Influence of the Cr loading in Cr/MCM-41 and TiO2/Cr/MCM-41 molecular sieves for the photodegradation of Acid Orange 7

Elías, Verónica Rita; Sabre, Ema V.; Sapag, Karim; Casuscelli, Sandra G.; Eimer, Griselda A.

doi:10.1016/j.apcata.2011.11.019

Cited by 48 publications

(94 citation statements)

References 51 publications

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“…Figure 3 spectra showed that mainly Cr 6+ species are present in samples synthesized by both methods (absorption range of 200-400 nm). 29,30,32 Nevertheless, the increase in the Cr 3+ species amount when the Cr content increased (absorption above 400 nm) is clear. This fact is evident for the Cr(DI)4.5 sample due to the increase in the absorption at wavelengths higher than 550 nm and its intense green color.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, the higher reduction temperatures observed for DI samples (TPR profiles not shown) would reveal the increased interaction of smaller size chromium species with the support. 30 This behavior would be due to the high dispersion favored by the direct incorporation method. When titania has been deposited on the Cr(WI)x and Cr(DI)x samples, the sharply decrease in the specific surface and pore volume can be associated with the presence of highly dispersed titania species and bigger size TiO 2 nano-particles that could be blocking the pores of the structure.…”

Section: Resultsmentioning

confidence: 99%

“…35 Meanwhile, WI would give rise to a higher proportion of these active species located on the surface of the mesopore walls. 30 However, in the case of Cr(DI)x samples, the X AO7 is practically constant for all the Cr contents, which could be evidencing that, although the Cr content increases, the limit of active species incorporation into the framework has already been reached.…”

Section: 32mentioning

confidence: 97%

“…WI samples were obtained as reported [29][30][31] using several concentrations of Cr solutions, corresponding to theoretical Cr loadings of 1.50, 3.50 and 5.00 wt%.…”

Section: Experimental Synthesismentioning

confidence: 99%

“…Then, these solids were submitted to desorption and calcination processes already described. 28 All solids were modified by TiO 2 according to 30 in order to evaluate the influence of a second metal on their photoactivity. The catalysts were named: TiO 2 /Cr(DI)x or TiO 2 /Cr(WI)x, where DI or WI indicates the method of Cr incorporation used, x indicates the theoretical Cr content (wt%), and TiO 2 is used in the case of the modification with Ti loading.…”

Section: Experimental Synthesismentioning

confidence: 99%

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Comparative Study of the Physicochemical Properties and Photocatalytic Activity of Modified McM-41 Synthesized by Direct (One-Step) Incorporation and Impregnation

Elías¹,

Sabre²,

Casuscelli³

et al. 2016

Química Nova

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publicado na web em 12/04/2016 MCM-41 structures were synthesized and modified by direct (one-step) incorporation (DI) and wet impregnation (WI) methods. The solids were characterized by XRF, XRD, N 2 adsorption and UV-Vis DR, and catalytically evaluated in the Acid Orange 7 (AO7) degradation under visible light. Significant influence of the presence, dispersion and location of the different Cr species on photoactivity was evident. Both synthesis methods allowed greater dispersion of the photoactive Cr species for lower metal content, enhancing efficiency for dye degradation. More specifically, after Ti loading in samples synthesized by DI, a notable AO7 degradation increase was associated with the strong heterojunction between Ti and Cr 6+ species, which wereare highly dispersed due to the DI method used.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: 32mentioning

confidence: 97%

“…WI samples were obtained as reported [29][30][31] using several concentrations of Cr solutions, corresponding to theoretical Cr loadings of 1.50, 3.50 and 5.00 wt%.…”

Section: Experimental Synthesismentioning

confidence: 99%

Section: Experimental Synthesismentioning

confidence: 99%

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Comparative Study of the Physicochemical Properties and Photocatalytic Activity of Modified McM-41 Synthesized by Direct (One-Step) Incorporation and Impregnation

Elías¹,

Sabre²,

Casuscelli³

et al. 2016

Química Nova

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Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Zhang

Yang

et al. 2018

ChemCatChem

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Cr‐modified MCM‐41 with different loadings were prepared and tested in the propane dehydrogenation (PDH) reaction. As for Cr/MCM‐41 system, the general knowledge was that high Cr loadings resulted in the reduction of silica surface hydroxyl groups, thus leading to the formation of inactive Cr(III) species, as clusters and/or crystalline Cr2O3. However, in the present work, isolated Cr(VI) states were identified in the Cr/MCM‐41 catalysts, instead of Cr(III) species, using UV‐vis and H2‐TPR. These isolated Cr(VI) species are difficult to reduce, causing the decreased activity for propane conversion and low selectivity towards C3H6 in the PDH process. In contrast, a good dispersion of the Cr species was obtained using a chromium column adsorption process, and the absence of the isolated state of Cr(VI) species on this sample contributed to high activity toward PDH process. The investigation of the isolated Cr(VI) species is very important for the Cr‐based PDH catalyst system.

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Preparation and adsorption property of attapulgite/carbon nanocomposite

Liu¹,

Yang²,

Xu³

et al. 2014

Environ. Prog. Sustainable Energy

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The attapulgite/carbon (ATP/C) nanocomposite was successfully prepared by two ecofriendly raw materials (ATP, which is a hydrated magnesium aluminum silicate widespread in nature, and d‐xylose, which can be obtained from rice hull, wheat straw, etc.) through a facile one‐pot hydrothermal procedure. The synthesis conditions, including reaction time, hydrothermal temperature, and the concentration of d‐xylose, were regulated to investigate the morphology, functional groups, and pore properties of ATP/C. Adsorption experiments demonstrated that the obtained ATP/C materials had great potential in treatment of methylene blue from aqueous solution. A possible formation mechanism of ATP/C nanocomposite was proposed by powder X‐ray diffraction, TG analysis, and N2 adsorption–desorption study, which revealed that carbon successfully anchored onto ATP by the chemical bond of SiOC. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 437–444, 2015

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Influence of the Cr loading in Cr/MCM-41 and TiO2/Cr/MCM-41 molecular sieves for the photodegradation of Acid Orange 7

Cited by 48 publications

References 51 publications

Comparative Study of the Physicochemical Properties and Photocatalytic Activity of Modified McM-41 Synthesized by Direct (One-Step) Incorporation and Impregnation

Comparative Study of the Physicochemical Properties and Photocatalytic Activity of Modified McM-41 Synthesized by Direct (One-Step) Incorporation and Impregnation

Investigation of the Isolated Cr(VI) Species in Cr/MCM‐41 Catalysts and its Effect on Catalytic Activity for Dehydrogenation of Propane

Preparation and adsorption property of attapulgite/carbon nanocomposite

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