VAPOR-PHASE SYNTHESIS OF LACTIDE FROM ETHYL LACTATE OVER TiO2/SiO2 CATALYST
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Keywords

ethyl lactate, lactide, supported catalysts, titanium dioxide.

How to Cite

Brei, V., Varvarin, A., Levytska, S., & Glushchuk, Y. (2019). VAPOR-PHASE SYNTHESIS OF LACTIDE FROM ETHYL LACTATE OVER TiO2/SiO2 CATALYST. Ukrainian Chemistry Journal, 85(7), 31-37. https://doi.org/10.33609/0041-6045.85.7.2019.31-37

Abstract

The lactide is monomer for production of polylac- tide – biodegradable polymer that use as an ecological packagingmaterial. In an industry the two-stage lactide synthesis is applied. At first, lactic acid condenses into the oligomer using Sn-octanoate catalyst, then oligo- mer depolymerizes to lactide. The drawbacks of this liquid-phase method are a significant amount of by- products — dimers and trimers of lactic acid and low lactide yield.Now a direct vapor-phase condensation of lactic acid and its esters to lactide is considered as alternative to the industrial process. One-stage lactide obtaining and use of solid catalysts are advantages of such method. In this work, the vapor-phase transfor- mation of ethyl lactate over supported TiO2/SiO2 and TiO2/Al2O3 oxides in nitrogen flow at 200–300 °С

was studied. The oxide samples were obtained by impregnating silica gel and γ -alumina with an approp- riate amount of titanium tetrabutoxide solution in iso- propanol, then dried at 80 oC, and finally calcined at 500 oC in air for 4 h. The catalysts were characterized by BET method, X-ray diffraction and UV-Vis diffuse reflectance spectroscopy. Catalytic experi- ments were carried out in a steel flow reactor at 200

–270 °С and atmospheric pressure. The load on a ca-talyst was varied in the interval of 8.2–36.4 mmol ethyllactate/(gcat⋅ h) that corresponds gas hourly space velo- city of the mixture of ethyl lactate and nitrogen of 1230–1490 h–1. It was shown that TiO2/SiO2 with5 wt.% content of titanium dioxide provides 48 % conversion of ethyl lactate with selectivity and pro- ductivity towards lactide 74 % and 7.0 mmol/(gcat⋅ h)at 270 °C, respectively. It was found thatTiO2/SiO2 is more efficiently for lactide producing (STY = 6.2 mmol/(gcat⋅ h) compared to TiO2/Al2O3catalyst (STY =1.8 mmol/(gcat⋅ h). It was shown that spent TiO2/ SiO2 catalyst fully restores activity after regenerati- on in air at 500 °С for 2 h. The two-stage scheme of ethyl lactate condensation with the participation of coordina- tion-unsaturated titanium ions is discussed.

https://doi.org/10.33609/0041-6045.85.7.2019.31-37
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References

Gupta A.P., Kumar V. New emerging trends insynthetic biodegradable polymers – Polylactide:A critique. Eur. Polymer. 2007. 43 (10): 4053.

Hu Y., Daoud W.A., Cheuk K.K.L., Lin C.S.K.Newly developed techniques on polycondensa-tion, ring-opening polymerization and polymermodification: focus on poly(lactic acid). Mate-rials. 2016. 9 (3): 123.

Auras R., Lim L.-T., Selke S.E.M., Tsuji H.(Eds). Poly(lactic acid): synthesis, structures,properties, processing and applications. (Hobo-ken: New Jersey, 2010).

Hamad K., Kaseem M., Yang H.W., Deri F., KoY.G. Properties and medical applications ofpolylactic acid: A review. eXPRESS PolymerLett. 2015. 9 (5): 435.

Patent US 5142023. Gruber P.R., Hall E.S., Kol-stad J.J., Iwen M.L., Benson R.D., Borchardt R.L.Continuous process for manufacture of lactidepolymers with controlled optical purity. 1992.

Patent US 5521278. O’Brien W.G., Cariel-lo L.A., Wells T.F. Integrated process for the manufacture of lactide. 1996.

Dusselier M., Van Wouwe P., Dewaele A.,Makshina E., Sels B.F. Lactic acid as a platformchemical in the biobased economy: the role ofchemocatalysis. Energy Environ. Sci. 2013. 6 (5):1415.

Van Wouwe P., Dusselier M., Vanleeuw E.,Sels B. Lactide synthesis and chirality control forpolylactic acid production. ChemSusChem. 2016.9: 907.

Patent US 5138074. Bellis H.E., Bhatia K.K.Continuous catalysed vapor phase dimeric cyclicester process. 1992.

Patent US 5332839. Benecke H.P., Markle R.A.,Sinclair R.G. Catalytic production of lactidedirectly from lactic acid. 1994.

Park J., Cho H., Hwang D.W., Kim S., Moon I.,Kim M. Design of a novel process for conti-nuous lactide synthesis from lactic acid. Ind.Eng. Chem. Res. 2018. 57 (35): 11955.

De Clercq R., Dusselier M., Makshina E.,Sels B.F. Catalytic gas-phase production of lac-tide from renewable alkyl lactates. Angew.Chem. 2018. 57 (12): 3074.

Tanabe К. Solid acids and bases. (Moscow: Mir,1973). [in Russian].

De Clercq R., Dusselier M., Poleunis C., Debec-ker D.P., Giebeler L., Oswald S., Makshina E.,Sels B.F Titania-silica catalysts for lactideproduction from renewable alkyl lactates: struc-ture-activity relations. ACS Catal. 2018. 8(9): 8130.

Varvarin A.M., Levytska S.I., Brei V.V. Vaporphase condensation of the ethyllactate into lactideover SnO2/SiO2 catalyst. Dopov. Nac. akad. naukUkr. 2018. No. 1: 73. [in Ukrainian].

Varvarin A.M., Levytska S.I., Brei V.V. Conver-sion of ethyllactate into lactide over acidSnO2/SiO2 catalyst. Catalysis and petrochemis-try, 2018. 27: 19. [in Ukrainian].

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