The thermal decomposition of alkali metal formates

Meisel, T.; Halmos, Z.; Seybold, K.; Püngor, E.

doi:10.1007/bf01911627

Cited by 57 publications

(51 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The decomposition of unsupported bulk alkali metal formates normally takes place at temperatures above 573 K [36]. The formate ions in the condensed liquid present in our catalysts decompose on Pd to give hydrogen and CO2 at much lower reaction temperature (333-353 K).…”

Section: Discussionmentioning

confidence: 93%

Hydrogen production from formic acid vapour over a Pd/C catalyst promoted by potassium salts: Evidence for participation of buffer-like solution in the pores of the catalyst

Liu

Bulushev

Beloshapkin

et al. 2014

Applied Catalysis B: Environmental

View full text Add to dashboard Cite

(D.A. Bulushev) 2 A B S T R A C T Doping a 1 wt.% Pd/C catalyst with alkali metal carbonates has a very significant promotional effect on its activity in hydrogen production from the decomposition of formic acid vapour (2 vol.%, 1 bar), potassium and caesium carbonates giving the largest effects. The K carbonate species present on the fresh catalysts react with formic acid to form formate ions, these being dissolved in a formic acid/water solution condensed in the pores of the support. The steadystate activities of the samples containing formate ions were 1-2 orders of magnitude greater than those of the unpromoted Pd/C and CO content was lower than 30 ppm. The activation energies for the reaction increased with doping from 66 to 88-99 kJ mol -1 , relatively independent of the cation of the dopant. Similar but lesser effects were found with unsupported Pd nanocrystals doped with K carbonate. The rate-determining step for the promoted samples appears to be the decomposition of formate ions on the Pd surface.

show abstract

Section: Discussionmentioning

confidence: 93%

Hydrogen production from formic acid vapour over a Pd/C catalyst promoted by potassium salts: Evidence for participation of buffer-like solution in the pores of the catalyst

Liu

Bulushev

Beloshapkin

et al. 2014

Applied Catalysis B: Environmental

View full text Add to dashboard Cite

show abstract

“…Shishido and Masuda (1971) also reported that metal ions such as Co, Ni, and Cu markedly catalyzed the decomposition of alkali formates to carbonates, reactions (38) and (39) rather than through oxalate. Meisel and Halmos (1971) studied the thermal decomposition of the C, to C, monobasic and the C, to C,, dibasic carboxylic acids (78) and Meisel et al (1975) studied the effects of variables on the relative amounts of oxalate or carbonate formed in the decomposition of alkali formates.…”

Section: 666)mentioning

confidence: 99%

Redox reaction and foaming in nuclear waste glass melting

Ryan¹

1995

View full text Add to dashboard Cite

SummaryFoaming has often been observed in experimental continuous liquid-fed, joule-heated, ceramic melters that produce simulated nuclear waste-containing borosilicate glass. Such foaming, which results in significantly decreased melter throughput rates, has been attributed to the release of 9 gas resulting from the decomposition of higher valency metal oxides to lower valency oxides. It has been claimed that this foaming can best be controlled by adding reducing agents to the melter feed. In particular, the use of formic acid has been proposed to 1) acidify the aqueous waste stream, thereby dissolving some of the hydrous oxides and improving feed rheology, and 2) act as a reducing agent to control foaming. This document, prepared at Pacific Northwest Laboratory, reviews studies of nuclear waste glass foaming and the effects of reducing agents, particularly formic acid, on such foaming. It reviews the redox chemistry of many of the potential oxidizing and reducing species in or added to the glass-melter feed with the objective of predicting some of the chemistry that occurs in the cold cap and the glass melt as they might affect the foaming phenomenon. The review is not exhaustive since the literature search was limited by the complexity of the subject, and unknown effects on the chemistry, including various unknown catalytic effects, will certainly be important in such complex mixtures.Based on this review, little is actually known about the causes of or best remedies for foaming in the nuclear waste glass melters. The actual temperature regime (cold cap(a) plus melt) in the melter that is most important to the actual melter foaming is unknown. Workers have made widely different implicit assumptions in this regard. No evidence was found that adequate testing of proposed foaming remedies with well designed control experiments has been conducted in the glass melters.There is significant evidence based on run experience that, in the absence of added reductants, acidic feeds do not foam nearly as badly as alkaline feeds. Although alkaline feeds promote formation of higher oxidation state metal species in the cold cap, it is far from clear that easier formation of higher oxidation state metals causes the apparent greater foaming with alkaline feeds. The problem is that no run data were found in which only acidity or alkalinity were the significant variables.Based on the results of this review, there is strong question whether the varying degree of melter foaming is caused by different extents of decomposition of higher oxidation state metal oxides releasing O,, and whether this foaming can, therefore, be best controlled by adding reductants. This concept, while somewhat reasonable, must be proven with carefully designed experiments having virtually identical feeds with and without reductants in adequate quantity. These experiments must also compare other factors such as feed acidity-alkalinity with other variables held constant. Available laboratory data on the effect of reductants do not, for one reason or another...

show abstract

“…These peaks can be related with dehydration processes, as was observed for the thermal decomposition of M(HCOO) 2 ·2H 2 O (M = Co, Ni) [28,29] and LiHCOO. [30] According to the TG curves they correspond to the release of 1.5 and 2.7 mol H 2 O molecules from the Co and Ni precursor, respectively. Above 200°C, the decomposition of the formate species occurs, which is registered on the DTA curves with several endo-and exothermic effects.…”

Section: Resultsmentioning

confidence: 99%

Ordered Olivine‐Type Lithium–Cobalt and Lithium–Nickel Phosphates Prepared by a New Precursor Method

2010

View full text Add to dashboard Cite

Keywords: Lithium / Cobalt / Nickel / Organic-inorganic hybrid composites / X-ray diffraction Single phases of olivine-type LiCoPO 4 and LiNiPO 4 were synthesized by thermal treatment of homogeneous lithiummetal-phosphate-formate precursors obtained by freeze drying of aqueous solutions of the corresponding metal formates and LiH 2 PO 4 . The structure, thermal behavior, and morphology of the precursors were studied by IR spectroscopy, DTA, and SEM. Cobalt and nickel phosphate-formate precursors have a composition LiMH x (PO 4 )(HCOO) x ·yH 2 O, where the formate and phosphate groups are mainly deprotonated. For the Co precursor the formate and phosphates ions are randomly coordinated to both Co and Li cations, whereas for the Ni precursor there is a preferential coordina-

show abstract

The thermal decomposition of alkali metal formates

Cited by 57 publications

References 7 publications

Hydrogen production from formic acid vapour over a Pd/C catalyst promoted by potassium salts: Evidence for participation of buffer-like solution in the pores of the catalyst

Hydrogen production from formic acid vapour over a Pd/C catalyst promoted by potassium salts: Evidence for participation of buffer-like solution in the pores of the catalyst

Redox reaction and foaming in nuclear waste glass melting

Ordered Olivine‐Type Lithium–Cobalt and Lithium–Nickel Phosphates Prepared by a New Precursor Method

Contact Info

Product

Resources

About