Photocatalytic valorization of ethanol and glycerol over TiO2 polymorphs for sustainable hydrogen production

Beltram, Alessandro; Romero‐Ocaña, Ismael; Jaén, Juan Josè Delgado; Montini, Tiziano; Fornasiero, Paolo

doi:10.1016/j.apcata.2015.09.022

Cited by 50 publications

(53 citation statements)

References 86 publications

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“…The selectivity of photocatalytic systems can be enhanced by two main strategies: modification of the photocatalyst and optimization of reaction conditions (e.g., aeration, type of solvent, concentration and type of anions [90], use of membranes) [91]. Not surprisingly, the TiO 2 phase composition was demonstrated to have an effect on the selectivity of many photocatalytic reactions, such as ammonia oxidation [92], photoinduced decomposition of acetone, oxygenate photoreforming [6], and selective oxidation of alcohols to aldehydes [91,93]. For instance, the product distribution of ammonia oxidation was different in the case of rutile, yielding nitrates as a major product, and of anatase and brookite, yielding mild-oxidation products such as nitrites and N 2 [92].…”

Section: Photocatalytic Studiesmentioning

confidence: 99%

“…Different polymorphs have distinct chemico-physical properties, such as electronic and optical properties, magnetism [2], ion conductivity [3], photo/electro-chromism [4], and surface energy and atom arrangement, which in turn affect the material performance in various applications, such as sensing [5] and photocatalysis [6,7]. Rationalizing the effect of crystal structure on the performance of a photocatalytic material is a pivotal research goal, since both Fe 2 O 3 and TiO 2 , the most investigated and widely used photocatalysts, may exist in different crystal structures [7,8].…”

Section: Introductionmentioning

confidence: 99%

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Brookite: Nothing New under the Sun?

2017

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Advances in the synthesis of pure brookite and brookite-based TiO 2 materials have opened the way to fundamental and applicative studies of the once least known TiO 2 polymorph. Brookite is now recognized as an active phase, in some cases showing enhanced performance with respect to anatase, rutile or their mixture. The peculiar structure of brookite determines its distinct electronic properties, such as band gap, charge-carrier lifetime and mobility, trapping sites, surface energetics, surface atom arrangements and adsorption sites. Understanding the relationship between these properties and the photocatalytic performances of brookite compared to other TiO 2 polymorphs is still a formidable challenge, because of the interplay of many factors contributing to the observed efficiency of a given photocatalyst. Here, the most recent advances in brookite TiO 2 material synthesis and applications are summarized, focusing on structure/activity relation studies of phase and morphology-controlled materials. Many questions remain unanswered regarding brookite, but one answer is clear: Is it still worth studying such a hard-to-synthesize, elusive TiO 2 polymorph? Yes.

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Section: Photocatalytic Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Brookite: Nothing New under the Sun?

2017

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“…The volume of the aqueous solution of glycerol with suspended photocatalyst was 600cm 3 . The Xe-arc lamp (100 W) was placed in the vertical axis of the reactor.…”

Section: The Experimental Procedures Of the Performed Photocatalytic mentioning

confidence: 99%

“…All the experiments of the process of photocatalytic conversion of glycerol into hydrogen were carried out in the quartz reactor with the volume 1200cm 3 that was cooled by water. The volume of the aqueous solution of glycerol with suspended photocatalyst was 600cm 3 .…”

Section: The Experimental Procedures Of the Performed Photocatalytic mentioning

confidence: 99%

“…The influence of the amount of photocatalyst (the concentration of the catalyst in the reaction mixture) added to the solution was also studied. The volume of the reaction mixture was equal to 600 cm 3 . The distribution of light dispersion depends on the amount of the photocatalyst and has a large impact on the performance of hydrogen production.…”

Section: The Photocatalytic Hydrogen Production Testsmentioning

confidence: 99%

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An Experimental Study of the Photocatalytic Hydrogen Production in the Laboratory-Scale Set-Up Depending on the Process Conditions

Stelmachowski¹,

Bednarczyk²,

Gmurek³

2017

WIT Transactions on Ecology and the Environment

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Concern for the environment and the use of renewable energy sources are the two main priorities of energy policy combined with an environmental policy that is based on the principles of sustainable development. Many aspects should be taken into account in the case of energy production based on biomass/biofuels, in particular, the possibility of the formation of additional by-products. Glycerol is the main by-product during the trans-esterification of vegetable oils to biodiesel. The photocatalytic hydrogen production from the glycerol-water solution is less energy consuming reaction in comparison (for example) with its steam reforming or bio-conversion because it can be processed under mild conditions and low temperature. The paper presents the experimental results of the application process of photocatalytic hydrogen production from an aqueous solution of glycerol, with the use of TiO2 doped with noble metals (platinum, palladium, silver) as a photocatalyst under solar-like light irradiation. The aim was to compare the hydrogen productivity depending on the catalyst concentration, the kind of the doped metal and the amount of the metal in the catalyst. The reaction (glycerol-water with suspended catalyst) mixture was irradiated by Xe-arc lamps (100 W). The influence of the doped metal on the hydrogen yield was studied for the photocatalysts prepared by the sol-gel and photodeposition method. The photocatalysts have been studied using scanning electron microscopy (SEM) with EDX (Quanta FEI 200F, Oxford Instruments X-Max50), X-ray powder diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS). It was proved, that glycerol is a good and efficient substance for the photocatalytic hydrogen production. The prepared and studied photocatalysts are characterized by high stability and very high yield under used process conditions. The experiments were performed in the quartz reactor with volume 1200 cm3. The volume of the reaction solution containing aqueous glycerol solution was 600 cm 3 . The maximum hydrogen production was about 269.13·10-3 [mole H2/(h·gcat)] and it was observed for TiO2 doped by platinum (1% by weight; prepared by photodeposition) for 4.5% aqueous solution of glycerol.

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Progress and Perspectives in Photo‐ and Electrochemical‐Oxidation of Biomass for Sustainable Chemicals and Hydrogen Production

Luo

Barrio

Sunny

et al. 2021

Advanced Energy Materials

254

197

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Elevated concentrations of atmospheric greenhouse gases (GHGs), particularly carbon dioxide (CO 2 ), have affected the global environment, causing climate deviations and threatening the biodiversity. [1,2] Deep-cutting solutions and new technologies are thus imperative to repay the carbon debt. [3] Hydrogen (H 2 ) is an ideal fuel to enable a successful transition to a global zero emission economy: With a gravimetric energy density more than double that of conventional fuels like diesel, gasoline, and natural gas it is a lightweight energy carrier which can be converted to electricity and water via fuel cells and thus holds great promise to cut emissions of the transport and energy sectors to zero. Furthermore, it is an energy dense chemical which is already used in the chemical industry (i.e., ammonia via the Haber-Bosch process) and steel manufacturing. However, these industries currently use brown (made from coal via gasification and subsequent water gas shift reaction) and gray (made by steam methane reforming) hydrogen which both have significant CO 2 footprints. Thus, synthesizing green (meaning renewable) hydrogen cost-effectively is a solution which could green such industries and the transport sector and simultaneously meet our growing demands for viable energy storage solutions. However, switching from fossilfuels to a hydrogen economy requires efficient technologies that permit clean, sustainable and cost-effective production, storage, and utilization of H 2 . [4][5][6] Water electrolysis is a clean technology for green H 2 production, where water is split into H 2 at the cathode while O 2 is generated at the anode. Thermodynamically, the energy input required for this reaction equals an applied voltage of 1.23 V but in practice >1.8 V is commonly applied due to the sluggish kinetics of the oxygen evolution reaction (OER). The kinetics of the OER are complex. In addition to the thermodynamic potential of 1.23 V, even the best OER catalysts to date show significant overpotentials (0.35-0.4 V) which is due to suboptimal scaling relation between OOH and OH adsorption energies. [7,8] As a consequence, a significant amount of energy is spent on Biomass is recognized as an ideal CO 2 neutral, abundant, and renewable resource substitute to fossil fuels. The rich proton content in most biomass derived materials, such as ethanol, 5-hydroxymethylfurfural (HMF) and glycerol allows it to be an effective hydrogen carrier. The oxidation derivatives, such as 2,5-difurandicarboxylic acid from HMF, glyceric acid from glycerol are valuable products to be used in biodegradable polymers and pharmaceuticals. Therefore, combining biomass-derived compound oxidation at the anode and hydrogen evolution reaction at the cathode in a biomass electrolysis or photo-reforming reactor would present a promising strategy for coproducing high value chemicals and hydrogen with low energy consumption and CO 2 emissions. This review aims to combine fundamental knowledge on photo and electro-assisted catalysis to provide a comprehensive und...

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Photocatalytic valorization of ethanol and glycerol over TiO2 polymorphs for sustainable hydrogen production

Cited by 50 publications

References 86 publications

Brookite: Nothing New under the Sun?

Brookite: Nothing New under the Sun?

An Experimental Study of the Photocatalytic Hydrogen Production in the Laboratory-Scale Set-Up Depending on the Process Conditions

Progress and Perspectives in Photo‐ and Electrochemical‐Oxidation of Biomass for Sustainable Chemicals and Hydrogen Production

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