水热处理和钨添加对低钒催化剂高温脱硝性能的影响

利用真空过量浸渍法在TiO₂和WO₃-TiO₂载体上负载0.5%钒（质量分数）制备了V₂O₅-TiO₂ （VTi）和V₂O₅/WO₃-TiO₂（VWTi）催化剂,并在含有10%（体积分数）水蒸气的空气氛下750℃水热处理24h得到处理态的VTi-A和VWTi-A催化剂。研究了水热老化和钨掺杂对催化剂脱硝效率的影响,并通过XRD、TEM、NH₃-TPD、H₂-TPR、XPS和Raman等表征方法对催化剂的结构和表面特性进行了表征分析。研究表明,水热处理和钨的协同作用使催化剂中产生更多的聚合态VO_x和低价态钒（V⁴⁺+V³⁺）。这两类活性物质所含有的氧物种具有较强SCR反应活性,可改善VWTi催化剂的高温脱硝性能,即使在酸性位数量减少的情况下仍有提升,这是低钒含量催化剂可满足燃气机组高温脱硝需求的主要原因。     

The states of vanadium species in V-SBA-15 synthesized under different pH values

V-SBA-15 (n_Si/V ≈ 10) mesoporous molecular sieves have been synthesized in different pH-value medias and characterized by XRD, N₂ adsorption, TEM, UV–vis, Raman, FT-IR, ESR, and NH₃-absorbed in situ FT-IR techniques. Results indicated that the pH value played an important role on the states of vanadium species in the prepared materials. As the pH value increased, the amount of the crystalline vanadium oxides decreased, the incorporated vanadium species with isolated tetrahedral (V⁵⁺) and square pyramidal coordination (VO²⁺) increased accordingly. At pH = 3.0, vanadium species were mainly in the silica framework and formed stronger acid sites, it seems to suggest that the linear configuration V⁵⁺–ONH₃H⁺–O–V⁴⁺ groups have been formed after ammonia was adsorbed. However, for the samples synthesized at the low pH values, the crystalline vanadium oxides existed and the amount of the dispersed tetrahedral vanadium species decreased, which caused the weaker acid sites.     

The effect of the nature of vanadium species on benzene total oxidation

The nature of the vanadium species present on V₂O₅/Al₂O₃ catalysts was investigated by using solid state ⁵¹V NMR, diffuse reflectance spectroscopy (DRS), X-ray diffraction (XRD) and temperature programmed reduction (TPR). ⁵¹V NMR and DRS analyses indicated the presence of V⁵⁺ in tetrahedral symmetry at low vanadium loading. A surface polymeric vanadium species and/or the bulk crystalline V₂O₅ were mainly observed at high vanadium loading as also detected by XRD. The positions of the absorption edges determined through the UV–VIS spectra allowed distinguishing between various tetrahedral symmetries. After TPR, the average oxidation state of vanadium depended on the vanadium content. The nature of vanadium species was related to the catalyst behavior on the benzene oxidation reaction. The catalysts containing high vanadium content were more active suggesting that a high amount of V⁴⁺ is responsible for the higher activity.     

Alumina supported Mo–V–Te–O catalysts for the ammoxidation of propane to acrylonitrile

The effect of Te addition over Mo–V–O catalysts supported on alumina is discussed for the ammoxidation of propane to acrylonitrile. Catalyst composition and atmosphere of activation are evaluated. Catalysts are characterized before and after catalytic reaction by XPS, XRD and in situ Raman spectroscopies. The absence of Te in catalysts formulation and the presence of a high amount of vanadium induce the presence of V⁵⁺ species and the formation of V₂O₅ oxide; associated with a decrease in acrylonitrile selectivity. The presence of Mo-based polyacids structures decreases the selectivity to acrylonitrile. V⁵⁺ sites are responsible of propane activation and of the subsequent -H abstraction to form the intermediate propylene. Then, a Mo–V rutile-like structure in which vanadium species are reduced as V⁴⁺, is responsible for nitrogen insertion and acrylonitrile formation. The formation of such structure is favoured when Te is added to catalysts and is promoted during propane ammoxidation.     

In situ TPR/TPO-Raman studies of dispersed and nano-scaled mixed V-Nb oxides on alumina

Various catalysts containing niobium and vanadium oxides supported on alumina were prepared by wet impregnation via aqueous solution using several precursors. The total loading of V and Nb oxides were below their dispersion limit on alumina. Vanadyl sulfate, ammonium metavanadate and ammonium niobate(V) oxalate were the precursors for supported vanadia and niobia. The reduction/oxidation properties were studied by conventional TPR/TPO and TPR/TPO-Raman. Surface vanadium oxide species tend to increase their polymerization degree upon TPR/TPO cycles. A broad weak feature near 900 cm⁻¹ appears associated to V³⁺–O–Al³⁺ bond vibration in the reduced vanadia-alumina catalysts. Niobia appears to retard vanadia reduction. Regarding supported niobia, a fraction of surface niobia is significantly more reducible than surface vanadia and another fraction is significantly less reducible. The more reducible niobia appears associated to an incipient Nb–Al–O phase that may account for a fluorescence background observed in the Raman spectra. The less reducible niobia phases appears associated to dispersed niobium oxide species on alumina. Niobium has an effect on vanadia reduction profiles in VNb/Al₂O₃ system.     

Influence of Bi–Fe additive on properties of vanadium phosphate catalysts for n-butane oxidation to maleic anhydride

The physico-chemical and catalytic properties of three ways of modified catalysts were studied, i.e. (i) the addition of both Bi and Fe (nitrate form) during the refluxing VOPO₄·2H₂O with isobutanol (Catalyst A), (ii) the simultaneous addition of BiFe oxide powder in the course of the synthesis of precursor VOHPO₄·0.5H₂O (Catalyst B) and (iii) the mechanochemical treatment of precursor VOHPO₄·0.5H₂O and BiFe oxide in ethanol (Catalyst C). It was found that surface area of the modified catalysts has increased except Catalyst B. The reactivity of the oxygen species linked to V⁵⁺ and V⁴⁺ was studied by using H₂-TPR, which also affected the catalytic performance of the catalyst. The conversion of n-butane decreases with an increment of oxygen species associated with V⁵⁺.     

Vanadium oxide supported on mesoporous Al2O3: Preparation, characterization and reactivity

The application of different techniques (diffuse reflectance-UV–vis, ⁵¹V NMR, FT-IR of adsorbed pyridine and TPR-H₂) in the characterization of vanadia supported on mesoporous Al₂O₃ catalysts shows that the nature of the vanadium species depends on the V-loading. At V-content lower than 15 wt.% of V-atoms (30% of the theoretical monolayer), vanadium is mainly in a tetrahedral environment. Higher V-contents in the catalyst leads to the formation of octahedral V⁵⁺ species and V₂O₅-like species. Both XRD and textural results indicate that the mesoporous structure of the support is mostly maintained after the vanadium incorporation, and therefore high surface areas were obtained on the final catalysts. Al₂O₃-suppported vanadia catalysts are active and selective in the oxidative dehydrogenation of ethane, although the catalytic behavior depends on the V-loading. High rates of formation of ethylene per unit mass of catalyst per unit time have also been observed as a consequence of the high dispersion of V-atoms on the surface of the support.     

Relationship between structural/surface characteristics and reactivity in n-butane oxidation to maleic anhydride: The role of V species

V/P/O-based catalysts were prepared by thermal treatments of VOHPO₄0·5H₂O precursors prepared with the organic procedure. Different methods for precursor dehydration led to compounds which were characterized by the prevailing presence of crystalline (VO)₂P₂O₇, but which also contained either V⁵⁺ species or V³⁺ species. The catalytic performance of these compounds in n-butane oxidation under almost-equilibrated conditions was compared. It was found that the presence of either V³⁺ or V⁵⁺ enhances the specific activity in n-butane oxidation, while the selectivity to maleic anhydride at low n-butane conversion (30%) remains substantially unaffected. A fully equilibrated, well-crystallized (VO)₂P₂O₇ was reduced with H₂. The reduced compound was more active than the fully equilibrated vanadyl pyrophosphate, while exhibiting comparable selectivity to maleic anhydride.     

介孔Cr(OH)3的制备及其对钒(Ⅴ)离子的吸附性能

以CrCl₃·6H₂O作为铬源,通过添加强碱制备出大比表面积（312.70 m²·g^-1）、高孔隙率（0.48 cm³·g^-1）的介孔Cr（OH）₃,并研究了其对溶液中钒（V）离子的吸附性能,考察了溶液pH、吸附剂用量、吸附温度、吸附时间等条件对吸附效果的影响。结果表明,当溶液pH在2.0~9.0、钒离子浓度为100~500 mg·L^-1时,采用该吸附剂均可实现溶液中钒离子的高效去除。在最优实验条件下,钒去除率接近100%,钒离子浓度可由500 mg·L^-1降至0.81 mg·L^-1。吸附热力学的研究结果表明,Cr（OH）₃对钒离子的吸附过程遵循Langmuir等温吸附;吸附过程符合拟二级反应动力学方程,反应级数为拟二级。     

活化液助溶剂对再生脱硝催化剂性能的影响

为了考察助溶剂对活化液的催化剂再生性能的影响,将某燃煤电厂失活退役的脱硝催化剂在相同清洗工艺下处理,随后分别浸入以草酸、乙醇胺作为助溶剂配制的活化液中,得到两个再生催化剂。采用XRF、氮气物理吸附法、原位吡啶吸附、NH₃-TPD、Raman、XPS、H₂-TPR以及固定床脱硝反应器等表征手段对新鲜样品、失活样品以及再生样品进行表面理化性质、脱硝性能测试评价。结果显示,脱硝催化剂失活的主要原因是飞灰中的碱金属K、Na造成催化剂的比表面积和孔容下降、表面Lewis酸性位数量减少、V⁵⁺比例下降、活性VO_x减少及氧化还原性能下降。同时发现,两个再生催化剂在等量活性组分钒条件下,脱硝性能却表现出较大差异,乙醇胺助溶活化液再生的样品Ethanol-cat性能恢复至新鲜催化剂的97%以上,而草酸助溶活化液再生的样品Oxalic-cat却几乎无再生效果,这是因为两种活化液中的活性组分钒状态不同,乙醇胺助溶活化液中钒离子可有效恢复失活催化剂的酸性位数量、V⁵⁺比例、活性物种VO_x     

CO2氧化乙苯脱氢制苯乙烯钒基氧化物催化剂研究进展

与现有乙苯直接脱氢工艺技术相比,CO₂氧化乙苯脱氢工艺具有缓解直接脱氢热力学平衡限制、苯乙烯选择性高、能耗低和二氧化碳资源化利用等显著优势,有望成为一条从乙苯生产苯乙烯的绿色工艺路线。为此,在总结乙苯直接脱氢反应体系和现有工业技术特点、面临的问题和发展方向的基础上,本文较为全面地分析了CO₂氧化乙苯脱氢的特点和反应机理,探讨了现有催化剂体系普遍快速失活的关键原因,表明高性能催化剂研究依然是推进CO₂氧化乙苯脱氢工业化应用的关键。鉴于钒基氧化物催化剂表现出较高的活性,成为近年来CO₂氧化乙苯脱氢相关研究关注的重点。为此,从钒物种含量及其聚集态结构、催化剂的氧化还原和酸碱性、催化剂表面积炭及其作用等角度,综合分析了活性中心结构、反应机理等方面的相关研究进展,认为孤立态V⁵⁺及其含量可能是决定钒基氧化物催化剂活性的关键,其稳定性主要取决于催化剂的氧化还原特性,而积炭对催化剂活性和稳定性的影响则与其组成和石墨化程度密切相关。基于上述认识,认为强化CO₂的高效活化、抑制V⁵⁺的深度还原等是今后钒基氧化物催化剂研究的重点发展方向,而利用移动固定床或提升管反应器等进行工艺优化,对推进CO₂氧化乙苯脱氢工业化应用具有重要的研究价值。     

Alumina-supported catalysts for propane oxidative dehydrogenation from mixed VXM(6−X)O19 (M=W, Mo) hexametalate precursors

γ-Al₂O₃ supported vanadium oxides were modified by tungsten and molybdenum oxides in order to improve dispersion and selectivity towards olefins in propane oxidative dehydrogenation (ODH). Both vanadium–tungsten and vanadium–molybdenum catalysts were obtained by adsorption of mixed isopolyanions (VW₅O₁₉⁵⁻, V₂W₄O₁₉⁴⁻, VMo₅O₁₉⁵⁻ and V₂Mo₄O₁₉⁴⁻) from aqueous solutions. The isopolyanion solutions were characterized by UV-Vis and ⁵¹V NMR spectroscopy. Vanadium, vanadium–tungsten and vanadium–molybdenum precursors and catalysts were also characterized by UV-Vis (diffuse reflectance) and solid state ⁵¹V NMR spectroscopy. An improved selectivity to propene in the presence of tungsten and molybdenum in VO_x/γ-Al₂O₃ was observed and attributed to dilution of vanadium by tungsten or molybdenum oxides on the γ-Al₂O₃ surface.     

Preparation and characterisation of vanadium catalysts supported over alumina-pillared clays

Supported vanadium-containing catalysts were prepared by impregnation of Al-pillared clays with NaVO₃ precursor aqueous solutions. A montmorillonite and a saponite, both natural as well as previously pillared with Al₁₃-Keggin polycations, were used as supports, being impregnated with solutions of the precursor by means of the incipient wetness technique. The layered structure of the supports is maintained after impregnation, and even after calcination of the impregnated solids at 500 °C, although with a significant worsening of the textural properties of the solids, in particular, a loss of specific surface area. Three crystalline vanadium-containing phases were identified in the impregnated solids, namely, NaV₃O₈, AlVO₄ and V₂O₅ (shcherbinaite). The reduction of these phases to V³⁺ species was observed as wide processes in the 450–750 °C range, all of them centred at ca. 600 °C.     

溶胶-凝胶原位合成钒钨钛催化剂及NH3-SCR性能

利用溶胶-凝胶技术原位合成V₂O₅-WO₃/TiO₂介孔结构脱硝催化剂。通过XRD、BET、SEM和XPS等手段对催化剂结构与组成进行表征,发现结构导向剂CTAB促进催化剂的比表面积和孔容的增加,促进催化剂活性组分的分散与裸露的V活性组分数量增加;且随CTAB含量的增加,V⁴⁺/V⁵⁺的比值降低,即降低了催化剂表面钒物种的氧化能力,有利于提高催化剂的低温脱硝活性与高温选择性。催化活性评价结果表明,CTAB对催化剂的脱硝活性有显著促进作用,当CTAB的添加量为0.01（质量）时,催化剂的脱硝活性大于90%的温度窗口最宽为212~393℃,200℃时脱硝效率达85.6%。     

Engineering the electronic and geometric structure of VOx/BN@TiO2 heterostructure for efficient aerobic oxidative desulfurization

Particle size governs the electronic and geometric structure of metal nanoparticles (NPs), shaping their catalytic performances in heterogeneous catalysis. However, precisely controlling the size of active metal NPs and thereafter their catalytic activities remain an affordable challenge in ultra-deep oxidative desulfurization (ODS) field. Herein, a series of highly-efficient VO_x/boron nitride nanosheets (BNNS)@TiO₂ heterostructures, therein, cetyltrimethylammonium bromide cationic surfactants serving as intercalation agent, BNNS and MXene as precursors, with various VO_x NP sizes were designed and controllably constructed by a facile intercalation confinement strategy. The properties and structures of the prepared catalysts were systematically characterized by different technical methods, and their catalytic activities were investigated for aerobic ODS of dibenzothiophene (DBT). The results show that the size of VO_x NPs and V⁵⁺/V⁴⁺ play decisive roles in the catalytic aerobic ODS of VO_x/BNNS@TiO₂ catalysts and that VO_x/BNNS@TiO₂-2 exhibits the highest ODS activity with 93.7% DBT conversion within 60 min under the reaction temperature of 130 °C and oxygen flow rate of 200 mL·min^–1, which is due to its optimal VO_x dispersion, excellent reducibility and abundant active species. Therefore, the finding here may contribute to the fundamental understanding of structure-activity in ultra-deep ODS and inspire the advancement of highly-efficient catalyst.     

Effect of Pt on the water resistance of Co-zeolites upon the SCR of NOx with CH4

The objective of this work was to study the promotional effect of Pt on Co-zeolite (viz. mordenite, ferrierite, ZSM-5 and Y-zeolite) and Co/Al₂O₃ on the selective catalytic reduction (SCR) of NO_x with CH₄ under dry and wet reaction stream. After being reduced in H₂ at 350°C, the PtCo bimetallic zeolites showed higher NO to N₂ conversion and selectivity than the monometallic samples, as well as a combination of the latter samples such as mechanical mixtures or two-stage catalysts. After the same pretreatment, under wet reaction stream, the bimetallic samples were also more active. Among the other catalysts studied with 5% of water in the feed, (NO = CH₄ = 1000 ppm, O₂ = 2%), the NO conversion dropped to zero over Co_2.0Mor at 500°C and GHSV = 30,000 h⁻¹, whereas it is 20% in Pt_0.5Co_2.0Mor. In Pt/Co/Al₂O₃ the NO_x conversion dropped below 5% with only 2% of water under the same reaction conditions. The specific activity given as molecules of NO converted per total metal atom per second were 16.5 × 10⁻⁴ s⁻¹ for Pt_0.5Co_2.0Fer, 13 × 10⁻⁴ s⁻¹ for Pt_0.5Co_2.0Mor, 4.33 × 10⁻⁴ s⁻¹ for Pt_0.5Co_2.0ZSM-5 and 0.5 × 10⁻⁴ s⁻¹ for Pt/Co/Al₂O₃. The Y-zeolite-based samples were inactive in both mono and bimetallic samples. The species initially present in the solid were Pt° and Co°, together with Co²⁺ and Pt²⁺ at exchange positions. Co° seems not to participate as an active site in the SCR of NO_x. Those species remained after the reaction but some reorganization occurred. A synergetic effect among the different species that enhances both the NO to NO₂ reaction, the activation of CH₄ and also the ability of the catalyst to adsorb NO, could be responsible for the high activity and selectivity of the bimetallic zeolites.     

Effective Au-Au-Clx/Fe(OH)y catalysts containing Cl for selective CO oxidations at lower temperatures

Supported Au catalysts Au-Au⁺-Cl_x/Fe(OH)_y (x < 4, y ≤ 3) and Au-Cl_x/Fe₂O₃ prepared with co-precipitation without any washing to remove Cl⁻ and without calcining or calcined at 400 °C were studied. It was found that the presence of Cl⁻ had little impact on the activity over the unwashed and uncalcined catalysts; however, the activity for CO oxidation would be greatly reduced only after Au-Au⁺-Cl_x/Fe(OH)_y was further calcined at elevated temperatures, such as 400 °C. XPS investigation showed that Au in catalyst without calcining was composed of Au and Au⁺, while after calcined at 400 °C it reduced to Au⁰ completely. It also showed that catalysts precipitated at 70 °C could form more Au⁺ species than that precipitated at room temperatures. Results of XRD and TEM characterizations indicated that without calcining not only the Au nano-particles but also the supports were highly dispersed, while calcined at 400 °C, the Au nano-particles aggregated and the supports changed to lump sinter. Results of UV–vis observation showed that the Fe(NO₃)₃ and HAuCl₄ hydrolyzed partially to form Fe(OH)₃ and [AuCl_x(OH)_4−x]⁻ (x = 1–3), respectively, at 70 °C, and such pre-partially hydrolyzed iron and gold species and the possible interaction between them during the hydrolysis may be favorable for the formation of more active precursor and to avoid the formation of Au–Cl bonds. Results of computer simulation showed that the reaction molecular of CO or O₂ were more easily adsorbed on Au⁺ and Au⁰, but was very difficultly absorbed on Au⁻. It also indicated that when Cl⁻ was adsorbed on Au⁰, the Au atom would mostly take a negative electric charge, which would restrain the adsorption of the reaction molecular severely and restrain the subsequent reactions while when Cl⁻ was adsorbed on Au⁺ there only a little of the Au atom take negative electric charge, which resulting a little impact on the activity.     

利用失效钒电解液回收钒制备偏钒酸铵工艺

为了提取失效钒电解液中有价钒元素,对全钒氧化还原液流电池失效钒电解液的回收利用进行了研究。在常温常压条件下,以氯酸钠作氧化剂对失效钒电解液进行深度氧化,使低价钒全部转变成五价钒,然后通过浓缩、沉钒、干燥等工艺过程,得到具有高附加值的偏钒酸铵。分析了回收过程的工艺原理,探讨了回收工艺的工艺条件。结果表明：NaClO₃对失效钒电解液的氧化是影响钒回收率的关键工艺过程,V⁴⁺：NaClO₃的最佳摩尔比为1：0.2,V³⁺：NaClO₃的最佳摩尔比为1：0.4;沉钒的最佳工艺条件为：钒液浓度为25～30g/L,pH为8.0～8.5,沉钒温度为50～60℃,加铵系数K为1.0～1.2,沉钒时间为80～120min。该工艺具有钒回收率高、成本低、操作简便、对环境友好等优点,在最佳工艺条件下钒的回收率可高达99%左右,为全钒液流电池失效钒电解液的回收利用提供了一条新途径。     

Water modification of PEG-derived VPO for the partial oxidation of propane

In this study, the PEG-derived VPO precursors were subject to water refluxing (90 °C, 8 h) and in situ activation in a steam-containing environment. For comparison, the VPO precursors without water refluxing were also activated in a similar manner. The IR measurement indicated that the majority of PEG in the precursor has been removed during water refluxing, and the VPO is essentially unenwrapped by PEG. The consequence is an increase of particle size and crystallinity of VPO as well as decreases in surface acidity and site density. The activation of catalysts in a stream-containing environment has an influence on the content of V⁵⁺ species and on the reduction behavior of the VPO catalysts. The VPO catalyst activated with 20% water vapor (by volume) in the feed shows the highest crystallinity. Compared with the non-PEG-derived VPO precursor, the PEG-derived one undergoes structure changes of higher severity during the water/steam treatments. The VPO catalyst generated from the PEG-derived precursor with water refluxing and activated with steam (20%) exhibited a propane conversion of 25% and a (AA + HAc) selectivity of 70%. The superior catalyst behavior can be interpreted in terms of the higher crystallinity of the (VO)₂P₂O₇ phase, the lower content of V⁵⁺ species, and the milder surface acidity as caused by the water/steam treatments.     

Nanosized perovskite-type oxides La1−xSrxMO3−δ (M = Co, Mn; x = 0, 0.4) for the catalytic removal of ethylacetate

Nanometer perovskite-type oxides La_1−xSr_xMO_3−δ (M = Co, Mn; x = 0, 0.4) have been prepared using the citric acid complexing-hydrothermal-coupled method and characterized by means of techniques, such as X-ray diffraction (XRD), BET, high-resolution scanning electron microscopy (HRSEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and temperature-programmed reduction (TPR). The catalytic performance of these nanoperovskites in the combustion of ethylacetate (EA) has also been evaluated. The XRD results indicate that all the samples possessed single-phase rhombohedral crystal structures. The surface areas of these nanomaterials ranged from 20 to 33 m² g⁻¹, the achievement of such high surface areas are due to the uniform morphology with the typical particle size of 40–80 nm (as can be clearly seen in their HRSEM images) that were derived with the citric acid complexing-hydrothermally coupled strategy. The XPS results demonstrate the presence of Mn⁴⁺ and Mn³⁺ in La_1−xSr_xMnO_3−δ and Co³⁺ and Co²⁺ in La_1−xSr_xCoO_3−δ, Sr substitution induced the rises in Mn⁴⁺ and Co³⁺ concentrations; adsorbed oxygen species (O⁻, O₂⁻, or O₂²⁻) were detected on the catalyst surfaces. The O₂-TPD profiles indicate that Sr doping increased desorption of the adsorbed oxygen and lattice oxygen species at low temperatures. The H₂-TPR results reveal that the nanoperovskite catalysts could be reduced at much lower temperatures (<240 °C) after Sr doping. It is observed that under the conditions of EA concentration = 1000 ppm, EA/oxygen molar ratio = 1/400, and space velocity = 20,000 h⁻¹, the catalytic activity (as reflected by the temperature (T_100%) for EA complete conversion) increased in the order of LaCoO_2.91 (T_100% = 230 °C) ≈ LaMnO_3.12 (T_100% = 235 °C) < La_0.6Sr_0.4MnO_3.02 (T_100% = 190 °C) < La_0.6Sr_0.4CoO_2.78 (T_100% = 175 °C); furthermore, there were no formation of partially oxidized by-products over these catalysts. Based on the above results, we conclude that the excellent catalytic performance is associated with the high surface areas, good redox properties (derived from higher Mn⁴⁺/Mn³⁺ and Co³⁺/Co²⁺ ratios), and rich lattice defects of the nanostructured La_1−xSr_xMO_3−δ materials.