Impacts of Gas Impurities from Pipeline Natural Gas on Methane Storage in Metal–Organic Frameworks during Long-Term Cycling

Abstract

The development of adsorbed natural gas (ANG) technology creates opportunities for use of pipeline natural gas as clean fuel in vehicles. Metal−organic frameworks (MOFs) are one class of materials that have received considerable attention as possible adsorbents in ANG applications. We examine how accumulation of trace components from pipeline natural gas will impact the performance of MOFs in ANG during long-term cycling. Our approach combines information from grand canonical Monte Carlo (GCMC) simulations of singlecomponent adsorption, ideal adsorbed solution theory (IAST) of multicomponent adsorption, and an isothermal model of tank cycling to assess accumulation of heavy hydrocarbons and tert-butyl mercaptan (TBM). In a series of MOFs, a reduction in deliverable energy up to 50% is observed after 200 cycles. These results highlight the importance of considering multicomponent effects during consideration of adsorbents for ANG applications.

Predictions of Hg0 and HgCl2 Adsorption Properties in UiO-66 from Flue Gas Using Molecular Simulations

“…It is noteworthy that even though the gas phase concentration of HgCl 2 is just 5 ppm, the molar uptake of HgCl 2 in UiO-66 is similar to that of N 2 and CO 2 . This is a striking example of the well-known observation that trace levels of high-molecular-weight species can play a critical role in the adsorption of gas mixtures. − Consistent with the single-component isotherms shown above, no significant adsorption of Hg 0 is predicted from this gas mixture. At the temperature and pressures shown in Figure , the uptake of all species is low (as indicated by the linearity of each isotherm), and the impact of HgCl 2 uptake on adsorption of CO 2 or N 2 is minimal.…”

Exemplar Mixtures for Studying Complex Mixture Effects in Practical Chemical Separations

“… 16 , 17 Examples have been described in which this phenomenon substantially reduces the net energy density of natural gas stored by an adsorbent over the course of many cycles. 18 , 19 …”

Hold on Tight: MOF-Based Irreversible Gas Sensors

“…The ability to isolate, adsorb, remove, or detect these gases in a stream of competing gases is key to industrial processes. Natural gas reserves exist with high levels (approaching 50%) of H 2 S, with competing species of H 2 O, CO 2 , and hydrocarbons. , Pipeline quality natural gas contains up to 10 ppm H 2 S with small quantities of H 2 O vapor and ppm levels of added mercaptans. − Flue gas from coal-fired power plants contains high levels of H 2 O with ppm levels of SO x and NO x . ,− Other commercially relevant flue gas stream examples include coal-fired flue gas (13% CO 2 , 6% H 2 O, ∼4% O 2 , 50 ppm CO, 420 ppm NO 2 , 420 ppm SO 2 , 76% N 2 ) and biogas (65% CH 4 , 32% CO 2 , 2% N 2 , 0.7% O 2 , and 0.3% H 2 S). These complex toxic gas mixtures are common worldwide, with reports indicating up to 10 4 distinct VOC species in the air of major cities. , …”