Photoreduction of Carbon Dioxide to Formic Acid, Formaldehyde, Methanol, Acetaldehyde and Ethanol Using Aqueous Suspensions of Strontium Titanate with Transition Metal Additives

Ulman, M.; Tinnemans, A. H. A.; Mackor, A.; Aurian-Blajeni, B.; Halmann, M.

doi:10.1080/01425918208909887

Cited by 49 publications

(18 citation statements)

References 7 publications

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“…Assuming the possibility of reactions (2) and (2a) occurring simultaneously, reaction (2a) would be much slower than reaction (2). The second distinct change in reaction rate could be caused by the completion of reaction (2) while the slower reduction (2a) is still going on.…”

Section: Discussionmentioning

confidence: 99%

Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen

et al. 2000

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The isothermal reduction of synthetic CoTiO 3 and NiTiO 3 in hydrogen (1 atm) was investigated using thermogravimetric analysis technique in the temperature range, 928-1287 K (CoTiO 3 ) and 884-1387 K (NiTiO 3 ). Shallow beds of fine titanate powders were reduced by hydrogen at a high flow rate. Quenched samples were analyzed by scanning electron microscopy. The rates of the reaction of the titanates with H 2 were very fast during the reduction of Co 2+ , Ni 2+ , or Fe 2+ ions into metals. The reduction of the remaining titanium oxide was very slow. The activation energy for the reduction of CoTiO 3 by hydrogen to Co and TiO 2 was evaluated to be 151 ± 1 kJ/mol, and the activation energy for the reduction of NiTiO 3 by hydrogen to Ni and TiO 2 was evaluated to be 153 ± 1 kJ/mol. The study was complemented by hydrogen reduction of synthetic TiO 2 (rutile). The results were also compared with the hydrogen reduction of FeTiO 3 .

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Section: Discussionmentioning

confidence: 99%

Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen

et al. 2000

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“…Formic acid, formaldehyde, methanol, acetaldehyde and ethanol were analyzed as previously described [34].…”

Section: Methodsmentioning

confidence: 99%

Photoassisted Reduction of Carbon and Nitrogen Compounds with Semiconductors

Halmann

Zuckerman

1986

Homogeneous and Heterogeneous Photocatalysis

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ABSTRACT. The conversion of visible light into the stored energy of chemical fuel was studied, using semiconductors as photosensi tizers. The reactions investigated were the reduction of carbonate ions to organic compounds and of nitrogen oxyanions to ammonia. Using suspensions of CdS, ZnS-CdS or Ti0 2 in 1M KOH and O.lM Na 2 S at 61 0 C, illuminated with a 150W Xe-Ia~~, w~!ound that there was a slow release of ammonia, 0.014 micromol h cm (illuminated area) which was the same whether the mixture was purged with argon or nitrogen gas. Addition of 0.2M potassium nitrate did not change the rate of release of ammonia. However, addition of potassium ni tri te caused a marked increase in the rate of production of ammonia. Using O. 13M potassium nitrite in 1M KOH, O.lM sodium ~ulfide at 61 0 C, the production rate of ammonia was 0.97 micromol/(h cm ) in th~ presence of Ti0 2 (70mg in 70ml reaction solution), 0.60 micromol/(h cm ~ in the presence of CdS (same concentration), and 0.55 micromol/(h cm ) in the presence of ZnS-CdS (70mg -50mg mixture). In the absence of sodium sulfide, and if sodium sulfite was substituted for sodium sulfide, the above photoassisted reduction of nitrite ions to ammonia was negligible. Also, there was no reaction in the dark. With CdS -ZnS in 0.5M potassium carbonate -O.lM sodium sulfide, illumination caused th:'9 producti2~ of ammoni~~ methanol a~d formaldehyde, at rates of 7.1xl0 ,1.5xl0 and 0.2xl0 mol h-cm-, respectively.

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“…A number of photo-active systems, some with the ability to convert reactants, including CO 2 and H 2 O, to compounds with greater enthalpy, emerged as a result of a number of papers in the late 1970s and early 1980s [2][3][4], Inoue et al, Hemminger et al, and Halmann et al [2,4,5]. reported the conversion of CO 2 and H 2 O to formic acid, formaldehyde, methanol and methane over a number of different semiconductors, including SrTiO 3 , TiO 2 and SiC.…”

Section: Introductionmentioning

confidence: 98%

Mechanistic and Adsorption Studies of Relevance to Photocatalysts on Titanium Grafted Mesoporous Silicalites

2011

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Ti-SBA-15 and Ti-MCM-41 were synthesized and evaluated as possible photocatalysts for the reduction of CO 2 , and for the photo-Kolbe decomposition of acetic acid. UV-Raman was used to study the adsorption of carbon dioxide, water, formic acid, and acetic acid over Ti-MCM-41 by monitoring the UV enhanced resonance peak of the totally symmetric stretching band of the grafted Ti species at 1,085 cm -1 . Acetic and formic acid dissociate on Ti-SBA-15 and Ti-MCM-41 to form acetate and formate, respectively. The conjugate bases subsequently interact strongly with Ti sites. Water interacts with the Ti sites, while no change in the amplitude of the 1,085 cm -1 band is observed in the presence of CO 2 . Photocatalysis experiments indicate that these mesoporous silicalites are active in the photo-Kolbe decomposition of acetic acid. CO 2 is formed by reaction of a hole with the acetate carboxylate groups. The methyl radical co-products react with a surface proton and an electron to form methane. No products resulting from the dimerization of methyl radicals are observed, presumably because of the highly dispersed active sites.

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Photoreduction of Carbon Dioxide to Formic Acid, Formaldehyde, Methanol, Acetaldehyde and Ethanol Using Aqueous Suspensions of Strontium Titanate with Transition Metal Additives

Cited by 49 publications

References 7 publications

Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen

Intrinsic reduction kinetics of cobalt- and nickel-titanates by hydrogen

Photoassisted Reduction of Carbon and Nitrogen Compounds with Semiconductors

Mechanistic and Adsorption Studies of Relevance to Photocatalysts on Titanium Grafted Mesoporous Silicalites

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