Fundamental researchers at the Colorado School of Mines have proposed a novel two-part 

system for separating impurities from natural gas in the Journal of Renewable and Sustaina

ble  Energy.  Natural  gas primarily contains methane, but impurities in the gaseous mixture 

need  to be removed before the methane can be put into the pipeline. The newly proposed 

purification system combines two separation methods and, in principle, promises to improve 

performance,  reduce  costs  and  diminish  ecological  side effects compared to benchmark 

technologies.

Natural  gas  processing  typically  relies  on  high-temperature  techniques  that  incur high 

operating  costs.  "We  propose  an  integrated  process  consisting  of  gas  hydrates  and 

membranes, to make the overall process of purifying natural gas potentially more economic

al  without  high-temperature  driven processes," said co-author Moises Carreon, an expert 

in membrane separating technologies.

Membrane  technology  applies  different  types  of  material  to filter out carbon dioxide and 

nitrogen from raw natural gas. Propane and hydrogen sulfide are also often present and can 

negatively affect membrane performance. A possible solution to this problem emerged when 

Carolyn Koh, an expert in hydrates, Pramod Warrier, postdoctoral researcher, and Carreon 

began talking.

"Hydrates form hydrogen-bonded water cages that trap the gases you want to separate," Ko

h said. "It's a potentially very selective way of trapping those gases." Different pressure and 

temperature  conditions  are  required  for  impurity hydrates to form compared to methane 

hydrates. The engineers decided to introduce selective hydrate formation as a preliminary 

step to the membrane separation process.