Methane preconcentration by adsorption: a methodology for materials and conditions selection

Abstract

Methane (CH 4) adsorption has been widely studied, mainly in the context of natural gas purification. A much less prominent, but highly relevant application is the preconcentration of CH 4 from ambient air. In this study, we compare six different commercial adsorbent materials with respect to their effectiveness for methane preconcentration: a macroporous polymeric resin (HayeSep D), multi-walled carbon nanotubes, two microporous metal-organic frameworks (HKUST-1 and ZIF-8), and two zeolites (5A and 13X). The most relevant properties, such as isosteric enthalpy of adsorption, specific surface area and the selectivity for CH 4 adsorption over N 2 were characterized by analyzing adsorption/desorption isotherms. Using these parameters, we discuss the tested adsorbents with respect to the most important properties and identify the most promising candidates. Furthermore we identify the experimental conditions that are expected to give the best results with respect to practical applications.

A versatile, refrigerant- and cryogen-free cryofocusing–thermodesorption unit for preconcentration of traces gases in air

“…The method of cryofocusing-thermodesorption is a common technique 5266 F. Obersteiner et al: A versatile, refrigerant-and cryogen-free cryofocusing-thermodesorption unit for that purpose (e.g. Aragón et al, 2000;Demeestere et al, 2007;Dettmer and Engewald, 2003;Eyer et al, 2016;Hou et al, 2006). In principal, an ambient air sample from either a sample flask or continuous flow for online measurement is preconcentrated on adsorptive material at a specific adsorption temperature, T A .…”

Real-time analysis of <i>δ</i><sup>13</sup>C- and <i>δ</i>D-CH<sub>4</sub> in ambient air with laser spectroscopy: method development and first intercomparison results

“…Laser spectroscopy in the mid-infrared (MIR) spectral range has emerged as a powerful alternative for the analysis of stable isotopes of CO 2 (Sturm et al, 2013), N 2 O (Köster et al, 2013;Mohn et al, 2012) and CH 4 (Bergamaschi et al, 1994(Bergamaschi et al, , 1998aSantoni et al, 2012). This development has been triggered by the invention and availability of quantum cascade lasers (QCL), which offer high optical power in continuous wave operation at room temperature (Faist, 2006;Faist et al, 2002). This enables the realization of compact, field-deployable instruments for real-time analysis at ppt (parts-per-trillion, pmole mole −1 ) level precision (Curl et al, 2010;McManus et al, 2010).…”

“…This resulted in 1.8 g of HayeSep D filled in a stainless steel tubing (length 90 cm, OD 4 mm, wall thickness 0.5 mm, volume 6.4 cm 3 ) and bracketed with glass wool (BGB Analytics AG, Switzerland) and wired mesh. HayeSep D has previously been identified as an excellent high capacity adsorbent material for CH 4 (Eyer et al, 2014). The tubing is curled around a custom-made cylindrical aluminum standoff (outer diameter 70 mm, height 28 mm) with an optimized wall thickness of 0.5 mm.…”

Automated simultaneous measurement of the δ13C and δ2H values of methane and the δ13C and δ18O values of carbon dioxide in flask air samples using a new multi cryo‐trap/gas chromatography/isotope ratio mass spectrometry system

“…Hayesep D had been tested previously for pre‐concentration purposes (see, for instance, Frank and Frank and references cited therein). More recently, Eyer et al . have studied this and other promising materials.…”

“…[48] Hayesep D had been tested previously for pre-concentration purposes (see, for instance, Frank and Frank [49] and references cited therein). More recently, Eyer et al [50] have studied this and other promising materials. While high absorption rates of methane were observed for other materials, the selectivity over the major air constituent (N 2 , O 2 , Ar) was best for Hayesep D. This finding is in line with our own observations.…”