Intensification of heterogeneous TiO 2 photocatalysis using an innovative micro-meso-structured-photoreactor for n -decane oxidation at gas phase

Filho, Batuira M. da Costa; Araújo, Alexandra M.; Silva, Gabriela V.; Boaventura, Rui A.R.; Dias, Madalena M.; Lopes, José Carlos B.; Vilar, Vítor J.P.

doi:10.1016/j.cej.2016.09.080

Cited by 61 publications

(20 citation statements)

References 70 publications

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“…One criterion particularly useful for comparing the performance of the reactors regarding their intensification potential is the specific volumetric yield (i.e. the yield of salicylic acid achieved per reactor volume per einstein irradiated) 38 . These results are summarized in Figure 8.…”

Section: On the Performance Of The Reactors Regarding Lightmentioning

confidence: 99%

Single-Phase Flow in a Micro-Structured Packed Bed Photo-Reactor: Effect of Packing Size on Flow Regime and on the Reactor Performance for Homogeneous Photocatalysis

Ramos

Couri²,

Teixeira³

2018

Preprint

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Dedicated research on photochemical reactors is fundamental to the application of this technology to real-life problems. In line with this trend, we report a study of structural parameters of micro-structured packed bed reactors (μPBR) regarding their ability to promote intensification. We present an investigation on the effects of the size of spherical packings on the developed flow regime, and its implications for the performance of the reactor on a photochemical reaction in aqueous phase. Tubular reactors were built with combinations of borosilicate glass tubes of two diameters (20 and 30 mm) packed with soda-lime glass spheres of three average diameters (1.0, 3.0 and 6.0 mm), alumina spheres of 6.0 mm diameter, and polished iron spheres of 5.0 mm diameter. Residence Time Distributions (RTD) were measured for each combination of outer tube and glass sphere sizes. Results showed that as the packing size decreases, the observed flow regime becomes closer to an ideal PFR, suggesting that smaller packings are more suitable to applications that require precise control of residence time. The aqueous-phase oxidation of benzoic acid by oxygen radicals generated by UV-A irradiation of nitrite ions was used as model photochemical reaction. We also observed that increasing the D/d<sub>p</sub> ratio for narrower reactors faster specific reaction rates are achieved, suggesting that intensification is possible in these reactors; however, the overall yield decreases, probably due to increased photon loss. Lastly, we found that glass spheres can be replaced by alumina spheres with little loss in light-collection efficiency, indicating an attractive pathway for immobilized photocatalysis.

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Section: On the Performance Of The Reactors Regarding Lightmentioning

confidence: 99%

Single-Phase Flow in a Micro-Structured Packed Bed Photo-Reactor: Effect of Packing Size on Flow Regime and on the Reactor Performance for Homogeneous Photocatalysis

Ramos

Couri²,

Teixeira³

2018

Preprint

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“…In the absence of photocatalysts, NO is very stable and cannot be photolysed under visible light irradiation [6]. Semiconductor photocatalysis as an alternative to conventional approaches mediated advanced oxidation technology for degradation of environmental pollutants [7][8][9][10] is attracting the most attention, especially considering the characteristics of in-situ generating reactive radicals species (e.g. • OH) as strong oxidants, and the operating cost for the process can be reduced dramatically when solar energy is used [11,12].…”

Section: Introductionmentioning

confidence: 99%

Boosting photocatalytic oxidation on graphitic carbon nitride for efficient photocatalysis by heterojunction with graphitic carbon units

Abdellatif

Zhang

Wang

et al. 2019

Chemical Engineering Journal

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Graphitic carbon nitride has been considered as a promising metal-free visible light photocatalyst for air pollutants oxidation due to its suitable band-gap energy and higher conduction band edge. Herein, we have developed a facile approach for dramatically downwards shifting band edge positions of carbon nitride up by about 1 eV via in-plane heterojunction with graphitic carbon units to enhance the oxidation capability of the electron holes generated from the valence band. The graphitic carbon units in junction with tri-s-triazine domains were clearly observed and its in-plane hybridization with carbon nitride was formed during the copolymerization using melamine with a small amount of m-phenylenediamine as the precursors. The direct intralayer junction between the tri-s-triazine and the graphitic carbon domain, essentially different with interlayer junction reported in literature, is able to shift downwards the band edge positions via merging electron density of states of carbon nitride with that of graphitic carbon, and thus would be beneficial for separation of photoexcited charge carriers and generation of hydroxyl radicals for the oxidation of pollutants. The hybrid photocatalyst prepared with a small quantity (less than 1%) of m-phenylenediamine and melamine as precursors has shown much enhanced NO oxidation to final products(NO 2 and NO 3-) and increased NO removal 10% than the one from melamine only.

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“…This intense illumination is vital to the stability of the catalyst as it provides complete oxidation of the n-hexane, preventing the accumulation of fouling by-products on the catalyst surface. The system developed was able to fully oxidize hexane in air using only a few milligrams of catalyst and short contact times [16,42], with excellent performance in terms of specific reaction rates compared to other photocatalytic systems reported in the literature for VOC abatement. The high stability of the catalyst under continuous and cyclic operation and the fact that photooxidation is carried under LED illumination with a low total input of energy, makes the system highly interesting for environmental applications.…”

Section: Discussionmentioning

confidence: 99%

“…Also, the energy consumption of this broad-band lamps are usually in the range of hundreds of watts while in the case of the LEDs only a few watts are enough to get a high irradiance output. For most powdered materials and wavelengths ranges, traditional light sources are not able to provide illumination of the photocatalyst beyond the first few particle monolayers of the catalyst bed, and therefore thin catalyst layers are typically used in photocatalytic reactors [12,16]. In contrast, our…”

Section: Effect Of Catalyst Loadingmentioning

confidence: 99%

“…In spite of the excellent stability and selectivity of Pt-based catalysts, the high cost of precious metals has prompted the search for: (i) lower cost catalysts based on more abundant and affordable transition metal oxides or semiconductors [12] and (ii) the development of novel reactor configurations equipped with alternative excitation sources to selectively activate and oxidize VOCs under milder conditions. Among these, it is worth mentioning the use of plasma discharges [13], microwaves and radiofrequency [14], microreactors [15,16] or photoreactors irradiated with UV-light sources [17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

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High-radiance LED-driven fluidized bed photoreactor for the complete oxidation of n-hexane in air

Bueno-Alejo

Hueso

Mallada

et al. 2019

Chemical Engineering Journal

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This work presents a highly efficient photo-reactor configuration for VOC abatement. It consists of a fluidized bed made of commercial, easy to fluidize, transparent borosilicate glass beads coated with commercial TiO 2 nanoparticles (0.15 to 2.3 wt% loadings). Herein, we demonstrate that the use of high-radiance/low consumption UV-LEDs as irradiation sources with a deeper light penetration under fluidizing conditions facilitates the photocatalytic response to achieve the complete oxidation of VOCs. The role of different parameters such as catalyst loading and irradiation power have been thoroughly studied and evaluated to maximize the full combustion of n-hexane. Under the high radiance (up to 2200 mW/cm 2) conditions used the bed heats significantly (up to 190 ºC), although this did not have an effect on the conversions reached, which

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Intensification of heterogeneous TiO 2 photocatalysis using an innovative micro-meso-structured-photoreactor for n -decane oxidation at gas phase

Cited by 61 publications

References 70 publications

Single-Phase Flow in a Micro-Structured Packed Bed Photo-Reactor: Effect of Packing Size on Flow Regime and on the Reactor Performance for Homogeneous Photocatalysis

Single-Phase Flow in a Micro-Structured Packed Bed Photo-Reactor: Effect of Packing Size on Flow Regime and on the Reactor Performance for Homogeneous Photocatalysis

Boosting photocatalytic oxidation on graphitic carbon nitride for efficient photocatalysis by heterojunction with graphitic carbon units

High-radiance LED-driven fluidized bed photoreactor for the complete oxidation of n-hexane in air

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