Investigation of hydrogen and methane adsorption/separation on silicon nanotubes: a hierarchical multiscale method from quantum mechanics to molecular simulation

Abstract

A combination of ab initio quantum mechanical (QM) calculations and canonical Monte Carlo (CMC) simulations are employed to investigate possible usage of singlewalled silicon nanotubes (SWSiNTs) as a novel media for hydrogen and methane adsorption as well as their separation from each other. By fitting the force field, a Morse potential model is selected as an efficient potential to describe the binding energies between both hydrogen-SiNTs and methane-SiNTs obtained from ab initio calculations. Then CMC simulations are performed to evaluate the adsorption and separation behaviors of H 2 and CH 4 on the three different sizes of SiNTs including (5, 5), (7, 7), and (9, 9) SiNTs at ambient temperatures and pressures from 1 up to 10 MPa. As a comparison, the adsorption and separation of H 2 and CH 4 on the (8, 8) CNTs which are isodiameter with (5, 5) SiNTs are also simulated. Results are indicative of remarkable enhancement of H 2 and CH 4 adsorption capacity on the SiNTs compared to the CNTs, which arise from stronger van der Waals (VDW) attractions. In the case of methane adsorption on SiNTs, the stored volumetric energy exceeds the goal of the US Freedom CAR Partnership by 2010, which can not be achieved by methane compression at such low pressures. Moreover, simulation results indicate that SiNTs preferentially adsorb methane relative to hydrogen in their equimolar mixture, which re-S. Balilehvand · S.M. Hashemianzadeh ( ) · S. Razavi ·

Nanoadsorbents: Classification, Preparation, and Applications (with Emphasis on Aqueous Media)

“…Recently, several attempts have been made to employ silicon nanotubes as solid phase in analytical separations. However, only a few studies have successfully implemented the hydrogen adsorption on SiNTs. − Balilehvand et al investigated the hydrogen and methane adsorption/separation on silicon nanotubes. They found that the capacity of hydrogen adsorption on SiNTs is considerably higher than that on CNTs.…”

Continual long-term monitoring of methane in wells above the Utica Shale using total dissolved gas pressure probes

“…3b). These observations illustrate the responsiveness of the P TDG -probe to short-term changes in downhole Note the different y-axis ranges P TDG , noting that the relatively slower changes in P TDG relative to P BUB may be partly due to methane sorption onto the silicon membrane (Balilehvand et al 2012). They also provide some insight into potential variability in P TDG related to the monitoring set-up.…”

Hydrogen storage efficiency of Fe doped carbon nanotubes: molecular simulation study

“…The effect of pressure on the selectivity of CH 4 over H 2 on SiNTs has displayed the same trend. 117 As mentioned, smaller molecules are more appropriate for packing in the CNT, the selectivity of CH 4 /H 2 decreases with increasing pressure.…”