The sulfur compounds present in petroleum fractions such as diesel can be removed by contact with a porous catalyst containing active metals such as Mo in the presence of hydrogen. If the catalyst is \(3 \mathrm{~mm}\) in radius and the concentration of sulfur in the liquid surrounding the catalyst is \(10 \mathrm{~mol} / \mathrm{m}^{3}\) find the rate of reaction. Assume that the reaction is of second order in sulfur concentration with a volumetric rate constant of \(5 \mathrm{~m}^{3} / \mathrm{mol} \cdot \mathrm{s}\). Note that these numbers are arbitrary and for illustration purposes only. Use \(D_{\mathrm{e}}=1 \times 10^{-9} \mathrm{~m}^{2} / \mathrm{s}\).