25 May 2011

Catalysis using functionalized mesoporous silica

Literature Discussion

Submitted by Randall Hicks, Wheaton College
Categories
Description: 

This paper, while not fundamentally groundbreaking, serves as a nice introduction to the field of mesoporous materials. I like that it covers synthesis, characterization, and an application of the materials. I have used this paper in our senior seminar course as the basis for discussion of this area of chemistry. Discussion questions cover aspects of sol-gel chemistry, powder diffraction, gas adsorption, IR, solid state NMR, UV-Vis, and catalysis.  

Learning Goals: 

Upon reading this paper, students should be able to:

• Describe at least one method by which mesoporous materials can be both synthesized and functionalized

• Explain how x-ray diffraction, gas adsorption, solid state NMR (and to a lesser extent, IR and UV-Vis) can be used to characterize mesoporous materials

Implementation Notes: 

As part of our seminar, each faculty member rotates through to present a paper for discussion in his or her area of chemistry. The class meets for 1 hr 20 minutes twice a week (Tuesday and Thursday). Students are given the paper on a Tuesday, without much preface, and are asked to briefly read over the work for Thursday. In class on that Thursday, I have them to present an overview of the paper and submit any terms with which they are unfamiliar. I spend the majority of that day giving an introduction to the field, defining unfamilair terms, and answering questions. Then I distribute a handout with specific questions for the students to answer. Some questions are to be done by all, others are assigned in groups. While the groups are evenly populated, I often assign a different number of question to each group. For instance, because students have been introduced to IR, NMR, and UV-Vis, I have one group tackle all three of these sections on the assignment. For topics with which they're not likely familiat (XRD, gas adsorption), I assign one of these per group. They have until the following Tuesday to work on the questions. At that point, I ask students to present their answers, and we resume the class discussion. (I have attached the handout that I give to students, and a version with my answers, below.) 

Related note: Although we are moving to a two-course inorganic sequence in AY 2012-13, I do not have the ability to "squeeze" materials chemistry into my (currently) one semester course; I therefore relish the opportunity to present this paper in our seminar course. If you have the time to cover materials in your normal inorganic sequence, you may be able to present this paper in one class instead of two. 

If you have faculty privileges on VIPEr, then solutions to the questions can be found in the linked learning object (see related activities).

Time Required: 
Two (2) 80-min classes
Evaluation
Evaluation Methods: 
Unless a student has done some independent research (lab or literature) in this area previously, I expect that none of them will have any experience with this work. Therefore, I assess on the effort that students made to answer the assigned questions and on their contribution to in-class discussion. The instructor of record (for senior seminar) is also present to observe the class proceedings and can decide how to integrate that into an overall grade for the course. 
Evaluation Results: 

Without the review of unfamiliar terms and concepts on the first day of the two-day activity, I doubt that many students would be able to tackle this paper. However, after going through all that, students do a fair job of answering the questions.

The answers to most of the "general questions" can be found from web searching. The students that are motivated to do so have dug up answers for these questions. Question #6 is difficult for them, but serves as a good point to initiate conversation about why larger mesoporous materials are useful. Question #7 is also foreign, but it usually comes up in the first class and so students can piece together a response for it here. 

Answering the "characterization method" questions has proven more difficult for the students, particulalry because most if not all of them lack experience with x-ray diffraction and gas adsorption techniques. They can look up Bragg's Law and calculate a parameter given the other values (solve for x, essentially) even if they don't know exactly what that value represents. A4 is particularly difficult as they need to find the answer in the accompanying paper. Responses to questions on gas adsorption are understandably murkier yet. Again, this is where I can go into more detail on the method in class discussion. On the other hand, questions in C and D on UV-Vis and IR, respectively, are easier for them given their familiarity with those techniques. These questions are usually answered well. D1, on site-isolation, sometimes requires further explanation. And, finally, while students have NMR experience from organic, they're not usually knowledgeable on solid-state NMR. Some of these answers can be found online or in the paper, but this is another are where a short discussion is helpful.

Depending on the length of discussion in a particular class, there is not always time to fully get into the catalysis results. However, the answers to these questions can be found in the main manuscript and are correctly reported.   

Creative Commons License: 
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