溶胶-凝胶法制备木质素碳基固体酸及其催化α-蒎烯水合反应性能研究

Study on Preparation of Carbon-based Solid Acid Derived from Kraft Lignin by Sol-Gels and Its Catalytic Hydration for α-Pinene

中文关键词:  溶胶-凝胶法  木质素水凝胶  碳基固体酸  催化水合  α-松油醇

Key Words:sol-gel method  lignin hydrogel  carbon-based solid acid  catalytic hydration  α-terpineol

中文摘要:

      以造纸黑液中提取的硫酸盐木质素为原料，通过溶胶-凝胶法合成了木质素水凝胶，再经过真空干燥、炭化及浓硫酸磺化合成木质素碳基固体酸，采用傅里叶变换红外光谱（FT-IR）、场发射扫描电子显微镜（SEM）、BET比表面积法、Boehm滴定法等手段对其进行表征分析，并将其应用于催化α-蒎烯水合反应以合成α-松油醇。结果表明，采用溶胶-凝胶法制备的木质素碳基固体酸具有丰富的孔隙结构和良好的催化性能，其比表面积可达281.25 m²/g，α-蒎烯的转化率为93.1%，α-松油醇产率为40.4%，选择性为43.4%。催化剂循环使用5次后，α-蒎烯的转化率降至86.7%，α-松油醇产率降至32.6%，催化性能下降的根本原因在于其表面磺酸基团的脱落。

Abstract:

      Kraft lignin， obtained from sulfate pulping black liquor， was used to synthesize hydrogel by sol-gel method， and then the hydrogel was dried by vacuum， followed by carbonization and sulfonation using concentrated sulfuric acid to obtain lignin carbon-based solid acid which was characterized and analyzed using FT-IR， SEM， BET specific surface area method， and Boehm titration and was further used in catalyzing α-pinene to synthesize α-terpineol. The results showed that the carbon-based solid acid prepared by sol-gel method was of rich pore structure with a BET specific surface area of 281.25 m²/g， the conversion rate of α-pinene of 93.1%， the yield of α-terpineol of 40.4%， and the selectivity of 43.4%. After the catalyst was recycled for 5 times， the conversion rate of α-pinene decreased to 86.7% and the yield of α-terpineol decreased to 32.6%. The root cause for the decline of catalytic performance of lignin carbon-based solid acid after recycling was the fall-off of sulfonic groups on its surface.