Titania Nanotubes-Bonded Sulfamic Acid as an Efficient Heterogeneous Catalyst for the Synthesis of n-Butyl Levulinate

Shuolin Zhou; Min Lei; Junzhuo Bai; Xianxiang Liu; Lu Wu; Min Long; Keying Huang; Dulin Yin

doi:10.3389/fchem.2022.894965

Titania Nanotubes-Bonded Sulfamic Acid as an Efficient Heterogeneous Catalyst for the Synthesis of n-Butyl Levulinate

Front Chem. 2022 May 2:10:894965. doi: 10.3389/fchem.2022.894965. eCollection 2022.

Authors

Shuolin Zhou¹, Min Lei¹, Junzhuo Bai¹, Xianxiang Liu², Lu Wu¹, Min Long¹, Keying Huang¹, Dulin Yin²

Affiliations

¹ School of Elementary Education, Changsha Normal University, Changsha, China.
² National and Local Joint Engineering Laboratory for New Petro-chemical Materials and Fine Utilization of Resources, Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha, China.

Abstract

The titania nanotubes-bonded sulfamic acid (TNTs-NHSO₃H) catalyst was designed and successfully fabricated by the post-synthesis modification method. The as-prepared catalyst was characterized by a variety of characterization techniques, including Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and thermogravimetry-differential thermal gravimetry (TG-DTG). The crystal structure of the TNTs still maintained during the modification process. Although the BET surface area was decreased, the amount of Brønsted acid sites can be efficiently fabricated on the TNTs. The catalytic activity of TNTs-NHSO₃H was examined for the synthesis of n-butyl levulinate (BL) from levulinic acid (LA) and furfuryl alcohol (FA). A relatively high selectivity (99.6%) at 99.3% LA conversion was achieved for esterification of levulinic acid owing to the strong Brønsted acidity sites. And also, the TNTs-NHSO₃H catalyst exhibited a higher reactivity for alcoholysis of FA and the yield of BL reached 90.4% with 100% FA conversion was obtained under the mild conditions.

Keywords: TiO2 nanotubes; alcoholysis; esterification; heterogenous catalyst; levulinate esters.