scholarly journals The influence of pre-treatment gas mixture upon the ammonia synthesis activity of Co–Re catalysts

2015 ◽  
Vol 68 ◽  
pp. 53-57 ◽  
Author(s):  
K. McAulay ◽  
J.S.J. Hargreaves ◽  
A.R. McFarlane ◽  
D.J. Price ◽  
N.A. Spencer ◽  
...  
Keyword(s):  
Ammonia Synthesis ◽  
Gas Mixture ◽  
Synthesis Activity ◽  
Pre Treatment

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.

The Study of Iron Catalyst for Ammonia Synthesis in Chemical Engineering

2012 ◽  
Vol 577 ◽  
pp. 97-100
Author(s):  
Dong Mei Zhao ◽  
Xue Peng Liu
Keyword(s):  
Chemical Engineering ◽  
Hydrogen Adsorption ◽  
Ammonia Synthesis ◽  
Iron Catalyst ◽  
Nitrogen Adsorption ◽  
Temperature Programmed Desorption ◽  
Iron Catalysts ◽  
Synthesis Activity ◽  
Temperature Programmed ◽  
Adsorption Intensity

The temperature programmed desorption technique is used to study the hydrogen adsorption on the catalytic surface of fused iron catalysts with different oxide precursors in chemical engineering. The different catalysts desorption active energy, desorped temperature and their amouts desorped have been attained. The desorption energies, desorped temperatures and desorption amounts have been related to the iron ratio (Fe2+/Fe3+). It is compared with the curve of ammonia synthesis activity against iron ratio. The inhibition of hydrogen in the ammonia synthesis reaction is verified, the adsorption intensity of hydrogen controls the inhibition to nitrogen adsorption

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>

A 3D-printed metal column for micro gas chromatography

Lab on a Chip ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 3435-3444
Author(s):  
Sooyeol Phyo ◽  
Sung Choi ◽  
Jaeheok Jang ◽  
Sun Choi ◽  
Jiwon Lee
Keyword(s):  
Gas Chromatography ◽  
Stationary Phase ◽  
Gas Mixture ◽  
Mixture Separation ◽  
Phase Coating ◽  
3D Printed ◽  
Pre Treatment

A square spiral 1 m-long column for gas mixture separation was 3D-printed out with the dimensions of 3.4 × 3.3 × 0.2, followed by pre-treatment and stationary phase coating.

Enhanced Ammonia Synthesis Activity of Ru Supported on Nitrogen-Doped Carbon Nanotubes

2014 ◽  
Vol 32 (8) ◽  
pp. 1418-1423
Author(s):  
Weijie GAO ◽  
Shujing GUO ◽  
Hongbo ZHANG ◽  
Xiulian PAN ◽  
Xinhe BAO
Keyword(s):  
Carbon Nanotubes ◽  
Ammonia Synthesis ◽  
Nitrogen Doped ◽  
Synthesis Activity ◽  
Nitrogen Doped Carbon

scholarly journals A Green Synthesis of Ru Modified g-C3N4 Nanosheets for Enhanced Photocatalytic Ammonia Synthesis

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Derek Hao ◽  
Jiawei Ren ◽  
Ying Wang ◽  
Hamidreza Arandiyan ◽  
Magnus Garbrecht ◽  
...  
Keyword(s):  
Nitrate Reduction ◽  
Carbon Nitride ◽  
Photocatalytic Performance ◽  
Ammonia Synthesis ◽  
Environmental Pollutant ◽  
Graphitic Carbon ◽  
Graphitic Carbon Nitride ◽  
Optimal Sample ◽  
Nitrate Adsorption ◽  
Synthesis Activity

Nitrate is a crucial environmental pollutant, and its risk on ecosystem keeps increasing. Photocatalytic conversion of nitrate to ammonia can simultaneously achieve the commercialization of environmental hazards and recovery of valuable ammonia, which is green and sustainable for the planet. However, due to the thermodynamic and kinetic energy barriers, photocatalytic nitrate reduction usually involves a higher selectivity of the formation of nitrogen that largely limits the ammonia synthesis activity. In this work, we reported a green and facile synthesis of novel metallic ruthenium particle modified graphitic carbon nitride photocatalysts. Compare with bulk graphitic carbon nitride, the optimal sample had 2.93-fold photocatalytic nitrate reduction to ammonia activity (2.627 mg/h/gcat), and the NH3 selectivity increased from 50.77% to 77.9%. According to the experimental and calculated results, the enhanced photocatalytic performance is attributed to the stronger light absorption, nitrate adsorption, and lower energy barrier for the generation of ammonia. This work may provide a facile way to prepare metal modified photocatalysts to achieve highly efficient nitrate reduction to ammonia.

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