Studija izomerizacije n-butana na kiselim WO3/ZrO2 katalizatorima potaknutim niobijem i lantanom: aktivnost izomerizacije n-butana

The requirement for environmentally friendly catalysts for the isomerization of alkanes has prompted research on the tungstate-zirconia (WZ) system. The present work examines the activity and selectivity of lanthanum (La) promoted tungstate-zirconia (LWZ) and niobium (Nb) promoted tungstate-zirconia (NWZ) catalysts. In this study, 1 % La promoted WZ (1 % LWZ) and 1 % Nb promoted WZ (1 % NWZ) catalysts were investigated in isomerization of n-butane in the presence of hydrogen. The studied catalysts were characterized by different methods: nitrogen physisorption, temperature programmed desorption of NH3, thermogravimetric analysis, and X-ray diffraction. The catalytic activity and selectivity were significantly improved by the addition of 1 % Nb. The redox process in the Nb-containing catalyst (1 % NWZ) played a central role by providing the highest acidic sites (283.53 µmol g–1) with appropriate activation energies for the skeletal rearrangement of the reactant (n-butane). Furthermore, this study highlights the determining role of the transfer process of adsorbed species from ZrO2 to W as well as to the Nb environment. The conversion of n-butane (27.34 %) and the selectivity to i-butane (92.34 %) for NWZ were significantly higher than WZ and LWZ catalysts. The experimental results revealed that Nb was a more effective promoter than La.Potreba za ekološki prihvatljivim katalizatorima primjenjivim za izomerizaciju alkana potaknuo je istraživanje sustava volframat-cirkonij (WZ). Ovaj rad ispituje aktivnost i selektivnost lantanom i niobijem potaknutih WZ katalizatora. U studiji je ispitana primjena WZ katalizatora potaknutih dodatkom 1 % lantana (1 % LWZ), odnosno 1 % niobija (1 % NWZ), u izomerizaciji n-butana u prisutnosti vodika. Karakterizacija je provedena različitim metodama: fizisorpcijom dušika, temperaturno programiranom desorpcijom amonijaka, termogravimetrijskom analizom i rendgenskom difrakcijskom analizom. Katalitička aktivnost i selektivnost znatno su poboljšani dodatkom 1 % niobija. Redoks-proces u katalizatoru koji je sadržavao niobij odigrao je glavnu ulogu osiguravajući najviše kiselih mjesta (283,53 µmol g–1) s odgovarajućom energijom aktivacije za preslagivanje n-butana. Konverzija n-butana (27,34 %) i selektivnost prema i-butanu (92,34 %) kod NWZ katalizatora bili su znatno veći nego kod WZ i LWZ katalizatora. Eksperimentalna istraživanja ukazuju učinkovitije poticanje dodatkom niobija u usporedbi s lantanom

Plasma treatment in textile industry

Plasma technology applied to textiles is a dry, environmentally- and worker-friendly method to achieve surface alteration without modifying the bulk properties of different materials. In particular, atmospheric non-thermal plasmas are suited because most textile materials are heat sensitive polymers and applicable in a continuous processes. In the last years plasma technology has become a very active, high growth research field, assuming a great importance among all available material surface modifications in textile industry. The main objective of this review is to provide a critical update on the current state of art relating plasma technologies applied to textile industryFernando Oliveira (SFRH/BD/65254/2009) acknowledges Fundacao para a Cioncia e Tecnologia, Portugal, for its doctoral grant financial support. Andrea Zille (C2011-UMINHO-2C2T-01) acknowledges funding from Programa Compromisso para a Cioncia 2008, Portugal

Hydrodynamics and mass transfer investigations in a biphasic plasma reactor

Abstract This work aims to investigate the radical mechanism responsible for the degradation of a highly soluble pollutant in water. The AG25 dye was chosen as substrate and the GAD-Spray as biphasic reactor to treat it remotely. The study is conducted through experiments and simulations using Comsol Multiphysics-chemical engineering module. The Hydrodynamics coupled with the plasma-reaction has demonstrated that a low mass transfer in the droplet favorites the removal of the pollutant. It indicates that the plasma-reactions take place at the stagnant liquid film are far from the bulk of the droplet. Numerical modeling fitted by the conversion rate of the reagent has shown that the peroxynitrous acid HOONO (PON) is responsible for the degradation of AG25 in water. Consequently, and according different kinetic mechanisms, a radical mechanism has been predicted based on this deduction. The removal and the degradation rates were of 88 and 83% respectively during 90 min after the plasma exposure. The results of simulations showed a significant agreement between the calculated and the real removal rate of AG25. Through this study, it can be confirmed that GAD-spray-tower plasma reactor is efficient to eliminate and degrade remotely a very soluble pollutant through the HOONO (PON) plasma long-lived species.</jats:p