Showing papers on "Lanthanum published in 2016"
TL;DR: It is demonstrated how the lanthanide contraction can be used to control strain effects and tune the activity, stability, and reactivity of these materials.
Abstract: The high platinum loadings required to compensate for the slow kinetics of the oxygen reduction reaction (ORR) impede the widespread uptake of low-temperature fuel cells in automotive vehicles. We have studied the ORR on eight platinum (Pt)–lanthanide and Pt-alkaline earth electrodes, Pt5M, where M is lanthanum, cerium, samarium, gadolinium, terbium, dysprosium, thulium, or calcium. The materials are among the most active polycrystalline Pt-based catalysts reported, presenting activity enhancement by a factor of 3 to 6 over Pt. The active phase consists of a Pt overlayer formed by acid leaching. The ORR activity versus the bulk lattice parameter follows a high peaked “volcano” relation. We demonstrate how the lanthanide contraction can be used to control strain effects and tune the activity, stability, and reactivity of these materials.
693 citations
TL;DR: SEM, XRD, XPS and FT-IR analysis suggested that the multi-adsorption mechanisms including precipitation, ligand exchange and complexation interactions can be evidenced during the phosphate adsorption process by La-composites in La-BC.
293 citations
TL;DR: A new nanocomposite adsorbent La-201 of extremely high capacity and specific affinity toward phosphate was fabricated and well characterized, and the formation of LaPO4·xH2O is verified to be the dominant pathway for selective phosphate adsorption by the immobilized nano-HLO.
Abstract: A new nanocomposite adsorbent La-201 of extremely high capacity and specific affinity toward phosphate was fabricated and well characterized, where hydrated La(III) oxide (HLO) nanoclusters were immobilized inside the networking pores of the polystyrene anion exchanger D-201. La-201 exhibited enhanced phosphate adsorption in the presence of competing anions (chloride, sulfate, nitrate, bicarbonate, and silicate) at greater levels (up to molar ratio of 20), with working capacity 2-4 times higher than a commercial Fe(III) oxide-based nanocomposite HFO-201 in batch runs. Column adsorption runs by using La-201 could effectively treat ∼6500 bed volumes (BV) of a synthetic feeding solution before breakthrough occurred (from 2.5 mg P/L in influent to <0.5 mg P/L in effluent), approximately 11 times higher magnitude than that of HFO-201. The exhausted La-201 could be regenerated with NaOH-NaCl binary solution at 60 °C for repeated use without any significant capacity loss. The underlying mechanism for the specific sorption of phosphate by La-201 was revealed with the aid of STEM-EDS, XPS, XRD, and SSNMR analysis, and the formation of LaPO4·xH2O is verified to be the dominant pathway for selective phosphate adsorption by the immobilized nano-HLO. The results indicated that La-201 was very promising in highly efficient removal of phosphate from contaminated waters.
252 citations
TL;DR: It is demonstrated that lanthanum ions embedded in zeolite pores can lower the temperature required for the carbonization of ethylene or acetylene, and a graphene-like carbon structure can be selectively formed inside the zeolites template, without carbon being deposited at the external surfaces.
Abstract: Three-dimensional graphene architectures with periodic nanopores—reminiscent of zeolite frameworks—are of topical interest because of the possibility of combining the characteristics of graphene with a three-dimensional porous structure. Lately, the synthesis of such carbons has been approached by using zeolites as templates and small hydrocarbon molecules that can enter the narrow pore apertures. However, pyrolytic carbonization of the hydrocarbons (a necessary step in generating pure carbon) requires high temperatures and results in non-selective carbon deposition outside the pores. Here, we demonstrate that lanthanum ions embedded in zeolite pores can lower the temperature required for the carbonization of ethylene or acetylene. In this way, a graphene-like carbon structure can be selectively formed inside the zeolite template, without carbon being deposited at the external surfaces. X-ray diffraction data from zeolite single crystals after carbonization indicate that electron densities corresponding to carbon atoms are generated along the walls of the zeolite pores. After the zeolite template is removed, the carbon framework exhibits an electrical conductivity that is two orders of magnitude higher than that of amorphous mesoporous carbon. Lanthanum catalysis allows a carbon framework to form in zeolite pores with diameters of less than 1 nanometre; as such, microporous carbon nanostructures can be reproduced with various topologies corresponding to different zeolite pore sizes and shapes. We demonstrate carbon synthesis for large-pore zeolites (FAU, EMT and beta), a one-dimensional medium-pore zeolite (LTL), and even small-pore zeolites (MFI and LTA). The catalytic effect is a common feature of lanthanum, yttrium and calcium, which are all carbide-forming metal elements. We also show that the synthesis can be readily scaled up, which will be important for practical applications such as the production of lithium-ion batteries and zeolite-like catalyst supports.
235 citations
TL;DR: Fe-Si-La is a promising adsorbent for the removal and recovery of phosphate from water and showed that adsorbed phosphate could be nearly completely desorbed with NaOH solution for further use.
220 citations
TL;DR: In this article, a comparative study of a series of doped ceria catalysts towards environmental applications like CO and soot oxidation catalysis is presented. And the physicochemical properties of the doped Ceria materials have been comparatively analyzed to correlate the influence of dopants with their improved behaviour in both the oxidation reactions.
Abstract: This article represents a comparative study of a series of doped ceria catalysts towards environmental applications like CO and soot oxidation catalysis. Transition and rare earth metals of varying size and reducibility property have been selected namely, zirconium (Zr), hafnium (Hf), iron (Fe), manganese (Mn), praseodymium (Pr), and lanthanum (La) as dopants. A facile coprecipitation approach has been used to incorporate the dopants into ceria lattice.The formation of homogeneous solid solutions and their respective physicochemical properties have been confirmed by employing XRD analysis, BET surface area measurements, TEM, Raman, UV-DRS, XPS, and TPR techniques. All the doped CeO2 samples exhibited smaller crystallite size, larger BET surface area, and higher amounts of oxygen vacancies than that of pure CeO2. CO oxidation has been performed in the presence of oxygen under atmospheric pressure, and 300–850 K temperature range in a fixed bed microreactor. Soot oxidation was carried out in presence of air using a thermo gravimetric analyzer within a much wider temperature window of 300–1273 K. The physicochemical properties of the doped ceria materials have been comparatively analyzed to correlate the influence of dopants with their improved behaviour in both the oxidation reactions. Vital role of ‘lattice oxygen’ in CO oxidation and ‘active oxygen species’ in soot oxidation on the catalyst surface has been considered, assuming that Mars and van Krevelen mechanism and active oxygen mechanism play the key role in CO and soot oxidation, respectively. The O 1s XP spectra confirmed that Mn doped ceria (denoted as CM) exhibited most loosely bound lattice oxygen and highest concentration of surface adsorbed oxygen species compared to other materials. Accordingly, a superior CO and soot oxidation activity have been observed for manganese doped ceria. Significant lowering of T50 (390 K and 669 K for CO and soot oxidation respectively) temperature have been observed in both the oxidation reactions; which is primarily attributed to the considerable lowering of lattice oxygen binding energy and higher concentration of surface adsorbed oxygen species.
174 citations
TL;DR: In this article, a La-promoted Ni-containing hydrotalcite-derived catalysts were prepared and tested in dry methane reforming at low-moderate temperatures, and the prepared materials were characterized by means of X-ray diffraction (XRD), temperature programmed reduction (H 2 -TPR) and CO 2 -temperature programmed desorption (TPD).
148 citations
TL;DR: In this paper, a 3D graphene-La2O3 composite is presented, which exhibits favorable adsorption performance to phosphate, providing a sorption capacity of 82.6 mg g/1 at pH 6.2.
Abstract: A three-dimensional adsorbent, i.e., lanthanum oxide decorated graphene composite (3D graphene–La2O3 composite), is prepared. The composite exhibits favorable adsorption performance to phosphate, providing a sorption capacity of 82.6 mg g–1 at pH 6.2. The adsorption behavior for phosphate fits the Langmuir model, and the adsorption kinetics fit a pseudo-second-order model, with rate constants of 0.1847 and 0.007 969 g mg–1 min–1 at phosphate concentrations of 35 and 142 mg L–1, respectively. For the removal of 25 mg L–1 phosphate in 1.0 mL aqueous medium, the commonly encountered anionic species in waters, e.g., Cl–, SO42–, and NO3–, pose no interfering effect at 8000 mg L–1, providing a favorable removal efficiency of 100% by 2.0 mg of composite. When 142 mg L–1 phosphate solution is treated, 100% and >80% adsorption efficiencies are achieved respectively in the presence of 1000 and 8000 mg L–1 of Cl–, SO42–, and NO3–. The high tolerance capacity against coexisting anionic species by the graphene–La2O3 c...
147 citations
TL;DR: NLZ could efficiently and simultaneously remove low concentration of ammonium and phosphate from contaminated waters and showed little pH dependence in the range from pH 3 to 7, while it decreased sharply with the pH increased above pH 7.
144 citations
TL;DR: In this article, a series of hydrotalcite-derived mixed oxides containing Ni/Mg/La/Al obtained by thermal decomposition were characterized by XRD, CO2-TPD and H2 -TPR.
137 citations
TL;DR: Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries but the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li-S battery.
Abstract: Lithium–sulfur (Li–S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries. However, the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li–S battery. In this work, lanthanum nitrate, as electrolyte additive, is introduced into Li–S battery to stabilize the surface of lithium anode. By introducing lanthanum nitrate into electrolyte, a composite passivation film of lanthanum/lithium sulfides can be formed on metallic lithium anode, which is beneficial to decrease the reducibility of metallic lithium and slow down the electrochemical dissolution/deposition reaction on lithium anode for stabilizing the surface morphology of metallic Li anode in lithium–sulfur battery. Meanwhile, the cycle stability of the fabricated Li–S cell is improved by introducing lanthanum nitrate into electrolyte. Apparently, lanthanum nitrate is an effective additive for the protec...
TL;DR: In this paper, it was found that La ions can greatly enhance the cytotoxicity and photocatalytic activity of ZnO nanoparticles towards various cell lines and Paracetamol drug.
TL;DR: In this article, solvent extraction and precipitation stripping were used to produce rare earth elements (REEs), and the results showed that about 95, 90, 87% and 80% of neodymium, lanthanum, cerium, and yttrium, respectively, can be extracted in optimum conditions of extraction.
TL;DR: The effect of natural DOC on the P binding capacity was tested using water and pore water from 16 Danish lakes, and it was revealed that the negative effect of added DOC was reduced with time.
TL;DR: In this article, a review of various processes for the recovery of lanthanum from metallurgical and non-metallurgical resources are reviewed. And a separate section on selective biosorption from various model and actual solutions is also included.
TL;DR: In this paper, a set of porous ceria, zirconia and lanthana supported nickel catalysts were successfully synthesized via a facile solid state citrate fusion method and used for the thermocatalytic decomposition of undiluted methane for the first time.
TL;DR: Soluble reactive P (SRP) release experiments on intact sediment cores indicated conditions of P retention (with the exception of two lakes) by sediments, indicating effective control of sediment P release, i.e. between two and nine years after treatment.
TL;DR: In this paper, a bifunctional oxygen electrode with simultaneous activity for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) was synthesized by direct growth of nitrogen-doped carbon nanotubes on the surface of a perovskite containing Co and Fe by means of chemical vapor deposition.
TL;DR: In this paper, the physicochemical properties of as-synthesized samples were characterized by the TG-DSC, FESEM, EDS, XRD, XPS, TEM, HRTEM and UV-vis DRS.
TL;DR: In this article, the influence of lanthanum on the thermal stability and photocatalytic activity of calcined hydrogenotitanate nanotubes (HNT) was evaluated.
Abstract: The influence of lanthanum on the thermal stability and photocatalytic activity of calcined hydrogenotitanate nanotubes (HNT) was herein evaluated. HNT samples were prepared through the hydrothermal treatment of TiO2 P25 in a concentrated NaOH solution (11.25 M) at 130 °C during 20 h followed by acid washing. La-doped titanates nanotubes (La–HNT) photocatalysts with optimum 1 wt% of La were then elaborated by incipient wetness impregnation method using lanthanum nitrate as precursor. La–HNT and HNT samples were then calcined at temperatures varying between 400 °C and 700 °C. Samples were characterized by means of nitrogen adsorption–desorption isotherms at 77K, X-ray diffraction (XRD), Raman spectroscopy, diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), transmission electron microscopy (TEM), ICP analysis and photocurrent experiments. The photocatalytic activities of La–HNT and HNT derived nanomaterials were then evaluated through the photocatalytic degradation of formic acid (FA). Main results reveal that lanthanum inhibits TiO2 crystallite growth and retards anatase transformation into the less active rutile phase. The addition of La ions to TiO2 results in a charge imbalance creating a high proportion of oxygen vacancies as evidenced by photocurrent, photoluminescence and Raman experiments. The photocatalytic experiments reveal that La-doped TiO2 helps to maintain a high photocatalytic activity level even after calcination at high temperatures contrary to La-free photocatalysts. The determination of kinetic parameters reveals that the maintaining of a high photocatalytic activity results from the synergetic effect between restriction of TiO2 crystallite size growth and formation of a high proportion of oxygen vacancies.
TL;DR: In this article, coal fly ash was used as a raw material for the production of a zeolite/hydrous lanthanum oxide hybrid material (ZHLO) and as a means of controlling internal phosphorus loading in lakes.
TL;DR: After more than 850 000 person‐years of worldwide patient exposure, there is no evidence that lanthanum carbonate is associated with adverse safety outcomes in patients with end‐stage renal disease.
Abstract: Despite 10 years of post-marketing safety monitoring of the phosphate binder lanthanum carbonate, concerns about aluminium-like accumulation and toxicity persist. Here, we present a concise overview of the safety profile of lanthanum carbonate and interim results from a 5-year observational database study (SPD405-404; ClinicalTrials.gov identifier: NCT00567723). The pharmacokinetic paradigms of lanthanum and aluminium are different in that lanthanum is minimally absorbed and eliminated via the hepatobiliary pathway, whereas aluminium shows appreciable absorption and is eliminated by the kidneys. Randomised prospective studies of paired bone biopsies revealed no evidence of accumulation or toxicity in patients treated with lanthanum carbonate. Patients treated with lanthanum carbonate for up to 6 years showed no clinically relevant changes in liver enzyme or bilirubin levels. Lanthanum does not cross the intact blood–brain barrier. The most common adverse effects are mild/moderate nausea, diarrhoea and flatulence. An interim Kaplan–Meier analysis of SPD405-404 data from the United States Renal Data System revealed that the median 5-year survival was 51.6 months (95% CI: 49.1, 54.2) in patients who received lanthanum carbonate (test group), 48.9 months (95% CI: 47.3, 50.5) in patients treated with other phosphate binders (concomitant therapy control group) and 40.3 months (95% CI: 38.9, 41.5) in patients before the availability of lanthanum carbonate (historical control group). Bone fracture rates were 5.9%, 6.7% and 6.4%, respectively. After more than 850 000 person-years of worldwide patient exposure, there is no evidence that lanthanum carbonate is associated with adverse safety outcomes in patients with end-stage renal disease.
TL;DR: In this article, the authors have studied the ORR on eight platinum (Pt)-lanthanide and Pt-alkaline earth electrodes, where M is lanthanum, cerium, samarium, gadolinium, terbium, dysprosium, thulium, or calcium.
Abstract: The high platinum loadings required to compensate for the slow kinetics of the oxygen reduction reaction (ORR) impede the widespread uptake of low-temperature fuel cells in automotive vehicles. We have studied the ORR on eight platinum (Pt)–lanthanide and Pt-alkaline earth electrodes, Pt5M, where M is lanthanum, cerium, samarium, gadolinium, terbium, dysprosium, thulium, or calcium. The materials are among the most active polycrystalline Pt-based catalysts reported, presenting activity enhancement by a factor of 3 to 6 over Pt. The active phase consists of a Pt overlayer formed by acid leaching. The ORR activity versus the bulk lattice parameter follows a high peaked “volcano” relation. We demonstrate how the lanthanide contraction can be used to control strain effects and tune the activity, stability, and reactivity of these materials.
TL;DR: In this article, the authors showed that the coating of nano-magnetite introduced substantial clogging in the micropores of PSAC, but increased meso-and macropores.
TL;DR: In this article, a new synthesized resin containing glycol amic acid was used for separation of scandium from a model solution containing Scandium, cerium, lanthanum, and aluminum.
TL;DR: In this paper, the surface exchange coefficient of Ruddlesden-Popper (R-P) phase lanthanum nickelates upon Mn doping as an intermediate temperature solid oxide fuel cells (IT-SOFCs) cathode is investigated.
TL;DR: In this paper, a successful nanohydrometallurgical separation of neodymium and lanthanum ions has been demonstrated by using superparamagnetic nanoparticles functionalized with ethylenediaminepropylsilane/diethylenetriaminepentaacetic acid, as complexing agents.
TL;DR: The authors' spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree, which could be used to photocatalytic water splitting for hydrogen production and as the concentration of Ov increasing up to 5%, the CeO1 exhibits a half-metallic properties.
Abstract: The magnetic properties and electronic structures of pure, doped and defective cerium oxide (CeO2) have been studied theoretically by means of ab initio calculations based on the density function theory (DFT) with the hybrid HF/DFT technique named PBE0. Carbon (C), nitrogen (N), phosphorus (P), sulphur (S), lanthanum (La) and praseodymium (Pr) doped in CeO2 and CeO2 containing oxygen vacancies (Ov) were considered. Our spin-polarized calculations show that C, N, Pr dopants and Ov defects magnetize the non-magnetic CeO2 in different degree. The optical band gap related to photocatalysis for pure CeO2, corresponding to the ultraviolet region, is reduced obviously by C, N, S, Pr impurities and oxygen vacancies, shifting to the visible region and even further to the infrared range. Especially, N-, S- and Pr-doped CeO2 could be used to photocatalytic water splitting for hydrogen production. As the concentration of Ov increasing up to 5%, the CeO2 exhibits a half-metallic properties.
TL;DR: A supercritical carbon dioxide anti-solvent precipitation methodology is used to prepare large surface area lanthanum based perovskites, making the deposition of 1 wt% AuPt nanoparticles feasible and producing an exceptionally high tartronic acid yield.
Abstract: Gold and gold alloys, in the form of supported nanoparticles, have been shown over the last three decades to be highly effective oxidation catalysts. Mixed metal oxide perovskites, with their high structural tolerance, are ideal for investigating how changes in the chemical composition of supports affect the catalysts' properties, while retaining similar surface areas, morphologies and metal co-ordinations. However, a significant disadvantage of using perovskites as supports is their high crystallinity and small surface area. We report the use of a supercritical carbon dioxide anti-solvent precipitation methodology to prepare large surface area lanthanum based perovskites, making the deposition of 1 wt% AuPt nanoparticles feasible. These catalysts were used for the selective oxidation of glycerol. By changing the elemental composition of the perovskite B site, we dramatically altered the reaction pathway between a sequential oxidation route to glyceric or tartronic acid and a dehydration reaction pathway to lactic acid. Selectivity profiles were correlated to reported oxygen adsorption capacities of the perovskite supports and also to changes in the AuPt nanoparticle morphologies. Extended time on line analysis using the best oxidation catalyst (AuPt/LaMnO3) produced an exceptionally high tartronic acid yield. LaMnO3 produced from alternative preparation methods was found to have lower activities, but gave comparable selectivity profiles to that produced using the supercritical carbon dioxide anti-solvent precipitation methodology.