Exploring the Impact of Zeolite Porous Voids in Liquid Phase Reactions: The Case of Glycerol Etherification by tert-Butyl Alcohol

C Miranda (1) , J Urresta (1) , H Cruchade (2) , A Tran (1) , M Benghalem (2) , A Astafan (2) , P. Gaudin (2) , T J Daou (3) , A. Ramírez (4) , Y Pouilloux (2) , A. Sachse (2) , L Pinard (2)

1 Univalle - Universidad del Valle [Cali]
2 IC2MP [Poitiers] - Institut de chimie des milieux et matériaux de Poitiers [UMR 7285]
3 IS2M - Institut de Science des Matériaux de Mulhouse
4 Universidad del Cauca [Popayán]

The role of acidity (nature, concentration, strength) and textural properties in the etherification of glycerol with tert-butyl alcohol was studied for a wide range acid catalysts, such as Amberlyst® 15, silica, alumina, silica alumina and four type of zeolite, i.e. FAU, MOR, ∗BEA and MFI. The etherification of glycerol by tert-butyl alcohol is a thermodynamically limited reaction that occurs through a successive reaction sequence and follows an Eley-Rideal type mechanism. We found major evidence that glycerol etherification is not only a function of the amount of Brønsted acid sites, but that it further proceeds via a product shape selectivity mechanism. Indeed, the formation of di-substituted ethers appears at very low conversions for zeolites compared to meso- and macroporous acid catalysts. ∗BEA and MFI zeolites feature similar confining voids and resulting thus in similar intrinsic acid strengths (as proved by n-hexane cracking), but differ in the connectivity (4 vs. 6 channels) and access to these voids (0.54 vs. 0.67 nm), which leads to diffusion issues, notably for the MFI zeolite.

Domaines: Chimie organique; Catalyse

C Miranda, J Urresta, H Cruchade, A Tran, M Benghalem, et al.. Exploring the Impact of Zeolite Porous Voids in Liquid Phase Reactions: The Case of Glycerol Etherification by tert-Butyl Alcohol. Journal of Catalysis, 2018, 365, pp.249-260. ⟨10.1016/j.jcat.2018.07.009⟩. ⟨hal-02352299⟩