Infrared study of hydroxyls on active CaO

Low, M. J. D.; Takezawa, Nobotsume; Goodsel, A. J.

doi:10.1016/0021-9797(71)90310-9

Cited by 32 publications

(32 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The broadening below 2700 cm -1 was previously explained as indicative of the presence of defect O 2sites. As the distance between "free" deuteroxide species is too great for hydrogen bonding to occur, there should be intermittent defects to facilitate hydrogen bonding induced broadening of the band due to the OH or OD stretching mode (Low et al, 1971). Therefore the presence of broadening indicates the formation of highly reactive surface sites when Ca(OH)2 is calcined.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Surface and bulk carbonate formation in calcium oxide during CO2 capture

2017

View full text Add to dashboard Cite

Calcium looping (CaL), the cyclic carbonation and calcination of limestone, is a prominent carbon capture option considering reduced parasitic energy consumption compared to amine scrubbing. The main issue preventing application is sorbent performance decay during cycling. Therefore hydration and extended carbonation reactivation strategies, as well as synthetic approaches to enhance or sustain reactivity, are of interest. Results of an investigation are presented on the impact of reactivation strategies on carbonate formation through detailed study using in-situ infrared spectroscopy. Surface and bulk carbonate formation regimes were readily distinguished allowing the influence of temporal, hydration and thermodynamic conditions within each regime to be studied. Surface chemistry of CaO during two initial cycles was shown to change. Significantly, it was shown that the CaO surface produced from the calcination of Ca(OH)2 possessed more highly reactive sites compared to the surface produced from CaCO3. The presence of water enhanced bulk carbonate formation at 300 °C and influenced the complexation of surface carbonates during looping. The results are of interest in the CaL community, offering molecular scale explanations for macroscale observations, whilst also informing on the role of humidity in direct air capture and sorption enhanced reaction processes.

show abstract

Section: Discussionmentioning

confidence: 99%

“…The broad band at 2636 cm -1 was due to physisorbed D2O. All assignments were taken from Low et al, 1971. Upon subsequent CO2 exposure (Figure 4b & d) bands due to surface carbonate species were observed.…”

Section: In-situ Ftirmentioning

confidence: 99%

Surface and bulk carbonate formation in calcium oxide during CO2 capture

2017

View full text Add to dashboard Cite

show abstract

“…70 Further oxidation to Mo(IV) was observed at 773 K, methane and small quantities of CO 2 were given off besides hydrogen. If, however, dehydroxylated alumina (pre-treatment at 1220 K) is used, mainly metallic molybdenum is formed at 1220 K in a helium atmosphere.…”

Section: ° Nhetmentioning

confidence: 98%

Nature and Estimation of Functional Groups on Solid Surfaces

Boehm

Knözinger

1983

Catalysis

View full text Add to dashboard Cite

“…Spectroscopic signals from dissociated and intact water molecules on many metal oxide surfaces have been presented in the literature over the years (see, for example, ref. [1][2][3][4][5][6][7][8][9] and here vibrational and electron spectroscopies have emerged as being especially informative. Thus, recently, some of the seemingly most simple and prototypic water/oxide systems, such as H 2 O/MgO(100), 2,3 H 2 O/CaO(100), 5,6 H 2 O/ZnO(10% 10) 8 and H 2 O/rutile-TiO 2 (110), 9 have been targets of vibrational spectroscopic studies of various flavors such as IRRAS (Infrared reflectionabsorption spectroscopy), SFG (sum-frequency generation), and FTIR (Fourier transform Infra-red) spectroscopy with an ATR (attenuated internal total reflection) device.…”

Section: Introductionmentioning

confidence: 99%

Red-shifting and blue-shifting OH groups on metal oxide surfaces – towards a unified picture

Kebede

Mitev

Briels

et al. 2018

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

We analyse the OH vibrational signatures of 56 structurally unique water molecules and 34 structurally unique hydroxide ions in thin water films on MgO(001) and CaO(001), using DFT-generated anharmonic potential energy surfaces. We find that the OH stretching frequencies of intact water molecules on the surface are always downshifted with respect to the gas-phase species while the OH- groups are either upshifted or downshifted. Despite these differences, the main characteristics of the frequency shifts for all three types of surface OH groups (OHw, OsH and OHf) can be accounted for by one unified expression involving the in situ electric field from the surrounding environment, and the gas-phase molecular properties of the vibrating species (H2O or OH-). The origin behind the different red- and blueshift behaviour can be traced back to the fact that the molecular dipole moment of a gas-phase water molecule increases when an OH bond is stretched, but the opposite is true for the hydroxide ion. We propose that familiarity with the relations presented here will help surface scientists in the interpretation of vibrational OH spectra for thin water films on ionic crystal surfaces.

show abstract

Infrared study of hydroxyls on active CaO

Cited by 32 publications

References 7 publications

Surface and bulk carbonate formation in calcium oxide during CO2 capture

Surface and bulk carbonate formation in calcium oxide during CO2 capture

Nature and Estimation of Functional Groups on Solid Surfaces

Red-shifting and blue-shifting OH groups on metal oxide surfaces – towards a unified picture

Contact Info

Product

Resources

About