The temperature-and methane adsorption-induced deformations of microporous activated carbon Sorbonorit-4 were measured by in situ dilatometry over a wide range of temperatures and pressures. The thermal expansion coefficient of Sorbonorit-4 in vacuum increased linearly with temperature within a range of 293−573 K. Methane adsorption in Sorbonorit-4 induced its contraction at low pressures and temperatures or expansion at high temperatures throughout the entire pressure range. An inversion of the temperature dependence of adsorption-induced strain (AIS) of Sorbonorit-4 was found. At low pressures and temperatures below 300 K, the AIS isotherm showed a contraction of Sorbonorit-4; its magnitude and corresponding pressure interval decreased with temperature. At T > 300 K, the temperature rise was accompanied by an adsorption-induced expansion of Sorbonorit-4 up to 0.08% at 393 K. At high pressures, the expansion decreased from 0.45 to 0.13% when the temperature increased from 213 to 393 K. The AIS of Sorbonorit-4 and differential isosteric heat of adsorption presented as functions of methane uptake changed within the same intervals of adsorption values, reflecting variations in the state of adsorbed molecules determined by contributions from the adsorbate−adsorbent and adsorbate−adsorbate interactions. The obtained results are essential for practical use of carbon adsorbents for natural gas storage.

The dependence of high temperature hydrogen activation on the structure of nanofibrous alu mina (filament diameter of 5 nm) was shown. Due to self organization, nanofibers are twisted in spirals and then in a second stage the spirals interlock and form alumina tubes, which then transform into bundles. In the process of hydrogen activation, the specific surface area changes and amorphous alumina nanowires develop into a nanocrystalline phase. TEM investigations showed that high temperature hydrogen activation led to the self organization of the alumina nanofibrous structure into hollow nanotubes with a diameter close to 30 nm.

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