Exam II - Winter 1995

1) The irreversible gas phase solid catalyzed reaction

is carried out isothermally in a differential packed bed reactor. The following data were recorded.

Run	-r'A	PA	PB	PC	PD
	mol/kg cat-min	atm	atm	atm	atm
1	5	1	1	0	0
2	5	1.25	0.5	20	20
3	5	0.876	2	5	0
4	5	1.25	.5	0	0
5	5	0.8	5	7	50
6	25	5	1	0	0
7	25	4	5	10	0
8	25	3.88	10	0	10
9	25	3.77	50	0	0
10	50	10	1	4	2

(a)Determine a rate law consistent with the experimental data.

(b)Suggest a mechanism and rate limiting step consistent with your rate law.

(c)Linearize your data and evaluate the rate law parameters (Note: you don't have to plot all the data, just a few representative points)

2) The elementary reversible gas phase reaction A <->2B is to be carried out adiabatically. Pure A is fed at a rate of 2 mol/min, a temperature of 100šC, and a concentration of 0.01 mol/dm³.

(b)What is the CSTR volume necessary to achieve 80% of the adiabatic equilibrium conversion?

Additional information:		Sample Data
Graphs of k(T) and KC are shown below.		T	k	KC	Xe
CpA = 5.0 cal/(mol - šC)		šC	min-1	mol/dm3	--
CpB = 2.5 cal/(mol - šC)		100	0.086	0.05	0.75
CpC = 5.0 cal/(mol - šC)		200	0.27	0.018
HR(100šC)=-3500 cal/mol A		300	0.62	0.0096
		400	1.05	0.006	0.36

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(25 pts)

3) The elementary reaction

2A -> 2B

is carried out in a moving bed reactor in which the catalyst decays by sintering. What catalyst weight is necessary to achieve 50% conversion for a catalyst loading rate of 5 kg/min? Pure A is fed to the reactor at a concentration of 0.2 mol/dm³ and a molar flow rate of 5.0 mol/min.

Additional Information
Specific Reaction Rate	k=1.0 dm6 /(mol-kg cat-min)
Catalyst decay constant	kd=0.04 min-1

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(15 pts)

3) The elementary reaction

A -> B

is irreversible and carried out adiabatically in a CSTR. The R(T) and G(T) (kcal/mol) are shown in the attached figure.

(a)What is the heat of reaction for this reaction?

(b)What is the heat capacity of species A?

(c)What is the entering temperature at which ignition will occur?

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