Influence of Physicochemical Properties of Ni/Clinoptilolite Catalysts in the Hydrogenation of Acetophenone.

Heterogeneous catalytic hydrogenation is an interesting alternative to conventional methods that use inorganic hydrides. The hydrogenation of acetophenone under heterogeneous conditions with the supported catalysts based on Ni is the most useful due to its redox properties and lower cost. As is well-known, catalyst support can significantly affect catalyst performance. We have investigated the influence of various physical-chemical parameters on the selective reaction of the hydrogenation of acetophenone by using different nickel catalysts on clinoptilolite supports, in four different forms: natural, previously modified with NH3 (Ni/Z+NH4 +), with HNO3 (Ni/Z+H+), and thermally treated (Ni/Z 500 °C). In particular, our work focuses on determining the influence of the mentioned physical-chemical parameters on the percentages of conversion and the selectivity of the catalysis. This study aims to identify the combination of parameters that allows for obtaining the best catalytic results. The identification of the physical-chemical parameters that determine the percentages of conversion and selectivity allows us to design optimal catalysts.

Catalytic hydrogenation of nitrate in water: improvement of the activity and selectivity to N2 by using Rh(III)-hexamolybdate supported on ZrO2-Al2O3.

Catalysts prepared on ZrO2, Al2O3 and ZrO2-Al2O3 (ZrAl-10) supported with Anderson heteropolyanion (RhMo6) as active phase were investigated for the elimination of NO3- from water. Raman characterization of pure and supported RhMo6 phase showed the presence of polymolybdic species of different degrees of complexity when RhMo6 was supported. The temperature-programmed reduction study revealed the synergic effect between Rh and Mo species, through which the reducibility of Mo was promoted by Rh, and different phase/support interactions were verified. Among the supports, ZrAl-10 presented the highest acidity due to the presence of ZrO2 in the tetragonal modification and high specific surface area (due to Al2O3), favouring rhodium-molybdenum active phase/support interaction and high dispersion. All catalysts prepared were active in removing NO3-, the one prepared with the RhMo6 phase on the ZrAl-10 support being the most active. These results point to the formation of an active surface with a high dispersion of Rh and Mo. The highest selectivity to N2 (99.3) exhibited by the RhMo6/ZrAl-10 catalyst is proposed to be related to the high Rh dispersion (0.755) and to the presence of Lewis acid sites (oxygen vacancies) of the tetragonal ZrO2 modification that favour NO3- adsorption through electrostatic interactions.

Fabrication of Green Diatomite/Chitosan-Based Hybrid Foams with Dye Sorption Capacity.

The latest tendency of the scientific community regards the development of different classes of green materials able to solve pollution problems caused by industrial and human activity. In this paper, chitosan and diatomite were used to produce a broad-spectrum hybrid adsorbent, either in powder or in monolithic form for environmental pollutant removal. Diatomite-chitosan-based powders and porous diatomite-chitosan hybrids were prepared and characterized by chemical-physical, thermal and morphological analysis. Moreover, their adsorbent capacity towards anionic dye (Indigo Carmine) was also evaluated. Obtained data showed that chitosan improves the adsorption capacity of both systems, increasing the uptake of dye in both diatomite-chitosan systems.