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At least 19 records

Adsorption of O2, SO2, and SO3, on nickel oxide - Mechanism for sulfate formation

Calculations based on the atom superposition and electron delocalization molecular orbital technique suggest that O2 will adsorb preferentially end-on at an angle 45 deg from normal on a nickel cation site on the (100) surface of NiO. SO2 adsorption is also stronger on the nickel site; SO2 bonds through the sulfur atom in a plane perpendicular to the surface. Adsorption energies for SO3 on the nickel and oxygen sites are comparable in the preferred orientation in which the SO3 plane is parallel to the surface. The calculations suggest that the strength of adsorption varies as O2 greater than SO2 greater than SO3. On activation, SO3 adsorbed to an O(2-) site forms a trigonal pyramidal SO4 species which yields, with a low barrier, a tetrahedral sulfate anion. Subsequently the anion reorients on the surface. Alternative mechanisms which require the formation of Ni(3+) or O(-) are discussed. NiSO4 thus formed may play a passivating role for the corrosion of Ni at low temperatures in the SO2 + O2 + SO3 atmospheres and an active role at high temperatures, as discussed in the experimental literature.

Mehandru, S. P.↗

Properties of Gaseous Deprotonated L-Cysteine S-Sulfate Anion [cysS-SO3]−: Intramolecular H-Bond Network, Electron Affinity, Chemically Active Site, and Vibrational Fingerprints

L-cysteine S-sulfate, Cys-SSO3H, and their derivatives play essential roles in biological chemistry and pharmaceutical synthesis, yet their intrinsic molecular properties have not been studied to date. In this contribution, the deprotonated anion [cysS-SO3]− was introduced in the gas phase by electrospray and characterized by size-selected, cryogenic, negative ion photoelectron spectroscopy. The electron affinity of the [cysS-SO3]• radical was determined to be 4.95 ± 0.10 eV. In combination with theoretical calculations, it was found that the most stable structure of [cysS-SO3]− (S1) is stabilized via three intramolecular hydrogen bonds (HBs); i.e., one O-H……N between the -COOH and -NH2 groups, and two N-H……O HBs between -NH2 and -SO3, in which the amino group serves as both HB acceptor and donor. In addition, a nearly iso-energetic conformer (S2) with the formation of an O-H……N-H……O-S chain-type binding motif competes with S1 in the source. The most reactive site of the molecule susceptible for electrophilic attacks is the linkage S atom. Theoretically predicted infrared spectra indicate that O-H and N-H stretching modes are the fingerprint region (2800 to 3600 cm−1) to distinguish different isomers. The obtained information lays out a foundation to better understand the transformation and structure–reactivity correlation of Cys-SSO3H in biologic settings.

74 ATOMIC AND MOLECULAR PHYSICS↗

Materials Data on NaH12AuC4(SO3)4 by Materials Project

NaAuC2H6(SO3)4(CH3)2 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of two methane molecules and one NaAuC2H6(SO3)4 sheet oriented in the (0, 0, 1) direction. In the NaAuC2H6(SO3)4 sheet, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent SCO3 tetrahedra. There are a spread of Na–O bond distances ranging from 2.40–2.60 Å. Au3+ is bonded in a square co-planar geometry to four O2- atoms. All Au–O bond lengths are 2.04 Å. C4+ is bonded in a trigonal non-coplanar geometry to three H1+ and one S2- atom. There is one shorter (1.09 Å) and two longer (1.10 Å) C–H bond length. The C–S bond length is 1.77 Å. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the second H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded to one C4+ and three O2- atoms to form distorted SCO3 tetrahedra that share a cornercorner with one NaO6 octahedra. The corner-sharing octahedral tilt angles are 19°. There is two shorter (1.45 Å) and one longer (1.57 Å) S–O bond length. In the second S2- site, S2- is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There is two shorter (1.45 Å) and one longer (1.56 Å) S–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to one Na1+ and one S2- atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Au3+ and one S2- atom. In the third O2- site, O2- is bonded in a bent 120 degrees geometry to one Au3+ and one S2- atom. In the fourth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Na1+ and one S2- atom. In the fifth O2- site, O2- is bonded in a single-bond geometry to one S2- atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and one S2- atom.

36 MATERIALS SCIENCE↗

Adsorption of O2, SO2, and SO3 on nickel oxide. Mechanism for sulfate formation

Calculations based on the atom superposition and electron delocalization molecular orbital (ASED-MO) technique suggest that O2 will adsorb perferentially end-on at an angle 45 deg from normal on a nickel cation site on the (100) surface of NiO. SO2 adsorption is also stronger on the nickel site; SO2 bonds through the sulfur atom is a plane perpendicular to the surface. Adsorption energies for SO3 on the nickel and oxygen sites are comparable in the perferred orientation in which the SO3 plane is parallel to the surface. On activation, SO3 adsorbed to an O2(-) site forms a trigonal pyramidal SO4 species which yields, with a low barrier, a tetrahedral sulfate anion. Subsequently the anion reorients on the surface. Possibilities for alternative mechanisms which require the formation of Ni3(+) or O2(-) are discussed. NiSO4 thus formed leads to the corrosion of Ni at high temperatures in the SO2+O2/SO3 The SO2+O2/SO3 atmosphere, as discussed in the experimental literature.

Mehandru, S. P.↗

Ceramic oxide reactions with V2O5 and SO3

Ceramic oxides are not inert in combustion environments, but can react with, inter alia, SO3, and Na2SO4 to yield low melting mixed sulfate eutectics, and with vanadium compounds to produce vanadates. Assuming ceramic degradation to become severe only when molten phases are generated in the surface salt (as found for metallic hot corrosion), the reactivity of ceramic oxides can be quantified by determining the SO3 partial pressure necessary for molten mixed sulfate formation with Na2SO3. Vanadium pentoxide is an acidic oxide that reacts with Na2O, SO3, and the different ceramic oxides in a series of Lux-Flood type of acid-base displacement reactions. To elucidate the various possible vanadium compound-ceramic oxide interactions, a study was made of the reactions of a matrix involving, on the one axis, ceramix oxides of increasing acidity, and on the other axis, vanadium compounds of increasing acidity. Resistance to vanadium compound reaction increased as the oxide acidity increased. Oxides more acidic than ZrO2 displaced V2O5. Examination of Y2O3- and CeO2-stabilized ZrO2 sintered ceramics which were degraded in 700 C NaVO3 has shown good agreement with the reactions predicted above, except that the CeO2-ZrO2 ceramic appears to be inexplicably degraded by NaVO3.

Jones, R. L.↗

Materials Data on Tl2Cu(SO3)2 by Materials Project

CuTl2(SO3)2 crystallizes in the monoclinic Cm space group. The structure is two-dimensional and consists of one CuTl2(SO3)2 sheet oriented in the (0, 0, 1) direction. Cu2+ is bonded in an octahedral geometry to six O2- atoms. There are a spread of Cu–O bond distances ranging from 2.02–2.57 Å. There are two inequivalent Tl3+ sites. In the first Tl3+ site, Tl3+ is bonded in a 2-coordinate geometry to two equivalent O2- atoms. Both Tl–O bond lengths are 2.84 Å. In the second Tl3+ site, Tl3+ is bonded in a distorted bent 120 degrees geometry to two equivalent O2- atoms. Both Tl–O bond lengths are 2.84 Å. There are two inequivalent S2+ sites. In the first S2+ site, S2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.52 Å) and two longer (1.57 Å) S–O bond length. In the second S2+ site, S2+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There is one shorter (1.52 Å) and two longer (1.57 Å) S–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Cu2+, two equivalent Tl3+, and one S2+ atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one S2+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Cu2+, two equivalent Tl3+, and one S2+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Cu2+ and one S2+ atom.

36 MATERIALS SCIENCE↗

Materials Data on SO3 by Materials Project

SO3 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of two SO3 ribbons oriented in the (0, 1, 0) direction. S6+ is bonded to four O2- atoms to form corner-sharing SO4 tetrahedra. There are a spread of S–O bond distances ranging from 1.42–1.66 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent S6+ atoms. In the second O2- site, O2- is bonded in a single-bond geometry to one S6+ atom. In the third O2- site, O2- is bonded in a single-bond geometry to one S6+ atom.

36 MATERIALS SCIENCE↗

Infrared Absorption Spectra of H2SO4, SO3, SO2, and H2O at 300C and 350C

Mid infrared absorption spectra of sulfuric acid (H2SO4), sulfur trioxide (SO3), sulfur dioxide (SO2), and water (H2O) were collected in a high temperature gas cell operating at either 300C or 350C. The spectra were collected using tunable external cavity quantum cascade lasers (ECQCLs) tuning, which were capable of operating over the wavelength range from approximately 7 microns to 9 microns, where H2SO4 and SO3 have their strongest absorption features. The spectra can be used as a library for developing gas sensors.

infrared absorption↗

An experimental study of SO3 dissociation as a mechanism for converting and transporting solar energy

The high temperature catalytic dissocation of SO3 is an important chemical process being considered in the development and application of solar-thermal energy conversion, transport, and storage systems. A facility for evaluating chemical converter-heat exchangers at temperatures to 1000 C with high flow rates of gaseous SO3 feedstock has been assembled and operated on the NMSU campus. Several quartz and metal reactors containing different catalyst configurations have been tested. Descriptions of the test facility and of the reactors are given along with a presentation and discussion of experimental results.

Mccrary, J. H.↗

Reactions of NaCl with Gaseous SO3, SO2, and O2

Hot corrosion of gas turbine engine components involves deposits of Na2SO4 which are produced by reactions between NaCl and oxides of sulfur. For the present investigation, NaCl single crystals were exposed at 100 to 850 C to gaseous mixtures of SO3, SO2, and O2. The products formed during this exposure depend, primarily, on the temperatures. The four product films were: NaCl-SO3; Na2S2O7; Na2SO4; and NaCl-Na2SO4. The kinetics of the reactions were measured.

Fielder, W. L.↗

Reactions of NaCl with gaseous SO3, SO2, and O2

Hot corrosion of gas turbine engine components involves deposits of Na2SO4 which are produced by reactions between NaCl and oxides of sulfur. For the present investigation, NaCl single crystals were exposed at 100 to 850 C to gaseous mixtures of SO3, SO2, and O2. The products formed during this exposure depend, primarily, on the temperatures. The four product films were: NaCl-SO3; Na2S2O7; Na2SO4; and NaCl-Na2SO4. The kinetics of the reactions were measured.

Fielder, W. L.↗

Determination of the Rate Coefficients of the SO2 plus O plus M yields SO3 plus M Reaction

Rate coefficients of the title reaction R(sub 31) (SO2 +O+M yields SO3 +M) and R(sub 56) (SO2 + HO2 yields SO3 +OH), important in the conversion of S(IV) to S(VI),were obtained at T =970-1150 K and rho (sub ave) = 16.2 micro mol/cubic cm behind reflected shock waves by a perturbation method. Shock-heated H2/ O2/Ar mixtures were perturbed by adding small amounts of SO2 (1%, 2%, and 3%) and the OH temporal profiles were then measured using laser absorption spectroscopy. Reaction rate coefficients were elucidated by matching the characteristic reaction times acquired from the individual experimental absorption profiles via simultaneous optimization of k(sub 31) and k(sub 56) values in the reaction modeling (for satisfactory matches to the observed characteristic times, it was necessary to take into account R(sub 56)). In the experimental conditions of this study, R(sub 31) is in the low-pressure limit. The rate coefficient expressions fitted using the combined data of this study and the previous experimental results are k(sub 31,0)/[Ar] = 2.9 10(exp 35) T(exp ?6.0) exp(?4780 K/T ) + 6.1 10(exp 24) T(exp ?3.0) exp(?1980 K/T ) cm(sup 6) mol(exp ?2)/ s at T = 300-2500 K; k(sub 56) = 1.36 10(exp 11) exp(?3420 K/T ) cm(exp 3)/mol/s at T = 970-1150 K. Computer simulations of typical aircraft engine environments, using the reaction mechanism with the above k(sub 31,0) and k(sub 56) expressions, gave the maximum S(IV) to S(VI) conversion yield of ca. 3.5% and 2.5% for the constant density and constant pressure flow condition, respectively. Moreover, maximum conversions occur at rather higher temperatures (?1200 K) than that where the maximum k(sub 31,0) value is located (approximately 800 K). This is because the conversion yield is dependent upon not only the k(sup 31,0) and k(sup 56) values (production flux) but also the availability of H, O, and HO2 in the system (consumption flux).

Hwang, S. M.↗

Materials Data on ZnH6C2(SO3)2 by Materials Project

ZnC2H6(SO3)2 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Zn2+ is bonded in a distorted octahedral geometry to six O2- atoms. There are a spread of Zn–O bond distances ranging from 2.02–2.46 Å. There are two inequivalent C4+ sites. In the first C4+ site, C4+ is bonded in a trigonal non-coplanar geometry to two H1+ and one O2- atom. Both C–H bond lengths are 1.10 Å. The C–O bond length is 1.40 Å. In the second C4+ site, C4+ is bonded in a trigonal non-coplanar geometry to two H1+ and one O2- atom. Both C–H bond lengths are 1.10 Å. The C–O bond length is 1.41 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.65 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one C4+ atom. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted water-like geometry to two O2- atoms. There is one shorter (1.54 Å) and one longer (1.56 Å) S–O bond length. In the second S2- site, S2- is bonded in a distorted water-like geometry to two O2- atoms. There is one shorter (1.54 Å) and one longer (1.56 Å) S–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+ and one S2- atom. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one S2- atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Zn2+, one C4+, and one H1+ atom. In the fourth O2- site, O2- is bonded in a bent 120 degrees geometry to one Zn2+ and one S2- atom. In the fifth O2- site, O2- is bonded in a trigonal planar geometry to one Zn2+, one H1+, and one S2- atom. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to one Zn2+, one C4+, and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on NaTl3(SO3)2 by Materials Project

NaTl3(SO3)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Na1+ is bonded in an octahedral geometry to six equivalent O2- atoms. All Na–O bond lengths are 2.51 Å. There are two inequivalent Tl+2.33+ sites. In the first Tl+2.33+ site, Tl+2.33+ is bonded in a distorted q6 geometry to nine equivalent O2- atoms. There are six shorter (3.02 Å) and three longer (3.11 Å) Tl–O bond lengths. In the second Tl+2.33+ site, Tl+2.33+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Tl–O bond lengths are 2.97 Å. S2+ is bonded in a trigonal non-coplanar geometry to three equivalent O2- atoms. All S–O bond lengths are 1.55 Å. O2- is bonded in a 2-coordinate geometry to one Na1+, four Tl+2.33+, and one S2+ atom.

36 MATERIALS SCIENCE↗

Physical-chemical examination of the N2O3-SO3-H2O system

It was found that when (NO)HSO4 is added to absolute H2SO4, specific conductivity rises sharply, possibly due to an increase in mutual interionic effects and viscosity as the (NO)HSO4 concentration rises. The addition of SO3 to the solution yielded a precipitate; a combination of analysis, IR spectroscopy and X-ray diffraction techniques indicated that this precipitate was (NO)HS2O7.

Linstroem, C.↗

Inorganic chemistry: Direct syntheses from pure liquid SO3 and from trivalent and pentavalent nitrogen derivatives

From pure liquid SO3 direct synthesis reactions were carried out with N2O5, NO2Cl, NOCl which yielded N2O54SO3, 3SO3, 2SO3-NO2Cl2SO3-NOCl2SO3 and NOCl2SO3, the latter being obtained for the first time in the pure state. In all cases the crystallized product was obtained by separating the constituents of the mixture and then going through a single viscous liquid phase.

Vandorpe, B.↗

Effects of SO2 and SO3 on the Na2SO4 induced corrosion of nickel

The effects of SO2 and SO3 in the environment on the hot-corrosion behavior of Ni in the temperature range 750-950 C has been studied. Below the melting point of Na2SO4 (884 C), rapid corrosion takes place by formation of a Na2SO4-NiSO4 melt which can penetrate the porous oxide scale and give rise to sulfide information by coming in contact with the metal. The distribution of the sulfides depends on the SO2 level in the ambient gas. Continued corrosion occurs by a sulfidation-oxidation mechanism. At temperatures above the melting point of Na2SO4, accelerated degradation occurs via dissolution of the surface scale, followed by reprecipitation of the oxide in a nonprotective form.

Misra, A. K.↗

Materials Data on Sr4CaMn2(SO3)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗