Characterization of lanthanum-modified γ-alumina by X-ray photoelectron spectroscopy and carbon dioxide absorption

Haack, Larry P.; deVries, J.E.; Otto, K.; Chattha, M. S.

doi:10.1016/0926-860x(92)85005-v

Cited by 91 publications

(35 citation statements)

References 17 publications

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“…The calcination temperature usually determines the crystal structure of La oxides, 23,24 which is critical in F adsorption. To investigate the structure of the La-oxide coatings, XRD analysis was used for LAA calcined at various temperatures, but no crystalline La oxide was found (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The O 1s spectra were simulated by considering Al-O 2À , Al-OH, La-O 2À , and La-OH. 24,33 The XPS peaks of Al-O 2À at 530.9 eV and Al-OH at 532.5 eV were observed in AA (Fig. 7a).…”

Section: 122930mentioning

confidence: 99%

“…The lower binding energies of La-O 2À and La-OH, compared with those of Al-O 2À and Al-OH, were in agreement with previous publications. 24,33 The difference in binding energies of La and Al can be attributed to the higher CN of O atoms with La (7.6, Table S2 †) than that with Al (4-6 (ref. 34)), and the longer interatomic distance of La-O (0.25 nm, Table S2 †) than that of Al-O (0.17-0.19 nm).…”

Section: 122930mentioning

confidence: 99%

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Synthesis, characterization and application of lanthanum-impregnated activated alumina for F removal

2013

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Elevated fluoride (F) in groundwater presents an obvious environmental concern. Adsorption using activated alumina (AA) is currently the best available technology for F removal, despite its low efficiency, pH dependence, and aluminium (Al) release. The motivation for our study is to synthesise a new F adsorbent by impregnating commercially available granulated AA with lanthanum oxide (LAA), and to explore its F adsorption mechanism on the molecular scale. Five cycles of lanthanum impregnation on AA followed by calcination at 573 K increased the La content up to 19.1% and the F removal from 18.1% by pristine AA to 92.4% by LAA. The SEM, TEM, XRD, TGA, and EXAFS results demonstrated that the 5-20 nm thin flakes of LaOOH on LAA were in an amorphous form, with 7.6 oxygen atoms around each La. This LaOOH layer was uniformly distributed inside the micropores of the 1-3 mm AA granules.LAA exhibited four fold higher F adsorption capacity than AA in the pH range 3.9 to 9.6, with substantially reduced Al release. The ability to regenerate and reuse LAA makes it an attractive sustainable material. Multiple complementary spectroscopic analyses demonstrated that ligand exchange between F and surface hydroxyl groups is the mechanism for F adsorption on LAA. Our work improves the understanding of F interaction with metal oxides on the molecular scale and presents an alternative solution for elevated F water treatment.

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Section: Resultsmentioning

confidence: 99%

“…The O 1s spectra were simulated by considering Al-O 2À , Al-OH, La-O 2À , and La-OH. 24,33 The XPS peaks of Al-O 2À at 530.9 eV and Al-OH at 532.5 eV were observed in AA (Fig. 7a).…”

Section: 122930mentioning

confidence: 99%

Section: 122930mentioning

confidence: 99%

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Synthesis, characterization and application of lanthanum-impregnated activated alumina for F removal

2013

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“…However, the addition of a few mol% La 2 O 3 to g-alumina has been found to result in improved surface area stability at high temperatures [11][12][13] . Using X-ray photoelectron spectroscopy (XPS), Haack et al 14 determined that for La/Al ratios o0. 15, La is probably present as a dispersed, low-coordinated La 3 þ phase, rather than as La 2 O 3 .…”

mentioning

confidence: 99%

Low-temperature carbon monoxide oxidation catalysed by regenerable atomically dispersed palladium on alumina

et al. 2014

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Catalysis by single isolated atoms of precious metals has attracted much recent interest, as it promises the ultimate in atom efficiency. Most previous reports are on reducible oxide supports. Here we show that isolated palladium atoms can be catalytically active on industrially relevant g-alumina supports. The addition of lanthanum oxide to the alumina, long known for its ability to improve alumina stability, is found to also help in the stabilization of isolated palladium atoms. Aberration-corrected scanning transmission electron microscopy and operando X-ray absorption spectroscopy confirm the presence of intermingled palladium and lanthanum on the g-alumina surface. Carbon monoxide oxidation reactivity measurements show onset of catalytic activity at 40°C. The catalyst activity can be regenerated by oxidation at 700°C in air. The high-temperature stability and regenerability of these ionic palladium species make this catalyst system of potential interest for low-temperature exhaust treatment catalysts.

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“…In zeolitic materials, both are known to possess similar properties in that they enhance acid site density in conjunction with mediating carbon lay down during fluidised catalytic cracking [29] and [20]. Additionally, their application as a phase stabiliser for transitional support materials such as titania and alumina has been documented [12,13]. It has been reported previously that simple perovskites of the type LaMO 3 (M = Ni/Co/Fe) have been reduced and then used as a catalyst in the DMR reaction.…”

Section: à1 ð2þmentioning

confidence: 99%

The effect of lanthanum addition on the catalytic activity of γ-alumina supported bimetallic Co–Mo carbides for dry methane reforming

Almuqati

Кузнецов

et al. 2014

Appl Petrochem Res

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The effect of lanthanum addition to c-alumina supported bimetallic carbides has been studied for the reaction of dry methane reforming using four different lanthanum loading levels of 1, 5, 10 and 15 wt% of lanthanum. It has been demonstrated that the addition of lanthanum to supported bimetallic carbides at low loading levels (1 wt%) results in smaller carbide crystallite sizes compared to catalysts containing either no lanthanum or higher lanthanum loading levels (5-15 wt%). Increased lanthanum loading results in increased carbon dioxide desorption at 500-700°C. Reactions indicated that increased lanthanum loading resulted in significantly reduced product yields due to increased reverse water-gas shift activity. All materials exhibited degrees of sintering during the reaction. It was found that cobalt reacted with lanthanum species to form a LaCoO 3 phase. The 1 wt% catalyst possessed superior catalytic properties for dry methane reforming and was tested for 100 h. After an initial loss of activity, the catalyst appeared to stabilise, however, a decrease of *3 % in the H 2 :CO ratio, evidence of carbide crystallite growth and carbon deposition, indicated that a shift in the side reactions had occurred during the reaction.

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Characterization of lanthanum-modified γ-alumina by X-ray photoelectron spectroscopy and carbon dioxide absorption

Cited by 91 publications

References 17 publications

Synthesis, characterization and application of lanthanum-impregnated activated alumina for F removal

Synthesis, characterization and application of lanthanum-impregnated activated alumina for F removal

Low-temperature carbon monoxide oxidation catalysed by regenerable atomically dispersed palladium on alumina

The effect of lanthanum addition on the catalytic activity of γ-alumina supported bimetallic Co–Mo carbides for dry methane reforming

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