SBA materials as support of iridium catalyst for hydrogenation reactions

Kiderys, Angelika; Kot, Monika; Janiszewska, Ewa; Pietrowski, Mariusz; Yang, C. S.; Zieliński, Michał

doi:10.1016/j.cattod.2019.03.018

Cited by 13 publications

(6 citation statements)

References 44 publications

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“…5,6 Following this approach, numerous transition metals, such as Ni, 7,8 Pd, 9 Ru, 10,11 Pt, 12 Co, 8 Mn, 8 Fe, 8 have been doped on the B-site of stoichiometric or A-site deficient mixed perovskite oxides and subsequently exsolved under a range of reducing atmospheres or through fast electrochemical reduction. Among the transition metals, iridium is a scarce but key element being used in a variety of applications 13 including water splitting reactions, [14][15][16][17] fuel cells, 18,19 hydrogenation reactions, 20 methane reformation 21,22 and auto-motive exhaust catalysis. [23][24][25][26] Specifically, CO oxidation applied in air purification and pollution control in automotive exhaust uses more than 60% of the annual production of noble metals.…”

Section: Introductionmentioning

confidence: 99%

“…Among the advantages of this method, is that exsolved NPs are homogeneously distributed in size and surface density, and the socketing into the surface of the perovskite support results in enhanced thermal and hydrocarbon/coking stability, as well as strain thereby potentially enhancing activity. , Following this approach, numerous transition-metals, such as Ni, , Pd, Ru, , Pt, Co, Mn, and Fe, have been doped on the B-site of stoichiometric or A-site deficient mixed perovskite oxides and subsequently exsolved under a range of reducing atmospheres or through fast electrochemical reduction. Among the transition metals, iridium is a scarce but key element being used in a variety of applications including water splitting reactions, − fuel cells, , hydrogenation reactions, methane reformation, , and automotive exhaust catalysis. − Specifically, CO oxidation applied in air purification and pollution control in automotive exhaust uses more than 60% of the annual production of noble metals. The commonly used catalysts are Pt, Rh, and Pd deposited on oxide supports, , which, even though highly active, suffer from sintering and poisoning .…”

Section: Introductionmentioning

confidence: 99%

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Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate

Calì

Kerherve

Naufal

et al. 2020

ACS Appl. Mater. Interfaces

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The search for new functional materials that combine high stability and efficiency with reasonable cost and ease of synthesis is critical for their use in renewable energy applications. Specifically in catalysis, nanoparticles, with their high surfaceto-volume ratio, can overcome the cost implications associated with otherwise having to use large amounts of noble metals. However, commercialized materials, i.e. catalytic nanoparticles deposited on oxide supports, often suffer from loss of activity due to coarsening and carbon deposition during operation. Exsolution has proven to be an interesting strategy to overcome such issues.Here the controlled emergence, or exsolution, of faceted iridium nanoparticles from a doped SrTiO3 perovskite is reported and their growth preliminary probed by in situ electron microscopy. Upon reduction of SrIr0.005Ti0.995O3 the generated nanoparticles show embedding into the oxide support, therefore preventing agglomeration and subsequent catalyst degradation. The advantages of this approach are the extremely low noble metal amount employed (~0.5% weight) and the catalytic activity reported during CO oxidation tests, where the performance of the exsolved SrIr0.005Ti0.995O3 is compared to the activity of a commercial catalyst with 1% loading (1% Ir/Al2O3). The high activity obtained with such low-doping shows the possibility for scaling up this new catalyst, reducing the high cost associated with iridium-based materials.Image analysis and calculations; XPS supplementary data; STEM-EDX maps of as-synthesised Ir0.5-STO (PDF)

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate

Calì

Kerherve

Naufal

et al. 2020

ACS Appl. Mater. Interfaces

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“…A comparison of the TOF (48.9 min −1 ) values obtained for the best Ir/Sil-OH catalyst with the results reported in the literature for iridium supported on different supports (SBA-3, Al 2 O 3 , SiO 2 [ 39 , 40 ], MgF 2 [ 19 ], magnesium oxo-fluoride [ 41 , 42 ]) shows that the iridium catalyst supported on modified silicalite-1 is a more promising catalyst— Table 6 .…”

Section: Resultsmentioning

confidence: 87%

Studies of New Iridium Catalysts Supported on Modified Silicalite-1—Their Structure and Hydrogenating Properties

et al. 2021

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This paper investigates the catalytic properties of the iridium catalysts supported on modified silicalite-1. Post-synthesis modification of silicalite-1, with solutions of ammonium compounds (NH4F and NH4OH), appeared to be an efficient method to generate the acidic sites in starting support. The modification of support led not only to changes in its acidity but also its porosity—formation of additional micro- and mesopores. The novel materials were used as supports for iridium. The iridium catalysts (1 wt.% Ir) were characterized by N2 adsorption/desorption measurements, temperature-programmed reduction with hydrogen (TPR-H2), H2 chemisorption, transmission electron microscopy (TEM), temperature-programmed desorption of ammonia (TPD-NH3), X-ray photoelectron spectroscopy (XPS) and tested in the hydrogenation of toluene reaction. The catalytic activity of iridium supported on silicalite-1 treated with NH4OH (higher porosity of support, better dispersion of active phase) was much higher than that of Ir supported on unmodified and modified with NH4F silicalite-1.

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“…The use of modified silica as iridium supports allowed to obtain a new class of catalysts characterized by high activities in the hydrogenation of toluene, greater than that of the iridium system supported on unmodified SiO 2 . A comparison of the activity obtained for the best Ir-SiO-F-0.1 catalyst with the results reported in the literature for iridium supported on modified acidic silica [ 8 ], alumina [ 26 ], as well as SBA-3 or SBA-15 [ 39 ], shows that the iridium catalyst supported on modified silica is more promising catalyst.…”

Section: Discussionmentioning

confidence: 91%

“…Turnover frequencies of the investigated catalysts as a function of temperature reaction are shown in Figure 9 . Optimum reaction conditions were established on the basis of our earlier results reported in [ 39 ].…”

Section: Resultsmentioning

confidence: 99%

Effect of Modification of Amorphous Silica with Ammonium Agents on the Physicochemical Properties and Hydrogenation Activity of Ir/SiO2 Catalysts

Kot

Wojcieszak²,

Janiszewska

et al. 2021

Materials

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The modification of commercial silica with solutions of NH4F or NH4Cl salts, followed by thermal treatment, enabled generation of the acidic sites in SiO2 and changed its textural properties. The use of ammonium salts solution also caused the generation of additional porosity. Using NH4F solution caused significant decrease in the specific surface area and the increase in the average pore diameter. The number and strength of resulting acid sites depend on the nature of anion in the applied ammonium salt and the concentration of salt solution. It has been found that the sample treated with NH4F presented higher total acidity (TPD–NH3) and the amount as well as the strength of acid sites increased with the concentration of the used modifier. As modified amorphous SiO2 materials used as a support for iridium (1 wt %, Ir(acac)3) nanoparticles permitted to obtain highly active catalysts for toluene hydrogenation under atmospheric pressure. The highest activity (expressed as the apparent rate and TOF) was obtained for iridium catalysts supported on silica modified by NH4F with the highest acidity. The modification of silica with NH4F favors the generation of centers able to adsorb toluene, which results in higher activity of this catalyst.

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SBA materials as support of iridium catalyst for hydrogenation reactions

Cited by 13 publications

References 44 publications

Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate

Exsolution of Catalytically Active Iridium Nanoparticles from Strontium Titanate

Studies of New Iridium Catalysts Supported on Modified Silicalite-1—Their Structure and Hydrogenating Properties

Effect of Modification of Amorphous Silica with Ammonium Agents on the Physicochemical Properties and Hydrogenation Activity of Ir/SiO2 Catalysts

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