In I/GCSE Chemistry, we will learn about nitrogen fixation.
Nitrogen fixation
Nitrogen fixing- the process of turning nitrogen from air into nitrogen compounds e.g. ammonia- used for pharmaceuticals, fertilisers
Nitrogen can be a limiting factor in some areas (e.g. third world) --> no crops
Nitrogen’s triple bond makes it very stable and thus it is very difficult to simply take nitrogen from air.
For this reason, we need to ‘fix’ nitrogen to meet demands.
There are biological + non-biological ways of fixing nitrogen. E.g. industry, combustion, agriculture.
Biological ways
Nitrogen-fixing bacteria can fix nitrogen at room temperatures and pressures.
The enzyme, and therefore catalyst, Nitrogenase converts nitrogen into ammonia. (Contains Fe/Mo/S)
In I/GCSE Chemistry, Other nitrogen fixing bacteria are found in rood nodules, legume plants, clovers.
Non-biological ways
Industrial nitrogen fixation --> increases amount of fixed nitrogen in the environment -->the natural Nitrogen Cycle is destroyed.
- Environmental: nitrate flows to sea -->algal bloom -->eutrophication + damaged ecosystems
- Health: nitrogen pollutes water -->humans drink polluted water -->serious health issues
Restoring the balance in the nitrogen cycle is vital for sustainable development.
Production
Ammonia production is a clean process b/c all reactants are used, atom economy=100%, recycled reactants.
- Mainly produces CO2 and nitrogen oxides, which are taken in by plants and levels are reduced.
Future feedstocks
Hydrogen is extracted from methane via steam forming.
When it comes to I/GCSE Chemistry, Methane fossil fuel sources are non-renewable (will run out), thus alternative ways of producing hydrogen should be thought about.
- E.g. electrolysis of water= cheap + renewable electrical supply (solar panels)--> reduces GHG’s
Catalysts
More efficient catalysts are being discovered, which allow reactions to take place at lower temperatures and pressures--> money + energy saved.
E.g. Ruthenium catalyst:
- Yield: 20%
- x40 pressure--> more expensive BUT benefits outweigh
Refer to I/GCSE Chemistry, Chemists study nitrogen fixing from nature e.g. study Nitrogenase structure--> make artificial ‘enzymes’ that mimic natural enzymes- this allows them find out more data to use artificial enzyme at room temperature and pressure = cheaper, efficient, less time consuming, less energy used.
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