Single-Crystalline-Phase Mo3VOx: An Efficient Catalyst for the Partial Oxidation of Acrolein to Acrylic Acid

ChemCatChem ◽  
2013 ◽  
Vol 5 (10) ◽  
pp. 2869-2873 ◽  
Author(s):  
Chen Chen ◽  
Nakatani Kosuke ◽  
Toru Murayama ◽  
Wataru Ueda
Keyword(s):  
Acrylic Acid ◽  
Partial Oxidation ◽  
Crystalline Phase ◽  
Efficient Catalyst ◽  
Single Crystalline

Preparation of Macroprous C12A7 Mayenite Monoliths via a Sol-Gel Process with Nitrates as Precursors

2018 ◽  
Vol 768 ◽  
pp. 211-217 ◽  
Author(s):  
Rui Wang ◽  
Yu Kun Sun ◽  
Bao Jia Qi Jiang ◽  
Hui Yang ◽  
Xing Zhong Guo
Keyword(s):  
Heat Treatment ◽  
Phase Separation ◽  
Binary System ◽  
Propylene Oxide ◽  
Crystalline Phase ◽  
Sol Gel ◽  
Single Crystalline ◽  
Sol Gel Process

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.

Zeolite Syntheses from Superalkaline Reaction Mixtures

1992 ◽  
Vol 57 (4) ◽  
pp. 788-793 ◽  
Author(s):  
Falk Fischer ◽  
Marianne Hadan ◽  
Günter Fiedrich
Keyword(s):  
Ir Spectroscopy ◽  
Crystalline Phase ◽  
Ion Concentration ◽  
Single Crystalline ◽  
Hydroxyl Ion ◽  
Type Zeolite

The synthesis of faujasite-type zeolite from superalkaline reaction mixtures are described. The contribution shows the influence of component K2O added in the system Na2O-Al2O3-SiO2-H2O with H2O/(K2O + Na2O) = 13-15. The reaction course was investigated in the range K2O/(K2O + Na2O) from about 0.07 to 0.5. Under used conditions it is quite possible to isolate faujasite-type zeolite as a single crystalline phase. By means of IR spectroscopy, low SiO2/Al2O3 ratios from 2.0 to 2.1 in the faujasite framework have been indicated. The low SiO2/Al2O3 ratios are interpreted by a higher stability of the Si-O-Al- than the Si-O-Si- bond with increasing hydroxyl ion concentration.

scholarly journals Aplicação de óxidos mistos de molibdênio, vanádio, tungstênio e cobre como catalisadores na produção do ácido acrílico

2020 ◽  
Author(s):  
◽  
W. M. Fantim
Keyword(s):  
Block Copolymer ◽  
Acrylic Acid ◽  
Hydrothermal Treatment ◽  
Crystalline Phase ◽  
Heterogeneous Catalysts ◽  
Raw Material ◽  
Oxide Content ◽  
Propene Oxidation ◽  
Synthesis Conditions ◽  
Catalyst Composition

Acrylic acid is a product with several applications in the chemical industry, the main one is the production of sodium polyacrylate, a superabsorbent material used in the toiletries manufacture. Currently acrylic acid is obtained from propene oxidation using heterogeneous Mo/Bi and Mo/V oxide-based catalysts. In this process, propene is first oxidized to acrolein, which is then oxidized to acrylic acid. Although this is already a consolidated process, propylene comes from petrochemical sources and thus there is a concern to search for alternative routes to the use of this raw material and one of the possibilities is to synthesize acrolein from glycerol dehydration using specific catalysts. For the project, heterogeneous catalysts were prepared to obtain the acrylic acid, first evaluated in the oxidation of acrolein and later in the glycerol oxideshydration. Three types of samples were synthesized with different compositions B1- Mo12V4,8W2,4Cu2,2Si8,4; B2-Mo12V2W0,5Si6,2 and B3-Mo12V2,7Si6,2) by four preparation methods, namely by evaporation, evaporation followed by hydrothermal treatment, hydrothermal treatment (TH) and using a block copolymer. For the last two methods a more detailed study was performed to determine the best synthesis conditions (Phase I), and it was found that the total dissolution of the reagents in the mixture before TH resulted in samples with higher crystallinity and less active phase loss in the liquid and the use of a cold dissolved block copolymer contributed to an increase in pore volume. In the second stage, the materials synthesized by the four proposed methods were characterized and evaluated in reactor in acrylic acid production. The samples B1 showed different crystalline phase formation depending on the preparation method used, and in samples B2 and B3 the main phase was identified as a-MoO3, regardless of the method used. The samples synthesized by evaporation followed by TH showed the highest selectivity for acrylic acid formation from acrolein for the same catalyst composition, which may be related to the higher vanadium oxide content present in samples identified by FRX and the formation of the crystalline phase V0.35Mo4,65O14. The best performance was observed in sample B1-EV+TH with selectivity of 50.59% and 3.61% for acrylic acid in the processes from acrolein and glycerol, respectively

Retracted Article: Monodisperse Ni3Fe single-crystalline nanospheres as a highly efficient catalyst for the complete conversion of hydrous hydrazine to hydrogen at room temperature

2013 ◽  
Vol 1 (21) ◽  
pp. 6425-6432 ◽  
Author(s):  
Dong Ge Tong ◽  
Dong Mei Tang ◽  
Wei Chu ◽  
Gui Fang Gu ◽  
Ping Wu
Keyword(s):  
Catalytic Activity ◽  
Room Temperature ◽  
Complete Conversion ◽  
Efficient Catalyst ◽  
Single Crystalline ◽  
Highly Efficient ◽  
Retracted Article

Monodisperse Ni3Fe single-crystalline nanospheres exhibited highly catalytic activity for the complete conversion of hydrous hydrazine to hydrogen at room temperature.

Na2HPO4-modified NaY nanocrystallites: efficient catalyst for acrylic acid production through lactic acid dehydration

2014 ◽  
Vol 4 (5) ◽  
pp. 1376-1385 ◽  
Author(s):  
Junfeng Zhang ◽  
Yuling Zhao ◽  
Xinzhen Feng ◽  
Min Pan ◽  
Jing Zhao ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Acrylic Acid ◽  
Acid Production ◽  
Surface Acidity ◽  
Formation Rate ◽  
Structural Features ◽  
Efficient Catalyst ◽  
Acid Yield

An acrylic acid yield of 74.3% and a formation rate of 12.0 mmol gcat−1 h−1 have been achieved at 340 °C by lactic acid dehydration over Na2HPO4-modified NaY nanocrystallites (NaY-n) due to appropriate surface acidity together with the unique structural features of NaY-n.

Reversible Diastereoselective Photocyclization of a Diarylethene in a Single-Crystalline Phase

2000 ◽  
Vol 122 (40) ◽  
pp. 9631-9637 ◽  
Author(s):  
Tetsuhiro Kodani ◽  
Kenji Matsuda ◽  
Taro Yamada ◽  
Seiya Kobatake ◽  
Masahiro Irie
Keyword(s):  
Crystalline Phase ◽  
Single Crystalline

Photochromism and Photomagnetism of Biindenylidene-Dione Derivative in a Single Crystalline Phase

2002 ◽  
Vol 389 (1) ◽  
pp. 33-37 ◽  
Author(s):  
Lili Xu ◽  
Jiben Meng ◽  
Hui Wang ◽  
Ping Li ◽  
Teruki Sugiyama ◽  
...  
Keyword(s):  
Crystalline Phase ◽  
Single Crystalline ◽  
Dione Derivative

Zeolite - Salt Occlusion: A Potential Route for the Immobilisation of Iodine-129?

2003 ◽  
Vol 807 ◽  
Author(s):  
Neil C. Hyatt ◽  
Joseph A. Hriljac ◽  
Alia Choudhry ◽  
Laura Malpass ◽  
Gareth P. Sheppard ◽  
...  
Keyword(s):  
Weight Loss ◽  
Uniform Distribution ◽  
Crystalline Phase ◽  
Thermally Stable ◽  
X Ray Diffraction ◽  
Single Crystalline ◽  
X Ray ◽  
Elemental Silver

ABSTRACTReactions of zeolite Na-A with AgI, and the sodium, copper and lead forms of zeolites A, LTA, X and Y with NaI, have been examined as possible starting routes to the long term immobilisation of iodine-129. Heating the salts in air, at 500°C, with the sodium forms of the zeolites leads to the formation of occlusion products, where the iodide salt migrates into the zeolite pores. Detailed studies of the Na-A / 5AgI complex indicate it has a uniform distribution of Na, Si, Al, Ag and I, and is thermally stable to ca. 750°C, where there is a substantial weight loss as iodine is released. In situ powder X-ray diffraction studies have been used to monitor the occlusion reaction at 400°C, and show that the occlusion product decomposes to produce a single crystalline phase at 800°C prior to further decomposition at 850°C to a mixture of nepheline and elemental silver.

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