Question

Problem 1: In is commonly accepted that the most complex step of a catalytic process is the diffusion within the catalyst particle. On the other hand diffusion of reaction product is depended on the shape and structure of the catalyst pellets. Considering the following catalytic reaction: AB It is requested to derive the expressions for dimensionless (normalized) concentration profile of the reactant (A) for the following two shapes of a catalyst: 1) A slab geometry (ii) A spherical geometry Compare the Thiele modulus's and effectiveness factors for a slab and a spherical geometry Step-by-step derivation is required, a short cur answer will nor do] Problem 2: A commercial process for dyhydrogenation of ethyl benzene uses 3 mm spherical catalyst particles. The reaction constant (ks) is 15 st, and the diffusivity of ethyl benzene in steam is 4 x 105 m/s under reaction conditions. Determine the effectiveness factor (n) this catalytic reaction. For simplicity the following relation for Thiele Modulus (9) is given: where, Ris the catalyst radius Problem 3: A catalytic desulfurization of Thiophene (C4H4S) reaction is taking place at 390 °C and 30 atm using a catalyst particle having an inside specific surface area of 180 m'/8, porosity of 0.4 and particle density of 1400 kg/m. The tortuosity factor (To) is 2. It is assumed that the concentration of Thiophene is very low and the pore fluid consists mainly hydrogen. Under this condition the Molecular (bulk) diffusivity of Thiophene (DAB) is 5.2 x 10 m/s. For the above reaction estimate the (i) Knudsen diffusivity and (ii) Effective diffusivity

solve problem 1

Answer 1

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CAS Fevene» Sactoy dv Ve(Cas) Ve(Ca) Re Ver(C) dr 1CS mam 3

GrG h) वक CP ymh toSPhere TA [) क) tamhp)

Givem Dp3 yl-3m RP S103 m 5y10-3 0.918 4x/0-5 De