Synthesis and crystal structure of mixed metal(III) tungstenyl(VI) ortho-pyrophosphates

Roy, Subrata Chandra; Raguž, Branimir; Assenmacher, Wilfried; Glaum, Robert

doi:10.1016/j.solidstatesciences.2015.09.006

Cited by 7 publications

(4 citation statements)

References 29 publications

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“…The W 6+ is displaced by 0.47 Å from the 8 i position occupied by Fe 3+ to the general position 16 j , labelled M 2’ in Table 4. In this position the W 6+ has two short W–O bonds, 1.65 Å (Table 6) characteristic of the tungstenyl group (Roy et al ., 2015). The partial substitution of M 6+ for Fe 3+ at M 2 is counterbalanced by a decrease in the As 3+ content.…”

Section: Discussionmentioning

confidence: 99%

The walentaite group and the description of a new member, alcantarillaite, from the Alcantarilla mine, Belalcázar, Córdoba, Andalusia, Spain.

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Hochleitner

Rewitzer

et al. 2020

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The general structural formula for the walentaite group is [((A1yA1’1–y), A2)(H2O)n][Bx(As2)2–x(As3)M1(M2)2(TO4)2(O,OH)7], based on heteropolyhedral layers of configuration [M1(M2)2(TO4)2(O,OH)6], with surface-coordinated species at the B, As2 and As3 sites, and with interlayer hydrated cation groups centred at the A sites. The group is divided into walentaite and halilsarpite subgroups based on T = P5+ and As5+, respectively. Alcantarillaite, (IMA2019-072), [Fe3+0.5□0.5(H2O)4][CaAs3+2(Fe3+2.5W6+0.5)(AsO4)2O7], is a new member of the walentaite group from the Alcantarilla wolframite mine, Belalcázar, Córdoba, Andalusia, Spain. It occurs most commonly as lemon-yellow fillings together with massive scorodite in fissures and cracks in quartz adjacent to löllingite. It is also found as tiny yellow rosettes lining vugs and as spheroids of ultrathin blades. It is associated with scorodite, pharmacosiderite, ferberite and schneiderhöhnite. Optically it is biaxial (–), with α = 1.703(calc), β = 1.800(5), γ = 1.850(5) and 2V = 68(1)° (white light). Dispersion is r > v, moderate. The optical orientation is X = a, Y = c and Z = b. The calculated density is 3.06 g cm–3. Electron microprobe analyses together with crystal structure refinement results gives the empirical formula [Fe3+0.52□0.48(H2O)4][(Ca0.44K0.11Na0.05Fe2+0.24□0.42)As3+1.83][Fe3+2.54Al0.03W6+0.43)((As0.65P0.35)O4)2O5.86(OH)1.14]. Alcantarillaite is orthorhombic, with an average structure described in Imma, and with a = 24.038(8) Å, b = 7.444(3) Å, c = 10.387(3) Å, V = 1858.6(11) Å3 and Z = 4. The structure (wRobs = 0.078 for 651 reflections to a resolution of 0.91 Å) differs most significantly from other walentaite-group members in having an interlayer A2 site occupied. Square-pyramidal polyhedra centred at the A2 sites form edge-shared dimers, (Fe3+)2O4(H2O)4. The dimers share vertices with TO4 anions in the layers on either side to form 8-sided channels along [010] occupied by H2O molecules.

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Section: Discussionmentioning

confidence: 99%

The walentaite group and the description of a new member, alcantarillaite, from the Alcantarilla mine, Belalcázar, Córdoba, Andalusia, Spain.

Grey

Hochleitner

Rewitzer

et al. 2020

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“…Several recent investigations have explored the physicochemical properties and the catalytic activity of mixed-metal phosphates in a systematic way. 12 …”

Section: Selective Oxidation Reaction and High-throughput Experimenta...mentioning

confidence: 99%

Learning Design Rules for Selective Oxidation Catalysts from High-Throughput Experimentation and Artificial Intelligence

et al. 2022

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The design of heterogeneous catalysts is challenged by the complexity of materials and processes that govern reactivity and by the fact that the number of good catalysts is very small in comparison to the number of possible materials. Here, we show how the subgroup-discovery (SGD) artificial-intelligence approach can be applied to an experimental plus theoretical data set to identify constraints on key physicochemical parameters, the so-called SG rules , which exclusively describe materials and reaction conditions with outstanding catalytic performance. By using high-throughput experimentation, 120 SiO 2 -supported catalysts containing ruthenium, tungsten, and phosphorus were synthesized and tested in the catalytic oxidation of propylene. As candidate descriptive parameters, the temperature and 10 parameters related to the composition and chemical nature of the catalyst materials, derived from calculated free-atom properties, were offered. The temperature, the phosphorus content, and the composition-weighted electronegativity are identified as key parameters describing high yields toward the value-added oxygenate products acrolein and acrylic acid. The SG rules not only reflect the underlying processes particularly associated with high performance but also guide the design of more complex catalysts containing up to five elements in their composition.

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“…XRPD pattern were recorded after each annealing step to control the progress of product formation until the thermodynamically stable mm-MPTB phase was obtained single-phase (see XRPD pattern in Figure 1 and Figures S1-S4). In case of (Rh [12] Lattice parameters of the MPTBs were determined using the program SOS [13] and α-SiO 2 (Merck, Darmstadt) as internal standard (see Table 1). Interestingly, the lattice parameters a and b which are parallel to the ReO 3 -type slabs of the (Rh,W)-MPTBs are smaller compared to the pure tungsten MPTBs, whereas the parameter c (perpendicular to the ReO 3 -type slabs) is enlarged (Table 1).…”

Section: Synthesismentioning

confidence: 99%

Mixed‐Metal Monophosphate Tungsten Bronzes Containing Rhodium and Iridium

et al. 2021

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Solution combustion synthesis followed by annealing in air led to the MPTB-related phosphates (Rh 1/6 W 5/6 O 3 ) 8 (PO 2 ) 4 , (Ir 1/6 W 5/ 6 O 3 ) 8 (PO 2 ) 4 (a = 5.258(2) Å, b = 6.538(3) Å, c = 17.322(8) Å), (Rh 1/ 9 W 8/9 O 3 ) 12 (PO 2 ) 4 and (Rh 2/21 W 19/21 O 3 ) 14 (PO 2 ) 4 . Single-crystals of the mixed-metal (Rh,W)-MPTBs at m = 4 and at m = 7 were grown by chemical vapor transport (CVT). Their crystal structures have been refined from X-ray single-crystal data {(Rh,W

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Synthesis and crystal structure of mixed metal(III) tungstenyl(VI) ortho-pyrophosphates

Cited by 7 publications

References 29 publications

The walentaite group and the description of a new member, alcantarillaite, from the Alcantarilla mine, Belalcázar, Córdoba, Andalusia, Spain.

The walentaite group and the description of a new member, alcantarillaite, from the Alcantarilla mine, Belalcázar, Córdoba, Andalusia, Spain.

Learning Design Rules for Selective Oxidation Catalysts from High-Throughput Experimentation and Artificial Intelligence

Mixed‐Metal Monophosphate Tungsten Bronzes Containing Rhodium and Iridium

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