Chromium oxide was supported on different commercial aluminas. Their characteristics were assessed by different techniques (X-ray diffraction, X-ray photoelectron, laser Raman, and electron paramagnetic resonance spectroscopies, and Brunauer−Emmett−Teller surface, temperature-programmed reduction, and temperature-programmed desorption measurements). The variation of the Cr3+/Cr6+ ratio was accounted for by the interaction between the chromium phase and the support. The tendency of Cr3+ to form aggregates such as Cr2O3 was induced by the support. The features of the support exert an influence upon chromium stabilization both in its oxidation states 6+ and 3+ and in the coordination of surface chromia species. The total acid sites and the oxidized chromium have a marked effect on activity and selectivity at initial operation times.

Experimental adsorption isotherms for methane in 5A zeolite over the pressure range 0–5 MPa have been obtained and analyzed using a statistical thermodynamical formulation which relates the observed macroscopic thermodynamic quantities to microscopic gas–solid interactions. The efficiency of the zeolite as a methane storage system has thus been evaluated.

One method of increasing the storage capacity of compressed natural gas, an alternative for vehicular fuel, is by adsorbing it on to microporous solids such as zeolites or activated carbons. NaX and NaY zeolites with different Si/Al ratios have been synthesized and characterized. Experimental adsorption isotherms for CH4 on these zeolites have been obtained at different temperatures over a pressure range of 0–5 MPa using a high-pressure volumetric apparatus. Isosteric heats of adsorption have been estimated and the isotherms analyzed applying a statistical thermodynamic model. The efficiency of this solid as a methane storage system has been evaluated and compared with other sorbents. Encouraging results have been obtained.

The adsorption isotherms of methane on synthetic (5A and 13X) and natural (Erionite) zeolites at different temperatures have been obtained through the use of a high-pressure volumetric adsorption apparatus over the pressure range 0–5 MPa. The isotherms have been analyzed on the basis of a statistical thermodynamic adsorption model, variation in the temperature allowing calculation of the isosteric heat of adsorption. The results show that these zeolites are highly efficient for methane storage at moderately low pressure (0.5–1 MPa).