This set of Unit Processes Multiple Choice Questions & Answers (MCQs) focuses on “Principles of hydrogenation catalyst”.
1. Hydrogenation catalysts are solids consisting of what?
a) Hydroxides
b) Phenols
c) Metals
d) All of the mentioned
View Answer
Explanation: Hydrogenation catalysts are solids consisting of metals and metal oxides.
2. An active catalyst has what type of absorptive powers?
a) Low
b) High
c) Moderate
d) None of the mentioned
View Answer
Explanation: These surface atoms, having varying degrees of unsaturation compared with the bulk metal or metal oxide, will strongly adsorb other substances with which they may come in contact, and active catalysts usually have high absorptive powers.
3. What is the need of catalyst poison?
a) Increase reaction
b) Increase temperature
c) Decrease reaction
d) None of the mentioned
View Answer
Explanation: Although absorption is closely related to the successful performance of a catalyst, it may ruin an active, catalyst, because other substances called catalyst poisons may be so strongly retained by these active atoms that the substance being hydrogenated can no longer reach the active or catalytic areas.
4. There is only one form of absorption.
a) True
b) False
View Answer
Explanation: Two forms of adsorption are now recognized: physical adsorption and chemisorption.
5. What happens when the amount of active surfaces increase?
a) More reaction
b) Less reaction
c) Less energy
d) More temperature
View Answer
Explanation: The speed of a hydrogenation will depend on the type and amount of active surface available.
6. Which of the following acts as a poison catalyst?
a) Sulphur
b) Nickel
c) Aluminium
d) Hydrogen
View Answer
Explanation: The most common poisons, such as sulphur, have to be tolerated, it is possible to utilize catalysts that contain sulphur. The molybdenum sulphides are examples of catalysts of this type. Under proper temperature and pressure conditions, these materials are effective hydrogenation catalysts.
7. Which of the following is an example of mixed mixture catalyst?
a) Nickel-copper
b) Nickel-alumina
c) Cobalt molybdate
d) All of the mentioned
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Explanation: Use of mixed-metal catalysts or promoted catalysts has been rapidly extended in recent years. More common mixtures with the well-known types of catalysts are nickel-copper, nickel-alumina, cobalt molybdate, nickel-tungsten sulphide, copper-zinc oxide, copper-chromium oxide, and zinc oxide-chromium oxide.
8. Contamination with foreign materials also causes poisoning?
a) Yes
b) No
View Answer
Explanation: Loss in activity from contamination with foreign materials is best characterized as poisoning.
9. What is meant by sintering?
a) Increase in activity
b) Increase in energy
c) Loss of activity
d) Decrease in activation energy
View Answer
Explanation: Loss in activity from a collapse and aggregation of the highly distended surface is best termed sintering.
10. Catalysts for use in industry depend on what?
a) Cost
b) Regeneration
c) Resistance to poisoning
d) All of the mentioned
View Answer
Explanation: Catalysts for use in industry depend on the following considerations: (1) cost of ingredients, (2) simplicity and reproducibility of preparation, (3) catalyst life, (4) ease of regeneration, (5) resistance to poisoning, (6) physical strength, and (7) resistance to thermal shock.
Sanfoundry Global Education & Learning Series – Unit Processes.
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