CHEM-E1 130 Gatalysis Exam

CHEM-E1 130 Gatalysis Exam

February 18,2020,14:00, time reserved: 4 h

Five questions; answer each question. Each question (1-5) ^is worth 9 points. Maximum: 45 points No materials allowed.

Students are not allowed to take the exam paper with them.

1.

Definition of a catalyst. Give the definition of a catalyst. On the basis of the definition, how does the catalyst affect a chemical process? What kinds of requirements are there for industrial catalysts?

2.

Explain briefly the following terms and concepts related to catalysis (1.5 ^pt each)

a.

^Micropore

b.

^Dispersion

c.

Distribution

d.

^Langmuir adsorption isotherm

e.

Tamman temperature

f.

18-electron rule

3.

Preparation of supported solid heterogeneous catalysts. What are the three fundamental stages of catalyst preparation [according to the lnternational Union of Pure and Applied Chemistry (IUPAC)I? Describe the principle ^of the pore volume impregnation method (also known as "dry impregnation") and how can one controlthe obtained metal loading with it. What are the expected benefits and limitations of this method for catalyst preparation?

4.

Gatalyst deactivation. Describe the phenomenon of catalyst deactivation by coking. Give example(s) of when it takes place and how it may affect the activity/selectivity/lifetime of the catalyst. Which measures can be taken to avoid catalyst deactivation by coking?

5.

Gatalyst characterization. An enthusiastic Master's thesis student prepared two supported rhodium (Rh) catalysts on titania (TiOt for testing in the reverse water gas shift reaction. The specific surface area of the titania support was 100 ^m2l9. The targeted metal contents were 0.1

and 10 t¡,tt-o/o; achieving these metal contents was verified with x-ray fluorescence (XRF)

analysis.

But: poor student! After the XRF.analysis, it wäs no longer clear, which sample was which; the samples had been mixed up! (The student will remember to label samples better next time.) Luckily, the student has participated in the CHEM-E1 130 Catalysis course and is familiar with several catalyst characterization methods. Which characterization methods could the student use to find out, which sample is which? Describe the principles of at least two different catalyst characterization methods and what you expect the student could find out with these methods related to solving the case. lf you make assumptions related to the samples of

pretreatments/metal particle size etc., please explain your assumptions clearly.

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