Vapor-phase benzene (Bz) hydrogenation over carbon-supported Pd catalysts has been studied [65, 66]. A 2.1% Pd/C catalyst prepared with a carbon black cleaned in H2 at 1223 K had a surface-weighted Pd crystallite size of 21 nm, giving a Pd dispersion of 5%, based on TEM. The carbon itself had an average mesopore diameter of 25 nm, while the average microspore diameter was 0.9 nm; thus the majority of the Pd resided in the mesopore. The highest activity of this catalyst at 413 K and 50 Torr Bz (Total P = 1 atm, balance H2) was 1:99 μ mole Bz s-1 g -1. The density of the catalyst was 0:60 g cm -3. The catalyst particle size distribution ranged from 10–500 microns (1 m = 10-6 m). (a) Assuming all the Pd is in the mesopore, are any mass transfer limitations expected based on the W-P criterion? (b) If, instead, this catalyst had all the Pd in the microspores and it gave this performance, would mass transfer limitations exist? Why?
Answer to relevant QuestionsGiven the stress state in Problem 1.13, find: the magnitude and direction of the maximum shear stress and illustrate with a sketchWith reference to Problem 1.15, find the magnitude of the maximum shear stress and show by sketch the orientation of the plane it acts on.Consider a three-dimensional state of stress characterized by: σxx = 20.69 σyy = 13.79 τxy = 0.0 σzz = 27.59 τzx = 0.0 τyz = 17.24 Where units are MPa and compression is positive. Find: the ...Given the strains: εxx = 2,000 εyy = 3,000 εzz = 4,500 γxy = −200 γyz = 300 γzx = 225 Where x = east, y = north, z = up, compression is positive, the units are micro inches per ...Consider gravity loading only under complete lateral restraint in flat strata with properties given in Table 1.2. Vertical stress at the top of the geologic column given in Table 1.2 is 1,000 psi. Compression is positive, ...
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