ChemInform Abstract: Vapor-Phase Aldol Condensation of Formaldehyde with Propionic Acid on Vanadium Pentoxide-Phosphorus Pentoxide.

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.

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Promoting effect of CeO2 addition to Ni/AC catalyst for vapor phase carbonylation of ethanol to propionic acid

Catalysis Communications ◽

10.1016/j.catcom.2009.05.025 ◽

2009 ◽

Vol 10 (14) ◽

pp. 1796-1799 ◽

Cited By ~ 9

Author(s):

Qing Zhang ◽

Huifang Wang ◽

Guosong Sun ◽

Kelin Huang ◽

Weiping Fang ◽

...

Keyword(s):

Propionic Acid ◽

Vapor Phase ◽

Promoting Effect

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Formation of Acrylaldehyde by Vapor-Phase Aldol Condensation I. Basic Oxide Catalysts

Bulletin of the Chemical Society of Japan ◽

10.1246/bcsj.64.1342 ◽

1991 ◽

Vol 64 (4) ◽

pp. 1342-1345 ◽

Cited By ~ 18

Author(s):

Mamoru Ai

Keyword(s):

Vapor Phase ◽

Aldol Condensation ◽

Oxide Catalysts ◽

Basic Oxide

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Effect of Zirconia Polymorph on Vapor-Phase Ketonization of Propionic Acid

Catalysts ◽

10.3390/catal9090768 ◽

2019 ◽

Vol 9 (9) ◽

pp. 768 ◽

Cited By ~ 2

Author(s):

Shuang Ding ◽

Jiankang Zhao ◽

Qiang Yu

Keyword(s):

Propionic Acid ◽

Vapor Phase ◽

Surface Concentration ◽

X Ray Diffraction ◽

In Situ Drifts ◽

X Ray ◽

Surface Intermediates ◽

Temperature Programmed ◽

Diffuse Reflectance Infrared

Vapor-phase ketonization of propionic acid derived from biomass was studied at 300–375 °C over ZrO2 with different zirconia polymorph. The tetragonal ZrO2 (t-ZrO2) are more active than monoclinic ZrO2 (m-ZrO2). The results of characterizations from X-ray diffraction (XRD) and Raman suggest m-ZrO2 and t-ZrO2 are synthesized by the solvothermal method. NH3 and CO2 temperature-programmed desorption (NH3-TPD and CO2-TPD) measurements show that there were more medium-strength Lewis acid base sites with lower coordination exposed on m-ZrO2 relative to t-ZrO2, increasing the adsorption strength of propionic acid. The in situ DRIFTS (Diffuse reflectance infrared Fourier transform spectroscopy) of adsorbed propionic acid under ketonization reaction reveal that as the most abundant surface intermediates, the monodentate propionates are more active than bidentate propionates. In comparison with m-ZrO2, the t-ZrO2 surface favors monodentate adsorption over bidentate adsorption. Additionally, the adsorption strength of monodentate propionate is weaker on t-ZrO2. These differences in adsorption configuration and adsorption strength of propionic acid are affected by the zirconia structure. The higher surface concentration and weaker adsorption strength of monodentate propionates contribute to the higher ketonization rate in the steady state.

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