I agree with your thermodynamics, I'm just concerned about finding a volume big enough to store climatically meaningful amounts of CO2 in that form. 40 billion metric tons per year of CO2 in the form you describe is around 30 billion cubic meters, and you need to find that much storage volume every year just to keep things from getting worse. If you want to actually make a dent, like rolling things back to the year 2000 (which likely isn't enough, but is a real impact), that's more like 600 billion metric tons or 450 billion cubic meters. That's roughly equivalent to 400 mountains 5000 feet tall. It's a huge volume of material we're talking about finding a place to store if we're actually trying to make a real dent in climate change.