Promotion effect of rare-earth elements on the catalytic decomposition of ammonia over Ni/Al2O3 catalyst

Okura, Keisho; Okanishi, Takeou; Muroyama, Hiroki; Matsui, Toshiaki; Eguchi, Koichi

doi:10.1016/j.apcata.2015.07.020

Cited by 108 publications

(66 citation statements)

References 31 publications

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“…Conventionally, supports with a high surface area, such as Ce 0.8 Zr 0.2 O 2 , mesoporous silica, and multiwalled carbon nanotubes (MWCNT), are effective for the high performance of Ni‐based catalytic systems. Moreover, the addition of rare‐earth elements improved the performance of Ni/Al 2 O 3 . These results suggested the suitability of the rare‐earth oxides for the support material of Ni catalysts.…”

Section: Introductionsupporting

confidence: 69%

“…in which k is a reaction rate constant, and α and γ are reaction orders. Our recent study confirmed that the reaction rate was independent of P

_{normalN_{2}}

over Ni catalysts . Thus, it was possible to neglect the effect of P

_{normalN_{2}}

on the reaction rate.…”

Section: Resultsmentioning

confidence: 99%

“…The hydrogen order of γ was negative, which implies that hydrogen inhibits catalytic ammonia decomposition. This result corresponded well with that of previous reports; it has been accepted that a large negative γ value indicates the significant lowering of the activity by hydrogen atoms adsorbed strongly on the active sites. In this study, the order of the absolute value of γ was: Ni/Al 2 O 3 (0.88)>Ni/CeO 2 (0.86)>Ni/Sm 2 O 3 (0.66)>Ni/Y 2 O 3 (0.48)>Ni/Gd 2 O 3 (0.46)>Ni/La 2 O 3 (0.45).…”

Section: Resultsmentioning

confidence: 99%

“…Moreover,t he addition of rare-earth elements improved the performance of Ni/Al 2 O 3 . [36] These results suggested the suitability of the rare-earth oxidesfor the support materialofNicatalysts. To the best of our knowledge,t he support effect of ar are-earth oxide on the ammonia decomposition reaction is not well understood.…”

Section: Introductionmentioning

confidence: 88%

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Ammonia Decomposition over Nickel Catalysts Supported on Rare‐Earth Oxides for the On‐Site Generation of Hydrogen

et al. 2016

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Ammonia decomposition has attracted the interest of many researchers as a promising process for the on‐site generation of H2. In this study, Ni catalysts supported on various rare‐earth oxides were prepared by the impregnation method and employed for ammonia decomposition. The Ni/Y2O3 catalyst exhibited the best performance among the samples investigated. The reaction kinetics study indicated that most of rare‐earth oxide supports were effective for the alleviation of the hydrogen inhibition phenomenon in the decomposition reaction. The desorption behavior of hydrogen has revealed that the amount of hydrogen atoms adsorbed strongly on the Ni surface up to high temperatures was relatively small in the case of Ni/Y2O3. Furthermore, for Ni/Y2O3 the optimal Ni loading was 40 wt % in terms of the catalytic activity because of the appropriate Ni dispersion.

show abstract

Section: Introductionsupporting

confidence: 69%

“…in which k is a reaction rate constant, and α and γ are reaction orders. Our recent study confirmed that the reaction rate was independent of P

_{normalN_{2}}

over Ni catalysts . Thus, it was possible to neglect the effect of P

_{normalN_{2}}

on the reaction rate.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 88%

See 2 more Smart Citations

Ammonia Decomposition over Nickel Catalysts Supported on Rare‐Earth Oxides for the On‐Site Generation of Hydrogen

et al. 2016

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“…Then, Okura et al. investigated Ni‐based catalysts modified by rare‐earth elements and revealed that the rare‐earth elements can promote the ammonia decomposition reaction by alleviating the hydrogen inhibition effect on the catalyst Ni surface. Kishimoto et al.…”

Section: Introductionmentioning

confidence: 99%

Development of 1 kW‐class Ammonia‐fueled Solid Oxide Fuel Cell Stack

et al. 2020

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Power generation performance and long‐term durability of ammonia‐fueled solid oxide fuel cell (SOFC) systems are investigated with SOFC stacks consisting of 30 planar anode‐supported cells. SOFC systems with three different operation modes are employed: direct ammonia, external decomposition and autothermal decomposition. A novel BaO/Ni/Sm2O3/MgO catalyst is newly developed for the external ammonia cracker, whereas a Co‐Ce‐Zr composite oxide catalyst is used for the autothermal ammonia cracker. Initial performance measurement and 1,000 h long‐term durability test of the stacks are conducted. The stack fueled with direct ammonia achieves 1 kW power output with 52% direct current (DC) electrical efficiency; a slight decrease in its performance compared with the stack with the mixture fuel of hydrogen and nitrogen is attributed to the decrease in the stack temperature caused by the endothermic ammonia decomposition reaction. The external ammonia cracker helps to maintain the stack temperature, improving the initial performance of the stack. The stack performance with the autothermal ammonia cracker is also comparable to those with the other operation modes. It is also demonstrated that the stacks fueled with ammonia have excellent stability during the long‐term tests and 57% energy conversion efficiency at ca. 700 W electrical output is achieved with the external ammonia cracker.

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Self‐Construction of Efficient Interfaces Ensures High‐Performance Direct Ammonia Protonic Ceramic Fuel Cells

He,

Hou,

et al. 2023

Advanced Materials

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Direct ammonia protonic ceramic fuel cells (PCFCs) are highly efficient energy conversion devices since ammonia as a carbon‐neutral hydrogen‐rich carrier shows great potential for storage and long‐distance transportation when compared with hydrogen fuel. However, traditional Ni‐based anodes readily suffer from severe structural destruction and dramatic deactivation after long‐time exposure to ammonia. Here a Sr2Fe1.35Mo0.45Cu0.2O6−δ (SFMC) anode catalytic layer (ACL) painted onto a Ni‐BaZr0.1Ce0.7Y0.1Yb0.1O3−δ (BZCYYb) anode with enhanced catalytic activity and durability toward the direct utilization of ammonia is reported. A tubular Ni‐BZCYYb anode‐supported cells with the SFMC ACL show excellent peak power densities of 1.77 W cm−2 in wet H2 (3% H2O) and 1.02 W cm−2 in NH3 at 650 °C. A relatively stable operation of the cells is obtained at 650 °C for 200 h in ammonia fuel. Such achieved improvements in the activity and durability are attributed to the self‐constructed interfaces with the phases of NiCu or/and NiFe for efficient NH3 decomposition, resulting in a strong NH3 adsorption strength of the SFMC, as confirmed by NH3 thermal conversion and NH3‐temperature programmed desorption. This research offers a valuable strategy of applying an internal catalytic layer for highly active and durable ammonia PCFCs.

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Promotion effect of rare-earth elements on the catalytic decomposition of ammonia over Ni/Al2O3 catalyst

Cited by 108 publications

References 31 publications

Ammonia Decomposition over Nickel Catalysts Supported on Rare‐Earth Oxides for the On‐Site Generation of Hydrogen

Ammonia Decomposition over Nickel Catalysts Supported on Rare‐Earth Oxides for the On‐Site Generation of Hydrogen

Development of 1 kW‐class Ammonia‐fueled Solid Oxide Fuel Cell Stack

Self‐Construction of Efficient Interfaces Ensures High‐Performance Direct Ammonia Protonic Ceramic Fuel Cells

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