# Chemical Reaction Engineering GATE-2019

**Q 1:** The desired liquid-phase reaction

is accompanied by an undesired side reaction

D+E\xrightarrow{k_2}G;\;\;\;\;r_G=k_1C_D^{0.4}C_E^{1.5}Four isothermal reactor schemes (CSTR: ideal Continuous-Stirred Tank Reactor; PFR: ideal Plug Flow Reactor) for processing equal molar feed rates of D and E are shown in the figure. Each scheme is designed for the same conversion. The scheme that gives the most favorable product distribution is:

**Q 2:** For a first-order reaction in a porous spherical catalyst pellet, diffusional effects are most likely to lower the observed rate of reaction for

**Q 3:** The elementary, irreversible, liquid-phase, parallel reactions 2A\rightarrow D and 2A\rightarrow U , take place in an isothermal non-ideal reactor. The C-curve measured in a tracer experiment is shown in the figure, where C(t) is the concentration of the tracer in g/m^{3} at the reactor exit at time t (in min).

The rate constants are k_{1} = 0.2 Litre/(mol min) and k_{2} = 0.3 Litre/(mol min). Pure A is fed to the reactor at a concentration of 2 mol/Litre. Using the segregated model, the percentage conversion in the reactor is _________ (rounded off to the nearest integer).

**Q 4:** A first-order irreversible liquid phase reaction A\rightarrow B\;(k=0.1\;min^{-1}) is carried out under isothermal, steady-state conditions in the following reactor arrangement comprising an ideal CSTR (Continuous-Stirred Tank Reactor) and two ideal PFRs (Plug Flow Reactors).

From the information in the figure, the volume of the CSTR (in Litres) is ________ (rounded off to the nearest integer).

**Q 5:** The elementary liquid-phase irreversible reactions

take place in an isothermal ideal CSTR (Continuous-Stirred Tank Reactor). Pure A is fed to the reactor at a concentration of 2 mol/Litre. For the residence time that maximizes the exit concentration of B, the percentage yield of B, defined as \left(\frac{net\;formation\;rate\;of\;B}{consumption\;rate\;of\;A}\times100\right) , is _______ (rounded off to the nearest integer).

**Q 6:** The elementary irreversible gas-phase reaction A\rightarrow B+C is carried out adiabatically in an ideal CSTR (Continuous-Stirred Tank Reactor) operating at 10 atm. Pure A enters the CSTR at a flow rate of 10 mol/s and a temperature of 450 K. Assume A, B, and C to be ideal gases. The specific heat capacity at constant pressure \left(C_{p_i}\right) and heat of formation \left(H_i^o\right) , of component i (i = A, B, C), are:

The reaction rate constant k(per\;second)=0.133exp\left[\frac ER\left(\frac1{450}-\frac1T\right)\right] , where E = 31.4 kJ/mol and universal gas constant R = 0.082 L atm/(mol K) = 8.314 J/(mol K). The shaft work may be neglected in the analysis, and specific heat capacities do not vary with temperature. All heats of formation are referenced to 273 K. The reactor volume (in Litres) for 75% conversion is _______ (rounded off to the nearest integer).

**Q 7:** Consider the reactor-separator-recycle process operating under steady-state conditions as shown in the figure.

The reactor is an ideal Continuous-Stirred Tank Reactor (CSTR), where the reaction A+B\rightarrow C occurs. Assume that there is no impurity in the product and recycle streams. Other relevant information are provided in the figure. The mole fraction of B (x_{B}) in the reactor that minimizes the recycle rate is ___________ (rounded off to two decimal places).