7/29/2019 Transport Theorem

1/2

Assignment Set 1

Advanced Reaction Engineering (CL 604)

Chemical Engineering, IIT - Gandhinagar

Submission by February 10, 2012 (5:00 PM)

February 3, 2012

1. Nitrogen and hydrogen react to form ammonia in the presence of a catalyst

12N2 +

32H2 NH3 (1)

The reactor in which this reaction is to be run is maintained at 450 K and have sufficiently

long residence time that equilibrium is achieved at the reactor exit.

The reaction is to be run in an isothermal, constant-volume reaction vessel with a feed

consisting of stoichiometric amounts of nitrogen and hydrogen. The initial pressure of the

reactant mixture (before any reaction has occurred) is 4 bar. What is the pressure in the

reactor and the species mole fractions when equilibrium is achieved?

2. Compute the equilibrium extent of decomposition of pure Nitrogen tetroxide due to chem-

ical reaction N2O4(g) = 2NO29(g) over the temperature range 200 to 400 K, at pressure0.1, 1 and 10 bar, where H0rxn(T) = 56189 + 12.08T 3.62 10

2T2.

3. The gas-phase reaction 2A+4B 2C which is first-order in A and first-order in B is to

be carried out isothermally in a plug-flow reactor. The entering volumetric flow rate is 2.5

dm3/min, and the feed is equimolar in A and B. The entering temperature and pressure

are 7270C and 10 atm, respectively. The specific reaction rate at this temperature is 4

dm3/g mol.min and the activation energy is 15,000 cal/g mol.

(a) What is the volumetric flow rate when the conversion of A is 25%?

(b) What is the rate of reaction at the entrance to the reactor?

(c) What is the rate of reaction when the conversion of A is 40%?

(d) What is the concentration of A at the entrance to the reactor?

(e) What is the concentration of A at 40% conversion of A?

(f) What is the value of the specific reaction rate at 12270C?

4. Compound A undergoes a reversible isomeiization reaction, A B, over a supported

metal catalyst. Under pertinent conditions, A and B are liq- uid, miscible, and of nearly

identical density; the equilibrium constant for the reaction (in concentration units) is 5.8.

In afied-bed isotheml flow reactor in which backmixing is negligible (i.e., plug flow), a

feed of pure A under- goes a net conversion to B of 55%. The reaction is elementary. Ifa second, identical flow reactor at the same temperature is placed downstream from the

first, what overall conversion of A would you expect if:

1

7/29/2019 Transport Theorem

2/2

Assignment Set 1 (CL 604) Advanced Reaction Engineering

(a) The reactors are directly connected in series?

(b) The products from the first reactor are separated by appropriate process- ing and

only the unconverted A is fed to the second reactor?

5. The endothermic liquid-phase elementary reaction, A + B C, is carried out adiabatically

in a flow reactor. An equal molar feed in A and B enters at 270C, and the volumetric flow

rate is 2 dm3/s and CAo = 0.1 kmol/m3.

(a) Calculate the PER and CSTR volumes necessary to achieve 85% conversion. What

are the reasons for the differences?

(b) What is the maximum inlet temperature one could have so that the boiling point of

the liquid (550 K) would not be exceeded even for complete conversion?

(c) Plot the conversion and temperature as a function of PER volume (i.e., distance down

the reactor).

(d) Calculate the conversion that can be achieved in one 500-dm3

CSTR and in two250-dm3 CSTRs in series.

where H0A (273) = -20 kcal/mol, H0

B (273) = -15 kcal/mol, H0

C (273) = -41 kcal/mol, CpA= CpB = 15 cal/mol. K, CpC = 30 cal/mol. K, k= 0.01

dm3

mol.sat 300 K, E = 10,000

cal/mol.

IIT - Gandhinagar February 3, 2012 2