Introducing nanovalve technique for natural gas storage

Abstract

In order for natural gas vehicles to be economically feasible in residential consumer sector, the limitations of the current natural storage approaches (Compressed Natural Gas and Liquefied Natural Gas) must be overcome. Advances in the Adsorbed Natural Gas storage approach have been made, however, these advances do not fit within the parameters (storage pressure of 35 bar) set by Advanced Research Projects Agency-Energy (ARPA-E) of the U.S. Department of Energy (DOE). The research presented here establishes a novel technique to effectively store methane. This nanovalved technique involves loading a pelleted adsorbent at high pressure, sealing a layer coated on the adsorbent pellet, and reducing the storage vessel to a low pressure. Using zeolite 5A beads as a model adsorbent and MCM-48 as a nanovalving layer, >50% of the maximum methane capacity of zeolite 5A (73 V/V) was able to be maintained after being reduced to a pressure of 1 bar. After establishing the feasibility of the nanovalving technique with MCM-48, again using zeolite 5A beads a model adsorbent, the impact of coordinating metal of MOF nanovalve layers was assessed. This study was to aid in designating material properties of the nanovalving layer that allow for better sealing and better performance. Aluminum was established as a desirable component in the nanovalving layer (two layers of Al-MOF on zeolite 5A beads was able to maintain 46% of the maximum methane capacity). The work herein illustrates the nanovalving technique can store a high percentage of loaded methane at low pressure. With a high methane capacity adsorbent and an optimized nanovalving layer, the possibility of achieving the storage targets set by ARPA-E is promising.