The chemical industry make bulk chemicals such as:
Sukphuric acid, ammonia, sodium hydroxide, phosoric acid.
The chemical industry also make fine chemicals such as:
Medicinal drugs, chemicals for fragrences, food additives.
The industry employs chemists for research and development to discover:
- new products to meet a new need.
- new ways to make a product more cheaply or sustainibly.
Government health and safety regulations control chemical processes and the transoptation and storage of the chemicals. The regualtions protect people such as workers.
Producing useful chemical stages.
1. convert raw materials into feedstocks
2. Convert feedstocks into products by synthesis. It happens in a reactor. Feedstocks may be fed into a reactor at high temperature or high pressure. The reactor may contain a catalyst.
3. The chemical plant separates products, by-products and waste which leave the reactor. Unreacted feedstock returns to the reactor.
4. Analysing the products to check purity.
Green chemistry aims to make processes as safe and sustainable as possible:
- using renewable feedstocks: e.g make polyester from corn starch rather than crude oil.
- Making the process efficient: measured as atom economy atom economy = mass of atoms in product / mass of atoms in reactant X 100%
- reducing waste: processes with higher atom economy, recyling, uses for by-products.
- Make processes more energy efficient: insulating pipes, use energy from exothermic reactions.
- lower energy demand of a process: use biocatalysts so it can run at low temp.
- cutting pollution from waste: remove harmful chemicals before sending them to landfill sites.
- Avoid hazardous chemicals: replace toxic feedstocks with chemicals that do not harm human health or the environment.
Making Ethanol by Fermentation.
There are 3 ways to produce Ethanol. One way is by Fermentation.
Fermentation converts sugars into Ethanol. Carbon dioxide is the by-product.
e.g : glucose sugar--------> Ethanol + carbon dioxide
Enzymes in yeast catalyse fermentation
The optimum temperature is 25-37 degrees Celsius.
- Above this temperature the enzymes denature.
- Below the reaction is too slow.
Making ethanol from Ethane.
Feedstock for this is Ethane and Steam.
Ethane is obtained from crude oil.
- The process uses a phosphoric acid catalyst.
- The best temp. is 300 and a pressure of 60 atmospheres.
- Ethane and steam are sent through the reactor many times.
- Side reactions make dangerous by-products.
Making Ethanol from waste Biomass
Waste biomass is being developed to produce Ethanol. these are the stages:
1. Pretreatment: mashing the biomass into small pieces.
2. Hydrolysis: Using genetically modified Enzymes to convert celluse into sugars.
3. Separating: sugars from other products.
4. Distilling: Ethanol to make a more concentrated solution.