磁性纳米钌催化剂制备及其催化甲苯氢化反应性能

采用共沉淀法制备Fe₃O₄粒子，用SiO₂对Fe₃O₄纳米粒子进行表面包覆，用改性聚乙烯吡咯烷酮对所得磁性粒子进行表面修饰，制备磁性纳米粒子负载钌催化剂Ru/PVP-DB-171/SiO₂/Fe₃O₄。红外光谱、X射线衍射、扫描电子显微镜及透射电子显微镜分析表明，所得粒子结构是面心尖晶石结构，Fe₃O₄为核，无定形SiO₂为壳，纳米钌吸附在磁性载体表面。该粒子具有高分散性，可用磁分离实现固液分离。以甲苯液相催化加氢反应为模型，评价磁性负载钌催化剂的催化性能，计算出甲苯氢化的活化能为16.6 kJ·mol^-1，在433 K和4.0 MPa条件下，反应转换数达30 262 mol·(mol-Ru）^-1，Ru催化剂可循环使用8次，添加助剂的种类和数量影响催化剂活性。

Preparation of magnetic ruthenium nanoparticle catalyst and its catalytic performance for toluene hydrogenation

Fe3O4 nanoparticles were prepared by co-precipitation method. Ru/PVP-DB-171/SiO2/Fe3O4 catalyst was prepared by coating the surface of Fe3O4 nanoparticles with SiO2 and then modifying the surface of the magnetic particles using modified ployvinylpyrrolidone. The as-prepared catalyst was characterized by FT-IR, XRD, SEM and TEM techniques. The characterization results showed that the nano ruthenium was dispersed on the surface of magnetic support, which consisted of core-shell Fe3O4- SiO2 structure with spinel Fe3O4 particle as core and unformed SiO2 layer as shell. The particles were high dispersed in organic solvent and could be separated by magnetic field. The catalytic performance of as-prepared catalyst was evaluated by using hydrogenation of toluene as a model reaction. The apparent activation energy for toluene hydrogenation was 16.6 kJ ·mol^-1 by calculation. The value of TON reached 30 262 mol·（mol-Ru）^-1under the condition of 433 K and 4.0 MPa. Ru/PVP-DB-171/SiO2/Fe3O4 catalyst for toluene hydrogenation could be reused for up to 8 times. The kinds and dosage of additives had influence on the performance of the catalyst.