@article{Sharanda_Mylin_Зінченко_Brei_2021, title={Vapor-phase oxidation of propylene glycol-methanol mixture to methyl lactate on CeO2/Al2O3 catalyst}, url={http://kataliz.org.ua/index.php/journal/article/view/19}, DOI={10.15407/kataliz2021.31.092}, abstractNote={<p>The vapor-phase oxidation of mixtures of propylene glycol with methanol and ethanol to methyl and ethyl lactate, respectively, on supported CeO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub>&nbsp;catalyst with 10 wt.% CeO<sub>2</sub> 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.<br>Studied oxidation of propylene glycol in the presence of methanol describes by total reaction<br>CH<sub>3</sub>CHOHCH<sub>2</sub>OH +O<sub>2</sub>&nbsp;+ СН<sub>3</sub>OH = CH<sub>3</sub>CHOHCOOСН<sub>3</sub>&nbsp;+2H<sub>2</sub>O<br>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 <sup>0</sup>C and load on a catalyst of &lt; 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 CeO<sub>2</sub>/SiO<sub>2</sub>&nbsp;contact was tested in this oxidation reaction also. However, CeO<sub>2</sub>/SiO<sub>2</sub> provides the low, up to 25%, selectivity towards methyl lactate at full propylene glycol conversion.<br>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 70wt.% could be obtained via vapor-phase oxidation of 20% mixture of propylene glycol with methanol by air oxygen on supported CeO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub>&nbsp;catalyst at 210 - 220°С and at time contact of 3-4 seconds.</p&gt;}, number={31}, journal={Catalysis and petrochemistry}, author={Sharanda, M.E. and Mylin, A.M. and Зінченко, О.Ю. and Brei, V.V.}, year={2021}, month={Nov.}, pages={92-97} }