Effect of mixed-valence of manganese on water oxidation activity of La1-xCaxMnO3 (0 ≤ x ≤ 1) solid solutions

The water oxidation reaction is one of the crucial process involves 4e^- and 4H⁺ transfer, which causes a high energy barrier and makes the water-splitting process a slow kinetic reaction. Herein, we have systematically observed the water oxidation activity of La_1-xCa_xMnO₃ (0≤ x ≤ 1) solid solutions by tuning the valence of Mn ion through selective substitution of La³⁺ with Ca²⁺. With increasing Ca concentration in La_1-xCa_xMnO₃ solid solutions, the water oxidation activity increases up to x = 0.5 and then decreases. Mixed-valence of Mn generated due to substitution of La³⁺ with Ca²⁺, which leads to the double exchange mechanism. This could results in high electrical conduction and a faster electron transfer rate because of the rapid charge exchange between Mn³⁺ and Mn⁴⁺ ions, which pinpoints the reason behind the enhanced oxygen evolution activity. Our findings will be a promising way to relate the Mn mixed-valence with its catalytic activity to design and development of efficient water oxidation catalysts.     

Synthesis of La0.2Sr0.8CoO3 and its electrocatalytic activity for oxygen evolution reaction in alkaline solution

The perovskite-type oxide La_0.2Sr_0.8CoO₃ was prepared by sol-gel process, which particle was irregular cube with particle size between 50 and 60 nm. A novel air electrode for oxygen evolution reaction prepared by using La_0.2Sr_0.8CoO₃ as a catalyst has a current density of 152 mA cm⁻² when the potential is 0.7 V (vs. Hg/HgO) in an alkaline medium (6 mol L⁻¹ KOH) under the air atmosphere. The research results show that n (C₆H₈O₇): n (M) = 1:1, pH = 9, calcination temperature 800 °C, 5 h calcination time is the best preparation process conditions.     

Effect of Fe,Ni and Zn dopants in La0·9Sr0·1CoO3 on the electrochemical performance of single-component solid oxide fuel cell

Fe-, Ni- and Zn- doped La_0·9Sr_0·1CoO₃ are prepared and a single-component solid oxide fuel cell composed of 30 wt% perovskite oxide and 70 wt% samarium-doped ceria (SDC)-(Li_0·67Na_0.33)₂CO₃ is fabricated and characterized. When doping with either Fe, Ni or Zn, most cations occupy the Co³⁺ sites. X-ray photoelectron spectroscopy and oxygen temperature-programmed desorption characterizations show that Zn-doped La_0·9Sr_0·1CoO₃ exhibits notably high surface oxygen, causing higher catalytic activity for oxygen reduction reaction (ORR) than that of nondoped La_0·9Sr_0·1CoO₃. Fe or Ni doping into La_0·9Sr_0·1CoO₃ decreases surface oxygen, resulting in a lower catalytic activity toward ORR than La_0·9Sr_0·1CoO₃. Furthermore, X-ray diffraction, temperature-programmed reduction and transmission electron microscopy characterizations prove that after reduction, Fe-doped La_0·9Sr_0·1CoO₃ is reduced to Co_0·72Fe_0.28 alloy-oxide core-shell nanoparticles, resulting in a high catalytic activity for hydrogen oxygen reaction (HOR). However, NiCo₂O₄ are formed during the reduction of Ni-doped La_0·9Sr_0·1CoO₃, exhibiting a low catalytic activity for the HOR. Similarly, the low catalytic activity of reduced Zn-doped La_0·9Sr_0·1CoO₃ for the HOR is caused by the formation of ZnCo₂O₄. A single component fuel cell composed with Fe-doped La_0·9Sr_0·1CoO₃-SDC-(Li_0·67Na_0.33)₂CO₃ exhibits the highest P_max of 239.1 mW cm⁻² at 700 °C with H₂ as fuel, indicating that HOR processes are rate-determining steps.     

La1-xSrxFeO3 perovskite-type oxides for chemical-looping steam methane reforming: Identification of the surface elements and redox cyclic performance

We report a family of perovskite-type oxides La_1-xSr_xFeO₃ (x = 0.1, 0.3, 0.5, 0.7, 1.0) prepared by combustion method as effective redox catalysts for methane partial oxidation and thermochemical water splitting in a cyclic redox scheme. The effect of Sr-doping on the characterizations and properties of these perovskite-type oxides were studied by means of X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H₂-TPR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). All the as-prepared and regenerated samples with various Sr substitutions exhibited pure crystalline perovskite structure. The oxygen carrying capacity of the La_1-xSr_xFeO₃ perovskites was improved by doping Sr into the La-site. Besides, Sr-substitution has obvious effects on the valences of the Fe cations in the B-site and the oxygen species distribution of the La_1-xSr_xFeO₃ perovskites. We recommend La_0.7Sr_0.3FeO₃ as the optimal oxygen carrier in the series because it gives the maximum O_la/O_ad (O_la and O_ad stand for lattice oxygen and adsorbed oxygen species, respectively.) ratio of 3.64:1, which can be regarded as a criterion for the reactivity and selectivity of partial oxidation of methane into syngas of the oxygen carriers. Up to 80% CH₄ conversion in the methane partial oxidation step and 96% of H₂ concentration in the water splitting step were achieved in ten successive redox tests conducted in a fixed bed reactor at 850 °C with La_0.7Sr_0.3FeO₃ as a redox catalyst. The electronic properties of the original LaFeO₃ cell and its lattice substituted by Sr were calculated based on the density functional theory method. Electronic structure analysis demonstrates that doping of Sr makes LaFeO₃ more electric conductive and its electron is prone to be excited. This is in agreement with the test results that La_0.7Sr_0.3FeO₃ exhibited better performance in chemical looping reactions.     

La1−xSrxCoO3 (x = 0.1-0.5) as the cathode catalyst for a direct borohydride fuel cell

Direct borohydride fuel cells (DBFCs), with a series of perovskite-type oxides La_1−xSr_xCoO₃ (x = 0.1-0.5) as the cathode catalysts and a hydrogen storage alloy as the anode catalyst, are studied in this paper. The structures of the perovskite-type catalysts are mainly La_1−xSr_xCoO₃ (_x = 0.1-0.5) oxides phases. However, with the increase of strontium content, the intensities of the X-ray diffraction peaks of the impure phases La₂Sr₂O₅ and SrLaCoO₄ are gradually enhanced. Without using any precious metals or expensive ion exchange membranes, a maximum current density of 275 mA cm⁻² and a power density of 109 mW cm⁻² are obtained with the Sr content of x = 0.2 at 60 °C for this novel type of fuel cell.     

Performance and stability of La0.5Sr0.5CoO3−δ perovskite as catalyst precursor for syngas production by partial oxidation of methane

The aim of this work was to investigate the performance and stability of the perovskite La_0.5Sr_0.5CoO_3−δ, as a potential catalyst precursor, for the synthesis gas production by partial oxidation of methane. For this purpose, the catalytic activity of La_0.5Sr_0.5CoO_3−δ was studied as a function of the temperature, flow rate and feed composition. In addition, its stability with the time-on-stream and redox cycles was also explored. Before and after testing, the catalyst precursor was characterized by X-ray diffraction, SEM-EDX and specific surface area (BET). The results evidenced a remarkable catalytic activity due to the stability of the cobalt, which is in a highly disperse state, in its reduced state. The CH₄ conversion and the CO and H₂ selectivities were enhanced with the increase of redox cycles. Finally, the precursor was totally regenerated to the initial perovskite structure under a specific thermal treatment.     

Investigation of La0.6Sr0.4Co1-xNixO3-δ (x=0, 0.2, 0.4, 0.6, 0.8) catalysts on solid oxide fuel cells anode for biogas dry reforming

The introduction of catalyst on anode of solid oxide fuel cell (SOFC) has been an effective way to alleviate the carbon deposition when utilizing biogas as the fuel. A series of La_0.6Sr_0.4Co_1-xNi_xO_3-δ (x = 0, 0.2, 0.4, 0.6, 0.8) oxides are synthesized by sol-gel method and used as catalysts precursors for biogas dry reforming. The phase structure of La_0.6Sr_0.4Co_1-xNi_xO_3-δ oxides before and after reduction are characterized by X-ray diffraction (XRD). The texture properties, carbon deposition, CH₄ and CO₂ conversion rate of La_0.6Sr_0.4Co_1-xNi_xO_3-δ catalysts are evaluated and compared. The peak power density of 739 mW cm^?2 is obtained by a commercial SOFC with La_0.6Sr_0.4Co_0.4Ni_0.6O_3-δ catalyst at 850 °C when using a mixture of CH₄: CO₂ = 2:1 as fuel. This shows a great improvement from the cell without catalyst for internal dry reforming, which is attributed to the formation of NiCo alloy active species after reduction in H₂ atmosphere. The results indicate the benefits of inhibiting the carbon deposition on Ni-based anode through introducing the La_0.6Sr_0.4Co_0.4Ni_0.6O_3-δ catalyst precursor. Additionally, the dry reforming technology will also help to convert part of the exhaust heat into chemical energy and improve the efficiency of SOFC system with biogas fuel.     

Electrochemical performance of La0.65Sr0.35MnO3 oxygen electrode with alternately infiltrated Sm0.5Sr0.5CoO3-δ and Sm0.2Ce0.8O1.9 nanoparticles for reversible solid oxide cells

La_1-xSr_xMnO₃ is a well-known oxygen electrode for reversible solid oxide cells (RSOCs). However, its poor ionic conductivity limits its performance in redox reaction. In this study, we selected Sm_0.5Sr_0.5CoO_3-δ (SSC) as catalyst and Sm_0.2Ce_0.8O_1.9 (SDC) as ionic conductor and sintering inhibitor to co-modify the La_0.65Sr_0.35MnO₃ (LSM) oxygen electrode through an alternate infiltration method. The infiltration sequence of SSC and SDC showed an influence on the morphology and performance of LSM oxygen electrode, and the influence was gradually weakened with the increasing infiltration time. The polarization resistance of the alternately infiltrated LSM-SSC/SDC electrode was 0.08 Ω cm² at 800 °C in air, which was 3.36% of the LSM electrode (2.38 Ω cm²). The Ni-YSZ/YSZ/LSM-SSC/SDC single cell attained a maximum power density of 1205 mW cm^?2 in SOFC mode at 800 °C, which was 8.73 times more than the cell with LSM electrode. The current density achieved 1620 mA .cm^?2 under 1.5 V at 800 °C in SOEC mode and the H₂ generation rate was 3.47 times of the LSM oxygen electrode.     

Solution plasma method assisted with MOF for the synthesis of Pt@CoOx@N-C composite catalysts with enhanced methanol oxidation performance

The key to direct methanol fuel cells (DMFCs) is the anode catalyst for methanol oxidation reaction (MOR) which has good catalytic activity and stability. Pt@CoO_x@N-C catalysts were synthesized by compounding Pt nanoparticles and CoO_x with nitrogen-doped porous carbon (N-C). Pt nanoparticles were prepared by solution plasma technique. CoO_x@N-C are derived from zeolitic-imidazolate-framework-67 (ZIF-67) by heat treatment at 700 °C. For MOR, Pt@CoO_x@N-C exhibits an outstanding electrocatalytic performance (mass activity of 2400 mA mg_Pt⁻¹) and stability (70% remained after 300 cycles) under acidic condition, which owing to the synergistic effects among the Pt nanoparticles, CoO_x and nitrogen-doped porous carbon. Pt@CoO_x@N-C shows such mass activity superior to that of Pt/C (460 mA mg_Pt⁻¹) due to the fact that CoO can adsorb –OH in the solution and then assist Pt to oxidize the CO-like intermediates to CO₂ which improves the resistance to CO poisoning of Pt nanoparticles. Therefore, solution plasma method assisted with metal-organic frameworks have good development prospects on synthesis of highly efficient electrocatalysts.     

Electrochemical performance of Sr1.9La0.1Fe1.5Mo0.5O6-δ symmetric electrode for solid oxide fuel cells with carbon-based fuels

La-doped Sr_2-xLa_xFe_1.5Mo_0.5O_6-δ perovskite oxides are synthesized and used as a symmetric electrode to evaluate the effect of La on the crystal structure, conductivity, and catalytic activity for O₂ reduction and H₂ oxidation reaction. The electronic doping effect dominates the oversize effect in Sr_2-xLa_xFe_1.5Mo_0.5O_6-δ oxide, resulting in unit cell volume expansion and decreased conductivity in air. In addition, the introduction of La increases the chemical structural stability of Sr₂Fe_1.5Mo_0.5O_6-δ in reducing condition due to the higher La–O bond compared with Sr–O bond, leading to high catalytic activity for the H₂ oxidation reaction. At 800 °C, the R_p values of Sr_1.9La_0.1Fe_1.5Mo_0.5O_6-δ symmetric cell in air and wet H₂ are as low as 0.075 and 0.21 Ω cm², respectively. Moreover, the peak power densities of 769, 561, 439, and 653 mW cm^?2 at 850 °C are obtained when wet H₂, CO, CH_4, and C₃H₈ are used as fuels on Sr_1.9La_0.1Fe_1.5Mo_0.5O_6-δ/LSGM/Sr_1.9La_0.1Fe_1.5Mo_0.5O_6-δ cell. The symmetric cell also shows excellent stability (>100 h) in wet H₂/air, implying Sr_1.9La_0.1Fe_1.5Mo_0.5O_6-δ oxide is a promising symmetric electrode material.     

Biomass to hydrogen-rich syngas via catalytic steam reforming of bio-oil

Hydrogen-rich syngas production from the catalytic steam reforming of bio-oil from fast pyrolysis of pinewood sawdust was investigated by using La_1−xK_xMnO₃ perovskite-type catalysts. The effects of the K substitution, temperature, water to carbon molar ratio (WCMR) and bio-oil weight hourly space velocity (W_bHSV) on H₂ yield, carbon conversion and the product distribution were studied in a fixed-bed reactor. The results showed that La_1−xK_xMnO₃ perovskite-type catalysts with a K substitution of 0.2 gave the best performance and had a higher catalytic activity than the commercial Ni/ZrO₂. Both high temperature and low W_bHSV led to higher H₂ yield. However, excessive steam reduced hydrogen yield. For the La_0.8K_0.2MnO₃ catalyst, a hydrogen yield of 72.5% was obtained under the optimum operating condition (T = 800 °C, WCMR = 3 and W_bHSV = 12 h⁻¹). The deactivation of the catalysts mainly was caused by coke deposition.     

Preparation of Cu0.1-xNixCe0.9O2-y catalyst by ball milling and its CO catalytic oxidation performance

A series of Cu_0.1-xNi_xCe_0.9O_2-y catalysts with different Cu/Ni molar ratios were prepared by the ball milling method. The obtained catalytic materials were characterized by XRD, H₂-TPR, BET, XPS and Ramen and the effects of different Cu/Ni content on the structure, properties and CO catalytic oxidation performance of the catalysts were explored. The results evidenced the formation of Cu–Ni–Ce mixed oxide solid solution in all ternary catalysts. In addition, there is a synergistic interaction between Cu and Ni in ternary catalysts, resulting in more oxygen vacancies and improved reduction performance, and hence demonstrating better CO catalytic oxidation activity in the ternary catalysts than binary ones. Under a GHSV of 60000 mL·g_cat⁻¹·h⁻¹, the required reaction temperature for reaching less than 10 ppm CO is lowed from 160 °C with Cu_0·1Ce_0·9O_2-y to 130 °C with Cu_0·07Ni_0·03Ce_0·9O_2-y.     

Study of partial oxidation reforming of methane to syngas over self-sustained electrochemical promotion catalyst

A self-sustained electrochemical promotion (SSEP) catalyst is synthesized for partial oxidation reforming (POXR) of CH₄ to produce syngas (H₂ and CO) at a relatively low temperature ranging from 350 to 650 °C. The SSEP catalyst is comprised of 4 components: microscopic Ni/Cu/CeO₂ anode, La_0.9Sr_0.1MnO₃ cathode, copper as electron conductor, and yttria-stabilized-zirconia as oxygen ion conductor, which form microscopic electrochemical cells to enable the self-sustained electrochemical promotion for the POXR process. The SSEP catalyst exhibited much better catalytic performance in POXR of CH₄ than a Ni–Cu–CeO₂ catalyst and a commercial Pt–CeO₂ catalyst. The CH₄ conversion over the SSEP catalyst is 29.4% at 350 °C and reaches 100% at 550 °C and the maximum selectivity to H₂ is on the level of 90% at 450–650 °C under a GHSV of 42,000 h⁻¹. The mechanism of the SSEP is discussed.     

Preparation of mesoporous nanocrystalline CuO–ZnO–Al2O3 catalysts for the H2 purification using catalytic preferential oxidation of CO (CO-PROX)

In this article, CuO–ZnO–Al₂O₃ catalysts with various copper contents were synthesized by a co-precipitation method and employed for the elimination of carbon monoxide from a mixture of 97% H₂, 1% CO and 2% O₂ at atmospheric pressure via carbon monoxide preferential oxidation (CO-PROX). The influence of the copper and zinc contents on the physicochemical characteristics and catalytic performance was investigated. The prepared samples were characterized using the N₂ adsorption-desorption (BET), X-ray diffraction (XRD), transmission and scanning electron microscopy (TEM and SEM) and temperature programmed reduction (TPR) techniques. The increment in CuO loading improved the activity of CuO–ZnO–Al₂O₃ catalysts for CO oxidation reaction. Among the prepared catalysts, the 50%CuO-3% ZnO-47% Al₂O₃ catalyst calcined at 400 °C with a BET area of 82.3 m²/g exhibited the best activity with a CO conversion of 88.9% at 125 °C. The effects of the presence of CO₂ and H₂O in the reaction feed stream and gas hourly space velocity (GHSV) were also studied.     

One-pot synthesis of Pd20-xAux nanoparticles embedded in nitrogen doped graphene as high-performance electrocatalyst toward methanol oxidation

Mixed Pd–Au bimetallic nanoparticles embedded nitrogen doped graphene composites (PdAu/NG180) are explored for efficient electrocatalytic oxidation of methanol. A simple hydrothermal one-pot polyol method, involving simultaneous reduction of both Pd and Au, is utilized for the synthesis of Pd_20-xAu_x/NG180 (x wt % = 0, 5, 10 and 15). This method is of multiple advantages such as inexpensiveness, reagent-free and environment-friendly being surfactant free. The morphology, crystal structure and chemical composition of NG180, Pd/NG180 and Pd_20-xAu_x/NG180 catalysts are analyzed by XRD, FESEM-EDX, TEM, XPS and Raman spectroscopy methods. Electrocatalytic activities of PdAu/NG180 nanocomposites toward methanol oxidation reaction (MOR) in alkaline media are investigated by cyclic voltammetry, chronoamperometry and CO stripping measurements. Pd_20-xAu_x/NG180 exhibited an increase in the electroactive surface area of Pd to twice by the coexistence of Au. In cyclic voltammetry studies, Pd₁₀Au₁₀/NG180 catalyst exhibits highest peak current density for MOR and is 1.5 times highly efficient compared to Pd₂₀/NG180 with an enhanced shift in the onset potential by 140 mV to lower overpotentials. Besides, Pd₁₀Au₁₀/NG180 catalyst exhibited enhanced electroactive surface area and long-time durability in comparison to Pd₂₀/NG180 catalyst. The steady state current density for MOR observed with Pd₁₀Au₁₀/NG180 at the end of 4000 s (98 mA mg⁻¹_Pd) is higher than those observed with all the other catalysts at the end of mere 1000 s alone (97, 61, and 32 mA mg⁻¹_Pd). The promising high electrocatalytic activity of Pd₁₀Au₁₀/NG180 is well corroborated from CO stripping experiments that the specific adsorption of CO onto Pd₁₀Au₁₀/NG180 (0.71 C m⁻²) is merely half to that observed onto Pd₂₀/NG180 (1.49 C m⁻²).     

Nano-sized RuO2 electrocatalyst improves the electrochemical performance for hydrogen oxidation reaction

Hydrogen oxidation reaction (HOR) can be applied to proton exchange membrane fuel cells to generate electrical energy and anode discharge. Due to its special properties, RuO₂ has been applied to supercapacitors, phenolic wastewater, textile industry wastewater, and degrading organic substances. However, there is few reports on the application of the RuO₂ catalyst to hydrogen oxidation reaction (HOR). In this study, we successfully obtained RuO₂ NPs using a simple and eco-friendly hydrothermal method. Furthermore, the electrochemical activity of RuO₂ NPs prepared at different concentration (0.15 M, 0.20 M) and different hydrothermal temperature (150 °C, 160 °C, and 170 °C) was evaluated by the hydrogen oxidation reaction. The particle size, composition, dispersion and morphology of the obtained RuO₂ catalysts were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). In addition, cyclic voltammograms (CV) were utilized to investigate the electrochemical activity of the RuO₂ catalysts. The results showed that the obtained catalyst at a hydrothermal temperature of 160 °C and a concentration of 0.15 M displayed a Brunauer-Emmett-Teller (BET) surface area of 26.74 m² g⁻¹. Meanwhile, the catalyst had a uniform distribution. The hydrogen oxidation current density of the obtained RuO₂ catalysts is upto 6 mA cm⁻², showing a good electrochemical activity for hydrogen oxidation reaction.     

Mn-induced Cu/Ce catalysts with improved performance for CO preferential oxidation in H2/CO2-rich streams

A series of xMnCu/Ce catalysts with constant low Cu loading of 1 wt% were prepared by the simple impregnation method. The obtained catalysts were characterized by XRD, BET, H₂-TPR and XPS, and the preferential oxidation of CO was evaluated in CO₂/H₂-rich atmospheres. It was shown that partial Mn and Cu could be incorporated into the Ceria lattice, forming surface ternary Cu–Mn–Ce oxide solid solutions. At Mn/Cu = 0.6, the catalyst presented strong interaction among Cu, Mn and Ce, had more Ce³⁺ and Mn⁴⁺ at the surface and showed the best catalytic performance, making CO conversion increase of 23.57% at 90 °C as compared with the Cu/Ce catalyst. For CO-Prox, the highest CO conversion was 94.7% with an oxidation selectivity of 78.9% at 125 °C. At this temperature, the catalyst revealed stable catalytic performance for a total TOS of 205 h. In addition, with CO/Ar as feed gas, CO conversion was 100%, confirming the negative effects of CO₂/H₂.     

Ruthenium substituted pyrochlore metal oxide catalysts Y2Ce2-xRuxO7-δ (x = 0–0.4) for oxidative steam reforming of ethanol

Metal oxides Y₂Ce_2-xRu_xO_7-δ (x = 0–0.4) with partial substitution of Ruⁿ⁺ cations in the host structure were synthesized to study their catalytic activity on oxidative steam reforming of ethanol (OSRE). The samples were characterized using X-ray diffraction (XRD), X-ray photoelectron spectra (XPS) and temperature-programmed reduction (TPR). The performances investigated by varied temperatures, Ru ion content, carbon-to-oxygen ratios and long-term stability. The lowest activation temperature on OSRE is 300 °C, which is significantly lower than that of La₂Ce_2-xRu_xO_7-δ (400 °C). The cell dimension of Y₂Ce_2-xRu_xO_7-δ was reduced compare to La₂Ce_2-xRu_xO_7-δ for the replacement of the Y³⁺ ion with La³⁺ ion. The reduced unit cell in the host structure not only increase the surface composition of the Ce⁴⁺ ions, but also induce the synergetic effect of Ruⁿ⁺/Ru⁴⁺ (n > 4) and Ce⁴⁺/Ce³⁺, which lead to the enhanced OSRE activity. The optimized catalyst Y₂Ce_1.6Ru_0.4O_7-δ showed selectivity of hydrogen S_H2 = 84(4)% (Y_H2 = 2.5(1) mol/mol EtOH) and carbon monoxide S_CO = 48(1)% for long-term stability test at T = 300 °C, C/O = 0.5, and O₂/C₂H₅OH = 1.5.     

Lanthanide modified Pt/CeO2-based catalysts for methane partial oxidation: Relationship between catalytic activity and structure

In most cases, reasonable design and construction of Pt/CeO₂-based catalysts and detailed exploration of relationship between its structural characteristics and the catalytic activity are crucial to improve the catalytic performance and reduce the cost. In this work, a series of CeO₂ doped with lanthanide metal ions (La, Nd, Er and Yb) has been successfully synthesized, and then Pt is introduced through impregnation. The morphology, structure and component analysis are characterized by SEM, TEM (HRTEM), EDS, XRD, ICP-AES, XPS, UV Raman, O₂-TPD, H₂-TPR and CO or O₂-pulse chemisorption, and the corresponding catalytic performances are developed by partial oxidation of methane. On the basis of the analysis of the structural properties of various catalysts, it is found that the Pt/CeLa catalyst shows the best catalytic performance due to its low valence state of Pt, excellent oxygen migration capacity and oxygen storage capacity, T₅₀ is 510 °C and the selectivity is superiority. What's more, the modification of CeO₂ by lanthanide metal ions especially La³⁺ can effectively change the oxygen activity of supports, so that this catalyst can be used in various redox catalytic reactions.     

Hydrogen production via catalytic propane partial oxidation over Ce1-xMxNiO3-λ (M=Al,Ti and Ca) towards solid oxide fuel cell (SOFC) applications

Indirect hydrogen production routes presented extensive compatibilities for distributed solid oxide fuel cell systems. Catalyst activity directly determines hydrogen production and profoundly affects the power generation. In this work, Ce_1-xM_xNiO_3-λ (M = Al, Ti and Ca) were synthesized for hydrogen production from propane partial oxidation (POx). From the results, it indicated that the choice of catalyst compositions could directly affect the microstructure during the preparation process. Also, different Ce_1-xM_xNiO_3-λ catalysts displayed distinctive carbon tolerance performances due to the different active particle sizes and surface properties of the catalysts. In general, the synthesized Ce_1-xM_xNiO_3-λ catalysts showed higher hydrogen production than a commercial nickel cerium catalyst. From the observation of a SOFC test system powered by injecting the generated H₂ from catalytic propane POx reaction, the obtained power density of CNO–Al displayed an increase of 22.6% compared to the commercial nickel cerium catalyst. It was quite impressive that the equivalent hydrogen (160 ml/min) produced over CNO–Al and the obtained power density (482.6 mW/cm²) of SOFCs were competitive while CNO–Ca presented an excellent stability with a better carbon tolerance performance for the long-term tests. The achievements of this work might offer a novel point of view for developing low-cost catalyst towards indirect hydrogen production for SOFC.