This set of Unit Processes Multiple Choice Questions & Answers (MCQs) focuses on “Industrial Processes-III”.
1. Hydrogenation of coal is not a sensitive reaction.
a) True
b) False
View Answer
Explanation: In the Hydrogenation of coal, the reaction is highly sensitive to changes in temperature because of the high-molecular-weight compounds present in the coal. Great care must be taken to avoid overheating, particularly during the preheating operations; otherwise, the components of the coal that still have their original molecular structure will tend to form coke and inert products not suitable for further hydrogenation.
2. Catalysts for the vapour-phase converts ______ to hydrocarbons?
a) Sulphur
b) Oxygen
c) Nitrogen
d) All of the mentioned
View Answer
Explanation: Catalysts for the vapour-phase step have to be sulphur-resistant and be able to convert sulphur, oxygen, and nitrogen-containing compounds to hydrocarbons.
3. Which one of the following is an effective catalysts for converting gas oil?
a) Molybdenum
b) Aluminum
c) Nickel
d) All of the mentioned
View Answer
Explanation: Molybdenum and tungsten sulphides are effective catalysts for converting gas oil into lower-molecular-weight and more saturated products. Such catalysts are not poisoned by sulphur compounds in the oils.
4. Which type of reaction is hydrogenation of gas oils?
a) Endothermic
b) Exothermic
c) Neutral
d) None of the mentioned
View Answer
Explanation: There is a net evolution of heat, for the reaction is exothermic. To control the temperature, intermediate cooling is sometimes effected by adding cold recycle gas at suitable points in the reactors.
5. Coal is a complex mixture of very _____ molecular-weight compounds.
a) Low
b) High
c) Moderate
d) None of the mentioned
View Answer
Explanation: Coal is a complex mixture of very high-molecular-weight compounds which apparently exist as an elaborate network of carbon rings.
6. What is meant by pasting oil?
a) High melting point
b) Low boiling point
c) High boiling point
d) None of the mentioned
View Answer
Explanation: The coal is first mixed with a high-boiling oil, called a pasting oil, and this mixture is forced into the high-pressure reaction chamber.
7. What is the temperature range of middle oil?
a) 50-80°C
b) 100-150°C
c) 140-180°C
d) 200-400°C
View Answer
Explanation: A portion of this product boiling in the range of about 200-400°C is commonly termed middle oil, and it may contain 10-20 per cent of phenol. Products boiling above the middle oil are recycled to the liquid-phase hydrogenation step.
8. In second stage, hydrocarbons are converted to _____ in hydrogenation of gas oils?
a) Gasoline range
b) Liquid-line range
c) Solid range
d) All of the mentioned
View Answer
Explanation: The middle oil is further hydrogenated in a second, or vapour-phase hydrogenation to convert it into hydrocarbons in the gasoline boiling range, i.e., those which boil to about 200°C atmospheric pressure.
9. What is/are the raw materials for liquefaction process?
a) Lignite
b) Bituminous
c) Anthracite
d) All of the mentioned
View Answer
Explanation: All types of lignite and most bituminous coals, except those which have progressed too far in the coalification process, such as anthracite, are satisfactory raw materials for liquefaction.
10. What are the properties of primary hydrogenation products?
a) High boiling oil
b) Heavy oils
c) Lighter oils
d) All of the mentioned
View Answer
Explanation: The primary hydrogenation products are heavy, high-boiling oils, which will crack if maintained at temperatures of 450°C (840°F) or above, into lighter oils, gasoline, and gas. If the time of hydrogenation is controlled, the liquefied product from the coal may be obtained as light oils, gasoline or gas, with the heavy pasting oil recovered unchanged.
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