Porous Material Captures Carbon Dioxide at Natural Gas Wellheads
A porous material invented in the lab of Rice University chemist James Tour sequesters carbon dioxide at ambient temperature with pressure provided by a natural gas wellhead and lets it go once the pressure is released. The material, a nanoporous solid of carbon with nitrogen or sulfur, is inexpensive and simple to produce compared with the liquid amine-based scrubbers used now, Tour said. His lab, with assistance from the National Institute of Standards and Technology (NIST), produced the patented material that pulls only carbon dioxide molecules from flowing natural gas and polymerizes them while under pressure naturally provided by the well. When the pressure is released, the carbon dioxide spontaneously depolymerizes and frees the sorbent material to collect more.
Transcript
00:00:04 most people don't realize that that natural gas when it comes out of the ground is contaminated 10 to 20 percent by co2 and sometimes in some parts of the world as much as 70 of the natural gas coming out of the ground is co2 we want to take that co2 and just send it right back down hole where it was
00:00:26 right at the wellhead so we don't have to just vent it to our atmosphere and deal with this greenhouse gas in the atmosphere so the way co2 is presently separated from natural gas is it goes through a tower of an aqueous amine aqueous amines are corrosive and the platforms are very large for
00:00:47 these so you have a large aqueous amine tower and you bubble the natural gas and co2 through it and it reacts with the co2 and holds it in there then you turn it off and you have to then heat this aqueous amine tower up to 125 to 140 degrees centigrade which is a huge energy cost to do this and then you can remove that co2 but
00:01:10 that's happening at a natural gas collection site and so there's no convenient way to deal with that co2 now that you've trapped and now is vented so it's generally vented to the air plus the footprint the area of the aqueous mean tower is extremely large
00:01:28 so it's energy intensive and it's space intensive and it's corrosive so what we've come up with is a material that is very simple it's a carbon derived material and we can make this from inexpensive polymers and we just heat this up in a single step the inexpensive polymers with a base like
00:01:50 potassium hydroxide which is extremely inexpensive we heat it up to 600 degrees and out comes this black powder this black powder will trap the co2 as it comes out with the natural gas and it will trap it we can do this at the well head where it's coming out of the ground we can trap it and that way it's much simpler in an
00:02:14 engineering way to take it and to pump it back down whole but what's also attractive in this whereas the aqueous amine tower only traps about 10 percent of co2 by weight this is trapping over 80 percent of the co2 by weight so in other words one kilogram of this material
00:02:33 will trap 0.8 kilograms of co2 this new mechanism by which we found to trap co2 could be enormous what we're trying as humankind to do is to limit co2 emissions from natural gas from the burning from flue gases to be able to limit this so if we can take co2
00:02:57 and convert it into a solid because the volume of a gas is very large compared to the volume of a solid so if we can take the co2 and polymerize it then we have a large advantage in being able to contain it at this point there is no way to easily trap co2 and trap it as a solid without going to extremely high
00:03:20 pressures which are totally unviable but what we've been able to do now is at very low pressures be able to polymerize co2 so this is going to allow us to trap it and maybe even contain it for hundreds or thousands of years as we learn how to now deal with it and react co2 and use it as
00:03:41 an important chemical for human use rather than venting to the atmosphere