Specific surface area and structures of aluminas from fibrillar pseudoboehmite

Coelho, A. C. Vieira; Rocha, Glaucia Aguiar; Santos, P. Souza; Santos, Helena Souza; Kiyohara, Pedro Kunihiko

doi:10.1590/s1517-70762008000200011

Cited by 26 publications

(8 citation statements)

References 11 publications

(7 reference statements)

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“…Thus, we should concurrently investigate both for accurate interpretation of toxicity data (Teow et al 2011;Fadeel and garcia-Bennett 2010). In this study, short-AlNRs were more stable thermodynamically than long-AlNRs (Souza Santosa et al 2000;Vieira coelho et al 2008), and the surface area of long-AlNRs with high aspect ratio (thinner and longer nanorod-shaped morphology) was estimated to be approximately 54 % larger than that of short-AlNRs, although the primary particle size of long-AlNRs was larger than that of short-AlNRs. However, hydrodynamic diameters and surface charges of both types of AlNRs were similar within the biological vehicle used in this study.…”

Section: Discussionmentioning

confidence: 80%

Comparison of the toxicity of aluminum oxide nanorods with different aspect ratio

et al. 2014

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Aluminum oxide nanoparticles are listed among 14 high-priority nanomaterials published by the Organization for Economic Co-operation and Development, but limited information is available on their potential hazards. In this study, we compared the toxicity of two different aluminum oxide nanorods (AlNRs) commercially available in vivo and in vitro. Considering aspect ratio, one was 6.2 ± 0.6 (long-AlNRs) and the other was 2.1 ± 0.4 (short-AlNRs). In mice, long-AlNRs induced longer and stronger inflammatory responses than short-AlNRs, and the degree reached the maximum on day 7 for both types and decreased with time. In addition, in vitro tests were performed on six cell lines derived from potential target organs for AlNPs, HEK-293 (kidney), HACAT (skin), Chang (liver), BEAS-2B (lung), T98G (brain), and H9C2 (heart), using MTT assay, ATP assay, LDH release, and xCELLigence system. Long-AlNRs generally produced stronger toxicity than short-AlNRs, and HEK-293 cells were the most sensitive for both AlNRs, followed by BEAS-2B cells, although results from 4 kinds of toxicity tests conflicted among the cell lines. Based on these results, we suggest that toxicity of AlNRs may be related to aspect ratio (and resultant surface area). Furthermore, novel in vitro toxicity testing methods are needed to resolve questionable results caused by the unique properties of nanoparticles.

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Section: Discussionmentioning

confidence: 80%

Comparison of the toxicity of aluminum oxide nanorods with different aspect ratio

et al. 2014

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“…The textural properties of the supports used in this paper are displayed in Table 1. Supports designated as G and A have textural properties corresponding to the traditional values found in the literature for these kinds of aluminas (Vieira Coelho et al 2008). After the treatment at high pH with aqueous ammonia, the silica support (S) resulted in a solid with a high S BET and high porosity compared with the untreated Aerosil Degussa (65m 2 /g and 0.14 cm 3 /g, respectively).…”

Section: Resultsmentioning

confidence: 69%

Use of Rh (III)-Heteropolymolybdate as Potential Catalysts for the Removal of Nitrates in Human Drinking Water: Synthesis, Characterisation and Catalytic Performance

Jaworski

Bertolini

Cabello

et al. 2018

Water Air Soil Pollut

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The investigation and development of technologies to remediate water contaminated with NO 3 − are constantly increasing. An economically and potentially effective alternative is based on the catalytic hydrogenation of NO 3 − to N 2 . With this objective, bimetallic RhMo 6 catalysts based on Anderson-type heteropolyanion (RhMo 6 O 24 H 6 ) 3− were prepared and characteri3ed in order to obtain well-defined bimetallic catalyst. The catalysts were supported on Al 2 O 3 with different textural properties and on silica. The heteropolyanion-support interaction wasanalysed by temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The differences obtained in activity and selectivity to the different products can be assigned to the different interaction between the RhMo 6 Anderson phase and the supports. The RhMo 6 /G, (G: γ-Al 2 O 3 ) system showed the best catalytic performance. This catalyst exhibited the lowest reduction temperature of Rh and Mo in the TPR assay and a Rh/Mo surface ratio similar to that of the original phase, as observed by XPS analysis. These studies allowed us to verify a synergic effect between Rh and Mo, through which Mo reducibility was promoted by the presence of the noble metal. The catalytic activity was favoured by the active sites generated from the Anderson phase. This fact was confirmed by comparing the activity of RhMo 6 /G with that corresponding to a conventional catalyst prepared through successive impregnation of both Rh (III) and Mo (VI) salts.

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“…The metallic Pt particle size of the spent Pt/(HZSM-48 + pseudoboehmite, 1:1) catalyst from the CO chemisorption increased to 6.5 nm compared to the metallic Pt particle size of 6.3 nm for the fresh catalyst, indicating that the sintering of Pt could be negligible during the MCP reforming reaction conditions. In addition, the phase transition from pseudoboehmite to aluminum oxide was not observed after catalytic test for 9 h. It has been reported that the phase transformation of pseudoboehmite occurs at a temperature higher than 470 • C [30].…”

Section: Ring Enlargement Reaction Of Methylcyclopentanementioning

confidence: 86%

Ring Enlargement of Methylcyclopentane over Pt/(HZSM-48+pseudoboehmite) Catalysts

Park

Kim

et al. 2019

Catalysts

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Platinum catalysts loaded on a hybrid support, composed of HZSM-48 and pseudoboehmite, were applied to the synthesis of benzene through methylcyclopentane (MCP) reforming in order to investigate the effect of the addition of pseudoboehmite to Pt/HZSM-48 for ring-enlargement reaction. A total of 0.5 wt% of platinum was impregnated on the hybrid support by using the incipient wetness method. Catalyst characterization was performed with nitrogen sorption, X-ray diffraction, temperature-programmed desorption of NH3, and infrared spectroscopy of adsorbed pyridine. It was found that mesoporous structures were well-developed in Pt/(HZSM-48 + pseudoboehmite) catalyst as a result of the pseudoboehmite addition, of which the average pore size was in the range of 7–8 nm. The presence of pseudoboehmite in the catalyst increases the total amount of acid sites and weakens the acid strength, compared with those of the Pt/HZSM-48 catalyst. Lewis acid sites were more abundant than Brönsted acid sites over the Pt/(HZSM-48+pseudoboehmite) catalysts. It was found that selectivity to the ring-enlargement reaction is dominant over selectivity to the ring-opening reaction over the Pt/(HZSM-48 + pseudoboehmite) catalysts. The benzene yield over Pt/(HZSM-48 + pseudoboehmite, 1:1) catalyst reached 65.1% at 450 °C and 0.3 h−1. As well as being influenced by the mesoporous structure, the higher activity and selectivity in MCP reforming was also determined by appropriate acidity of the Pt/(HZSM-48 + pseudoboehmite) catalysts.

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Specific surface area and structures of aluminas from fibrillar pseudoboehmite

Cited by 26 publications

References 11 publications

Comparison of the toxicity of aluminum oxide nanorods with different aspect ratio

Comparison of the toxicity of aluminum oxide nanorods with different aspect ratio

Use of Rh (III)-Heteropolymolybdate as Potential Catalysts for the Removal of Nitrates in Human Drinking Water: Synthesis, Characterisation and Catalytic Performance

Ring Enlargement of Methylcyclopentane over Pt/(HZSM-48+pseudoboehmite) Catalysts

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