Synthesis of 1,3-Diols from Isobutene and HCHO via Prins Condensation-Hydrolysis Using CeO2 Catalysts: Effects of Crystal Plane and Oxygen Vacancy

Abstract

Abstract:We herein report the synthesis of 3-methyl-1,3-butanediol from isobutene and HCHO in water via a Prins condensation-hydrolysis reaction over CeO 2 , which is a water-tolerant Lewis acid catalyst. The CeO 2 exhibits significant catalytic activity for the reaction, giving 95% HCHO conversion and 84% 3-methyl-1,3-butanediol selectivity at 150 • C for 4 h. The crystal planes of CeO 2 have a significant effect on the catalytic activity for the Prins reaction. The (110) plane shows the highest catalytic activity among the crystal planes investigated (the (100), (110), and (111) planes), due to its higher concentration of Lewis acid sites, which is in line with the concentration of oxygen vacancies. Detailed characterizations, including NH 3 -TPD, pyridine-adsorbed FT-IR spectroscopy, and Raman spectroscopy, revealed that the concentration of Lewis acid sites is proportional to the concentration of oxygen vacancies. This study indicates that the Lewis acidity induced by oxygen vacancy can be modulated by selective synthesis of CeO 2 with different morphologies, and that the Lewis acidity and oxygen vacancy play an important role in Prins condensation and hydrolysis reaction.

Transformations of Biomass, Its Derivatives, and Downstream Chemicals over Ceria Catalysts

“…Therefore, ceria is suitable for Lewis acid-catalyzed reactions involving water. Subsequent works also show that ceria exhibits good catalytic performance in the aqueous solution. , …”

“…Based on the bioethanol-to-olefins process, the obtained olefins are further subjected to Prins condensation with formaldehyde over ceria, followed by hydrolysis and dehydration to obtain dioxanes, high-carbon diols, enols, and dienes. So far, CeO 2 nanoparticles, CeO 2 nanorods, and Pr-doped CeO 2 , have been reported for these reactions in batch liquid reactors. Wang et al reported that pure ceria gave 95% yield of 1,3-butanediol in the hydrolysis of 4-methyl-1,3dioxane and a total yield of 60% in the Prins condensation of propylene and formaldehyde, followed by hydrolysis.…”

“…A positive correlation also arises between the Vö concentration and catalytic activity of M-CeO 2 . Ceria with different nanoshapes also shows obvious reactivity differences . CeO 2 -nanorods affording a higher Vö show better Prins condensation-hydrolysis activity.…”

“…Subsequent works also show that ceria exhibits good catalytic performance in the aqueous solution. 20,21 Surface probe technology can also help us understand the Lewis acid−base pair on the surface of ceria more clearly. Wu et al have investigated the acid and base of ceria with different morphologies (rod, cube, and octahedra) in detail by in situ IR spectroscopy with several probing molecules.…”

“…Compared with supported superacids, bases, and molecular sieves, metal oxides appear to have better structural stability and resistance to deactivation. − Among various metal oxides, CeO 2 seems to be one of the most promising catalysts in catalyzing conversion of biomass feedstocks. CeO 2 -based catalytic materials have been reported to demonstrate relatively high water resistance properties, and they are able to catalyze ethanol hydrolysis, , olefin Prins condensation, ,− fermentation broth upgrading reactions, and biomass to liquid-fuel . The easily reversible redox cycle of cerium ions (Ce 3+ /Ce 4+ ) leads to the production of nonstoichiometric CeO 2– x nanomaterials, making ceria have redox properties as well as special Lewis acid–base active sites.…”