Synthesis and characterization of potassium-modified alumina superbases

Wang, Ying; Zhu, Jian Hua; Huang, Wenyu

doi:10.1039/b100084p

Cited by 47 publications

(38 citation statements)

References 17 publications

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“…The desorption of CO 2 may restore the initial basic site, and as a result the temperature of the decomposition of carbonates may reflect, to some extent, the bond strength be- tween CO 2 and the basic site, or in other words, it may give insights to the basic strength of the surface sites. Following this concept, it appears from TPD profiles that the higher the carbonate loading the more sites of higher basic strength are formed on the surface, confirming the results found by Wang et al [30,38,40] It might be that a population of sites with appropriate basic strength is specifically involved in the reversible CO 2 sorption at 400 8C. In situ structural analysis and spectroscopic investigations were therefore carried out to identify rearrangements taking place in the sorbent under working conditions.…”

Section: Reversible Capacity and Carbonate Decompositionsupporting

confidence: 76%

“…Moreover, potassium carbonate promoted magnesium oxide showed only a very low reversible CO 2 -adsorption capacity compared to the aluminium oxide based materials. Hence, it seems that the interaction between the g-alumina surface or aluminium oxide centres and potassium carbonates does play a key role in the formation of sites [37][38][39] that do actively and reversibly fix carbon dioxide under the experimental conditions used. Temperature-programmed desorption (TPD) studies were carried out to analyse the decomposition of carbonates for various samples.…”

Section: Reversible Capacity and Carbonate Decompositionmentioning

confidence: 99%

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The Crucial Role of the K⁺–Aluminium Oxide Interaction in K⁺‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO₂ Sorption at High Temperatures

et al. 2008

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CO(2)-free hydrogen can be produced from coal gasification power plants by pre-combustion decarbonisation and carbon dioxide capture. Potassium carbonate promoted hydrotalcite-based and alumina-based materials are cheap and excellent materials for high-temperature (300-500 degrees C) adsorption of CO(2), and particularly promising in the sorption-enhanced water gas shift (SEWGS) reaction. Alkaline promotion significantly improves CO(2) reversible sorption capacity at 300-500 degrees C for both materials. Hydrotalcites and promoted hydrotalcites, promoted magnesium oxide and promoted gamma-alumina were investigated by in situ analytical methods (IR spectroscopy, sorption experiments, X-ray diffraction) to identify structural and surface rearrangements. All experimental results show that potassium ions actually strongly interact with aluminium oxide centres in the aluminium-containing materials. This study unambiguously shows that potassium promotion of aluminium oxide centres in hydrotalcite generates basic sites which reversibly adsorb CO(2) at 400 degrees C.

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Section: Reversible Capacity and Carbonate Decompositionsupporting

confidence: 76%

Section: Reversible Capacity and Carbonate Decompositionmentioning

confidence: 99%

The Crucial Role of the K⁺–Aluminium Oxide Interaction in K⁺‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO₂ Sorption at High Temperatures

et al. 2008

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“…Many research studies have focused on analyzing K 2 CO 3 catalyst activity for methanolysis of vegetable oil [13][14][15][16][17][18]. The obtained data showed that 90% of oil conversion could be achieved for less than 2 h at moderate temperature.…”

mentioning

confidence: 88%

“…For this reason, potassium carbonate is usually used as promoter to modify the base properties of alumina, alumina/silica, cinder or hydrotalcite as support [14][15][16][17]. However, activity of catalyst containing potassium carbonate is mainly the result of potassium leaching into methanol [16].…”

mentioning

confidence: 98%

Mechanochemical synthesis of CaO•ZnO.K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil

Kesić¹,

Lukić²,

Zdujić

et al. 2015

CI&CEQ

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The goal of this study was to prepare a CaO·ZnO catalyst containing a small amount of K 2 CO 3 and analyze its activity for biodiesel synthesis. The catalyst was prepared using the following procedure: CaO and ZnO (mole ratio of 1:2), water and K 2 CO 3 (in various amounts) were mechanochemically treated and after milling heated at 700 °C in air atmosphere for obtaining mixed CaO·ZnO/ x K 2 CO 3 oxides (x = 0, 1, 2 and 4 mol of K 2 CO 3 per 10 mol of CaO). All the samples were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), infrared spectroscopy (FTIR), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), particle size laser diffraction (PSLD) distribution, solubility measurement of Ca, Zn and K ions in methanol as well as by determination of their alkalinity (Hammett indicator method). Prepared CaO·ZnO/ x K 2 CO 3 composite powders were tested as catalysts for methanolysis of sunflower oil at 70 °C using mole ratio of sunflower oil to methanol of 1:10 and with 2 mass% of catalyst based on oil weight. The presence of K 2 CO 3 in prepared samples was found to increase the activity of catalyst, and that such effect is caused by homogeneous-heterogeneous catalysis of biodiesel synthesis.

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“…[14,22]. 이렇게 형성 된 활성자리인 Al-O-K와 Al-O 2 -K에서 반응물인 메탄올은 메톡시 화 이온으로 되어 트리글리세리드와 반응을 통해 바이오디젤을 생 성하게 된다 [23]. 셋째, γ-Al 2 O 3 촉매와 결합하지 않은 K 2 CO 3 는 고 온에서 CO 2 를 방출하면서 강한 염기촉매의 특성을 갖는 K 2 O가 되 어, 바이오디젤의 생성반응에 참여하게 된다 [11][12][13].…”

Section: 서 론unclassified

Development of Solid Base Catalyst K₂CO₃/γ-Al₂O₃for the Production of Biodiesel

심연주¹,

김종훈²,

김의용³

2016

Korean Chemical Engineering Research

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− The applications of heterogeneous catalyst have been relatively active area of research in the biodiesel process. These catalysts have the benefit of easy recovery and reusability of the catalyst. The objective of this study is to find out significant effect of calcination temperature on K 2 CO 3 /γ-Al 2 O 3 catalytic activity in the biodiesel formation reaction. As a results, the temperature at which a catalyst was calcined had very important influence on the catalytic activity. The catalytic activity increased up to 600?, but it severely decreased above the temperature. The reduction of catalyst activity at high temperature would be due to the deduction of the active sites of Al-O-K and Al-O 2 -K.

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Synthesis and characterization of potassium-modified alumina superbases

Cited by 47 publications

References 17 publications

The Crucial Role of the K⁺–Aluminium Oxide Interaction in K⁺‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO₂ Sorption at High Temperatures

The Crucial Role of the K⁺–Aluminium Oxide Interaction in K⁺‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO₂ Sorption at High Temperatures

Mechanochemical synthesis of CaO•ZnO.K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil

Development of Solid Base Catalyst K₂CO₃/γ-Al₂O₃for the Production of Biodiesel

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Synthesis and characterization of potassium-modified alumina superbases

Cited by 47 publications

References 17 publications

The Crucial Role of the K+–Aluminium Oxide Interaction in K+‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO2 Sorption at High Temperatures

The Crucial Role of the K+–Aluminium Oxide Interaction in K+‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO2 Sorption at High Temperatures

Mechanochemical synthesis of CaO•ZnO.K2CO3 catalyst: Characterization and activity for methanolysis of sunflower oil

Development of Solid Base Catalyst K2CO3/γ-Al2O3for the Production of Biodiesel

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The Crucial Role of the K⁺–Aluminium Oxide Interaction in K⁺‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO₂ Sorption at High Temperatures

The Crucial Role of the K⁺–Aluminium Oxide Interaction in K⁺‐Promoted Alumina‐ and Hydrotalcite‐Based Materials for CO₂ Sorption at High Temperatures

Development of Solid Base Catalyst K₂CO₃/γ-Al₂O₃for the Production of Biodiesel