Environmental Catalysis Module

MODULE SUMMARY | ACTIVITY SUMMARIES | RELATED SIMULATION | RELATED SEMINARS

MODULE SUMMARY

In the Environmental Catalysis Module, a joint project with the Institute for Environmental Catalysis at Northwestern University, students learn what a catalyst is and become aware of the use of catalysis to promote environmental protection. Besides introducing the concept of catalysis, the module also focuses other issues such as catalytic selectivity, specificity, poisoning, condition optimization, and waste minimization. The first activity of the module introduces the concept of catalysis in a visual and dramatic way. Then students conduct an Internet search on catalysis research, the aim of which is to emphasize the personal relevance of catalysis with regard to environmental issues. In the remaining activities, students analyze different types of catalytic systems, including homogeneous and heterogeneous acid catalysis, thermocatalysis applied to eliminate gaseous pollutants, and photocatalytic degradation of water pollutants using nanocrystalline titania (TiO₂), all of which are emblematic of a variety of research areas in environmental catalysis. In their study, students focus on concepts such as catalytic selectivity, specificity, poisoning, condition optimization, and waste minimization. Finally, in the culminating design project, students are challenged to design, construct, test, and evaluate a unique catalytic system to eliminate water pollutants.

ACTIVITY SUMMARIES

Activity 1: Catalyzing with Platinum Black

To observe the effect of a catalyst, students hold three types of paper both treated and untreated with the catalyst platinum black over a beaker of methanol. They infer that a reaction has occurred by observing whether the paper burns. Based on their knowledge of the reactions that took place, students form a hypothesis as to why some of the papers burned faster. Students also learn that one of the products of the catalyzed combustion of methanol is heat and that heat is one of the reactants of the combustion of the paper. Thus, the two reactions are coupled, as so many reactions are in nature (e.g., photosynthesis).

Activity 2: Searching for Catalysts

Students conduct an Internet search to identify catalysts that are used in industrial processes, natural processes, and waste treatment. After sharing their findings with classmates, students compare and contrast the catalysts and draw conclusions about them.

Activity 3: Catalyzing a Reaction Using a Heterogeneous Acid Catalyst

Students use acid catalyst resin beads to catalyze the hydrolysis of methyl acetate to acetic acid and methanol. They determine whether the reaction occurred by using baking soda to test for the presence of acetic acid. After confirming that the acid catalyst is necessary for the hydrolysis reaction to occur, students clean the catalyst and reuse it in the hydrolysis reaction. Based on their observations, students infer that heterogeneous acid catalysts are safer and easier to reuse than homogeneous acid catalysts. Thus, the use of heterogeneous acid catalysts is better for the environment.

Activity 4: Using Metal Catalysts to Degrade a Noxious Gas

Students set up an experiment to evaluate how various heterogeneous metal catalysts can be used to destroy an air "pollutant" by catalyzing the conversion of "pollutants" into safer substances; it could be as simple as vinegar (a source of acetic acid), or it could be a smell. The "pollutant" is passed over a heated metal catalyst and would not be detected because it has reacted with the catalyst. When the same experiment is done without the catalyst, the pollutant is detected. There are a lot of opportunities to test out various variables:  temperature, catalyst, pollutant, detection method.

Activity 5: Using Photocatalysis to Degrade a Water Pollutant

In this activity, students explore the use of photocatalysis, a more energy efficient catalyst system that does not require the use of heat, for eliminating pollutants. The activity involves destroying pollutant molecules in water using ultraviolet light and titanium dioxide (TiO₂) nanocrystalline particles. An organic dye (methylene blue) is used to simulate the water pollutant; the solution goes from deep blue to light blue or clear at short or long times, depending on the UV exposure. This ties in nicely with light-harnessing, photosynthesis, and even ozone depletion.

Design Project: Designing a Catalytic System to Eliminate a Pollutant

Using what they learn about catalysis from previous activities, students design and test a functional catalytic system. The goal is to design a system that uses a catalyst to degrade the "pollutant," which is simulated with amyl acetate in artificial banana flavoring. The system should consist of a catalyst, a setup, and a recommended set of conditions.

» Sample Activity Pages (PDF)

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