Temat: desilication - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Effect and mechanism of surface pretreatment on desulfurization and desilication from low-grade high-sulfur bauxite using flotation
Autorzy:: Zhou, Jieqiang
Mei, Guangjun
Yu, Mingming
Li, Haonan
Tematy:: bauxite
surface pretreatment
flotation
desulfurization and desilication; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/110740.pdf Link otwiera się w nowym oknie
Opis:: Surface pretreatment using a hot alkaline solution was carried out to improve the effect of desulfurization and desilication on low-grade bauxite with high sulfur content. The results demonstrated that, after surface pretreatment, a maximum grade and recovery of 66.17% and 87.27%, respectively, were achieved, and the sulfur content and ratio of A/S were 0.19% and 7.09, respectively. The surface pretreatment mechanism was further analysed by XRD and SEM analyses. The improved results of desulfurization and desilication were attributed to the selective corrosion of aluminosilicate minerals in coarse particles, reducing the active silicon sites on the surface of coarse particles as well as enhancing the cation exchange between the collector and aluminosilicate minerals.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Hierarchic zeolites studied by IR spectroscopy : acid properties of zeolite ZSM-5 desilicated with NaOH and NaOH/tetrabutylamine hydroxide
Autorzy:: Datka, Jerzy
Tarach, Karolina
Góra-Marek, Kinga
Opis:: Acid properties of zeolites ZSM-5 desilicated in pure NaOH and in mixtures of NaOH/tetrabutylamine hydroxide (TBAOH) of various concentrations of basic solutions as well as of different proportions between NaOH and TBAOH were investigated. IR studies of pyridine sorption informed on the concentration of both Bronsted and Lewis acid sites and on the acid strength of SiOHAl groups. The nature of Lewis sites was followed by CO sorption. The accessibility of acid sites was detected by the sorption of hindered pivalonitrile molecules. It has been shown that the concentration of Bronsted sites increased as the result of the decrease of Si/Al due to desilication in diluted basic solutions (0.1 M and 0.2 M). The concentration of protonic sites in parent zeolite and zeolites treated with diluted bases determined in IR studies was approximately the same as the Al content determined by chemical analysis. The desilication in more concentrated bases (0.5 M) resulting in partial destruction of zeolite led to generation of weakly acidic protonic sites (not SiOHAl groups). The acid strength of the SiOHAl groups decreased with the progress of desilication. It is interpreted as the result of the extraction the Al atoms generating the strongest SiOHAl groups. The IR experiments of CO sorption confirmed that Lewis acid sites were formed by the dehydroxylation. IR studies of pivalonitrile sorption showed that desilication, which produced mesopores, improved the accessibility of acid sites. This effect was more distinct when desilication was done with NaOH/TBAOH mixture.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 3.

Tytuł:: A flotation combined extraction process for improving the whiteness of phosphogypsum
Autorzy:: Li, Jiangli
Guo, Yongjie
Fan, Peiqiang
Li, Haibin
Chen, Ciyun
Xu, Shuai
Du, Lingpan
Tematy:: phosphogypsum
whiteness
desilication
high-value utilization
floatation
extraction; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/24085918.pdf Link otwiera się w nowym oknie
Opis:: Every year, the production of industrial phosphoric acid generates more than 100 Tg of phosphogypsum (PG), leading to significant environmental damage and the occupation of a vast amount of land space. The urgent need to explore applications for PG has become increasingly apparent. However, impurities such as organic substances, slime, phosphorite, and SiO2 reduce the whiteness of PG, making it difficult to utilize for high-value applications. To address this issue, this study employed a two-stage flotation process to remove the majority of impurities, including SiO2, organic substances, and fine slime adhered to the surface of PG particles. The raw PG sample was first sieved to remove some SiO2 particles. After flotation, sulfuric acid and tributyl phosphate were introduced to decompose the PG particles and remove the impurities wrapped inside. Following this flotation combined extraction process, the whiteness of the PG sample improved from 54.1% to 92.9%, meeting the requirements for building walls and filters.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Hierarchically structured ZSM-5 obtained by desilication as new catalyst for DME synthesis from methanol
Autorzy:: Mirocha-Kubień, Natalia
Macina, Daniel
Chmielarz, Lucjan
Piwowarska, Zofia
Rutkowska, Małgorzata
Opis:: A new type of micro–mesoporous materials with properties of ZSM-5 zeolite was tested as catalysts for the synthesis of dimethyl ether (DME) from methanol. The catalytic performance of ZSM-5 was improved by generation of mesoporosity using desilication method (alkaline leaching of framework Si). It was shown that controlled modification of the porous structure and acidity of the zeolitic samples strongly influences their catalytic activity, selectivity and stability in the process of DME synthesis. Desilication of ZSM-5 zeolite resulted in a development of the mesoporous structure and enhancement of its acidity, what was confirmed by N2-sorption measurements, IR-DRIFT spectroscopy and NH3-TPD. Desilicated zeolite samples exhibited higher catalytic activity and stability in the process of DME synthesis in comparison to parent ZSM-5. Moreover, micro–mesoporous zeolites were more resistant for poisoning by coke deposits in comparison to conventional ZSM-5 catalyst.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 5.

Tytuł:: Flotation separation of quartz from phosphorite using an imidazole ionic liquid collector and its adsorption mechanism
Autorzy:: Zhao, Yuanyuan
Xu, Wei
Mei, Guangjun
Yu, Mingming
Yang, Siyuan
He, Zhan
Tematy:: reverse flotation
imidazole ionic liquid
desilication
phosphorite
quartz; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/2146857.pdf Link otwiera się w nowym oknie
Opis:: In this study, an imidazole ionic liquid (dodecyl-tri-methylimidazolium chloride) was employed as a collector to separate quartz from phosphorite. The micro-flotation experiments of a single mineral found that it had selective collecting ability for quartz than phosphorite. Mixed mineral flotation experiments confirmed that efficient separation results could be obtained using the imidazole ionic liquid as the collector. A concentrate with a 31.44% grade of phosphorite could be obtained with a 0.285 kg/Mg collector dosage at neutral pH, which was much better than the traditional collector dodecylamine. The adsorption mechanism of the imidazole ionic liquid on the surface of phosphorite and quartz was investigated by contact angle and zeta potential measurements, Fourier transform infrared and X-ray photoelectron spectroscopy analyses. These results showed that the adsorption of imidazole ionic liquid at the quartz surface was stronger than that of phosphorite, and the collector adsorbability difference between quartz and phosphorite resulted in the efficient flotation separation. Consequently, the dodecyl-tri-methylimidazolium chloride salt is an effective collector for reverse flotation of quartz from phosphorite.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: The mechanism study on deep eutectic solvent for desilication of magnetite by reverse flotation
Autorzy:: He, Zhan
Liu, Cai
Mei, Guangjun
Zhao, Yuanyuan
Cheng, Qian
Song, Xianwei
Tematy:: reverse flotation
deep eutectic solvents collector
desilication
magnetie
quartz; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/1845237.pdf Link otwiera się w nowym oknie
Opis:: Magnetite reverse flotation using a new deep eutectic solvent synthesized by lactic acid and CTAC as the collector has been investigated in this work. The flotation test results were compared with dodecylamine. The CTAC/lactic acid DES increased the grade of total iron to 66.69%, and the reduce quartz content to 6.67%, which were preferable to dodecylamine (the grade of Fe in the concentrate is 63.47%, and the grade of quartz in the concentrate is 9.13%). The depression performance and adsorption mechanism of CTAC/lactic acid DES on surface of magnetite and quartz are investigated by FT-IR, zeta potential and XPS. The results show that the adsorption of CTAC/lactic acid DES on quartz surface is more effective than that of magnetite. Therefore, deep eutectic solvent is an effective reagent for reverse flotation of magnetite as collector.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: The mechanism study on deep eutectic solvent for desilication of magnetite by reverse flotation
Autorzy:: He, Zhan
Liu, Cai
Mei, Guangjun
Zhao, Yuanyuan
Cheng, Qian
Song, Xianwei
Tematy:: reverse flotation
deep eutectic solvents collector
desilication
magnetie
quarto; Pokaż więcej
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Powiązania:: https://bibliotekanauki.pl/articles/2146858.pdf Link otwiera się w nowym oknie
Opis:: Magnetite reverse flotation using a new deep eutectic solvent synthesized by lactic acid and CTAC as the collector has been investigated in this work. The flotation test results were compared with dodecylamine. The CTAC/lactic acid DES increased the grade of total iron to 66.69%, and the reduce quartz content to 6.67%, which were preferable to dodecylamine (the grade of Fe in the concentrate is 63.47%, and the grade of quartz in the concentrate is 9.13%). The depression performance and adsorption mechanism of CTAC/lactic acid DES on surface of magnetite and quartz are investigated by FT-IR, zeta potential and XPS. The results show that the adsorption of CTAC/lactic acid DES on quartz surface is more effective than that of magnetite. Therefore, deep eutectic solvent is an effective reagent for reverse flotation of magnetite as collector.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Desilication of highly siliceous zeolite ZSM-5 with NaOH and NaOH/tetrabutylamine hydroxide
Autorzy:: Tarach, Karolina
Martínez Triguero, Joaquín
Datka, Jerzy
Rey, Fernando
Drozdek, Marek
Góra-Marek, Kinga
Kuśtrowski, Piotr
Opis:: The results of both chemical and XPS analysis pointed out that desilication of highly siliceous ZSM-5 of Si/Al = 164 was more effective in the surface zone than in the bulk, contrary to zeolite ZSM-5 of Si/Al = 31.6. According to the IR studies in parent zeolite the concentration of protonic sites was very close to the concentration of Al indicating that all Al atoms can form Si-OH-Al. The results of our quantitative IR studies strongly support the realumination thesis, i.e. some Al atoms extracted in basic solutions are subsequently reinserted forming new acidic hydroxyls. In desilicated zeolites all Al atoms were able to form protonic sites, however part of them dehydroxylated during the activation of zeolite producing Lewis acid sites according to the stoichiometry: one protonic site was transformed into one Lewis site. Low temperature nitrogen adsorption revealed that the alkaline treatment of highly siliceous zeolite with 0.2 M NaOH/TBAOH mixture produced mesopores of smaller diameter and narrower pore size distribution than in the case of zeolite of medium Si/Al ratio. This result can be explained by low concentration of Al which similarly as TBA+ cations plays the role of pore directing agents (PDA). Contrary to TBA+, the presence of Al in desilication mixture, led to the formation of larger pores. Therefore, in highly siliceous zeolite TBA + played dominant role as PDA producing narrower pores. Highly siliceous zeolite with uniform distribution of relatively narrow pores may be useful catalyst or catalyst support. The influence of desilication temperature on porosity development was also investigated. The increase of desilication temperature from 338 to 353 K resulted in both more extensive demetalation (more Si and Al is extracted) and the distinct increase of the volume and surface of mesopores. Both lower concentration of protonic sites and higher concentration of Lewis sites confirmed partial zeolite destruction upon desilication at elevated temperature. The experiments of pivalonitrile sorption followed by IR spectroscopy showed a significant increase of accessibility of acid sites to bulky pivalonitrile molecules.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 9.

Tytuł:: Hierarchic zeolites: zeolite ZSM-5 desilicated with NaOH and NaOH/tetrabutylamine hydroxide
Autorzy:: Tarach, Karolina
Datka, Jerzy
Wach, Anna
Kuśtrowski, Piotr
Olejniczak, Zbigniew
Opis:: The desilication of zeolite ZSM-5 (Si/Al = 31.6) was performed by the treatment with NaOH of various concentrations (0.1, 0.2, 0.5 and 1 M) and with NaOH/TBAOH mixtures of various concentrations and ratios between both bases. The information on the composition of both bulk and surface was obtained by ICP-OES and XPS, respectively. It has been found that diluted NaOH solutions extracted Si equally from the surface and bulk of ZSM-5. In more concentrated NaOH the desilication from the bulk was more effective than from the surface. The MAS NMR studies showed that Si(4Si,0Al) was less stable and was removed from the zeolite structure before Si(3Si,1Al). Higher stability of Si(3Si,1Al) was explained by the repulsion of AlO4- and OH-. According to the IR results the desilication, leading to mesopore formation, increased distinctly the amount of Si-OH on mesopore walls and also the contribution of acidic Si-OH-Al. Calcination of desilicated zeolite at air atmosphere resulted in a significant loss of tetrahedral Al due to the "steaming" of zeolite with water physisorbed in mesopores facilitated by lower stability of framework injured by desilication. Both NMR and IR studies suggested that the stability of Si atoms in the zeolite framework increased in the following order: (SiO) 3Si-OH < (SiO)3Si-OSi < (SiO)3Si-OAl. Porosimetric experiments evidenced that the NaOH treatment produced mesopores with very broad pore size distribution (a majority of pore diameters was close to 20 nm). The desilication with the NaOH/TBAOH mixtures produced mesopores of higher surface area and pore volume but of smaller diameter than with NaOH alone. We suppose that in the presence of TBAOH a larger number of narrower pores is formed, or narrow pores penetrate zeolite crystal more deeply.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 10.

Tytuł:: Catalytic cracking performance of alkaline-treated zeolite Beta in the terms of acid sites properties and their accessibility
Autorzy:: Tarach, Karolina
Martínez Triguero, Joaquín
Igualada López, M.C.
Tekla, Justyna
Datka, Jerzy
Mlekodaj, Kinga
Brylewska, Kamila
Rey, Fernando
Góra-Marek, Kinga
Makowski, Wacław
Opis:: The zeolite Beta is considered as a promising additive for FCC catalyst in diesel oil production. In this article, it is shown that hierarchical zeolite Beta obtained by an optimized desilication procedure increases diesel and propylene yields during gas-oil cracking reaction. The alkaline treatment of zeolite Beta (Si/Al = 22) by desilication with NaOH and NaOH&TBAOH was investigated. The catalytic performance improvement of desilicated zeolite Beta has been rationalized by deep characterization of the samples including X-ray diffraction, low-temperature adsorption of nitrogen, solid-state 29Si MAS NMR and IR studies of acidity. Finally, the catalytic performance of the zeolites Beta was evaluated in the cracking of n-decane, 1,3,5-tri-iso- propylbenzene, and vacuum gas oil. It was found that desilication with NaOH&TBAOH ensures the more uniform intracrystalline mesoporosity with the formation of narrower mesopores, while preserving full crystallinity resulting in catalysts with the most appropriated acidity and then with better catalytic performance.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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