This chapter presents a brief review of the recent applications of the quantum chemical calculati... more This chapter presents a brief review of the recent applications of the quantum chemical calculations in the catalysis for renewable energy production. In this, an introductory vision about the use of ab initio calculations in the field of the renewable energies is presented. It is worth mentioning that the quantum chemistry field is an extensive area with many methodologies and theoretical approaches; therefore, to shed some light on the application of this area on the catalysis for renewable energy production, the chapter is divide into two sections according to the employed theoretical approximation, that is, the cluster model approach and the periodic approach. The first section describes the cluster model approximation, followed by a discussion of recent works in hydrogen storage, biodiesel and methanol conversion fields, and the second section describes the basic principles of the periodic approximation, basis set used in this approximation, and illustrative examples in the cat...
Abstract DFT periodic calculations were carried out in order to gain more insight in relation wit... more Abstract DFT periodic calculations were carried out in order to gain more insight in relation with the stability of the (0 0 1) and (1 0 0) surfaces of the hexagonal WO3. These surfaces display an uncommon instability which could be attributed to their high polarity and the intrinsic instability problems of the hexagonal phase. Indifferently of the slab thickness, the internal structure of the slabs suffers distortion even at levels of a total loss of the hexagonal phase structure. Stoichiometric and non-stoichiometric O reconstructions do not seem to be practical mechanisms to solve the instability problem of these surfaces, leaving only the partial frozen slabs an efficient way to model the hexagonal (0 0 1) and (1 0 0) surfaces. However, the surface energy of these surfaces is dependent of the optimized layers instead of the frozen ones. Results obtained for the CO adsorption on the (0 0 1) surface showed that a model with six layers and two internal layers frozen to the atomic position of the bulk structure is enough to reach the structural and energetic stability of the CO adsorption.
ONIOM(DFT:PM3) calculations were carried out to investigate and characterize possible acid sites ... more ONIOM(DFT:PM3) calculations were carried out to investigate and characterize possible acid sites of SAPO‐11 molecular sieve. Two functionals were employed: B3LYP and ωB97X‐D. This last functional includes dispersion effects that are absent in the former. Benzene, pyridine, and ammonia interaction energies as well as the OH stretching frequencies of the POH, SiOH, and bridged Si(OH)Al groups were used to characterize the acid sites. This work shows that the adsorption of benzene on the surface is as strong as the adsorptions inside main channel of SAPO‐11. Pyridine adsorption on the surface is weaker than the one corresponding to the main channel. NH3 molecule interacts strongly with all OH groups or acid sites present in SAPO‐11. Moreover, the results reveal that it is possible to adsorb two NH3 molecules at only one Brønsted site. The adsorption of the second NH3 molecule is energetically favorable mainly due to the hydrogen bond formation between the NH3 molecules. In general the ...
Computational and Theoretical Chemistry, May 1, 2019
Abstract The interaction of CO2, CO, H2O, N2, N2O and O2 with the isoreticular metal-organic fram... more Abstract The interaction of CO2, CO, H2O, N2, N2O and O2 with the isoreticular metal-organic frameworks [Co(bdc)(pz)]n and [Co(bdc)(bpy)]n was studied. The ONIOM (M06/6-31G(d)HF/6-31G(d)) was applied to determine the structural and thermodynamic changes produced by the interaction among these small molecules and the framework structures. All the calculated adsorption energies are in the range of van der Waals non-covalent interactions, both influenced by dipole-quadrupole and quadruple-quadrupole electrostatic forces as well as confinement effect due to the different cavity sizes. The Δ H ads values obtained for the adsorption of CO2, CO and N2O suggest that [Co(bdc)(pz)]n and [Co(bdc)(bpy)]n framework structures are potential materials for the capture of these gases at standard conditions, which [Co(bdc)(bpy)]n exhibits greater adsorptive selectivity of post-combustion CO2, with a CO2/N2 energy ratio around 150% higher than [Co(bdc)(pz)]n.
Abstract Water adsorption on the (001) and (100) surfaces of monoclinic and hexagonal WO3 was stu... more Abstract Water adsorption on the (001) and (100) surfaces of monoclinic and hexagonal WO3 was studied using a periodic DFT approach. The results showed that dissociation of water on these surfaces is less energetically favourable than molecular adsorption and such phenomenon is a consequence of surface deformations induced by OH groups. Water interacted stronger with the five-fold tungsten atoms of the hexagonal surfaces than with those atoms of the monoclinic surfaces. Nevertheless, adsorption energies are almost the same between both hexagonal and monoclinic surfaces when all available active surface sites were occupied by water molecules, that is, at the maximum water coverage. On monoclinic surfaces, water adsorption gradually became less stable as the coverage increased, but the opposite behaviour was observed with dissociative adsorption. On the (001) surfaces of the hexagonal structures, both molecular and dissociative adsorption became less stable as water coverage increased. On the other hand, on the (100) surface, dissociation was only observed at the maximum coverage. All surfaces remain hydrated at low temperatures; whereas at higher temperatures the most stable structures are the clean surfaces. Lastly, the formation of a monolayer of OH groups on hexagonal surfaces helps to avoid distortion, which provides an explanation of why hexagonal surfaces are observed experimentally despite of being intrinsically unstable.
A periodic density functional study of the V, Fe, and Ni sublayer doped MgO(100) and BaO(100) sur... more A periodic density functional study of the V, Fe, and Ni sublayer doped MgO(100) and BaO(100) surfaces was carried out using a periodic approach in the context of the GGA approximation. Results suggest that doping atoms accommodate better in the MgO than in BaO because covalent radii of the doping atoms are closer to that of the Mg atom. Sizes of the doping atom, bulk forces, and electronic effects play an important role in the structural changes observed in doped surfaces studied herein. From all the doped studies, Ni doped Ba(100) surface is shown to be a promising material for trapping molecules with partially occupied states.
The electronic, adsorption and structural properties of a layered coordination polymer (CP), the ... more The electronic, adsorption and structural properties of a layered coordination polymer (CP), the {[Cu(3,4-pvb)2]·x(dmf)·y(H2O)}n (x=4; y=0 or x=3.5; y=1), formed by the coordination of {3-[2-(4-pyridyl)vinyl]}benzoate (3,4-pvb-) to copper(II), was studied...
Journal of Computational Methods in Sciences and Engineering, 2009
ABSTRACT Quantum chemistry calculations were carried out, using density functional theory, in ord... more ABSTRACT Quantum chemistry calculations were carried out, using density functional theory, in order to investigate the thermodynamic properties, enthalpy (ΔH), Gibbs free energy (ΔG) and equilibrium constant (K$_{eq}$), for the dissociation of a series of methylmercury series compounds. Two kind of pseudopotentials were studied, the relativistic compact effective potentials and the Stuttgart pseudopotential. The B3LYP, BLYP, BP86 and BMK functionals were employed. The calculations were performed in gas phase and in presence of solvent. The results reveal that, none of the studied functionals was able to reproduce the experimental C-Hg and Hg-X, X=Cl, Br and I bond distances. The presence of solvent, water, acetonitrile and dimethylsulfoxide, has a strong influence on the ΔH and ΔG values. On the other hand, the results show that there is a lineal correlation between the logarithm of the experimental K$_{eq}$(exp) and the calculated K$_{eq}$(theo). This type of correlation could be useful in the resolution of problems related with the contamination by methylmercury compounds.
This chapter presents a brief review of the recent applications of the quantum chemical calculati... more This chapter presents a brief review of the recent applications of the quantum chemical calculations in the catalysis for renewable energy production. In this, an introductory vision about the use of ab initio calculations in the field of the renewable energies is presented. It is worth mentioning that the quantum chemistry field is an extensive area with many methodologies and theoretical approaches; therefore, to shed some light on the application of this area on the catalysis for renewable energy production, the chapter is divide into two sections according to the employed theoretical approximation, that is, the cluster model approach and the periodic approach. The first section describes the cluster model approximation, followed by a discussion of recent works in hydrogen storage, biodiesel and methanol conversion fields, and the second section describes the basic principles of the periodic approximation, basis set used in this approximation, and illustrative examples in the cat...
Abstract DFT periodic calculations were carried out in order to gain more insight in relation wit... more Abstract DFT periodic calculations were carried out in order to gain more insight in relation with the stability of the (0 0 1) and (1 0 0) surfaces of the hexagonal WO3. These surfaces display an uncommon instability which could be attributed to their high polarity and the intrinsic instability problems of the hexagonal phase. Indifferently of the slab thickness, the internal structure of the slabs suffers distortion even at levels of a total loss of the hexagonal phase structure. Stoichiometric and non-stoichiometric O reconstructions do not seem to be practical mechanisms to solve the instability problem of these surfaces, leaving only the partial frozen slabs an efficient way to model the hexagonal (0 0 1) and (1 0 0) surfaces. However, the surface energy of these surfaces is dependent of the optimized layers instead of the frozen ones. Results obtained for the CO adsorption on the (0 0 1) surface showed that a model with six layers and two internal layers frozen to the atomic position of the bulk structure is enough to reach the structural and energetic stability of the CO adsorption.
ONIOM(DFT:PM3) calculations were carried out to investigate and characterize possible acid sites ... more ONIOM(DFT:PM3) calculations were carried out to investigate and characterize possible acid sites of SAPO‐11 molecular sieve. Two functionals were employed: B3LYP and ωB97X‐D. This last functional includes dispersion effects that are absent in the former. Benzene, pyridine, and ammonia interaction energies as well as the OH stretching frequencies of the POH, SiOH, and bridged Si(OH)Al groups were used to characterize the acid sites. This work shows that the adsorption of benzene on the surface is as strong as the adsorptions inside main channel of SAPO‐11. Pyridine adsorption on the surface is weaker than the one corresponding to the main channel. NH3 molecule interacts strongly with all OH groups or acid sites present in SAPO‐11. Moreover, the results reveal that it is possible to adsorb two NH3 molecules at only one Brønsted site. The adsorption of the second NH3 molecule is energetically favorable mainly due to the hydrogen bond formation between the NH3 molecules. In general the ...
Computational and Theoretical Chemistry, May 1, 2019
Abstract The interaction of CO2, CO, H2O, N2, N2O and O2 with the isoreticular metal-organic fram... more Abstract The interaction of CO2, CO, H2O, N2, N2O and O2 with the isoreticular metal-organic frameworks [Co(bdc)(pz)]n and [Co(bdc)(bpy)]n was studied. The ONIOM (M06/6-31G(d)HF/6-31G(d)) was applied to determine the structural and thermodynamic changes produced by the interaction among these small molecules and the framework structures. All the calculated adsorption energies are in the range of van der Waals non-covalent interactions, both influenced by dipole-quadrupole and quadruple-quadrupole electrostatic forces as well as confinement effect due to the different cavity sizes. The Δ H ads values obtained for the adsorption of CO2, CO and N2O suggest that [Co(bdc)(pz)]n and [Co(bdc)(bpy)]n framework structures are potential materials for the capture of these gases at standard conditions, which [Co(bdc)(bpy)]n exhibits greater adsorptive selectivity of post-combustion CO2, with a CO2/N2 energy ratio around 150% higher than [Co(bdc)(pz)]n.
Abstract Water adsorption on the (001) and (100) surfaces of monoclinic and hexagonal WO3 was stu... more Abstract Water adsorption on the (001) and (100) surfaces of monoclinic and hexagonal WO3 was studied using a periodic DFT approach. The results showed that dissociation of water on these surfaces is less energetically favourable than molecular adsorption and such phenomenon is a consequence of surface deformations induced by OH groups. Water interacted stronger with the five-fold tungsten atoms of the hexagonal surfaces than with those atoms of the monoclinic surfaces. Nevertheless, adsorption energies are almost the same between both hexagonal and monoclinic surfaces when all available active surface sites were occupied by water molecules, that is, at the maximum water coverage. On monoclinic surfaces, water adsorption gradually became less stable as the coverage increased, but the opposite behaviour was observed with dissociative adsorption. On the (001) surfaces of the hexagonal structures, both molecular and dissociative adsorption became less stable as water coverage increased. On the other hand, on the (100) surface, dissociation was only observed at the maximum coverage. All surfaces remain hydrated at low temperatures; whereas at higher temperatures the most stable structures are the clean surfaces. Lastly, the formation of a monolayer of OH groups on hexagonal surfaces helps to avoid distortion, which provides an explanation of why hexagonal surfaces are observed experimentally despite of being intrinsically unstable.
A periodic density functional study of the V, Fe, and Ni sublayer doped MgO(100) and BaO(100) sur... more A periodic density functional study of the V, Fe, and Ni sublayer doped MgO(100) and BaO(100) surfaces was carried out using a periodic approach in the context of the GGA approximation. Results suggest that doping atoms accommodate better in the MgO than in BaO because covalent radii of the doping atoms are closer to that of the Mg atom. Sizes of the doping atom, bulk forces, and electronic effects play an important role in the structural changes observed in doped surfaces studied herein. From all the doped studies, Ni doped Ba(100) surface is shown to be a promising material for trapping molecules with partially occupied states.
The electronic, adsorption and structural properties of a layered coordination polymer (CP), the ... more The electronic, adsorption and structural properties of a layered coordination polymer (CP), the {[Cu(3,4-pvb)2]·x(dmf)·y(H2O)}n (x=4; y=0 or x=3.5; y=1), formed by the coordination of {3-[2-(4-pyridyl)vinyl]}benzoate (3,4-pvb-) to copper(II), was studied...
Journal of Computational Methods in Sciences and Engineering, 2009
ABSTRACT Quantum chemistry calculations were carried out, using density functional theory, in ord... more ABSTRACT Quantum chemistry calculations were carried out, using density functional theory, in order to investigate the thermodynamic properties, enthalpy (ΔH), Gibbs free energy (ΔG) and equilibrium constant (K$_{eq}$), for the dissociation of a series of methylmercury series compounds. Two kind of pseudopotentials were studied, the relativistic compact effective potentials and the Stuttgart pseudopotential. The B3LYP, BLYP, BP86 and BMK functionals were employed. The calculations were performed in gas phase and in presence of solvent. The results reveal that, none of the studied functionals was able to reproduce the experimental C-Hg and Hg-X, X=Cl, Br and I bond distances. The presence of solvent, water, acetonitrile and dimethylsulfoxide, has a strong influence on the ΔH and ΔG values. On the other hand, the results show that there is a lineal correlation between the logarithm of the experimental K$_{eq}$(exp) and the calculated K$_{eq}$(theo). This type of correlation could be useful in the resolution of problems related with the contamination by methylmercury compounds.
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