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03000CH308052002

Surface Reaction: AS + BS > CS +S

Desorption: CS > C +S

With help of figures differentiate between porous and supported catalysts

Define overall effectiveness factor? Derive expression for overall effectiveness
factor

Briefly explain Mears Criterion for external diffusion.

A catalytic reaction A> 4B, is studied in a PFR using various amounts of catalyst
and 20 L/h pure A feed at 3.2 atm and 117 °C. The concentration of A in the

effluent stream is recorded as follows:

Catalyst used (kg) 0.16

CA out (mol/L) | 0.074 | 0.06 | 0.044 | 0.029

Deduce a rate expression for the reaction assuming 1* order reaction.
Derive expression for Internal effectiveness factor
PART C

Answer any two full questions, each carries 20 marks.
A particle of radius R reacts with a gas and forms a stable non flaking product layer
on its surface. With a neat figure representing the problem, derive an expression for
conversion of particle using the shrinking core model if chemical reaction controls
the overall reaction.
Using suitable figures for irreversible reaction, reversible endothermic reaction and
reversible exothermic reactions explain the concept of optimum temperature
progression.
With neat figure explain progressive conversion model. Give two examples.
With a neat figure, derive the rate equation for mass transfer of gas A being
physically absorbed in to a liquid B.
Derive an expression for conversion for a non-adiabatic reaction from energy
balance. Draw a sketch of conversion vs temperature showing the shifting of
adiabatic line due to heat exchange.
A batch of spherical solids of uniform size is treated by a gas in a constant
environment reactor. Solid is converted to for a firm non-flaking product according
to shrinking core model. The conversion is 87.5% for a reaction time of 1 hour and
reaction is 100% complete in 2 hours. Verify the data given for the three rate

controlling mechanisms and infer on the findings.

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