Brønsted Acid-Triggered\nFast Synthesis Pathway\nof Furfural to Ethyl Levulinate by PtZn Supported on ZSM‑5\nNanosheets

Furfural (FUR) is widely used to synthesize alkyl levulinate\n(AL),\nan important biomass-derived compound for industrial use. Traditional\nsynthesis pathways, including hydrogenation, etherification, and hydrolysis,\nare slow due to high activation energy requirements. This study presents\na pathway using ethyl levulinate (EL) as a model AL. The process starts\nwith the acetalization of FUR to produce 2-(diethoxymethyl)furan (DEMF)\nusing a Brønsted acid–based ZSM-5 nanosheet-supported\nPtZn (PtZn/ZSM-NS) catalyst. DEMF is then hydrogenolyzed to form 2-(ethoxymethyl)furan\n(EMF), which is hydrolyzed to produce EL at a rate of 29.8 mmol·g<sup>–1</sup>h<sup>–1</sup>, over 20 times faster than with\na Lewis acid–based catalyst. In the initial step, Brønsted\nacid sites on the PtZn/ZSM-NS activate ethanol to generate an acetate-like\nintermediate (COO<sup>θ</sup>), which facilitates the acetalization\nof FUR to produce DEMF. This step is crucial for efficiently producing\nEL using the PtZn/ZSM-NS catalyst. Subsequently, EMF is easily formed\nthrough the hydrogenolysis of DEMF instead of through the etherification\nof furfuryl alcohol. Additionally, highly dispersed PtZn alloys on\nPtZn/ZSM-NS are essential for optimizing the adsorption strength,\nthereby accelerating the overall reaction. Using this pathway, the\nPtZn/ZSM-NS catalyst achieves an EL yield of up to 89.5 wt % at 200\n°C in just 1 h.