Multicomponent Bismuth Research Articles

Precise structure-tailoring of multicomponent nanocatalysts enabled by continuous flow-controlled flash nanoprecipitation technique

Nanostructured catalysts with diverse compositions offer an exciting prospect for various catalytic applications. The precise control of nanostructures allows to tune the physicochemical properties of nanocatalysts and improve their performance. However, most preparative methods rely on conventional batch systems, which require tedious procedures and cause low productivity. Herein, we reported a novel engineered flash nanoprecipitation (FNP) technique to synthesize well-structured nanocatalysts in a continuous-flow procedure with intelligent operation and high productivity, in which a series of multicomponent bismuth oxyhalides (BiOClxBr1-x) were demonstrated as the model catalysts. This method was established on the uninterrupted continuous synthesis of BiOClxBr1-x with precisely controlled microstructure by simply altering the flow rate ratio of precursor fluids in the reactor. The computational fluid dynamics (CFD) simulation showed that the automized flow setup could achieve the accurate control over the intensified fluid mixing. Significantly, a volcano relationship between the halogen compositions and catalytic activities toward photodegradation of tetracycline (TC) was observed, which indicated that the structural changes enabled band structure-dependent regulation. The FNP-processed BiOCl0.75Br0.25 possessed a balanced redox ability and light absorption, thus located at the peak of volcano with a five-fold enhancement of intrinsic photocatalytic activity. Overall, this work provides a promising prospect of continuous-flow technique in the engineered manufacturing of the advanced nanomaterials, offering fine-tuning of the nanostructures of materials with low cost and high productivity.

SYNTHESIS OF MULTICOMPONENT COMPOUNDS WITH A PIROCHLORE-TYPE STRUCTURE

The possibility of solid-phase synthesis of multicomponent bismuth niobates and tantalates with pyrochlore-type structure (sp. gr. Fd-3m), containing atoms of transition 3d-elements in equimolar quantities is shown. The composition of this type pyrochlores can be described by stoichiometric formula Bi2Cr1/6Mn1/6Fe1/6Co1/6Ni1/6Cu1/6Ta(Nb)2O9 ± ?. A feature of synthesis of pyrochlores is a multi-stage high-temperature heat treatment process at a temperature of 650, 850, 950, 1050 °С for 60 hours. In the case of bismuth tantalate based pyrochlore, impurity phase of triclinic bismuth orthotantalate ?-BiTaO4 (sp. gr. P-1) is formed in trace amounts (? 8 mol.%). Complex pyrochlore based on bismuth niobate is characterized by a dense, low-porous microstructure in contrast to loose, porous tantalum pyrochlore with an average grain size of ? 2 µm. The unit cell parameter for pyrochlores containing niobium and tantalum is 10.4927(10.4922) ?, respectively.

Selective oxidation of biomass‐based 5‐hydroxymethylfurfural to 2,5‐diformylfuran catalyzed by multicomponent molybdenum‐based catalyst

AbstractBACKGROUNDOn the way to convert biomass‐derived products as a renewable and environment‐friendly source to high‐value added chemicals, one great challenge is the effective control of selectivity in the reaction. Here, we contribute a heterogeneous catalysis method for selective transformation of biomass‐based 5‐hydroxymethylfurfural (HMF) into 2,5‐diformylfuran (DFF) via multicomponent bismuth molybdate catalyst. The influence of the different pH value on the catalytic activity of the catalyst were investigated. In addition, to evaluate the catalytic performance of the catalyst in the selective oxidation of HMF, a variety of important reaction parameters such as the reaction temperature, catalyst amount, atmosphere, and solvent were examined.RESULTSThe catalyst prepared with pH value in the range of 1–2 exhibits the optimal catalytic activity in the selective aerobic oxidation of the hydroxy group of HMF. As a result, the target compound of DFF could be obtained with excellent yield (99%) and high selectivity (> 99%) in the presence of 0.25 mg Co9Fe3BiMo12O51 (pH = 1–2) in DMSO at 130 °C under O2 atmosphere. In addition, the catalyst Co9Fe3BiMo12O51 could be reused several times without a significant loss of its catalytic activity.CONCLUSIONIn this work, a heterogeneous catalytic approach to oxidizing HMF to DFF using Co9Fe3BiMo12O51 as catalyst and molecular oxygen as oxidant was established. The O2 temperature‐programmed desorption (O2‐TPD) characterization indicated that the pH value of co‐precipitation obviously affected the oxygen mobility and storage capacities in the catalysts, which is related to the catalytic performance in the selective aerobic oxidation. © 2022 Society of Chemical Industry (SCI).

Investigation of structural and optical properties of Pr3+ doped and Pr3+/Dy3+ co-doped multicomponent bismuth phosphate glasses for visible light applications

Pr3+ doped 59.5P2O5+15Bi2O3+10BaF2+10xF+05TeO2+0.5Pr6O11 glasses and Pr3+/Dy3+ co-doped 59P2O5+15Bi2O3+ 10BaF2+ 10xF + 05TeO2+0.5Dy2O3+0.5Pr6O11 glasses (where xF = LiF, NaF, MgF2, KF, CaF2 and SrF2) were synthesized using melt quenching route. Structural properties were researched for different modifier fluorides. With the dopant constant concentration the absorption and luminescence intensity variance influenced by this multicomponent incorporation has been observed. The energy transfer between resonance levels of Pr3+ and Dy3+ through fluorescence studies also examined for Mg and Sr glasses. Long-range nature of prepared glasses, morphological studies with elemental probe, various functional groups pertaining to glass matrices and the non-bridging oxygen bonds with PO4 tetrahedron or depolymarization of oxygen bonds in the presence of the modifier cations with phosphates were thoroughly understood with PXRD, FTIR and 31P NMR characterizations. Judd-Ofelt (J-O) theory has been adopted to estimate important optical parameters. From the fluorescence studies laser characteristic parameters such as optical band gains (σe × τR) and gain bandwidths (σe × Δλeff) were calculated and compared in the present fabricated glasses influenced by various modifiers.

Magnetic behavior of Fe-doped of multicomponent bismuth niobate pyrochlore

Abstract Two series of iron-containing solid solutions Bi2Mg1−x Fe x Nb2O9+δ and Bi2MgNb2−2x Fe2x O9−δ of pyrochlore structure were obtained by the traditional solid phase synthesis method. The electronic state and character of exchange interactions of iron atoms in solid solutions were investigated by methods of magnetic dilution and NEXAFS-spectroscopy. According to X-ray spectroscopy and magnetic susceptibility data, iron(III) atoms are distributed mainly in octahedral positions of niobium(V) and in a dominant amount are in the charge state of Fe(III) in the form of monomers and exchange-bonded clusters mainly with antiferromagnetic type of exchange. Differences in magnetic behavior of iron-containing solid solutions of both series have been revealed. Antiferromagnetic and ferromagnetic exchange can be realized between iron atoms, which, with increasing concentration of paramagnetic atoms and averaging structure distortions, becomes less significant. The parameters of exchange interactions in clusters and distribution of iron paramagnetic atoms depending on the concentration of solid solutions have been calculated.

Dielectric and magnetic properties, NEXAFS spectroscopy of Co-doped of multicomponent bismuth niobate pyrochlore

Two series of Bi2Mg1-xCoxNb2O9 and Bi2MgNb2-2xCo2xO9-δ preparations with pyrochlore structure were synthesized using solid phase method. It was found that solid solutions are formed in Bi2MgNb2-2xCo2xO9-δ series, foreign phases of MgNb2O6 and Bi5Nb3O15 are fixed in Bi2Mg1-xCoxNb2O9 samples, no impurity cobalt-containing phases were detected. The method of magnetic susceptibility and NEXAFS-spectroscopy investigated the electronic state and character of exchange interactions of cobalt atoms in solid solutions with the pyrochlore structure. According to X-ray spectroscopy and magnetic susceptibility of cobalt atoms in solid solutions in a dominant amount are in the charge state of Co(II) in the form of monomers and exchange-bound clusters mainly with antiferromagnetic type of exchange. Ceramics Co-doping of multicomponent bismuth niobate pyrochlore has at room temperature a high dielectric permeability of 84 and small dielectric losses of 0.001. The energy of activation of conductivity is equal to 0.75–1.03 eV. This type of ceramics with excellent dielectric properties can potentially be used as multilayer ceramic capacitors.

Redox Behavior Analysis of Multicomponent Bismuth Molybdate Catalyst by Using In-situ XAFS

Redox Behavior Analysis of Multicomponent Bismuth Molybdate Catalyst by Using In-situ XAFS

Effects of zirconium content on the catalytic performance of BiMoZrx in the oxidative dehydrogenation of 1‐butene to 1,3‐butadiene

AbstractBACKGROUNDOxidative dehydrogenation (ODH) of 1‐butene has been considered as a potential process for manufacturing 1,3‐butadiene (BD). The introduction of metal oxides to pure bismuth molybdate, a promising catalyst for the ODH reaction, can be expected to improve the catalysts performance. In this work, multicomponent bismuth molybdate oxide (BiMoZrx) catalysts for ODH of 1‐butene were prepared by a co‐precipitation method with variation of zirconium content (x = 0–0.5), and the influence of zirconium on catalytic performance was investigated.RESULTSThe zirconium content has a significant effect on the structure and performance of the catalyst. The conversion of 1‐butene and the BD yield over BiMoZrx catalysts display volcano curves with respect to zirconium content. Among the catalysts tested, BiMoZr0.4 exhibits superior activity.CONCLUSION1‐butene temperature‐programmed re‐oxidation (TPRO) and X‐ray photoelectron spectroscopy (XPS) characterizations demonstrate that zirconium content is related to the oxygen mobility of BiMoZrx catalysts, and oxygen mobility is a crucial factor determining catalytic performance in the ODH reaction. © 2014 Society of Chemical Industry

Mesostructural Bi-Mo-O catalyst: correct structure leading to high performance

Structure-activity relationship has been one of the main topics of research on catalysts all the time. Component and structure are the two moieties governing the performance of solid materials as catalysts. Multicomponent bismuth molybdates are well known catalysts for propene oxidation but pure crystalline phases of bismuth molybdate are inactive for the reaction. We have designed mesostructural Bi-Mo-O catalyst with pure bismuth molybdate nanocrystals attached to molybdenum oxide nanobelts and found it is a high performance catalyst for the reaction, though the two domains themselves are inactive. The strongly expitaxial interaction between the two domains causes the lattice shrinkage and distortion of the bismuth molybdate nanocrystals and extremely promotes their catalytic activity toward propene oxidation while keeping high selectivity at the same time. The results are instructive for design of nano oxide catalysts with mesostructures leading to high performance.

Effect of Bi 2O 3 content on physical and optical properties of 15Li 2O–15K 2O– xBi 2O 3–(65− x) B 2O 3: 5V 2O 5 glass system

Multi-component bismuth borate glasses doped with vanadium ions 15Li 2O–15K 2O– xBi 2O 3–(65− x) B 2O 3: 5V 2O 5, ( x=3, 5, 7, 10, 12 and 15) have been prepared using conventional melt quench technique. Characterization of the prepared glasses has been done using X-ray diffraction, differential scanning calorimetry and density measurements. The effect of Bi 2O 3 content on the optical properties of the present glass system is studied from the optical absorption spectra recorded in the wavelength range 200–800 nm. The fundamental absorption edge has been identified from the optical absorption spectra. The values of optical band gap for indirect allowed transitions have been determined using available theories. The origin of the Urbach energy is associated with the phonon-assisted indirect transitions. The density and molar volume studies indicate that Bi 2O 3 in these glasses is acting partly as network modifier and partly as network former. The variations in the optical band gap energies, density and molar volume with Bi 2O 3 content have been discussed in terms of changes in the glass structure. Values of the theoretical optical basicity, average crosslink density and the average electronic polarizability are also reported.

Catalytic conversion of urea to biuret: A catalyst screening study

Biuret was synthesized from urea in a batch reactor using various homogeneous and heterogeneous catalysts, with the aim of searching for efficient catalyst in converting non-catalytic reaction to catalytic reaction. For this purpose, zeolite, heteropolyacid, organic acid and base, multicomponent bismuth molybdate, and multicomponent bismuth molybdate-alumina mixed catalysts were tested. It was revealed that the performance of catalytic reaction was better than that of non-catalytic reaction in the synthesis of biuret from urea. Among the homogeneous acid and base catalysts tested, thionyl chloride (SOCl2) showed the best catalytic performance. Among the heterogeneous catalysts tested, on the other hand, a mixed catalyst comprising multicomponent bismuth molybdate (Co8Fe3Bi1Mo12O50) and alumina showed the best catalytic performance.

Production of 1,3-Butadiene From C4 Raffinate-3 Through Oxidative Dehydrogenation of n-Butene Over Bismuth Molybdate Catalysts

Recent progress on the bismuth molybdate catalysts for oxidative dehydrogenation of n-butene to 1,3-butadiene was reported in this review. A number of bismuth molybdate catalysts, including pure bismuth molybdates (α-Bi2Mo3O12, β-Bi2Mo2O9, and γ-Bi2MoO6) and multicomponent bismuth molybdates, were prepared by a co-precipitation method for use in the production of 1,3-butadiene from C4 raffinate-3 through oxidative dehydrogenation of n-butene. It was observed that multicomponent bismuth molybdate catalyst was more efficient than pure bismuth molybdate catalyst in the oxidative dehydrogenation of n-butene. Various experimental measurements such as temperature-programmed reoxidation, X-ray photoelectron spectroscopy, and O2-temperature-programmed desorption analyses were carried out to elucidate the different catalytic activity of bismuth molybdate catalysts. It was revealed that a bismuth molybdate catalyst with a higher oxygen mobility showed a better catalytic performance in terms of conversion of n-butene and yield for 1,3-butadiene. We have successfully demonstrated from experimental findings that oxygen mobility of bismuth molybdate catalyst played a key role in determining the catalytic performance in the oxidative dehydrogenation of n-butene to 1,3-butadiene.

Preparation, characterization and catalytic activity of Bi−Mo-based catalysts for the oxidative dehydrogenation ofn-butene to 1,3-butadiene

Multicomponent bismuth molybdates were prepared by a co-precipitation method for use in the oxidative dehydrogenation ofn-butene to 1,3-butadiene. The effect of divalent and trivalent metals on the catalytic performance of multicomponent bismuth molybdate catalysts was investigated. It was found that the metal ratio of Fe/Bi/Mo=3∶1∶12 was favorable for the reaction. The successful formation of Ni X Co8−X Fe3Bi1Mo12O50 (X=0−8) catalysts was well confirmed by XRD and ICP-AES measurements. The multicomponent bismuth molybdate catalysts showed a better catalytic performance than the pure γ-Bi2MoO6 catalyst. Among the Ni X Co8−X Fe3Bi1Mo12O50 (X=0−8) catalysts, Ni3Co5Fe3Bi1Mo12O50 showed the highest yield of 1,3-butadiene.

Oxidative dehydrogenation of n-butene to 1,3-butadiene over multicomponent bismuth molybdate (M II9Fe 3Bi 1Mo 12O 51) catalysts: Effect of divalent metal (M II)

Multicomponent bismuth molybdate (M II 9Fe 3Bi 1Mo 12O 51) catalysts with different divalent metal (M II = Mg, Mn, Co, Ni, and Zn) were prepared by a co-precipitation method, and were applied to the oxidative dehydrogenation of n-butene to 1,3-butadiene. Effect of divalent metal (M II) on the catalytic performance of M II 9Fe 3Bi 1Mo 12O 51 catalysts was investigated. X-ray photoelectron spectroscopy (XPS) measurements were conducted to determine the oxygen mobility of M II 9Fe 3Bi 1Mo 12O 51 catalysts. It was found that the catalytic performance of M II 9Fe 3Bi 1Mo 12O 51 catalysts was closely related to the oxygen mobility of the catalysts. The yield for 1,3-butadiene was monotonically increased with increasing oxygen mobility of the catalysts. Among the catalysts tested, the Co 9Fe 3Bi 1Mo 12O 51 catalyst with the highest oxygen mobility showed the best catalytic performance in the oxidative dehydrogenation of n-butene.

Effect of Oxygen Capacity and Oxygen Mobility of Pure Bismuth Molybdate and Multicomponent Bismuth Molybdate on their Catalytic Performance in the Oxidative Dehydrogenation of n-Butene to 1,3-Butadiene

Pure bismuth molybdate (γ-Bi2MoO6) and multicomponent bismuth molybdate (Co9Fe3Bi1Mo12O51) catalysts were prepared by a co-precipitation method, and were applied to the oxidative dehydrogenation of n-butene to 1,3-butadiene. The Co9Fe3Bi1Mo12O51 catalyst showed a better catalytic performance than the γ-Bi2MoO6 catalyst in terms of conversion of n-butene and yield for 1,3-butadiene, indicating that the multicomponent bismuth molybdate was more efficient than the pure bismuth molybdate in the oxidative dehydrogenation of n-butene. It was revealed that the crucial factor determining the catalytic performance of Bi–Mo-based catalyst in the oxidative dehydrogenation of n-butene is not the amount of oxygen in the catalyst involved in the reaction (oxygen capacity) but the intrinsic mobility of oxygen in the catalyst involved in the reaction (oxygen mobility). The enhanced catalytic performance of Co9Fe3Bi1Mo12O51 was due to its facile oxygen mobility.

Reactivity of n-butene isomers over a multicomponent bismuth molybdate (Co9Fe3Bi1Mo12O51) catalyst in the oxidative dehydrogenation of n-butene

Abstract Oxidative dehydrogenation of n- butene isomers to 1,3-butadiene was carried out over a multicomponent bismuth molybdate (Co 9 Fe 3 Bi 1 Mo 12 O 51 ) catalyst. The yield for 1,3-butadiene over the catalyst decreased in the order of 1-butene > mixture of 1-butene and 2-butene > 2-butene. The oxidative dehydrogenation of n- butene to 1,3-butadiene favorably occurred with increasing 1-butene content, while the total oxidation of n- butene to CO 2 was promoted with increasing 2-butene content. It is believed that the Co 9 Fe 3 Bi 1 Mo 12 O 51 catalyst retained more selective oxygen species for the reaction with 1-butene than for the reaction with 2-butene, leading to the facile oxidative dehydrogenation of 1-butene to 1,3-butadiene.

Catalytic performance of multicomponent bismuth molybdates (Ni Fe3Bi1Mo12O42+) in the oxidative dehydrogenation of C4 raffinate-3 to 1,3-butadiene: Effect of nickel content and acid property

Abstract Multicomponent bismuth molybdate (Ni X Fe 3 Bi 1 Mo 12 O 42+ X ) catalysts were prepared by a co-precipitation method with a variation of nickel content, and were applied to the oxidative dehydrogenation of C 4 raffinate-3 to 1,3-butadiene. Conversion of n -butene and selectivity for 1,3-butadiene over Ni X Fe 3 Bi 1 Mo 12 O 42+ X catalysts showed volcano-shaped curves with respect to nickel content. As a consequence, yield for 1,3-butadiene also showed a volcano-shaped curve with respect to nickel content. Among the catalysts tested, Ni 9 Fe 3 Bi 1 Mo 12 O 51 showed the best catalytic performance. Acid properties of Ni X Fe 3 Bi 1 Mo 12 O 42+ X catalysts were measured by NH 3 -TPD experiments, with the aim of correlating the catalytic performance with the acid property of the catalysts. It was observed that either total acidity or acid strength was not directly correlated with the catalytic performance of Ni X Fe 3 Bi 1 Mo 12 O 42+ X catalysts. However, the conversion of n -butene was increased with increasing surface acidity of the catalyst. The largest surface acidity of the Ni 9 Fe 3 Bi 1 Mo 12 O 51 catalyst was responsible for its enhanced catalytic performance in the oxidative dehydrogenation of C 4 raffinate-3. The facile oxygen mobility of the γ-Bi 2 MoO 6 phase in the Ni 9 Fe 3 Bi 1 Mo 12 O 51 catalyst also played an important role in enhancing the catalytic performance of the Ni 9 Fe 3 Bi 1 Mo 12 O 51 catalyst.

State of Chromium in Solid Solutions of Multicomponent Bismuth Niobates with Pyrochlore Structure

Magnetic susceptibility of solid solutions of multicomponent bismuth niobates with pyrochlore structure containing chromium atoms was studied. The parameters determining the state of chromium atoms and the exchange coupling between the paramagnetic atoms were calculated. The best agreement between the experimental and theoretically calculated magnetic moments of the chromium atoms is observed on the condition that all the chromium atoms in the Bi2MgNb2O9 structure are in the form of ferromagnetic exchange-coupled dimers with an exchange parameter J 18 cm-1.

Effect of alumina in multicomponent bismuth phosphate catalyst supported on silica-alumina for propylene ammoxidation reaction

The effect of compositions of silica-alumina support on multicomponent bismuth phosphate catalyst (MBP) was investigated for the propylene ammoxidation. It is appears that small amounts of Al2O3 cause retardation of the ammoxidation reaction, which would be due to activation of the selective oxidation pathway. It is understood from such results that the catalytic action of the MBP is essentially different with that of the multicomponent bismuth molybdate catalyst (MBM), which is generally used as propylene ammoxidation catalyst.

Catalytic Wall Reactor as a Tool for Isothermal Investigations in the Heterogeneously Catalyzed Oxidation of Propene to Acrolein

The vapor phase oxidation of propene to acrolein is a highly exothermic reaction. To ensure isothermal reaction conditions, a catalytic wall reactor was used for detailed investigations on the reaction behavior on a multicomponent bismuth−molybdate oxide catalyst. The reaction temperature showed only small influence on the selectivity to acrolein, but a significant optimum at about 360 °C is observed. The results further indicate a change in the rate-determining step: while at low temperatures (<360 °C) catalyst reoxidation is rate determining, with increasing oxygen content accelerating the formation of acrolein considerably, its influence disappears at higher temperatures. Not only does water increase the selectivity to acrolein, but also, at low temperatures, it improves catalyst reoxidation remarkably. Additionally, the formation of the most important side products (acrylic acid, carbon oxides, acetaldehyde, formaldehyde, and acetic acid) was observed, depending on the reaction parameters.