Preparation of hierarchically porous spinel CoMn 2 O 4 monoliths via sol–gel process accompanied by phase separation

Author(s):  
Xuanming Lu ◽  
Kazuyoshi Kanamori ◽  
George Hasegawa ◽  
Kazuki Nakanishi
2020 ◽  
Vol 44 (28) ◽  
pp. 12307-12316
Author(s):  
Wei Liu ◽  
Daoyan Feng ◽  
Hui Yang ◽  
Xingzhong Guo

Hierarchically porous MnO/C composites with interconnected macropores and co-continuous skeletons were fabricated via a sol–gel process combined with phase separation, followed by a two-step combustion.


2013 ◽  
Vol 14 (4) ◽  
pp. 045007 ◽  
Author(s):  
Wenyan Li ◽  
Yang Zhu ◽  
Xingzhong Guo ◽  
Kazuki Nakanishi ◽  
Kazuyoshi Kanamori ◽  
...  

2021 ◽  
Vol 3 ◽  
Author(s):  
Xuanming Lu ◽  
Kazuki Nakanishi

The sol–gel process accompanied by phase separation is one of the methods to prepare hierarchically porous monoliths, hierarchically porous monolith, which is applicable not only to oxides but also to various materials compositions such as metal phosphates, organic-polymers/carbons, metal-organic frameworks. It is not until recently, however, that progress has been made in the preparation of low-valence metal oxide HPMs, such as those of magnesium, manganese, cobalt, nickel, etc. Due to the difficulty of divalent metal precursors to form homogeneous gels, different approaches from those established for trivalent and tetravalent counterparts have been attempted. This short review introduces the methods and trials in the preparation of metal oxide HPMs from divalent metal salts.


2020 ◽  
Vol 7 (11) ◽  
pp. 1656-1666 ◽  
Author(s):  
Xuanming Lu ◽  
Kazuyoshi Kanamori ◽  
Kazuki Nakanishi

Abstract Hierarchically porous monoliths based on copper (Cu), cobalt (Co) and manganese (Mn) oxides with three-dimensionally (3D) interconnected macropores and open nanopores were prepared using metal bromides as precursors via a sol–gel process accompanied by phase separation. The difficulty of gelation for low-valence metal cation was overcome by introducing a highly electronegative Br atom near to the metal atom to control the rates of hydrolysis and polycondensation. The 3D interconnected macropores were obtained using appropriate polymers to induce phase separation. The domain sizes of macropores and skeletons can be controlled by reaction parameters such as concentration and/or average molecular weight of polymers, and the amount of hydrochloric acid. The crystalline metal oxide monoliths with their 3D interconnected macroporous structure preserved were obtained after heat treatment in air.


2018 ◽  
Vol 768 ◽  
pp. 211-217 ◽  
Author(s):  
Rui Wang ◽  
Yu Kun Sun ◽  
Bao Jia Qi Jiang ◽  
Hui Yang ◽  
Xing Zhong Guo

Macroporous Ca12Al14O33(C12A7) mayenite monoliths have been successfully prepared via a sol-gel process in the presence of propylene oxide (PO) and poly (ethyleneoxide) (PEO). Gelation of CaO-Al2O3binary system with nitrates salts as additional precursors is accelerated by PO as an acid scavenger, while PEO works as a phase separation inducer to mediate the phase separation of the system. Appropriate PO and PEO amounts allow the formation of monolithic xerogel with interconnected macropores and co-continuous skeletons. The resultant dried gels are amorphous and the single crystalline phase Ca12Al14O33mayenite forms after heat-treatment at 1100 °C in air, while the macrostructure is preserved with a porosity as high as 78% and smoother and denser skeletons.


2018 ◽  
Vol 6 (19) ◽  
pp. 9041-9048 ◽  
Author(s):  
Yosuke Hara ◽  
Kazuyoshi Kanamori ◽  
Kei Morisato ◽  
Riichi Miyamoto ◽  
Kazuki Nakanishi

Iron(iii) oxyhydroxide and oxide monoliths with controlled multiscale porosity have been successfully fabricated via the sol–gel process accompanied by phase separation.


2020 ◽  
Vol 166 ◽  
pp. 104997
Author(s):  
Bartosz Babiarczuk ◽  
Daniel Lewandowski ◽  
Anna Szczurek ◽  
Krzysztof Kierzek ◽  
Matthias Meffert ◽  
...  

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