Surface acidity and basicity of oxide catalysts: From aqueous suspensions to in situ measurements

Glazneva, Tatiana S.; Kotsarenko, N. S.; Paukshtis, E. A.

doi:10.1134/s0023158408060104

Cited by 62 publications

(30 citation statements)

References 48 publications

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“…Figures 8 and 9 show the IR spectra of pure γ Al 2 O 3 samples the same samples containing 10 mol % silica, both calcined at 550 and 800°С, in the region of the stretching vibrations of OH groups. The same set of hydroxyl groups was present in the spectra of the γ Al 2 O 3 sample: four types of bridging groups charac terized by the absorption bands ν(OН) at 3670, 3685, 3700, and 3730 cm -1 and three types of terminal groups characterized by absorption bands at 3750, 3775, and 3792 cm -1 [23,24]. An increase in the tem perature leads to a decrease in the intensity of all types of absorption bands due to OH groups.…”

Section: Resultsmentioning

confidence: 99%

Effect of silica on the stability of the nanostructure and texture of fine-particle alumina

et al. 2012

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The effect of the modification of aluminum oxide with silicon oxide on the stability of fine parti cle γ and δ Al 2 O 3 phases upon heat treatment in the wide temperature range of 550-1500°C was studied. It was found that the γ and δ Al 2 O 3 phases modified with silica are thermally stable up to higher temperatures than pure aluminum oxide. This is due to changes in the real structure of the modified samples, specifically, an increase in the concentration of extensive defects stabilized by hydroxyl groups bound to not only alumi num atoms but also silicon atoms. It is likely that Si-OH groups, which are thermally more stable than Al⎯OH groups, stabilize the microstructure of γ and δ Al 2 O 3 to higher temperatures, as compared with alu minum oxide containing no additives. Simultaneously, an increase in the thermal stability of the modified samples is accompanied by the retention of a high specific surface area and a developed pore structure at higher treatment temperatures.

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Section: Resultsmentioning

confidence: 99%

Effect of silica on the stability of the nanostructure and texture of fine-particle alumina

et al. 2012

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“…Among the catalysts, Pd/HZSM-5-15 showed the largest total acidity. It is known that acid sites are created by incorporating Al into the framework of HZSM-5 [25,26]. Therefore, it can be inferred that total acidity of Pd/HZSM-5-X catalysts increased with increasing the amount of Al incorporated into the framework of HZSM-5.…”

Section: Effect Of Acid Additive On the Catalytic Performancementioning

confidence: 97%

“…Among the catalysts, Pd/HZSM-5-30 showed the highest B/L ratio. It is known that Brönsted acid site of HZSM-5 is attributed to bridging hydroxyl group in Si-OH-Al linkage [25,26]. It has also been reported that Lewis acid site of HZSM-5 is formed on the Al in hydroxoaluminum complex [25].…”

Section: Acid Property Of the Catalystsmentioning

confidence: 97%

Direct synthesis of hydrogen peroxide from hydrogen and oxygen over Pd/HZSM-5 catalysts: Effect of Brönsted acidity

Park

Lee

Song

et al. 2012

Journal of Molecular Catalysis A: Chemical

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“…45,100,171,[246][247][248][249] When water is used in a heterogeneous system, the intrinsic properties of the catalyst surface could be modified due to solvation effects, 178 with the concomitant modification of its catalytic activity. The are several theories and explanations about the effects of using polar protic solvents, such as water, on the catalyst surface: generation of a Brønsted site from the reaction of OH from water (Lewis base) with a Lewis site (M n+ ) 250 ; transformation of Brønsted sites into Lewis sites, and competition of water with basic probe molecules for both types of acid sites. 251 These molecules, such as pyridine, trimethylphosphine, acetone, acetonitrile, are frequently used to distinguish acidic and not acidic surface OH groups, and to characterize the accessibility and strength of Brønsted acid sites.…”

Section: Effect Of the Solventmentioning

confidence: 99%

The challenge of converting biomass polysaccharides into levulinic acid through heterogeneous catalytic processes

Covinich

Clauser

Felissia

et al. 2019

Biofuels Bioprod Bioref

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The differences between a biorefinery and an oil refinery are determined by the higher oxygen content of the biorefinery's biomass, its high degree of functionalization, its low thermal stability, its polar components, which are mostly acidic, its highly heterogeneous structure, and its quality variation as result of genotypic and phenotypic characteristics. Levulinic acid (LA) is one of the main high value‐added chemicals that can be produced from lignocellulosic biomass as raw material. The main challenges for the conversion of lignocellulosic biomass to levulinic acid are related to the improvement of the technologies to obtain a pure and cost‐competitive product, the design and use of efficient heterogeneous catalysts, and the improvements in the selectivity and useful life of the catalyst. This is an up‐to‐date review of the state of knowledge about the heterogeneous catalytic conversion of biomass into LA, addressing the technical hurdles that impede the attainment of high yields. This work outlines the chemistry of LA synthesis and discusses in detail the influence of the lignocellulosic raw material, reaction time, temperature, solvent according to the chemical pathway, and efficiency of the chosen Lewis and Brønsted solid acid catalysts. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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Surface acidity and basicity of oxide catalysts: From aqueous suspensions to in situ measurements

Cited by 62 publications

References 48 publications

Effect of silica on the stability of the nanostructure and texture of fine-particle alumina

Effect of silica on the stability of the nanostructure and texture of fine-particle alumina

Direct synthesis of hydrogen peroxide from hydrogen and oxygen over Pd/HZSM-5 catalysts: Effect of Brönsted acidity

The challenge of converting biomass polysaccharides into levulinic acid through heterogeneous catalytic processes

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