scholarly journals Co/Ba/La2O3 catalyst for ammonia synthesis under mild reaction conditions

2021 ◽  
Author(s):  
Katsutoshi Nagaoka ◽  
Shin-ichiro Miyahara ◽  
Katsutoshi Sato ◽  
Yuta Ogura ◽  
Kotoko Tsujimaru ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Nickel Catalysts ◽  
Ruthenium Catalysts ◽  
Synthesis Rate ◽  
Turnover Frequency ◽  
Reaction Conditions ◽  
Synthesis Activity ◽  
Co Nanoparticles ◽  
Ammonia Poisoning ◽  
Nanoparticle Catalyst

Ruthenium catalysts may allow realization of renewable energy–based ammonia synthesis processes using mild reaction conditions (<400 °C, <10 MPa). However, ruthenium is relatively rare and therefore expensive. Here, we report a Co nanoparticle catalyst loaded on a basic Ba/La2O3 support and pre-reduced at 700 °C (Co/Ba/La2O3_700red) that showed higher ammonia synthesis activity at 350 °C and 1.0–3.0 MPa than two benchmark Ru catalysts, Cs+/Ru/MgO and Ru/CeO2. The synthesis rate of the catalyst at 350 °C and 1.0 MPa (19.3 mmol h−1g−1) was 8.0 times that of Co/Ba/La2O3_500red and 6.9 times that of Co/La2O3_700red. The catalyst showed activity at temperatures down to 200 °C. High-temperature reduction induced formation of a BaO-La2O3 nano-fraction around the Co nanoparticles, which increased turnover frequency, inhibited Co nanoparticle sintering, and suppressed ammonia poisoning. These strategies may also be appliable to nickel catalysts.

scholarly journals Barium Oxide Encapsulating Cobalt Nanoparticles Supported on Magnesium Oxide: Active Non-noble Metal Catalyst for Ammonia Synthesis under Mild Reaction Condition

2021 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
Takaaki Toriyama ◽  
...  
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Ammonia Synthesis ◽  
Metal Catalyst ◽  
Synthesis Rate ◽  
Rate Determining Step ◽  
Scanning Transmission ◽  
Synthesis Activity ◽  
And Migration ◽  
Co Nanoparticles

<p>To realize a sustainable, carbon-free society, catalysts for the synthesis of ammonia using renewable energy under mild reaction conditions (<400 °C, <10 MPa) are needed. Ru-based catalysts are currently the most promising candidates; however, Ru is expensive and of low abundance. Here, we discovered that encapsulation of Co nanoparticles with BaO enhanced the ammonia synthesis activity of the Co, and that a simple Ba-doped Co/MgO catalyst pre-reduced at an unusually high temperature of 700 °C (Co@BaO/MgO-700red) showed outstanding ammonia synthesis activity. <a>The ammonia synthesis rate (24.6 mmol g<sub>cat</sub></a><sup>−</sup><sup>1</sup> h<sup>−</sup><sup>1</sup>) and turnover frequency (0.255 s<sup>−</sup><sup>1</sup>) of the catalyst at 350 °C and 1.0 MPa were 22 and 64 times higher, respectively, than those of the non-doped parent catalyst. At the same temperature but higher pressure (3.0 MPa), the ammonia synthesis rate was increased to 48.4 mmol g<sub>cat</sub><sup>−</sup><sup>1</sup> h<sup>−</sup><sup>1</sup>, which is higher than that of active Ru-based catalysts. Scanning transmission electron microscopy and energy dispersive X-ray spectrometry investigations revealed that after reduction at 700 °C the Co nanoparticles had become encapsulated by a nano-fraction of BaO. The mechanism underlying the formation of this unique structure was considered to comprise reduction of oxidic Co to metallic Co, decomposition of BaCO<sub>3</sub> to BaO, and migration of BaO to the Co nanoparticle surface. Spectroscopic and density-functional theory investigations revealed that adsorption of N<sub>2</sub> on the Co atoms at the catalyst surface weakened the N<sub>2</sub> triple bond to the strength of a double bond due to electron donation from the Ba atom of BaO <i>via</i> adjacent Co atoms; this weakening accelerated cleavage of the triple bond, which is the rate-determining step for ammonia synthesis.</p>

scholarly journals Barium Oxide Encapsulating Cobalt Nanoparticles Supported on Magnesium Oxide: Active Non-noble Metal Catalyst for Ammonia Synthesis under Mild Reaction Condition

2021 ◽  
Author(s):  
Katsutoshi Sato ◽  
Shin-ichiro Miyahara ◽  
Kotoko Tsujimaru ◽  
Yuichiro Wada ◽  
Takaaki Toriyama ◽  
...  
Keyword(s):  
Triple Bond ◽  
Density Functional ◽  
Ammonia Synthesis ◽  
Metal Catalyst ◽  
Synthesis Rate ◽  
Rate Determining Step ◽  
Scanning Transmission ◽  
Synthesis Activity ◽  
And Migration ◽  
Co Nanoparticles

<p>To realize a sustainable, carbon-free society, catalysts for the synthesis of ammonia using renewable energy under mild reaction conditions (<400 °C, <10 MPa) are needed. Ru-based catalysts are currently the most promising candidates; however, Ru is expensive and of low abundance. Here, we discovered that encapsulation of Co nanoparticles with BaO enhanced the ammonia synthesis activity of the Co, and that a simple Ba-doped Co/MgO catalyst pre-reduced at an unusually high temperature of 700 °C (Co@BaO/MgO-700red) showed outstanding ammonia synthesis activity. <a>The ammonia synthesis rate (24.6 mmol g<sub>cat</sub></a><sup>−</sup><sup>1</sup> h<sup>−</sup><sup>1</sup>) and turnover frequency (0.255 s<sup>−</sup><sup>1</sup>) of the catalyst at 350 °C and 1.0 MPa were 22 and 64 times higher, respectively, than those of the non-doped parent catalyst. At the same temperature but higher pressure (3.0 MPa), the ammonia synthesis rate was increased to 48.4 mmol g<sub>cat</sub><sup>−</sup><sup>1</sup> h<sup>−</sup><sup>1</sup>, which is higher than that of active Ru-based catalysts. Scanning transmission electron microscopy and energy dispersive X-ray spectrometry investigations revealed that after reduction at 700 °C the Co nanoparticles had become encapsulated by a nano-fraction of BaO. The mechanism underlying the formation of this unique structure was considered to comprise reduction of oxidic Co to metallic Co, decomposition of BaCO<sub>3</sub> to BaO, and migration of BaO to the Co nanoparticle surface. Spectroscopic and density-functional theory investigations revealed that adsorption of N<sub>2</sub> on the Co atoms at the catalyst surface weakened the N<sub>2</sub> triple bond to the strength of a double bond due to electron donation from the Ba atom of BaO <i>via</i> adjacent Co atoms; this weakening accelerated cleavage of the triple bond, which is the rate-determining step for ammonia synthesis.</p>

scholarly journals Enhanced Ammonia Synthesis Activity of Ceria-Supported Ruthenium Catalysts Induced by CO Activation

ACS Catalysis ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 1331-1339
Author(s):  
Bingyu Lin ◽  
Biyun Fang ◽  
Yuyuan Wu ◽  
Chunyan Li ◽  
Jun Ni ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Ruthenium Catalysts ◽  
Co Activation ◽  
Synthesis Activity

scholarly journals Enhanced Ammonia Synthesis Activity of Ceria-Supported Ruthenium Catalysts Induced by CO Activation

2020 ◽  
Author(s):  
Bingyu Lin ◽  
Biyun Fang ◽  
Yuyuan Wu ◽  
Chunyan Li ◽  
Jun Ni ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Ruthenium Catalysts ◽  
Co Activation ◽  
Synthesis Activity

ChemInform Abstract: Influence of Method of Preparation on Ammonia Synthesis Activity of Cesium Promoted Ruthenium Catalysts Supported on Active Carbon (AC).

ChemInform ◽  
2010 ◽  
Vol 26 (9) ◽  
pp. no-no
Author(s):  
S. K. MASTHAN ◽  
K. S. R. RAO ◽  
P. K. RAO ◽  
L. KALUSCHNYAYA ◽  
S. M. YUNUSOV ◽  
...  
Keyword(s):  
Active Carbon ◽  
Ammonia Synthesis ◽  
Ruthenium Catalysts ◽  
Synthesis Activity

Improved ammonia synthesis activity of Ce doped barium tantalate supported Ru catalysts

2021 ◽  
Author(s):  
Jia Huang ◽  
Yushi Zhao ◽  
Mingwei Yuan ◽  
Jinjun Li ◽  
Zhixiong You
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Ammonia Synthesis ◽  
Ru Catalysts ◽  
Synthesis Activity

Ce doping could increase the specific surface area and reducibility of the barium tantalate carrier, which is beneficial to Ru based ammonia synthesis.

Reaction de méthanation du gaz de synthèse: Influence de la température de calcination des catalyseurs à base de nickel

1993 ◽  
Vol 71 (1) ◽  
pp. 107-111
Author(s):  
M. Ghazi ◽  
J. Barrault
Keyword(s):  
Nickel Content ◽  
Great Part ◽  
Extreme Temperature ◽  
Nickel Catalysts ◽  
Economic Situation ◽  
Reaction Conditions ◽  
Methanation Reaction ◽  
Different Temperatures ◽  
Usual Process ◽  
Important Activity

Due to their important activity and selectivity, nickel catalysts are often used to realize the methanation reaction; however, the usual process based on these catalysts is not fitted for the present economic situation. To raise their stability, three catalysts with similar nickel content but calcinated at different temperatures have been studied for the reaction of methanation. The results obtained show that the catalyst calcinated at the highest temperature (973 K) shows the greatest promise because a great part of its activity and of its stability is preserved even when the reaction conditions are extreme (temperature of 773 K).

Microwave-assisted synthesis of MgO–CNTs supported ruthenium catalysts for ammonia synthesis

2007 ◽  
Vol 8 (12) ◽  
pp. 1881-1885 ◽  
Author(s):  
Qing-Chi Xu ◽  
Jing-Dong Lin ◽  
Jun Li ◽  
Xian-Zhu Fu ◽  
Ying Liang ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Ruthenium Catalysts ◽  
Microwave Assisted Synthesis ◽  
Microwave Assisted
Sign in / Sign up

Export Citation Format

Share Document