Sustainable Valorization of C5 Sugars to Lactic Acid via Heterogeneous La(OTf)3/SBA-15 Catalysts: A One-Pot Strategy for Biomass Utilization

Abstract

Lactic acid (LA) is a pivotal platform chemical with extensive applications, and its production from lignocellulosic biomass via catalytic processes offers a sustainable alternative to conventional methods. However, existing heterogeneous catalysts often face challenges such as intricate synthesis procedures, ion leaching, carbon deposition at elevated temperatures, and limited recyclability. In this study, La(OTf)₃/SBA-15 heterogeneous catalysts were prepared through a two-step process involving hydrothermal synthesis followed by impregnation loading. The catalyst was employed in the one-pot conversion of C5 sugars, specifically xylose and xylan, to LA. Under optimized conditions (250 °C for 60 min), the xylose conversion rate achieved was 98%, yielding 49.73% LA. In the xylan system, the LA yield was 36.88%. Moreover, the catalyst demonstrated commendable recyclability, maintaining an LA yield of 40.03% after five cycles. The ordered two-dimensional hexagonal mesoporous structure of the SBA-15 carrier was maintained after La(OTf)₃ loading, as evidenced by XRD and TEM. A high surface area and uniform mesoporosity of catalysts were confirmed by N₂ adsorption–desorption, while successful loading of La(OTf)₃ was further verified by FT-IR and XPS. The synergistic combination of La(OTf)₃ with SBA-15 facilitated the efficient conversion of bioresources, underscoring the potential of heterogeneous catalysts in biomass valorization processes.