Catalysis:Problems:Problem 1

From Wiketomica
Revision as of 16:09, 8 July 2010 by Kmbenjamin (talk | contribs)

2. Postulate a catalytic mechanism for catalyst A. To accomplish this task, it may be useful to try to view individual events and answer individual questions with the simulation module, such as:

a. How does CO adsorb? Molecularly or dissociatively? Can you visualize the adsorption event? Describe it in words.
b. How does O2 adsorb? Molecularly or dissociatively? Can you visualize the adsorption event? Describe it in words.
c. Can you visualize the surface reaction happening? (You may need to slow down the simulation delay to “see” this happen.) Describe it in words.
d. Show, by way of derivation, how this mechanism leads to the same rate law equation, with the same concentration dependence, as in problems #1. Be sure to state all assumptions that you make during your derivation.

1. Determine the dependence of the rate of reaction (CO2 production) on the concentrations of the reactants (reaction orders) for isothermal catalytic CO oxidation at 600 K on catalyst A. To help discern the concentration effects, it may be useful to graph the rate of CO2 production vs. each species’ concentration. Propose a catalytic rate law (not just a power law model) for this system. To accomplish this task, you will need to have reaction rate information, which can come from an analysis of real-time simulation data (one option is the method of initial rates[ref]). Determine rate and equilibrium constants for you proposed rate law for the given catalyst A system at 600 K, using the data collected.

2. Compare your catalytic mechanistic model to the simulation data you collected for one case (one set of reactant concentrations) of CO oxidation on catalyst A at 600 K.

3. Estimate the Arrhenius parameters for the actual surface reaction present in the catalytic mechanism posed from problem #1 above.

3. Determine the heat of reaction for CO oxidation on catalyst A via a calorimetry experiment. To accomplish this, you will want to run the reactor in adiabatic mode, and use a suitable energy balance (or combined mole and energy balance). Relevant mean heat capacity data is given below:

Keep in mind that you do not need to let the reaction run to completion to accomplish this task (the simulation may take too long to run). For accuracy, it is recommended to try and stop the reaction at a configuration where there is little or no material absorbed on the catalyst surface (all atoms and molecules in the gas phase).

4. Investigate a second catalyst material, catalyst B for its reaction behavior.

a. Is the rate of reaction the same for catalyst B as it is for catalyst A? Does the rate law you generated in problems #1-3 of the level 2 problems succeed or fail to capture the reaction kinetics for this catalyst?
b. Can you determine what chemical/physical phenomenon is causing the difference in rate?
c. To mitigate this problem with catalyst B, which square well potential parameters would you adjust? Could this parameter affect other aspects of the reaction chemistry?