New Mars Forums

SpaceNut

Administrator

From: New Hampshire

Registered: 2004-07-22

Posts: 29,310

Re: Mars Insitu Fuels made from atmosphere, regolith, water

We have to may topics that talk about co2 to methanol creation but they all need catalysts to get efficviency of conversion.

Experts craft metal catalysts for efficient methanol synthesis from CO2

Calliban

Member

From: Northern England, UK

Registered: 2019-08-18

Posts: 3,572

Re: Mars Insitu Fuels made from atmosphere, regolith, water

Decomposing perchlorates that have been washed out of the Martian regolith, may turn out to be a more energy efficient way of producing oxygen than electrolysis.
https://www.chemistryworld.com/features … 48.article

If we are bringing hydrogen from Earth, then it can be used to produce methanol by direct reaction with CO2 over a suitable catalyst.

CO2 + 2H2 = CH3OH

There would appear to be no need for electrolysis.  To combust the methanol, we do need extra oxygen.

CH3OH + 1.5O2 = 2H2O + CO2

We need to bring 4 tonnes of hydrogen to make 32 tonnes of methanol.  And we need 48 tonnes of oxygen for every 32 tonnes of methanol.  Thats a ratio of 1:8:12.  Provided we can mine the perchlorates and reduce them for a practical energy cost, each tonne of hydrogen shipped from Earth gives us 20 tonnes of propellant.

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"Plan and prepare for every possibility, and you will never act. It is nobler to have courage as we stumble into half the things we fear than to analyse every possible obstacle and begin nothing. Great things are achieved by embracing great dangers."