
on the titanium oxide surface.
The present paper deals with the determination of optimal conditions for preparing spray-dried granules and slurries, based on the characteristics of granules and supplied slurries. These characteristics were evaluated by the compression and stress-relaxation method, and by the centrifugal consolidation method, respectively. Spray drying of the flocculated slurry resulted in low-density granules with a spherical and solid morpholo gy, which ensures a high compressibility. Another important factor governing the press forming is to adjust the amount of binder so as to improve the visco-elastic deformation of granules; this leads to a better homogeneity of the resulting compacts.
kƿȡ᧸ǦǮɁɱɲʀ△Ϣཪ⒈ǽϣ ââȹʀȷബ༔࿇ؔǽ╫ኝââ ʈ ઌშɿ᎓ ѝᅻɿᏊ ᚂʶȖ ۵ୖےগકগકрకકᮾ᳣ᲇᢼ֝൧కકଗფࢫ464-8603 ۵ୖےల٣Ჷٚ˃ᨊThe particle-packing structure of Al 2 O 3 slurry was evaluated by using constant pressure filtration. The influences of initial solid concentration and dispersant amount on the cake forming behavior were discussed. It was shown that the packing fraction of formed cake is almost independent of filtration pressure under 10 volಚ of initial solid concentration. However at a relatively high solid concentration 20 and 35 volಚ, the packing fraction of cake increased with filtration pressure. The cake forming behavior was classified into four patterns by plotting the resistance of the formed cake as a function of particle volume in the formed cake; the plots were a a straight line, b a convex curve, c a concave curve, and d a combination of a concave curve and a flat line. The particle dispersion and flocculate degree were discussed on the basis of the results obtained by constant-pressure filtration.
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