The low-cost and environmentally friendly solid acid catalysts for the efficient synthesis of ethyl levulinate fuel additives were prepared from pine needles through the partial carbonization, followed by a hydrothermal H₂SO₄ sulfonation procedure. The resultant sulfonated carbon catalysts possessed an amorphous carbon structure and high contents of the sulfate groups. Other than that, they had good thermal stability and the total acid density was as high as 2.28 mmol g⁻¹. In this work, noticeably, the parameters of both synthetic and catalytic reactions were optimized to enhance the conversion of levulinic acid (LA). The results showed that the LA conversion was as high as 96.1% over the catalysts carbonizated at 700 °C for 90 min and sulfonated at 160 °C for 15 h under the optimized conditions (5:1 ethanol/LA molar ratio, 5 wt% catalyst dosage, 80 °C reaction temperature, 8 h reaction time). Meanwhile, the recyclability experiments confirmed that the resultant catalysts exhibited satisfactory reusability and the corresponding conversion of LA was maintained as 63.0% in the fourth run. Remarkably, the reused catalysts can be easily activated again and the corresponding LA conversion could reach up to 90.1%. The results demonstrated that the catalysts had great potential in the synthesis of biofuels, which could be efficient and could have excellent recyclability.

用于高效合成乙酰丙酸乙酯燃料添加剂的低成本，环保型固体酸催化剂，是由松针通过部分碳化，然后进行水热H ₂ SO ₄磺化工艺制备的。所得的磺化碳催化剂具有无定形碳结构和高含量的硫酸根基团。除此之外，它们具有良好的热稳定性，总酸密度高达2.28 mmol g ^-1。在这项工作中，值得注意的是，优化了合成和催化反应的参数，以提高乙酰丙酸（LA）的转化率。结果表明，在最佳条件下（5：1乙醇/ LA摩尔比，5 wt％），在700°C碳化90分钟并在160°C磺化15 h的催化剂，LA转化率高达96.1％。催化剂用量，80°C反应温度，8 h反应时间）。同时，可循环性实验证实，所得催化剂表现出令人满意的可重复利用性，并且在第四轮中LA的相应转化率保持在63.0％。值得注意的是，重复使用的催化剂可以轻松地再次激活，相应的LA转化率可达到90.1％。结果表明，该催化剂在生物燃料合成中具有巨大的潜力，