Question

Choose the option that correctly matches in Group 1 with those in Group 2
Group 1: (P) coking, (Q) poisoning, (R) sintering
Group 2: (I) prolonged exposure of catalyst to high temperature, (II) deposition of carbonaceous material on catalyst surface, (III) irreversible chemisorption of molecules on active sites of catalyst

• A. (P) - (III), (Q) - (I), (R) - (II)
• B. (P) - (II), (Q) - (III), (R) - (I)
• C. (P) - (II), (Q) - (I), (R) - (III)
• D. (P) - (I), (Q) - (III), (R) - (II)

Hint:

To easily distinguish catalyst deactivation modes:
Coking = Carbon/Physical blockage.
Poisoning = Chemical/Chemisorption of impurities.
Sintering = Thermal/Structural collapse.

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to match different catalyst deactivation mechanisms (Group 1) with their physical descriptions (Group 2).
This is a standard topic in industrial heterogeneous catalysis.

Step 2: Key Formula or Approach:
We define and analyze the three main deactivation mechanisms listed:
1. Coking: Physical deposition of carbonaceous residues.
2. Poisoning: Chemical chemisorption of impurities.
3. Sintering: Thermal structural degradation.

Step 3: Detailed Explanation:

• Coking (P): This is the physical deposition of carbonaceous material (coke) on the catalyst surface and inside its pores.
This layer covers the active sites and can block pore entrances, restricting access.
This matches description

(II): deposition of carbonaceous material on catalyst surface.

• Poisoning (Q): This occurs when impurity molecules in the feed chemically react with or strongly chemisorb onto the active sites of the catalyst.
This block is typically irreversible and inactivates those sites.
This matches description

(III): irreversible chemisorption of molecules on active sites of catalyst.

• Sintering (R): This is a thermal deactivation process where prolonged exposure to high temperatures causes the catalyst's active metal crystallites to grow or coalesce, reducing the active surface area.
It can also cause the support structure to collapse.
This matches description

(I): prolonged exposure of catalyst to high temperature.


Step 4: Final Answer:
The correct match is (P) - (II), (Q) - (III), (R) - (I).