Vapor-phase intramolecular aldol condensation of 2,5-hexanedione to 3-methylcyclopent-2-enone over ZrO2-supported Li2O catalyst

2017 ◽  
Vol 92 ◽  
pp. 105-108 ◽  
Author(s):  
Daolai Sun ◽  
Shigenori Chiba ◽  
Yasuhiro Yamada ◽  
Satoshi Sato
Keyword(s):  
Vapor Phase ◽  
Aldol Condensation

Vapor-phase oxidation of propylene glycol-methanol mixture to methyl lactate on CeO2/Al2O3 catalyst

2021 ◽  
pp. 92-97
Author(s):  
M.E. Sharanda ◽  
◽  
A.M. Mylin ◽  
O.Yu. Zinchenko ◽  
V.V. Brei ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
Vapor Phase ◽  
Flow Reactor ◽  
Aldol Condensation ◽  
Ethyl Lactate ◽  
Molar Ratio ◽  
Methyl Lactate ◽  
Reactor Inlet ◽  
Phase Oxidation ◽  
Al2o3 Catalyst

The vapor-phase oxidation of mixtures of propylene glycol with methanol and ethanol to methyl and ethyl lactate, respectively, on supported CeO2/Al2O3 catalyst with 10 wt.% CeO2 content was studied. The steel flow reactor with a fixed catalyst bed (4 cm3) was used. 20 wt.% solution of propylene glycol in alcohol was fed to the reactor inlet by Waters 950 pump at LHSV= 0.5-0.8 h-1. Reaction temperature and pressure were varied in the interval of 190-250 0C and 1.3-1.8 bars respectively. Compressed air was given to the reactor inlet at the molar ratio of propylene glycol/O2 = 1. The reaction products were analyzed using gas chromatography (Agilent 7820A) and 3C NMR (Bruker Avance 400) methods. Studied oxidation of propylene glycol in the presence of methanol describes by total reaction CH3CHOHCH2OH +O2 + СН3OH = CH3CHOHCOOСН3 +2H2O At first, hydroxyacetone is formed that is further oxidized to pyruvic aldehyde, which attaches alcohol to form hemiacetal. Then, hemiacetal of methyl glyoxal rearranges into methyl lactate by Cannizzaro. At 220 0C and load on a catalyst of < 2 mmol PG/gcat/h, the selectivity towards methyl lactate reaches 70 wt.% at 100 % propylene glycol conversion. The main by-products are formed as the result of acetaldehyde transformation. Acetaldehyde could be formed at hydroxyacetone aldol decondensation. In the presence of ethanol, the formation of a significant amount of acetaldehyde and its aldol condensation products as well as the formation of diethoxyethane are observed. Therefore, ethyl lactate selectivity at 100 % propylene glycol conversion does not exceed 45 %. Supported CeO2/SiO2 contact was tested in this oxidation reaction also. However, CeO2/SiO2 provides the low, up to 25%, selectivity towards methyl lactate at full propylene glycol conversion. It was shown that at the same conditions methyl lactate is formed with higher selectivity then ethyl lactate. The high methyl lactate yield up to 70 wt.% could be obtained via vapor-phase oxidation of 20% mixture of propylene glycol with methanol by air oxygen on supported CeO2/Al2O3 catalyst at 210 - 220°С and at time contact of 3-4 seconds.

scholarly journals Vapor-Phase Aldol Condensation of n-Butylaldehyde by Molten Basic Catalyst.

1993 ◽  
Vol 19 (6) ◽  
pp. 1060-1066
Author(s):  
Tadaatsu Ido ◽  
Tetsuya Yoshida ◽  
Shigeo Goto
Keyword(s):  
Vapor Phase ◽  
Aldol Condensation ◽  
Basic Catalyst

Formation of Methyl Acrylate from Methyl Acetate and Formaldehyde Condensation over Solid Base Catalysts

2012 ◽  
Vol 629 ◽  
pp. 376-380 ◽  
Author(s):  
Ya Nan Wang ◽  
Qun Long Wang ◽  
Huan Hui Chen ◽  
Jia Lei Zhang ◽  
Zhi Rong Zhu
Keyword(s):  
Acrylic Acid ◽  
Vapor Phase ◽  
Methyl Acrylate ◽  
Methyl Acetate ◽  
Aldol Condensation ◽  
Solid Base ◽  
Base Property ◽  
Support Materials ◽  
Solid Base Catalysts ◽  
Base Catalysts

The vapor-phase aldol condensation of methyl acetate (MeOAC) with formaldehyde (HCHO) to form methyl acrylate was investigated over solid base catalysts. A variety of solid base catalysts were prepared by loading Cs2O over SiO2 or Al2O3 as the support materials. The properties of the solid base catalysts were characterized by XRD, BET and CO2-TPD. The results of the vapor-phase aldol condensation indicated that SiO2 and Al2O3 modified with Cs2O showed high conversation of methyl acetate and high selectivity of methyl acrylate. 22.6% conversation of methyl acetate and 16.5% yield of acrylic acid and methyl acrylate were obtained over Cs-Al2O3. In addition, Cs-SiO2 exhibited about 42% selectivity to methyl acetate. The high yield of acrylic acid and methyl acrylate is attributed to the high base property of catalysts.

Vapor phase aldol condensation over fully ion-exchanged montmorillonite-rich catalysts

2003 ◽  
Vol 241 (1-2) ◽  
pp. 1-13 ◽  
Author(s):  
A Azzouz ◽  
D Messad ◽  
D Nistor ◽  
C Catrinescu ◽  
A Zvolinschi ◽  
...  
Keyword(s):  
Vapor Phase ◽  
Aldol Condensation
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