磁性碱木素胺稳定的Ru纳米粒子催化α-蒎烯加氢反应

Hydrogenation of α-Pinene Catalyzed by Ru Nanoparticles Stabilized by Magnetic Alkali Lignin Amine

通过Mannich反应在碱木素结构中引入胺源,再结合共沉淀法制备了包裹Fe3O4磁核的稳定金属粒子的碱木素胺载体,并进一步构建了催化可再生资源α-蒎烯加氢反应的Ru纳米粒子催化剂.通过元素分析、粉末X射线衍射、傅里叶变换红外光谱、电感耦合等离子体原子发射光谱、透射电子显微镜、热重分析和X射线光电子能谱等方法对该催化剂进行表征.结果表明,碱木素中的苯环和含氧基团均对金属粒子有稳定作用,但胺源的引入可更加有效地稳定金属粒子.经过对催化剂制备工艺、木质素类型、胺源类型和胺源含量的筛选,得到活性最优的催化剂Fe3O4@0.8ALN1-Ru, Ru负载量为1.92 mmol/g, Ru粒子粒径为(2.1±0.5)nm.该催化剂在n(α-蒎烯)/n(Ru)=65.8, 1 MPa H2条件下70℃催化1 mLα-蒎烯加氢反应2 h,可获得99.64%的α-蒎烯转化率和96.52%的顺式蒎烷选择性,并表现出良好的重复使用稳定性.

Alkali lignin amine was prepared by introducing amine into alkali lignin structure via Mannich reaction to improve the stability performance for metal nanoparticles.Then the alkali lignin amine was wrapped around Fe3O4 magnetic nucleus by co-precipitation method and used as a carrier to construct Ru metal nanoparticle catalyst for hydrogenation of α-pinene.Elemental analysis(EA),X-ray diffraction(XRD),Fourier transform infrared(FTIR),inductively coupled plasma-atomic emission spectroscopy(ICP-AES),transmission electron microscope(TEM),thermogravimetric analysis(TG),X-ray photoelectron spectroscopy(XPS)and other characterizations showed that except for the benzene ring and oxygen-containing groups in alkali lignin,the introduced amine source had exhibited more efficient stabilization for metal nanoparticles.Fe3O4@0.8ALN1-Ru,with a Ru loading of 1.92 mmol/g and Ru particle size of(2.1±0.5)nm,was found the most active catalyst of α-pinene hydrogenation after the study on catalyst preparation process,lignin type,amine source type and amine content.It exhibited a good catalytic performance with 99.64% conversion of α-pinene and 96.52%selectivity for cis-pinene when it catalyzed 1 mL of α-pinene and 1 MPa H2 at a dosage of 0.05 g and 70 ℃ for 2 h.Moreover,it’s good reuse stability confirmed by a five-run test,which provides a novel method for the development of high value-added lignin-based catalysts.