In situ IR spectroscopy for developing catalysts and catalytic processes

Lercher, Johannes A.; Veefkind, Victor A.; Fajerwerg, Katia

doi:10.1016/s0924-2031(98)00094-0

Cited by 27 publications

(12 citation statements)

References 40 publications

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“…In situ FTIR technology is a crucial tool for investigation of the local interactions between the active sites and molecular CO 2 , in which the asymmetric stretching mode of CO 2 ( ν 3 =2349 cm −1 ) is infrared active and thus serves as a handle for identifying the nature of the adsorption behavior. As shown in Figure S23 (Supporting Information), infrared spectra collected from a blank sample in a CO 2 atmosphere exhibit a strong peak centered at 2334 cm −1 , which is attributed to the ν 3 band of CO 2 . In the case of MOF‐525‐Co, the adsorption of CO 2 onto the exposed Co II adsorption sites resulted in a 31 cm −1 red shift of the ν 3 band because of the electron donation from the oxygen lone pairs on CO 2 to the unoccupied Co II orbitals.…”

Section: Figurementioning

confidence: 99%

Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework

et al. 2016

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Modular optimization of metal–organic frameworks (MOFs) was realized by incorporation of coordinatively unsaturated single atoms in a MOF matrix. The newly developed MOF can selectively capture and photoreduce CO2 with high efficiency under visible‐light irradiation. Mechanistic investigation reveals that the presence of single Co atoms in the MOF can greatly boost the electron–hole separation efficiency in porphyrin units. Directional migration of photogenerated excitons from porphyrin to catalytic Co centers was witnessed, thereby achieving supply of long‐lived electrons for the reduction of CO2 molecules adsorbed on Co centers. As a direct result, porphyrin MOF comprising atomically dispersed catalytic centers exhibits significantly enhanced photocatalytic conversion of CO2, which is equivalent to a 3.13‐fold improvement in CO evolution rate (200.6 μmol g−1 h−1) and a 5.93‐fold enhancement in CH4 generation rate (36.67 μmol g−1 h−1) compared to the parent MOF.

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Section: Figurementioning

confidence: 99%

Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework

et al. 2016

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“…To further validate the source of the generated CO and CH 4 products,anisotopic experiment using 13 CO 2 as substrate was performed under identical photocatalytic reaction conditions,a nd the products were analyzed by gas chromatography and mass spectra. As shown in Figure S22 (Supporting Information), the peak at m/Z = 29 and m/Z = 17 could be assigned to 13 CO and 13 CH 4 ,respectively,indicating that the carbon source of CO and CH 4 does indeed originate from the CO 2 used.…”

mentioning

confidence: 96%

“…As shown in Figure S23 (Supporting Information), infrared spectra collected from ab lank sample in aC O 2 atmosphere exhibit astrong peak centered at 2334 cm À1 ,which is attributed to the n 3 band of CO 2 . [13] In the case of MOF-525-Co,the adsorption of CO 2 onto the exposed Co II adsorption sites resulted in a3 1cm À1 red shift of the n 3 band because of the electron donation from the oxygen lone pairs on CO 2 to the unoccupied Co II orbitals.T he enhanced CO 2 adsorption activity over MOF-525-Co and MOF-525-Zn, as well as the in situ FTIR spectra, reveal the strong interaction between molecular CO 2 and adsorption sites,and also demonstrate the integration of the active centers and reagents adsorption sites. Therefore,e nhanced CO 2 reduction activity can be guaranteed with the implantation of metal ions in the porphyrin moiety.…”

mentioning

confidence: 99%

Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework

et al. 2016

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Modular optimization of metal-organic frameworks (MOFs) was realized by incorporation of coordinatively unsaturated single atoms in a MOF matrix. The newly developed MOF can selectively capture and photoreduce CO with high efficiency under visible-light irradiation. Mechanistic investigation reveals that the presence of single Co atoms in the MOF can greatly boost the electron-hole separation efficiency in porphyrin units. Directional migration of photogenerated excitons from porphyrin to catalytic Co centers was witnessed, thereby achieving supply of long-lived electrons for the reduction of CO molecules adsorbed on Co centers. As a direct result, porphyrin MOF comprising atomically dispersed catalytic centers exhibits significantly enhanced photocatalytic conversion of CO , which is equivalent to a 3.13-fold improvement in CO evolution rate (200.6 μmol g h ) and a 5.93-fold enhancement in CH generation rate (36.67 μmol g h ) compared to the parent MOF.

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“…For the case of heterogeneous catalysts, special techniques have been developed that allow the observation of the catalytically active surface. [17][18][19][20][21] But most of these techniques require special measuring conditions which deviate considerably from those of the catalyst in its working state. The difference between the conditions for spectroscopy and the high pressures in SCF processes can be compared to the situation known as ''pressure gap.''…”

Section: Introductionmentioning

confidence: 99%

High pressure view-cell for simultaneous in situ infrared spectroscopy and phase behavior monitoring of multiphase chemical reactions

Schneider

Grunwaldt

Bürgi

et al. 2003

Review of Scientific Instruments

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A new type of high pressure spectroscopy view-cell for investigation of multiphase reactions is presented. It allows visual observation of the reaction mixture at conditions up to 200°C and 200 bar. Measurements of the reactor cell's upper part by transmission spectroscopy with variable path length and of the cell's bottom part by attenuated total reflection ͑ATR͒ spectroscopy can be performed quasi-simultaneously. By coating the internal reflection element with a catalyst film, in situ investigations of heterogeneous catalysts can be performed. The potential of this new experimental setup is demonstrated using examples of heterogeneous and homogeneous catalytic reactions. For the heterogeneously catalyzed hydrogenation of ethyl pyruvate over Pt/Al 2 O 3 in ''supercritical'' ethane the reaction progress could be monitored by spectroscopic investigation of the fluid phase. Quantitative evaluation of the spectra combined with digital imaging of the reaction mixture allowed simultaneous determination of phase behavior and reaction kinetics. ATR-IR spectra of the catalyst film could be measured at the same time. In the homogeneously catalyzed formylation of morpholine with ''supercritical'' carbon dioxide and hydrogen, not only number and nature, but also the composition of the different phases could be determined. The catalyst was found to be confined to the liquid phase. Although the aim of these preliminary studies was to test the functionality of the new cell, already significant new insight on the investigated catalytic reactions could be gained.

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In situ IR spectroscopy for developing catalysts and catalytic processes

Cited by 27 publications

References 40 publications

Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework

Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework

Efficient Visible‐Light‐Driven Carbon Dioxide Reduction by a Single‐Atom Implanted Metal–Organic Framework

High pressure view-cell for simultaneous in situ infrared spectroscopy and phase behavior monitoring of multiphase chemical reactions

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