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Heterogeneous Catalysts

Assignment 6, due on Nov. 13


All diagrams must be hand drawn, no photocopies or computer images will be accepted.

  1. Exercise 6.1 of Inorganic Chemistry by Swaddle suggests that Japanese chemists got good yields of methane by the reaction H2 + CO2 = CH4 + CO using a catalyst in which nickel metal is an important component. Nickel is known (Section 17.4) to form a gas carbonyl, Ni(CO)4. Propose some steps of reaction at the molecular level to explain how the reactions proceed leading to the products.

    Is nickel metal a suitable catalyst for the catalytic converter? Explain why or why not.

  2. Exercise 6.2 of Inorganic Chemistry by Swaddle points out that heterogeneously catalyzed reactions differ from homogeneous counterparts in two important ways.

    What are the rate expressions for the two cases?

    At high temperature limit when the fraction of catalyst surface area covered by reactants is zero, what will the apparent activation energy Eapp be?

    Use the techniques suggested in Exercise 2.2 (Assignment 2) to answer the above problem.

  3. The band gap for titanium dioxide has been suggested to be 3.2 eV. Calculate the frequency and wavelength of the photons whose energy is 3.2 eV.

    In what region of the radiation spectrum are these photons?

    Explain how the energy of the photons activates solid TiO2 for possible catalytic activities when light of this region is absorbed by titanium dioxide?

    How does the excitation lead to the photocatalytic decomposition of water? What techniques are used to overcome the difficulties. (See Section 6.5 of Inorganic Chemistry by Swaddle.)

  4. What are some of the limiting factors of productions when heterogeneous catalysts are used in a chemical manufacture?

    Give an example to illustrate how the activation energy is affected by the use of a heterogeneous catalyst.