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

Zhixin Zhang,Xuebin Liu,Jian Zhang,Jianmin Lu,Yehong Wang,Feng Wang,Min Wang

doi:10.3390/inorganics5040075

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 CeO2, which is a water-tolerant Lewis acid catalyst. The CeO2 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 CeO2 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 NH3-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 CeO2 with different morphologies, and that the Lewis acidity and oxygen vacancy play an important role in Prins condensation and hydrolysis reaction.

Highlights

The Prins condensation of olefins with aldehydes is one of the most important organic reactions, allowing one to obtain alkyl-m-dioxanes, 1,3-diols, conjugated diolefins, and other valuable compounds [1,2]
It can be can be ascribed to the pyridine adsorbed on Lewis acid sites; these results indicate that the CeO2 found that the
The relative oxygen vacancy concentration of CeO2 samples are shown in Table 1 and Combined with the catalytic performances, Lewis acid site concentration, and oxygen vacancy concentration (Figure 5), we found an increase in FA conversion when changing the shape of CeO2

Summary

Introduction

The Prins condensation of olefins with aldehydes is one of the most important organic reactions, allowing one to obtain alkyl-m-dioxanes, 1,3-diols, conjugated diolefins, and other valuable compounds [1,2]. Among these chemicals, 1,3-diols is a commodity chemical that is mainly used as a building block in polymerization and as a surfactant. Both the Prins condensation and hydrolysis reaction require acid catalysts [3,15,16]. A single-stage 3-methyl-1,3-butanediol synthesis from isobutene and HCHO in water is one interesting route to be investigated, and a water-tolerant acid catalyst is critical

Methods

Results

Conclusion