Can we decarbonise the chemical industry? Flashcards
What is the difference between decarbonise and defossilise?
- Decarbonise: Reducing or eliminating CO₂ emissions from a system, process, or economy (i.e. the energy associated with chemical process)
- Defossilise: Completely eliminating fossil fuel use in favour of alternative energy sources
The chemical industry has grown from around 35-27% from 1900 to 2019
How polluting is this industry
- The industry is a large contributor to carbon emissions
How efficient is the chemicals industry
- The pharamceutricals industries takes cheap reagents and makes expensive products so can afford inefficient process
- The peterochemical industry is high efficient where is takes cheap reagents and makes slightly expensive products - cannot afford efficiencies
Crude oil is a complex mixture of many things, what does it include?
(These components depends on the geological location of where its from)
- Hydrocarbons: Alkanes, Cycloalkanes, Aromatics, Alkenes
- Non-hydrocarbons: Sulfur compounds, Nitrogen compounds, oxygen compounds, metals
- Other compounds: Asphaltenes, Resins
Crude oil is seperated through
What component concerns the chemical industry
- Fractional distillsation
- Naptha: ~20% of the carbon atoms which comes from crude oil
What is Naptha cracked into to make more useful materials?
- Ethylene (C2)
- Propylene (C3)
- Butadiene (C4)
- (plus a really small aromatics stream)
- These streams create 100s thousands of diverse products with different structures etc
Naptha is a mixture of simple hydrocarbons of different lengths
It is then broken down using a steamcracker, how does this work?
- Push through an oven which cleves the molecule into small C2, C3 and C4 fragements
- It is then cooled, condensed and distilled and seperated
- It costs about 1.6 tons of CO₂ of ethylene (some of this can be used but most cannot)
What are the differences between defossilising vs decarbonising for streamcracking of Naptha?
- Defossilising: using biomass rather than crude oil in the cracker, forming bio naptha
- Decarbonising: Changing the energy used to run the cracker to something renewable
Why has the transition to defossilisation of streamcrackers not occured?
- Because they are hugely expensive plants to build and hence there is no economic insertive to built a new plant using biomass
- Only switched when the old plant has depreciated
- However e-cracking embedded in existing networked processes is very smart e.g. BASF Verbund
By decarbonising the feedstock of chemistry…
…you intrinsically decarbonise the entirety of the molecular supply chain that sits underneath it
What is an easy way to reduce the energy usage of steamcracking?
- By heating the pipe not an oven, then heating a smaller amount of material
- Not using convection with indirect heating
- By doing this like this you will decrease the associated energy demands of the molecule derived from these materials
What is the drawback from just decarbonising the heating from steamcracking?
- The current feedstock (petroleum/crude) is non-renewable
- Business are usual need adoption of recycling of technical carbon products BUT recycling rates are not high enough
- Therefore bio-naptha demonstrates a viable reduction of crude demand
Why is transitioning to E-cracking is easier said than done?
- Reducing the demand for say ethylene, would also reduce the production of other C3 + C4 components
- This would increase the tension onto everything downstream from butadiene and propylene because there is less available = prices goes up
Why is CO₂ described as a chemical sink
CO₂ is quite inert due to it having a large ΔH (enthalpy). The only way to get CO₂ to react is investing huge amounts of energy to reduce the carbon (this is the key challenge of using CO₂ as a feedstock because where will all this energy come from – burning fossil fuel)
What type of reactions may be preferred for activating CO₂ and why?
The timescale in which we can sequester CO₂ is important on the impact it will have on the atmospheric CO₂ concentration. Mineralisation reactions will form carbamates which will have a very long lifetime in the environment – seen as a longer-term strategy for the sequestration of CO₂
Name ways we can use CO₂ as a resource
- Urea synthesis
- Salicylic Acid (Kolbe Schmidt)
- Organic carbonates
- Polymer application
- Water Gas Shift (synthesis gas- Fischer Tropsch)
What could be another way to make petrochemical feedstock other than biomass?
- Could use CO₂ as a feedstock for the future (could allow the steady state concentration of atmospheric CO₂ to be managed too)
- Alternative to petrochemical derived carbon
An example of power to X is the direction hydrogenation of CO₂
Through reacting CO₂ with hydrogen, you can form methanol or methane which can be used to replace the petrochemical alternatives and fuels or feedstock
This reaction requires selective catalysis
What are some issues with ‘Power to X’
Through reacting CO₂ with hydrogen, you can form methanol or methane which can be used to replace the petrochemical alternatives and fuels or feedstock
This reaction requires selective catalysis
What are some issues with ‘Power to X’
- The process requires in injection of Hydrogen, and it depends where this hydrogen comes from
- Energy for the process come from (could use renewables to overcome this)
Describe an example of a place which has used the concept of power to X
A plant in Iceland uses geothermal energy to product methanol from CO₂ via electrolysis
The methanol can then be used as a fuel or energy material
Microbial Electrosynthesis on the side of an electron can be used for…
- Use microbial electrolysis on the side of an electrode, which delivers hydride/electrons to the system
- Microorgansms use CO₂ as a feedstock to produce valuable chemicals, fuels, and biomaterials
Another way to consider sustainability in the chemistry industry is, how do we heat chemical reactions efficiently (Power-2-Heat)
What is the conventional heating process?
- Fill up a oil bath, and fill up a sand bath
- Heat the sand bath, and subsequently heat the oil bath
- Put the reaction system (flask) in and the reaction system heats from the glass walls
- The vessel is stirred to ensure mass transport + heat transport
- But this type of heating is intrinsically poor
Another way to consider sustainability in the chemistry industry is, how do we heat chemical reactions efficiently (Power-2-Heat)
What is Microwave/Magnetic heating processes?
- Microwaves - interactions of EM with dipoles or induced dipoles within the starting material - could be used to target the reaction site
- Magnetic induction - Coupling of oscillating field to create torsional motion - friction
- More efficient at heating than conventional heating
What is Sonochemistry?
- Using an oscillating field (sound wave) creates small bubbles within the mixture
- This is due to the expansion + contracion of the surface tension
- As these bubble collapse, there is a dissipation that generates surface tension which is then dissipated in the mixture
- This generates rapid heating to high temperatures
How can plasma be used for heating?
- You would form a plasma discharge around a chemical reaction which is flowing in a pipe
- This discharge comes from high tension electrodes
- This essentially generates ions inside which dissipate energy
- Giving again the transfer of energy into chemical processes
Sum up the four key consideration of how to make the chemical industry more sustainable?
- Alternative feedstocks: Synthetic feedstocks from carbon capture, biomass feedstock, biomass waste feedstock, blue/green hydrogen
- Process decarbonisation: renewables, microgrids/energy storage, CCS
- Resource Stewardship: recycling, circular recovery, waste-to-energy
- Digital transformation
Describe what the BASF Verbund system does?
- The Verbund system creates efficient value chains that extend from basic chemicals right through to high-value-added products
- In addition, the by-products of one plants can be used as the starting materials of another
- In this system, chemical processes consume less energy produce higher product yields and conserve resources
- In that manner, we save on raw materials and energy, minimise emissions, cut logistics costs and exploit synergies
What does this show?
- It is a graphic taken from the environmental science and technology journal which shows how humanity has exceeded a planetary boundary related to environmental pollutants and other “novel entities” including plastics
- Shown to be the case for; Biosphere integrity, Climate change, Biogeochemical flows (P+N), Novel Enities, and Land-system change
What are the 4 key take away from this?
- Overcoming the reliance of non-renewables is difficult due to massive commerical + economic inertia which has to be overcome to replace the technology/capital investment
- Naphtha will continue to be a feedstock, qs if bio or normal
- Opportunity to use electrochemical methods to supplant tranditional thermal routes
- Where does the power/energy come from
