Unit 5 - Carbon Dioxide as a Feedstock Flashcards
Why is CO2 inert?
Its enthalpy of formation is very low, -394 kJ mol-1.
What is the challenge with using CO2 as a feedstock?
As it is very inert and has a low enthalpy of formation, energy needs to be invested to reduce the CO2 so it can be used.
How can the challenge of CO2 being inert be overcome?
A catalyst can be used to lower the energy barrier or energetic reactants can be used.
For example, a Grignard reagent can be used to add CO2 to a molecule which forms a carbonyl bond.
What are some of the direct uses of CO2?
Carbonation of drinks.
Inert gas in packaging of food.
Solvent.
Enhanced oil recovery (forcing CO2 into oil wells to make the oil accessible).
What are some of the uses of CO2 as a resource?
Urea and salicylic acid synthesis.
Organic carbonates.
Polymer applications.
Reverse water gas shift chemistry in the Fischer-Tropsch reaction.
How many tonnes of urea are produced each year?
160 million tonnes.
The chemical plants are located near cheap energy sources.
What is urea known as in terms of CO2 sequestration?
Transient sequestrant as the urea decomposes to form CO2 when applied to the fields.
What percentage of the nitrogen applied as a fertiliser is used by the plants?
Around 15%.
What is an example of a reaction that uses CO2 as a feedstock?
The Kolbe-Schmidt reaction which is used to make salicylic acid.
The production of cyclic carbonates is another example.
As a comonomer in a polymer.
What is the water-gas shift reaction?
CO + H2O ⇌ CO2 + H2
