Oxygen-deficient titania as alternative support for Pt catalysts for the oxygen reduction reaction

Zhao, Anqi; Masa, Justus; Xia, Wei

doi:10.1016/s2095-4956(14)60202-3

Cited by 20 publications

(16 citation statements)

References 32 publications

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“…This is thought to be due to the reducible nature of the TiO 2 support. Previously, Zhao et al demonstrated that oxygen deficient titania (TiO 2‑ x ) can be obtained by the thermal treatment of anatase TiO 2 under flowing H 2 . The difference between filter + TiO 2 + H 2 and filter + TiO 2 controls (data not shown) indicated minimal changes in vapor composition except for a significant increase in water production (52%).…”

Section: Resultsmentioning

confidence: 85%

“…These HPA materials were selected based on their HDO and alkylating activity toward pyrolysis model compounds . Similar activity was promoted with molybdenum oxide supported catalysts, − and it was determined that the redox properties of molybdenum oxide influenced the reaction selectivity. − Due to the unique redox properties of molybdenum oxide, a reducible support material (i.e., TiO 2 ) was leveraged in an attempt to further stabilize and tune the activity of the Mo-HPA via a charge-transfer mechanism between the TiO 2 support and HPA …”

Section: Experimental Materials and Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Catalytic Hot-Gas Filtration with a Supported Heteropolyacid Catalyst for Preconditioning Biomass Pyrolysis Vapors

Peterson

Engtrakul

Wilson

et al. 2019

ACS Sustainable Chem. Eng.

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During ex situ catalytic fast pyrolysis (CFP) of biomass, the separation of reactive char and alkali/alkaline particulates from biomass pyrolysis vapors by hot-gas filtration (HGF) leads to improved vapor stability and quality. HGF in tandem with chemical tailoring (e.g., partial deoxygenation) of the clean pyrolysis vapors, denoted as catalytic hot-gas filtration (CHGF), has the potential to further improve vapor composition by removing reactive oxygen moieties and protect downstream upgrading catalysts from fouling. Downstream upgrading refers to both vapor phase upgrading (e.g., ex situ CFP) and condensed phase upgrading (e.g., hydrotreating). Consequently, CHGF (as a single unit operation) was evaluated for preconditioning pyrolysis vapors for downstream upgrading processes. In order to understand the effective operating conditions that successfully filter and partially deoxygenate pyrolysis vapors, a titania-supported molybdenum heteropolyacid (Mo-HPA/TiO2) catalyst was studied for use in CHGF. Here, pine pyrolysis vapors were generated in a small pilot-scale pyrolyzer and transferred to a CHGF unit via a continuous-flow slipstream. In the CHGF unit, the pyrolysis vapors were filtered and upgraded over a packed Mo-HPA/TiO2 catalyst bed. Real-time monitoring and identification of the products formed were achieved by molecular beam mass spectrometry. The results showed that under a hydrogen-rich environment, the pine vapors were partially deoxygenated and alkylated over the Mo-HPA/TiO2 catalyst. Reactivity studies revealed that an increase in hydrogen concentration and a reduction in weight-hourly space velocity enhanced deoxygenation and alkylation. Time-on-stream (TOS) studies showed stable product formation up to 1 h with little change in catalyst activity. Additionally, the liquid product was collected using a custom fractional condensation unit (built in-house) and analyzed by gas chromatography mass spectrometry to confirm that the product was partially deoxygenated and alkylated. The combination of CHGF and fractional condensation allowed for chemical and physical removal of both foulant and value-added compounds (e.g., phenols, alkylphenols, methoxyphenols, cyclopentenones) for additional enhancement of downstream upgrading processes. The pre- and postreaction catalysts were characterized using temperature-programmed desorption, N2 physisorption, and elemental analysis with results indicating some catalyst coking. A hydrogen-based catalyst regeneration procedure restored the reacted catalyst activity to that of fresh Mo-HPA/TiO2.

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Section: Resultsmentioning

confidence: 85%

Section: Experimental Materials and Methodsmentioning

confidence: 99%

Catalytic Hot-Gas Filtration with a Supported Heteropolyacid Catalyst for Preconditioning Biomass Pyrolysis Vapors

Peterson

Engtrakul

Wilson

et al. 2019

ACS Sustainable Chem. Eng.

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show abstract

“…For this reason, the production of electrical energy from chemical reactions by using fuel cells is a really interesting matter from both the industrial and fundamental research points of view [ 1 , 2 , 3 ]. Oxygen Reduction Reaction (ORR) takes place on the cathode in a fuel cell and several works can be found in the published literature about the synthesis and optimization of electro-catalytic materials for this reaction [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 ]. Of these, platinum-based electro-catalysts happen to be the most widely studied, since Pt is the most active metal for ORR [ 1 , 6 , 7 , 8 , 9 , 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, the rising price of platinum and other precious metals as Pd or Ir makes it more difficult to commercialize devices containing them. This is the reason why non precious metal electro-catalysts are more numerous and more studied in order to lower the costs of fuel cells [ 2 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ].…”

Section: Introductionmentioning

confidence: 99%

Electrodes Based on Carbon Aerogels Partially Graphitized by Doping with Transition Metals for Oxygen Reduction Reaction

et al. 2018

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A series of carbon aerogels doped with iron, cobalt and nickel have been prepared. Metal nanoparticles very well dispersed into the carbon matrix catalyze the formation of graphitic clusters around them. Samples with different Ni content are obtained to test the influence of the metal loading. All aerogels have been characterized to analyze their textural properties, surface chemistry and crystal structures. These metal-doped aerogels have a very well-developed porosity, making their mesoporosity remarkable. Ni-doped aerogels are the ones with the largest surface area and the smallest graphitization. They also present larger mesopore volumes than Co- and Fe-doped aerogels. These materials are tested as electro-catalysts for the oxygen reduction reaction. Results show a clear and strong influence of the carbonaceous structure on the whole electro-catalytic behavior of the aerogels. Regarding the type of metal doping, aerogel doped with Co is the most active one, followed by Ni- and Fe-doped aerogels, respectively. As the Ni content is larger, the kinetic current densities increase. Comparatively, among the different doping metals, the results obtained with Ni are especially remarkable.

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“…The current electrocatalysts are mainly classified into three groups: precious metals, non-precious metals, and carbon-based materials. Pt and its alloys are most well studied and active electrode for ORR [202][203][204][205][206] . Additionally, nonprecious metals compounds which are composed of non-precious metal and nitrogen-contained organic compounds are also promising electrocatalysts for ORR [156,[207][208][209][210] .…”

Section: Oxygen Electrochemistrymentioning

confidence: 99%

Nanostructured energy materials for electrochemical energy conversion and storage: A review

Zhang

Cheng

Zhang

2016

Journal of Energy Chemistry

424

185

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Oxygen-deficient titania as alternative support for Pt catalysts for the oxygen reduction reaction

Cited by 20 publications

References 32 publications

Catalytic Hot-Gas Filtration with a Supported Heteropolyacid Catalyst for Preconditioning Biomass Pyrolysis Vapors

Catalytic Hot-Gas Filtration with a Supported Heteropolyacid Catalyst for Preconditioning Biomass Pyrolysis Vapors

Electrodes Based on Carbon Aerogels Partially Graphitized by Doping with Transition Metals for Oxygen Reduction Reaction

Nanostructured energy materials for electrochemical energy conversion and storage: A review

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