1. It is proposed to reduce the concentration of NO in an effiuent stream from a plant by passing it through a packed bed of spherical porous carbonaceous pellets. A 2% NO - 98% air mixture, on a mole basis, flows at a rate of 1x10m/s through a 2 inch inner diameter tube packed with porous solid at a temperature of 1173 K and a pressure of 101.3 kPa. The reaction: NO +C co + NI is first-order in NO: -No = "SCNO and occurs primarily in the pores inside the pellet (note that this does not mean that you may neglect diffusional limitations to mass transfer to the pellets), where: m? Sa = internal surface area = 530 m? k" - 4.42x10-10 Fluid properties @ 1173K: kinematic viscosity (v): 1.53x10 m/s gas-phase diffusivity (DAB): 2.0x10 m/s effective diffusivity (D.): 2.66x10 m/s Catalyst and bed properties: pore radius (r): 1.3x10m bed porosity (es or ): 0.5 bed density (p): 1.4x10 g/m pellet radius (Rp): 3x10 m g cat m's Y = 1 A Assuming constant volumetric flow, the design equation becomes: dC-nk"SCA Vo dW where 77 NE nk"S 1 + kolac and, the effectiveness factor for a first-order reaction in spherical pellets is given by the first- order Thiele modulus: w 3 (coth - 1) 2K" . = Rp. DY d) Calculate the overall effectiveness factor, e) Calculate the weight of solid catalyst necessary to reduce the NO concentration to below the EPA limit of 0.002%. f) Calculate the reactor length based on the pipe diameter and this calculated weight