Equipment to make Plastic on a Venus Space Colony
I’ve previously talked about manufacture and construction on Venus. As explained in my story on Venus colonization, colonists will have to live above the cloud tops in floating aerostats (balloon structures). Raw materials for production of things will hence be based on the gasses in the atmosphere such as:
- Carbon dioxide
- Sulfuric acid
- Nitrogen
Unlike Mars, early Venus colonies focused on local resource utilization will not be mining rocks like the Martians but use chemical processing plants.
The most important material for Venus colonists will be plastic, as it is made from carbon, hydrogen and oxygen primarily, which is available in abundance in the atmosphere. Lets speculate on what kind of equipment they would use to make this plastic.
My assumption here is that we won’t start with huge colonies. There will be space constraints, so we can’t exactly reproduce a huge factory like on earth.
Small Processing Plants
This actually exists, they are called small processing plants and used as pilot plants. That is essentially a small scale factory to test production before you do the real thing. Instead of producing a few deci liter in the lab, you can make several liters in a small processing plant. You can find examples of these at e.g. Swiss Buchiglass.
To be able to produce many different kinds of chemical with need flexibility to use the same equipment for many different kinds of kinds of chemical production.
This rules out flow based processing. Instead we must typically use batch reactors:
- When you need a large range of products. Want to be able to reuse reactor for different reactions.
Loop Reactor
Loop reactors are used, for example, in the manufacture of poly(ethene) and the manufacture of poly(propene).
All plastic is basically taking some gas molecules and chaining them together. So poly(ethylene) is made by chaining ethylene gas molecules.
The Process to make a plastic such as Polyethylene
Encyclopædia Britannica has a discussion of what the process to make Polyethylene plastic is like.
An important ingredient is a catalyst called Ziegler-Natta. Catalysts are typically some kind of metal or other chemical compound which helps a chemical reaction happen but which does not get consumed in the production. Meaning we can keep using the catalyst over and over again. It does not become part of the plastic.
Often you see catalysts as some sort of sold coating inside a reaction chamber. However we can add Ziegler-Natta as liquid to the reactor (reaction vessel).
The Ziegler-Natta polymerization of ethylene
Ethylene gas is pumped under pressure into a reaction vessel, where it polymerizes under the influence of a Ziegler-Natta catalyst in the presence of a solvent. A slurry of polyethylene, unreacted ethylene monomer, catalyst, and solvent exits the reactor. Unreacted ethylene is separated and returned to the reactor, while the catalyst is neutralized by an alcohol wash and filtered out. Excess solvent is recovered from a hot water bath and recycled, and a dryer dehydrates the wet polyethylene to its final powder form.
Chemical Reactors in Operation
Here is video of a small chemical reactor in operation. For a discussion of the various parts that make up a chemical reactor look at my previous story.
Next, What can you make out of CO2
Without any metals but abundance of carbon dioxide, it is useful with a more in depth discussion of the kinds of things you can make with it. That will be covered in my next story.
