Question

Identify the catalyst used to transform carbon monoxide from water gas into carbon dioxide

• A. Potassium dichromate
• B. Sodium chromate
• C. Iron chromate
• D. Nickel

Hint:

Iron chromate, a Fe-Cr oxide mixture, catalyses the shift of CO to CO2.

Answer 1

The Correct Option is C

Step 1: Understanding the Process:
Water gas is a mixture of CO and \(\text{H}_2\). To get more hydrogen, CO in it is converted to \(\text{CO}_2\) by steam. This is called the water gas shift reaction.

Step 2: Key Reaction:
\[ \text{CO} + \text{H}_2\text{O} \xrightarrow{\text{catalyst, 673 K}} \text{CO}_2 + \text{H}_2 \]

Step 3: Detailed Explanation:
The catalyst used in this step is iron chromate (the iron-chromium catalyst), at about 673 K. The \(\text{CO}_2\) formed is then removed by scrubbing with sodium arsenite solution, leaving nearly pure hydrogen. This is how dihydrogen is made on the industrial scale.

Step 4: Why the other options are wrong.
Potassium dichromate (A) and sodium chromate (B) are oxidising agents used in solution, not catalysts for this gas phase process. Nickel (D) is used for steam reforming of methane and for hydrogenation, not for the shift step.

Final Answer:
The catalyst is iron chromate, option (C). \[ \boxed{\text{Iron chromate (C)}} \]