Stability of clay-based catalysts in contact with water vapour

The search for cleaner processes is one of the major challenges in modern chemical industries. In this context clay derived materials are environmentally friendly catalysts that can be easily tailored to optimize their catalytic activity for a precise reaction of interest. Furthermore, clay-based catalysts can be easily separated, recovered and reused and their versatility, low cost, high catalytic activity and/or selectivity render them very attractive materials. Considering that the stability towards water vapour is a crucial aspect for catalytic performance and reuse of the catalysts, we present a study of the pore structure stability, in the presence of water vapour, of clay catalysts prepared by acid activation with HCl solutions and ion-exchange with sodium, aluminium and iron, from a natural clay collected at Serra de Dentro (Porto Santo Island, Portugal) [1]. For elucidating the influence of water vapour on the pore structure stability, water vapour adsorption- -desorption isotherm, at 298 K, was determined on each sample by gravimetric method as well as n-pentane adsorption−desorption isotherms, at 298 K, which were determined before and after the corresponding water adsorption-desorption isotherms. Prior to the measurements, the samples were outgassed during 5 h at 473 K and the adsorptives were outgassed by repeated freeze–thaw cycles. The results to be reported in the communication allow us to state that, upon contact with water vapour, the less acid activated catalysts suffered some reduction in pore volume reflecting changes in the pore structure, while the more acid activated catalysts and those prepared by ion-exchange presented excellent stability upon one cycle of water vapour adsorption-desorption. The results are corroborated by nitrogen adsorption-desorption isotherms determined, at 77 K, before and after the water and n-pentane adsorption-desorption measurements.

Do nada às pequenas coisas: Heranças das vanguardas da segunda metade do séc. XX

Ao longo do séc. XX, a necessidade de libertar a arte das regras que a oprimiam e o desejo de conhecer os seus limites e significados levaram os artistas a atitudes extremas. Monocromia, ready-made, galerias vazias, objectos desmaterializados ou invisíveis são faces de uma aproximação da arte ao nada. Estas atitudes deixaram todos os caminhos em aberto. Entre eles a arte das pequenas coisas, que privilegia o espírito criativo humano, o prazer de fazer, a atenção ao quotidiano e a reutilização de matérias-primas. /ABSTRACT: ln the twentieth century, the unchained of art from the academic rules, and the push ofknowledge to the edge brings artists to the extreme. Monochrome painting, ready-mades, empty galleries, formlessness or invisible objects are actual results from this kind of attitude. From this point forward every path is open for the artists. Among them the "tiny things art’ emerges as an expression of human creativity, as a "joie de faire", gathering the attention from the everyday's world and reuse of quotidian materials.

“ The Creation of an Urban Landscape” in Adaptive reuse,the modern movement toward the future, 14th international conference proceedings, Do_co.mo.mo international, Lisboa ( indexed by SCOPUS)

The headquarters and park of the Calouste Gulbenkian Foundation in Lisbon represent the first modern Portuguese environment with an outstanding relation between exterior and interior as a spatial continuum . As such, the project refused the more common conceptual attitude of interior plus exterior. This unitary view revealed a clear understanding of the proposed site for the project and what could have been Calouste Sarkis Gulbenkian (1869-1955) expectations, while concretizing Modern Movement ideals regarding landscape architecture and architecture. Through its design the park mediates the relation between the buildings’ super-structures, the urban context, and the human scale, while generating a unifying system established by the complicity between natural and synthetic materials. From the first moment of the project’s design process, this complicity resulted in a set of strategies that met programmatic