Problem $4.$ Determination of Catalyst Requirements for a Fixed$-$Bed Reactor

We want to build a packed bed reactor filled with $1\mathrm{.}2cm$ porous catalyst particles

$=2000k\frac{g}{m^3},D_{\text{e}\text{f}\text{f}}=2{10}^{-6}\frac{m^3}{m}$ cats