Synthesis and High Hydrogen Storage Capacity of Zeolite-Like Carbons Nanocast Using As-Synthesized Zeolite Templates

Abstract

As-synthesized zeolite β has been successfully used as a template for the preparation, via chemical vapor deposition, of well ordered zeolite-like carbon materials. The carbon materials have high surface area (1720−2535 m2/g) and high pore volume (1.09−1.56 cm3 g-1) and exhibit some zeolite-like structural ordering replicated from the zeolite template. Carbon materials prepared at 800 and 850 °C are nongraphitic and retain the particle morphology of the zeolite templates. Carbon prepared at 900 °C contains some graphitic domains (as indicated by XRD patterns) and irregular particles that are dissimilar to the zeolite template particles. We observed hydrogen uptake of up to 5.3 wt % at −196 °C and 20 bar, and 2.3 wt % at 1 bar, for the carbon materials. The hydrogen uptake is dependent on the surface area of the carbons. The use of as-synthesized (rather than calcined) zeolite β significantly improves the carbon yield and reduces the number of steps in the preparation of the templated carbons.

Large Surface Area Ordered Porous Carbons via Nanocasting Zeolite 10X and High Performance for Hydrogen Storage Application

“…34,48,51 Similar hysteresis loops in isotherms have also previously been observed for ordered porous carbons using other kinds of zeolites as the hard template. 29,30,33,36,47 On the other hand, the representative TEM images of the 10Xc-70 in Figures 3b and S2 (Supporting Information) further demonstrate that a part of the carbon precursors does have deposits on the external surface of the 10X zeolite template, and the carbons do have some randomly distributed mesopores, which are in excellent agreement with XRD and N 2 isotherms observations.From the pore structure parameters listed in Table 1, we can obviously find that the pore textures of carbons are largely dependent on the preparation conditions, namely, surface area and total pore volume of carbons derived from the liquid−gas two-step routes are much larger than ones from the single gas CVD process. As expected, carbons that exhibit well-developed zeolite-like orderings generally have a higher proportion of micropore surface area and pore volume.…”

“…reported by the group of Mokaya, 29,34,36,40,47,51,54 who demonstrated that a significant proportion of micropores at 0.6 nm is beneficial for enhancing the hydrogen storage capacities, especially for high pressures. Therefore, we have reason to believe that the carbons reported here probably also have high hydrogen storage uptakes.…”

“…29,36−40 Furthermore, it should be admitted that hydrogen uptake for 10Xc-70 is slightly higher than some previously reported data on the carbons templated from other zeolites. 4,30,34,47,51 As we stated above, however, buoyancy effects have great effects on the adsorption results especially for light gas at high pressures; therefore, results for hydrogen adsorption must be subjected to accurate buoyancy corrections. The importance of buoyancy corrections in calculating actual hydrogen storage capacities at high pressures can be illustrated here.…”

Functionalization of Porous Carbon Materials with Designed Pore Architecture

“…Carbon samples cast from zeolite b exhibited a particularly high hydrogen uptake of 6.9 wt % at 20 bar and 2.6 wt % at 1 bar at À196 8C. [238,239] However, for all nanoporous carbons tested, the room temperature absorption was much lower. Although the isosteric heat of adsorption in the smaller micropores (8 kJ mol…”

Ordered Porous Nanomaterials: The Merit of Small

“…Unlike the soft templating method, in which the surfactant arranges itself during the synthesis process in order to give rise to the desired structure if the appropriate synthesis conditions are met, the hard templating method relies on the use of preshaped solid forms as templates, which, upon deposition of the desired oxide species and removal of the "mold" gives rise to the final desired material. This method may be found in the literature with other names such as nanocasting [205,225,226], exotemplating [227], or repeated templating method [207]. Porous Al 2 O 3 supports prepared by anodic oxidation (AAO or anodized aluminium oxide) [228,229] were used initially as a mold to prepare carbons, metals, or other nanostructures by a variety of techniques such as electrodeposition [230], Chemical Vapour Deposition (CVD) [231][232][233], Plasma-Enhanced Chemical Vapour Deposition (PE-CVD) [234], or Atomic Layer Deposition [235].…”