Amount Of Zr Research Articles

Synthesis, optimization, electrochemical and electrochromic properties of Zr-doped NiO films by chemical spray pyrolysis

Zirconium (Zr)-doped NiO films with different contents were successfully synthesized via the chemical spray pyrolysis technique. The structure, morphology, optical and electrochemical behaviors of these films were investigated by X-ray diffraction (XRD), Raman spectrometer, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), UV–Vis-NIR spectrophotometry, cyclic voltammetry (CV), and chronoamperometry (CA). XRD results suggested that the synthesized samples have the cubic crystal structure and a preferred orientation along the plane (111). Raman spectra further confirmed the successful incorporation of zirconium ions into the NiO films. SEM images explained that the surfaces of the doped films were composed of uniform and dense nanoparticles. EDS analysis suggested that Zr, Ni and O elements were uniformly distributed on the films. The optical results showed that the band gap decreases from 3.53 eV to 3.47 eV as the increase of zirconium doping content. The electrochemical analysis suggested that zirconium doping improved the specific capacitance of the NiO films (the NiO film with the Zr amount of 7 %, 59 F/g at 6 mV/s). In addition, the NiO film with 5 % Zr doped amount exhibited the largest ΔOD (81 %), the largest CE (60.37 cm2/C), and the fastest coloring time (tc =2.1 s) and bleaching time (tb = 2.4 s). These results showed that this film had the excellent electrochromic properties, suggesting that the optimal Zr doped amount of NiO films is 5 %. As a novel kind of electrochromic material, the Zr-doped NiO film has broad application prospects in smart windows, green buildings and energy efficient utilization fields.

Influence of Zr addition on the microstructure, mechanical and electrical properties of Mo-Cu alloy

In order to strengthen the overall properties of Mo-Cu alloy, Zr was added to Mo-Cu alloy to enhance the bond strength of Mo/Cu interface and form solid solution strengthening effect. The excellent properties of Mo-Cu-Zr blocks were attained through infiltrating Cu-Zr blocks containing various Zr contents into the Mo skeleton. Compared to the incoherent interface of Mo/Cu in Mo-Cu block, the addition of Zr changed its interface to the coherent interface of Mo-Zr/Cu-Zr. All Mo-Cu-Zr alloy blocks possessed high densification degrees (97.1 %∼98.4 %) to assure the excellent general properties. Besides, the formations of Mo-Zr and Cu-Zr solid solutions assured the block owned excellent mechanical strength. Especially, the addition of Zr purified the grain boundary through absorbing oxygen to produce ZrO2 which prevented the Mo-Zr grain growth. As increasing Zr amount from 0 to 4.73 wt%, the Mo-Zr (or Mo) grain size reduced from 5 to 4.0 μm. Mo-Cu sintered sample containing 2.40 wt% Zr possessed the highest tension strength of 494 MPa. Besides, since the finer grain size of Mo-Zr alloy, this block also owned the highest micro-hardness (250 HV) and bending strength (1626 MPa), respectively. But, the generations of Cu-Zr solid-solution and ZrO2 also damaged the electrical conductivities to a certain extent. Specifically, as the addition amount of zirconium increased from 0 to 2.40 wt%, the conductivity decreased from 42.67 % to 32.15 %IACS.

The influence of zirconium addition on microstructure evolution, precipitation behavior, and properties of Cu–Ni–Ti alloy

This study systematically investigated the effects of a small amount of Zr addition on the microstructure evolution, mechanical, and electrical properties of Cu–Ni–Ti alloy, specifically focusing on Cu–3Ni–1Ti - (0.3Zr). The results indicate that adding an appropriate amount of Zr significantly enhances the mechanical properties and over-aging resistance of the Cu–Ni–Ti alloy, with only a slight decrease in conductivity. After aging at 500 °C for 2 h, Cu–3Ni–1Ti-0.3Zr exhibits an ultimate tensile strength of 673 MPa and a conductivity of 53 % IACS. Even after extending the aging time to 10 h, the tensile strength and conductivity remain high at 646 MPa and 61 % IACS, respectively. Microscopic analysis reveals that the addition of Zr promotes the formation of fine Ni3Ti phase during solidification and solution treatment, improving the deformation resistance and enhances its yield strength of the alloy in the cold-rolled state. Additionally, it hinders the migration of grain boundaries，suppressing the recovery and recrystallization processes, thus maintaining high mechanical properties and over-aging resistance. Furthermore, the precipitation of coherent or semi-coherent nano Ni3Ti phases during the aging process positively affects the alloy's yield strength and conductivity. The Oworan and dislocation strengthening mechanisms resulting from nano Ni3Ti phases are the primary mechanisms enhancing the yield strength of Cu–3Ni–1Ti-0.3Zr alloy, contributing approximately 87 %.

Synthesis, characterization and As(III) scavenging behaviours of mango peel waste loaded with Zr(IV) ion from contaminated water

Raw mango peel (RMP) was first saponified to yield saponified mango peel (SMP), which was then loaded with Zr(IV) ions to form a biosorbent for As(III) scavenging.The biosorption behaviors and mechanisms of As(III) scavenging using RMP and Zr(IV)-loaded saponified mango peel (Zr(IV)-SMP) were investigated batchwise. The As(III) scavenging efficiency of RMP increased from 20.13 % to 87.32 % after Zr(IV) loading. Optimum contact time of 6 h has been investigated for As(III) scavenging by Zr(IV)-SMP, and the data on kinetics is well fitted to the pseudo-second-order (PSO) model. Similarly, isotherm data of Zr(IV)-SMP fitted well to the Langmuir isotherm model with the maximum As(III) scavenging potential of 45.52 mg/g. Chloride (Cl−) and nitrate (NO3−) have negligible influence on As(III) scavenging, but sulphate (SO42−) interferes significantly. The exhausted Zr(IV)-SMP could be easily regenerated by treating with 2MNaOH. A mechanistic study indicates that As(III) scavenging is primarily contributed to electrostatic interaction and ligand exchange, which is confirmed from both instrumental and chemical characterizations techniques. Tubewell underground water polluted with a trace amount of arsenic (98.63 μg/L) could be successfully lowered down to the WHO standard (10 μg/L) by applying a small amount of Zr(IV)-SMP. Therefore, the Zr(IV)-SMP investigated in this work can be a low-cost, environmentally benign, and promising alternative for scavenging trace levels of arsenic from contaminated water.

Structure-activity relationships of zirconium-modified copper-based catalysts during methanol steam reforming

Acknowledged as an ideal method for in situ hydrogen generation, methanol steam reforming (MSR) requires high-performance catalysts to enhance production efficiency. Herein, we prepared a series of Zr-modified Cu-based catalysts by a coprecipitation method and conducted a systematic analysis of the impacts of structural variations on MSR performance. Extensive characterization reveals a strong dependence of the catalyst’s surface structure on Zr content. Introducing a moderate amount of Zr to the Cu/ZnO catalysts forms ZnZrOx solid solution and increases Cu dispersion, forming more Cu-ZnZrOx and Cu-ZnO interfacial sites with higher H2 production rate. Further increases in Zr content enlarge Cu nanoparticles and multiply Cu-ZrO2 interfacial sites. The optimal catalyst with a Zn/Zr molar ratio of 5, with the richest Cu-ZnO/Cu-ZnZrOx interfacial sites, achieves the highest H2 production rate of 117.4 mmolH2gcat-1h-1 at 200 °C, which is 1.3 times and 6.8 times higher than those of Cu/ZnO and Cu/ZrO2, respectively.

Comprehensive Study of Zr-Doped Ni-Rich Cathode Materials Upon Lithiation and Co-Precipitation Synthesis Steps.

Ni-rich layered oxides LiNi1-x-yMnxCoyO2 (NMC811, x = 0.1 and y = 0.1) are considered promising cathode materials in lithium-ion batteries (LiBs) due to their high energy density. However, those suffer a severe capacity loss upon cycling at high delithiated states. The loss of performance over time can be retarded by Zr doping. Herein, a small amount of Zr is added to NMC811 material via two alternative pathways: during the formation of the transition metal (TM) hydroxide precursor at the co-precipitation step (0.1%-Zr-cp) and during the lithiation at the solid-state synthesis step (0.1%-Zr-ss). In this work, the crystallographic Zr uptake in both 0.1%-Zr-ss and 0.1%-Zr-cp is determined and quantified through synchrotron X-ray diffraction and X-ray absorption spectroscopy. We prove that the inclusion of Zr in the TM site for 0.1%-Zr-cp leads to an improvement of both specific capacity (156 vs 149 mAh/g) and capacity retention (85 vs 82%) upon 100 cycles compared to 0.1%-Zr-ss where the Zr does not diffuse into the active material and forms only an extra phase separated from the NMC811 particles.

A Phase-Field Study of Spinodal Decomposition Impeded by Irradiation in U-Mo and U-Mo-Zr Alloys.

The phase-field method, coupled with the micro-elastic model and irradiation-induced cascade mixing model, has been employed to investigate the spinodal decomposition in U-Mo and U-Mo-Zr alloys. The microstructure evolution of U-Mo or U-Mo-Zr alloys under different initial conditions, such as the alloy composition, aging temperature and irradiation intensity, were simulated to study the effect of cascade mixing on the miscibility gap, morphology and volume fraction of the decomposed phases. The simulation results demonstrate that irradiation-induced cascade mixing impedes the process of spinodal decomposition, and that irradiation shrinks the composition range of the miscibility gap in the alloys. Irradiation-induced cascade mixing slows down the anisotropic growth rate of the spinodal decomposition, yet this phenomenon can be weakened with increasing aging temperature. Adding an appropriate amount of Zr to a U-Mo alloy can effectively prevent the contraction of the miscibility gap caused by irradiation.

Comparative analysis of the brazing mechanism and wear characteristics of brazed diamond abrasive with Zr-alloyed Cu-based filler metals

In this work, Zr-alloyed (0 wt%, 0.5 wt%, 1.5 wt%, 2 wt%) Cu-based filler metals were successfully prepared for brazing diamond abrasive tools. The microstructure and brazing mechanism were investigated via scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The effects of brazing temperature and brazing time on the wear properties of diamond abrasive were investigated when the addition amount of Zr is 1 wt%. It found that, adding 1 wt% Zr, the microstructure of the filler metal alloy is uniformly refined and dense. The mechanical properties of the brazed diamond abrasives showed that the brazed Cu-based filler metal with 1 wt% Zr showed the best wear resistance, with the uneven and three-body wear rates reaching 18.8 % and 12.5 %. The findings from the various brazing processes indicated that the optimal grinding performance of the brazed joints was achieved at a brazing temperature of 940 °C and a holding time of 6 min. Under these conditions, the diamond dropout rate was measured at 6.3 %, while the rate of uneven wear reached 18.8 %.

Construction of Oxygen Vacancies of Zr-Doped CeO2 with Enhanced Dye Adsorption Performance

Congo red (CR), a highly pigmented anionic dye, is highly toxic and resistant to degradation. The discharge of CR wastewater into the natural environment can lead to ecological destruction and harm to human health. CeO2 as an adsorbent possesses the advantages of excellent acid and alkali resistance, biocompatibility, stable physical and chemical properties, and nontoxic by-products. The impact of Zr doping on the adsorption performance of nano-CeO2 was investigated. XPS and Raman characterisation revealed that Zr doping effectively enhanced the oxygen vacancy ratio at the active sites for CR adsorption on the surface of nano-CeO2. When the doping amount of Zr was 3%, the nanoparticles with the best adsorption properties were obtained, and the adsorption amount of CR at room temperature was as high as 3642.05 mg/g, which was approximately three times the adsorption amount of undoped CeO2. This excellent adsorption property shows good prospects for the removal of anionic dyes from wastewater.

Precipitation hardening and structure evolution in hypereutectic Al-6 % Fe-Zr alloys subjected to ultrasonic melt processing

The objective of this research was to study the influence of Zr concentration and ultrasonic melt processing (USP) on the microstructure and precipitation hardening of a hypereutectic Al-6% Fe alloy. Such alloys have a good potential in high-temperature, wear-resistant, and conducting applications but suffer from coarse structure and low strength/ductility, which prevents their processing. The microstructure of the studied alloys consisted of primary Al13Fe4 intermetallics and (Al)+Al13Fe4 eutectic colonies, which were successfully refined by adding Zr and performing USP. The mechanisms of USP and Zr were confirmed for the Al-6 % Fe alloys with a range of Zr additions. The structure refinement led to improved hardness and tensile properties of the alloys. All studied alloys demonstrated strong precipitation hardening effect with hardness increasing 4–5 times, reaching 170 HV for the alloy with 0.4 % Zr after annealing at 400 ℃ for 20 hrs. The electrical conductivity increased from 25 % IACS in the as-cast alloy to 40% IACS in the annealed Al-6% Fe-0.4 % Zr alloy. The prime novelty of this work is a considerable increase of hardness upon annealing, i.e. more than 100 HV, in the Al-6 % Fe alloy with only minute traces of Zr (<0.01 %). The precipitation phenomena were investigated by transmission electron microscopy. The precipitation of the semi-coherent Al13Fe4 phase with Zr segregated to its surface was observed for the first time. All studied alloys (with minute and larger Zr additions) showed the precipitation of this phase, while the alloys with the larger amount of Zr also demonstrated the precipitation of the metastable L12 Al3Zr phase. Therefore, the properties improvement was attributed to the structure refinement and the formation of Zr-modified Al13Fe4 and Al3Zr precipitates in the microstructure.

Strength and stability through variable micro segregation behaviour of Ta and Zr solutes at intermetallic interfaces in Al-Cu alloys

A small amount of Zr and Ta are added to aluminium-copper (Al-Cu) alloys, and the evolution of strengthening phases with multi-step heat-treatment and their stability after prolonged thermal exposure at 250 °C has been studied. The L12 ordered (Al,Cu)3(Zr,Ta) precipitates were formed in the Al-matrix, followed by preferential nucleation of Cu-rich θ"/θ' plates on the L12/matrix interfaces. Transmission electron microscopy and atom probe tomography studies established the segregation of Zr and Ta at θ' plate/matrix in the aged alloys. It is shown that Zr segregates at coherent broad interfaces of θ' plate and inhibits the growth of these interfaces. Segregation of Ta primarily occurs at the growing θ' plate interface in the lengthening direction (semi-coherent interface) along with Zr and restricts the lengthening of the plate. The restricted growth triggers sympathetic nucleation of newer plates at the plate edges to sustain the growth process. A yield strength of ∼475 MPa at room temperature is recorded due to the presence of ordered precipitates and the growth restriction of θ' plate. Segregation of slow diffusing elements (Zr and Ta) also enhances the thermal stability of the microstructure.

Effect of sputtering-target composition on the structure, dielectric, ferroelectric, and energy storage properties of highly (00l)-oriented Ba(ZrxTi1–x)O3 films

It is relatively easy to obtain highly oriented/textured Ba(ZrxTi1–x)O3 (BZT) films by magnetron sputtering, but it is complicated to control the composition of these sputtered oriented films. Here, a series of BZT ceramic targets with different ingredients (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) and a BaTiO3 (x = 0) target were fabricated by solid-state sintering. Then, the corresponding BZT thin films were deposited on LaNiO3 (LNO) buffered Pt/Ti/(001)Si substrates adopting radio-frequency magnetron sputtering. Benefit from the prefabricated (001)-LNO buffer layer and optimized BZT film preparation process, all BZT films exhibit highly (00l) preferred orientation. However, the degree of orientation, lattice parameter, dielectric properties, ferroelectric behaviors, and energy-storage characteristics are all highly dependent on the Zr content of BZT films sputtered by targets with the same composition. (00l)-oriented BZT films with relatively low Zr content have a better crystalline structure [narrower full width at half maximum (FWHM), larger grains]. It is also found that the rising of the Zr content in (00l)-oriented BZT films will result in a larger out-of-plane lattice parameter, and these results indicate that the doping amount of Zr will strongly change the heterointerface stress/strain states and the growth mode of the oriented films, and then effectively tailor their electric performances.

The Study on Heat Treatment Microstructure and Properties of Extruded Al-Mg-Si-Mn-Cr-Zr Alloy

In order to obtain a high-strength Al-Mg-Si aluminum alloy with a tensile strength of more than 400MPa, a trace amount of Zr is added to the 6082 aluminum alloy to obtain an Al-1.0Mg-1.05Si-0.55Mn-0.15Cr-0.045Zr alloy. The mechanical properties and microstructure of the extruded Al-1.0Mg-1.05Si-0.55Mn-0.15Cr-0.045Zr alloy were studied by tensile performance test, metallography, scanning electron microscope (SEM), transmission electron microscope (TEM), electron backscatter diffraction (EBSD) observation and energy spectrum analysis. The results show that, after 545°C×2h+170°C×8h heat treatment, the alloy has the best mechanical properties. The tensile strength, yield strength and elongation at break reached 423MPa, 402MPa and 14%, respectively. The alloy strengthening mechanism is mainly due to the large number of dispersed needle-like β′ phases, sub-micron α-Al(MnCrFe)Si phases, α-Al(MnFe)Si phases and micron-level α-Al(MnCrFe)Si phases precipitated inside the grains and grain boundaries. The alloy precipitates sub-micron α-Al(MnCrFe)Si phase, α-Al(MnFe)Si phase and micron-level α-Al(MnCrFe)Si phase. After the alloy is treated at 545°C×2h+170°C×8h, a large number of dispersed needle-like β″ precipitations are uniformly precipitated in the inside the grains respectively. These precipitations can improve the strength of the material. The average grain size of the alloy is 7.41μm, and a bimodal grain structure composed of low-angle grain boundaries and high-angle grain boundaries is formed.

Reaction Mechanism of Combustion Synthesized ZrC–2ZrB&lt;sub&gt;2&lt;/sub&gt;-Based Cu Cermets

The reaction process of ZrC–2ZrB2-based Cu cermets from the (1 − x wt.%)(1B4C–3Zr)–x wt.%Cu system (Zr/B4C = 3 in molar ratio) was explored. Results showed that ZrC and ZrB2 were mostly produced through the dissolution of B4C into a preformed Zr–Cu liquid. With an increase in x, the synthetic ZrC–2ZrB2 and generated heat were reduced. This effect decreased an ability for Zr–Cu liquid to propagate in the reactants, and restrained the dissolution Zr. As a result, the complete synthesis of ZrC–2ZrB2 failed in the systems with a higher Cu content (e.g., 50 wt.%). Furthermore, after the precipitation of ZrC and ZrB2, the liquid surrounding would prevent ZrC and ZrB2 from growing. Increasing Cu content enhanced the amount of Zr–Cu melt. This behavior contributed to a decline in ZrC–2ZrB2 particle sizes, and the production of fine ceramic particles (∼200 nm). It is also revealed that the formation of ZrC–2ZrB2 is a multistep process, which results in the inhomogeneity of ZrC–2ZrB2 particle sizes. A valuable approach was proposed to explore the relationship between reaction process and synthesized products of combustion synthesis-related technique.

Interface characteristic of Zr-based metallic glass and copper by laser pulse welding

The crystallization behavior of amorphous alloys during welding is more complex than that of traditional metals. In this paper, the Zr-based amorphous alloy and copper crystals were welded by pulsed laser butt welding method, the crystallization behavior of the amorphous alloy/crystalline metal welding interface is deeply studied. The results show that Zr2Cu and Zr2Ni crystal phases appear at the interface between Zr based amorphous alloy and copper, and a Cu rich region is formed at the amorphous side of the interface. A small amount of Zr, Ni, Ti diffuses to the Cu side, forming ZrO2, TiO2, CuO and other oxides on the surface of the sample. These oxides will cause changes in the voltage potential at the interface.

Improvement of Curie temperature and magnetic entropy change of a Fe88Zr8B4 metallic glass by minor Nd substitution

A small amount of Zr in the Fe88Zr8B4 metallic glass (MG) was replaced by Nd and the fully amorphous Fe88Zr8-xNdxB4 (x = 2, 4) ribbons were successfully fabricated. The influences of Nd substitution on the glass formability, Curie temperature and magnetic entropy change (−ΔSm) of a Fe88Zr8B4 MG were investigated. It was found that the minor Nd substitution not only results in the improved glass formability, but also enhances the −ΔSm peak to ∼ 3.65 J/(kg×K) at 314 K for x = 2, and to ∼ 4.10 J/(kg×K) at 335 K for x = 4 under 5 T. The mechanisms for the weak spin-glass-like behavior and the improvement of −ΔSm induced by minor Nd substitution were investigated.

Joint effect of Zr and Cu on the properties of new powder metallurgy Ti–Zr–Cu alloys

The performance of Ti alloys are directly related to their composition, where Zr and Cu are generally used, respectively, because of their non-toxic and antibacterial behaviour. As not previously reported in literature, this study considered the joint effect of Zr and Cu on the processing and properties of Ti, where Ti–Zr–Cu alloys were manufactured via powder metallurgy. It was found that Zr and Cu decrease the compressibility (86.5–88.05%), and Zr hinders whilst Cu boosts densification; therefore, the Ti–Zr–Cu alloys achieved higher relative sintered compact density values (93.6–94.5%) compared to sintered pure Ti (93.5%). Adding Zr and Cu changes the microstructure to lamellar, and their incremental addition refines the microstructure and leads to the formation of a eutectoid (sub)structure. As the amount of Zr and Cu increases, the Ti–Zr–Cu alloys become stronger (YS: 365–792 MPa, and UTS: 447–849 MPa) and less ductile (1.6–13.7%). However, they still primarily fail in a ductile manner, due to the microstructural changes (e.g. smaller interlamellar spacing) and strengthening effects (e.g. solid solution) brought about by the incremental addition of the alloying elements.

Deploying radical inter-transition from [rad]OH to supported NO3[rad] on Mono-dentate NO3--modified ZrO2 to sustain fragmentation of aqueous contaminants

To advance aqueous pollutant degradation using OH, H2O2 (OH carrier) should be cleaved homolytically on a non-reducible metal oxide (ZrO2) rather than heterolytically on a reducible counterpart (MnO2), given the merits of H2O2 homolysis such as improved OH productivity, unnecessity to recover H2O2 activators (Lewis acidic metals; LA) via electron reduction, and minute LA leaching. This paper presents a methodology to exploit H2O2 homolysis with the rate-determining step of endothermic OH desorption, thereby proposing the coupling of H2O2 homolysis and exothermic radical inter-conversion of OH → NO3SUP (supported NO3) to create the overall OH → NO3SUP route. ZrO2 was modified with NO3− functionalities (NO3SUP precursors) to form ZrO2-N, where NO3-SUP species were located close to Zr4+ (LA) and Brönsted acidic -OH (BA) sites, whose acidic strengths must be elevated to facilitate OH desorption for reducing the energy barrier (EBARRIER) of the overall OH → NO3SUP route. NO3-SUP species were bound to the ZrO2 surface via mono-dentate configuration only, thereby avoiding LA loss (rate in a per-gram↑), escalating LA/BA strengths (EBARRIER↓), and imparting two free oxygens available to OH → NO3SUP (rate in a per-site↑). Moreover, NO3SUP species extract electrons from contaminants via electron transfer to recover NO3-SUP species used for recurring OH → NO3SUP, while sustaining pollutant fragmentation efficiency by circumventing surface poison accumulation. Hence, NO3SUP on ZrO2-N revealed higher efficiencies in fragmenting bisphenol A or recycling phenol degradation than OH evolved from ZrO2. In addition, ZrO2 outperformed MnO2 in exploiting NO3SUP species, thus showing greater recyclability in mineralizing textile wastewater, while leaching a negligible amount of Zr.

Aerosol-assisted CVD method for the synthesis of solid particles of t-YSZ-Fe3O4

This work details the production of solid composite particles by the aerosol-assisted chemical vapor deposition method. With this method it is feasible to produce at low temperature (450 °C) the tetragonal phase of zirconium oxide stabilizing it with yttrium oxide (YSZ) and cubic iron oxide (Fe3O4) at the same time. The particles have a solid morphology in which both metal oxides coexist without mixing. The average size of the obtained particles is 329 ± 81 nm, moreover, each particle is formed by thousands of crystallites of size 2 ± 0.5 nm. The formation of solid structures is due to the amount of Zr and Y found in each particle. These particles can be applied as reinforcements of metallic structures.•A simple and low-cost method for producing composite particles to be applied as reinforcing agents for metal structures.•The particles are formed by two phases of tetragonal yttria-stabilized zirconia (t-YSZ) and cubic Fe3O4, which was synthesized following a one-step process via the aerosol-assisted chemical vapor deposition method (AACVD).•The tetragonal phase of ZrO2 is obtained at 450 °C stabilizing it with ∼3.8% of yttrium oxide.

Doping low amount of Zirconium in Rh-LTO to prepare durable catalysts for dry reforming of methane

Zr doped Rh-La2Ti2O7 with different amounts of Zr were prepared with a sol-gel process and used as catalysts for dry reforming of methane. The samples as prepared were characterized by a series of methods including powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and temperature-programmed reduction (TPR). The XPS and XAS spectra revealed the effect of doped Zr in the electronic environment of catalysts. The results showed that when the doping amount of Zr was at a low level, the activity and stability of the DRM catalyst were significantly improved. Tests of catalytic activity showed that the reforming performance of Rh-LTZO-x catalysts was affected by the Zr/Ti loading ratio. It was favored when Zr/Ti ratio was low and incomplete methane conversion was observed when Zr/Ti=1. Compared to Rh-LTO, the optimized catalyst Rh-LTZO-10 enhanced conversion of methane and carbon dioxide from 77% to 86%, 83% to 90%, respectively. The optimized catalyst Rh-LTZO-10 exhibited long stability life over 200 h of the reaction and there was only a small amount of carbon deposition. The low amount of Zr doping may accelerate the transfer rate or number of electrons during the reaction, enhance the interaction between the active component Rh and the support, so that Rh can stably exist in the structure and achieve long stability in DRM reaction.