47 documents found, page 1 of 5
Methanol dissociation on bimetallic surfaces: validity of the general Bronsted-...
Fajin, Jose L. C.; Cordeiro, M. Natalia D. S.; Gomes, Jose R. B.Density functional theory (DFT) calculations were employed to study the dissociation of the O-H bond in methanol on several planar and stepped bimetallic transition metal surfaces, composed of elements showing high or moderate activity towards this reaction, namely, Ni, Rh, Ru, Ir, Pd, Au, Zn and Cu. The activation energies for the O-H bond cleavage were compared with those estimated using a Bronsted-Evans-Pola...
Molecular dynamics simulation of diffusion coefficients and structural properti...
Vaz, Raquel V.; Gomes, Jose R. B.; Silva, Carlos M.Molecular dynamics (MD) simulations were employed to compute tracer diffusion coefficients (D-12) of propanone, butanone, 2-pentanone and 3-pentanone in supercritical CO2, which are in quite good agreement with experimental data available in the literature. It was confirmed that D-12 is enhanced by pressure decrease, temperature increase, and solute size reduction. The radial distribution functions, spatial dis...
Why are some cyano-based ionic liquids better glucose solvents than water?
Batista, Marta L. S.; Passos, Helena; Henriques, Bruno J. M.; Maginn, Edward J.; Pinho, Simao P.; Freire, Mara G.; Gomes, Jose R. B.Among different classes of ionic liquids (ILs), those with cyano-based anions have been of special interest due to their low viscosity and enhanced solvation ability for a large variety of compounds. Experimental results from this work reveal that the solubility of glucose in some of these ionic liquids may be higher than in water a well-known solvent with enhanced capacity to dissolve mono-and disaccharides. T...
Striking HIV-1 Entry by Targeting HIV-1 gp41. But, Where Should We Target?
Teixeira, Catia; Barbault, Florent; Couesnon, Thierry; Gomes, Jose R. B.; Gomes, Paula; Maurel, FrancoisHIV-1 gp41 facilitates the viral fusion through a conformational switch involving the association of three C-terminal helices along the conserved hydrophobic grooves of three N-terminal helices coiled-coil. The control of these structural rearrangements is thought to be central to HIV-1 entry and, therefore, different strategies of intervention are being developed. Herewith, we describe a procedure to simulate ...
Interaction of CO2 and CH4 with Functionalized Periodic Mesoporous Phenylene-Si...
Lourenco, Mirtha A. O.; Siquet, Christophe; Sardo, Mariana; Mafra, Luis; Pires, Joao; Jorge, Miguel; Pinto, Moises L.; Ferreira, PaulaNonfunctionalized and functionalized periodic mesoporous phenylene-silicas (Ph-PMOs) with different kinds of amine groups were prepared and their capacity to uptake CO2 and CH4 molecules were experimentally evaluated considering biogas upgrading. It was found that aminopropyl groups grafted to the free silanols of the Ph-PMO displayed the highest selectivity for CO2 gas, adsorbing 26.1 times more CO2 than CH4 a...
Insights into CO2 and CH4 Adsorption by Pristine and Aromatic Amine-Modified Pe...
Lourenco, Mirtha A. O.; Siquet, Christophe; Santos, Joao; Jorge, Miguel; Gomes, Jose R. B.; Ferreira, PaulaThe synthesis and characterization of pristine and amine-functionalized periodic mesoporous phenylene-silicas having different pore sizes are reported. We explore the potential of these materials for CO2/CH4 separation, by studying the adsorption of pure CO2 and pure CH4 gases. The aminated periodic mesoporous phenylene-silica with the smallest pore size is the best adsorbent to CO2, presenting a Henry's consta...
Effect of the Exchange-Correlation Potential on the Transferability of Bronsted...
Fajin, Jose L. C.; Vines, Francesc; Cordeiro, M. Natalia D. S.; Illas, Francesc; Gomes, Jose R. B.As more and more accurate density functional methods emerge, the transferability of Bronsted-Evans-Polanyi (BEP) relationships obtained with previous models is an open question. In this work, BEP relationships derived from different density functional theory based calculations are analyzed to answer this question. In particular, BEP relationships linking the activation energy of O-H bond breaking reactions taki...
Turning periodic mesoporous organosilicas selective to CO2/CH4 separation: depo...
Lourenco, Mirtha A. O.; Silva, Ricardo M.; Silva, Rui F.; Pinna, Nicola; Pronier, Stephane; Pires, Joao; Gomes, Jose R. B.; Pintof, Moises L.Nowadays, CO2/CH4 separation is considered extremely important with respect to making biogas economically viable. The search for efficient materials for biogas upgrading is at the cutting edge of research in the field of energy. Periodic mesoporous organosilicas (PMO) are highly suitable for application as selective adsorbents for CO2 as they have concomitant high specific surface areas and tunable surface prop...
Computational and Experimental Study of the Behavior of Cyano-Based Ionic Liqui...
Batista, Marta L. S.; Kurnia, Kiki A.; Pinho, Simao P.; Gomes, Jose R. B.; Coutinho, Joao A. P.The solvation of cyano- (CN-) based ionic liquids (ILs) and their capacity to establish hydrogen bonds (H-bonds) with water was studied by means of experimental and computational approaches. Experimentally, water activity data were measured for aqueous solutions of ILs based on 1-butyl-3-methylimidazolium ([BMIM](+)) cation combined with one of the following anions: thiocyanate ([SCN](-)), dicyanamide ([DCA](-)...
Vapor-Liquid Equilibria of Imidazolium Ionic Liquids with Cyano Containing Anio...
Khan, Imran; Batista, Marta L. S.; Carvalho, Pedro J.; Santos, Luis M. N. B. F.; Gomes, Jose R. B.; Coutinhot, Joao A. P.Isobaric vapor-liquid equilibria of 1-butyl-3-methylimidazolium thiocyanate ([C(4)C(1)im][SCN]), 1-butyl-3-methylimidazolium dicyanamide ([C(4)C(1)im][N(CN)(2)]), 1-butyl-3-methylimidazolium tricyanomethanide ([C(4)C(1)im] [C-(CN)(3)]), and 1-ethyl-3-methylimidazolium tetracyanoborate ([C(2)C(1)im][B(CN)(4)]), with water and ethanol were measured over the whole concentration range at 0.1, 0.07, and 0.05 MPa. Ac...