scholarly journals Investigation of the hydrothermal aging of an Mn-based mullite SmMn2O5 catalyst of NO oxidation

RSC Advances ◽  
2017 ◽  
Vol 7 (77) ◽  
pp. 49091-49096 ◽  
Author(s):  
Lina Xue ◽  
Ka Xiong ◽  
Haijun Chen ◽  
Kyeongjae Cho ◽  
Weichao Wang

The decrease in the catalytic performance for NO oxidation of the Mn-based mullite SmMn2O5 after being subjected to hydrothermal aging was mainly caused by an ∼3-fold decrease in its specific surface area (BET).

2020 ◽  
Vol 26 (5) ◽  
pp. 200394-0
Author(s):  
Jie Zhang ◽  
Ben Dong ◽  
Ding Ding ◽  
Shilong He ◽  
Sijie Ge

In this paper, MnO<sub>2</sub> catalyst were firstly prepared and modified by four kinds of anionic precursors (i.e., NO<sub>3</sub><sup>-</sup>, AC<sup>-</sup>, SO<sub>4</sub><sup>2-</sup> and Cl<sup>-</sup>) through redox precipitation method. After that, bio-treated coking wastewater (BTCW) was prepared and employed as targeted pollutants to investigate the catalytic ozonation performance of prepared-MnO<sub>2</sub> catalyst was investigated and characterized by the removal efficiencies and mechanism of the prepared bio-treated coking wastewater (BTCW), which was employed as the targeted pollutants. Specifically, the effects of specific surface area, crystal structure, valence state of Mn element and lattice oxygen content on catalytic activity of MnO<sub>2</sub> materials were characterized by BET, XRD and XPS, respectively. Results showed that COD of BTCW could be removed 47.39% under MnO<sub>2</sub>-NO<sub>3</sub><sup>-</sup> catalyst with 2 h reaction time, which was much higher than that of MnO<sub>2</sub>-AC<sup>-</sup> (3.94%), MnO<sub>2</sub>-SO<sub>4</sub><sup>2-</sup> (12.42%), MnO<sub>2</sub>-Cl<sup>-</sup> (12.94%) and pure O<sub>3</sub> without catalyst (21.51%), respectively. So, MnO<sub>2</sub>-NO<sub>3</sub><sup>-</sup> presented the highest catalytic performance among these catalysts. The reason may be attributed to a series of better physiochemical properties including the smaller average grain, the larger specific surface area and active groups, more crystal defect and oxygen vacancy, higher relative content of Mn<sup>3+</sup> and adsorbed oxygen (O<sub>ads</sub>) than that of another three catalysts.


Author(s):  
Yang Yu ◽  
Xiao-Xiong Wang ◽  
Guixu Xie ◽  
Junqing Ma ◽  
Tianyang Lv ◽  
...  

Piezoelectric catalysis is an emerging research field in recent years. Since the catalytic reaction usually occurs on the surface, the specific surface area is very important for piezoelectric catalysis. Therefore,...


2008 ◽  
Vol 61 (2) ◽  
pp. 144 ◽  
Author(s):  
Ali A. Mirzaei ◽  
Maryam Galavy ◽  
Vahid Eslamimanesh

Co–Ce catalysts prepared by the coprecipitation method were tested for production of light olefins. The effect of different preparation conditions including the [Co]/[Ce] molar ratio, aging time, calcination conditions, different supports, and loading of optimum support on the structure and catalytic performance of different catalysts were investigated. It was found that catalyst containing 80% Co/20% Ce/15% SiO2, which was aged for 2 h and calcined at 600°C for 6 h, is the optimum modified catalyst for the conversion of synthesis gas to light olefins. Characterization of both precursors and calcined catalysts (before and after the test) was carried out using scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) specific surface area measurements. The morphology of the catalysts was investigated by SEM and the surface areas of these catalysts were studied by BET. It was shown that all of the different preparation variables influenced the morphology and also the specific surface area of the catalyst precursors and calcined catalysts.


Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3566
Author(s):  
Yawen Wang ◽  
Zahra Gohari Bajestani ◽  
Jérôme Lhoste ◽  
Sandy Auguste ◽  
Annie Hémon-Ribaud ◽  
...  

High-specific-surface-area MgF2 was prepared by microwave-assisted solvothermal synthesis. The influences of the solvent and the magnesium precursors, and the calcination atmospheres, on the nanoparticle sizes and specific surface areas, estimated by X-Ray Powder Diffraction, N2 sorption and TEM analyses, were investigated. Nanocrystallized (~7 nm) magnesium partially hydroxylated fluorides (MgF2−x(OH)x) with significant specific surface areas between 290 and 330 m2∙g−1 were obtained. After activation under gaseous HF, MgF2−x(OH)x catalysts underwent a large decrease of both their surface area and their hydroxide, rates as shown by their 19F and 1H solid-state NMR spectra. Expect for MgF2 prepared from the acetate precursor, an activity of 30–32 mmol/h∙g was obtained which was about 40% higher compared with that of MgF2 prepared using Trifluoroacetate method (21.6 mmol/h∙g).


Molecules ◽  
2022 ◽  
Vol 27 (2) ◽  
pp. 356
Author(s):  
Naushad Ahmad ◽  
Rizwan Wahab ◽  
Salim Manoharadas ◽  
Basel F. Alrayes ◽  
Munawwer Alam ◽  
...  

The transition metal-based catalysts for the elimination of greenhouse gases via methane reforming using carbon dioxide are directly or indirectly associated with their distinguishing characteristics such as well-dispersed metal nanoparticles, a higher number of reducible species, suitable metal–support interaction, and high specific surface area. This work presents the insight into catalytic performance as well as catalyst stability of CexSr1−xNiO3 (x = 0.6–1) nanocrystalline perovskites for the production of hydrogen via methane reforming using carbon dioxide. Strontium incorporation enhances specific surface area, the number of reducible species, and nickel dispersion. The catalytic performance results show that CeNiO3 demonstrated higher initial CH4 (54.3%) and CO2 (64.8%) conversions, which dropped down to 13.1 and 19.2% (CH4 conversions) and 26.3 and 32.5% (CO2 conversions) for Ce0.8Sr0.2NiO3 and Ce0.6Sr0.4NiO3, respectively. This drop in catalytic conversions post strontium addition is concomitant with strontium carbonate covering nickel active sites. Moreover, from the durability results, it is obvious that CeNiO3 exhibited deactivation, whereas no deactivation was observed for Ce0.8Sr0.2NiO3 and Ce0.6Sr0.4NiO3. Carbon deposition during the reaction is mainly responsible for catalyst deactivation, and this is further established by characterizing spent catalysts.


Nanoscale ◽  
2017 ◽  
Vol 9 (35) ◽  
pp. 13334-13340 ◽  
Author(s):  
Hao Zhang ◽  
Xiaobin Xu ◽  
Haifeng Lin ◽  
Muhammad Aizaz Ud Din ◽  
Haiqing Wang ◽  
...  

Ultrathin nanocrystals generally provide a remarkable catalytic performance due to their high specific surface area and exposure of certain active sites.


2017 ◽  
Vol 19 (45) ◽  
pp. 30418-30428 ◽  
Author(s):  
Yihong Xiao ◽  
Wanlu Zhu ◽  
Guohui Cai ◽  
Meilian Chen ◽  
Yong Zheng ◽  
...  

A novel non-stoichiometric YxInO3+δ (YIO-x, 0.8 ≤ x ≤ 1.04) perovskite catalyst with a large number of oxygen vacancies and high specific surface area was synthesized using glycine self-propagating gel combustion.


CrystEngComm ◽  
2021 ◽  
Author(s):  
Tao-Tao Lv ◽  
Huai-Zhong Xing ◽  
Hong-Mei Yang ◽  
Hui-Xiang Wang ◽  
Jing Shi ◽  
...  

A simple and efficient strategy for synthesizing high-performance crystalline catalyst Cu2O hollow spheres with a large specific surface area was demonstrated.


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