Capture and release of acid gasses using tunable organic solvents with aminopyridine
A class of water lean, organic solvents that can bind with various acid gasses to form acid gas bound molecules having a high degree of intramolecular hydrogen bonding which enables their use as regenerable solvents for acid gas capture. Unlike the other devices described in the prior art, the present invention takes advantage of shortened distances between the portions of the molecule that form hydrogen bonds within the structures when loaded with an acid gas so as to create a molecule with a higher internal bonding affinity and a reduced proclivity for agglomeration with other molecules.
1. A method for capturing an acid gas from a stream containing that acid gas the method comprising the step of;
contacting the stream with a gas selective capture sorbent having a liquid phase at less than 100 degrees C., the gas selective capture sorbent comprising an amino pyridine that reversibly binds an acid gas under a first set of conditions to form a solid phase zwitterionic carbamate salt and releases the acid gas under a second set of conditions, wherein the amino pyridine has the structure:
wherein n is greater than zero and R 1 and/or R 2 includes an amine selected from the group consisting of an alkyl amine or a dialkyl amine.
2. The method of claim 1 wherein one of R 1 and R 2 includes an amine selected from the group consisting of an alkyl amine or a dialkyl amine, and the other of R 1 and R 2 comprises an alkyl group slected from the group consisting of Me, Et, Pr, iPr, Bu, iBu, t-Bu, cyclobutyl, cyclopentyl, and cyclohexyl.
3. The method of claim 1 wherein the gas selective capture sorbent is a lean liquid having less than 10 percent water.
4. The method of claim 1 wherein the gas selective capture solvent retains a viscosity at or below about 300 cP at a maximum loading of acid gas therein.