PVP辅助制备Pt/SBA-15催化剂及催化性能研究

PVP assisted synthesis of Pt/SBA-15 catalysts and their catalytic performance

使用胶体法制备Pt/SBA-15,并且在制备过程中加入高分子封端剂可以防止Pt纳米颗粒团聚和生长、促使Pt纳米颗粒进入孔道当中,并且在O_(2)气氛下煅烧,可以去除高分子封端剂,Pt/SBA-15的催化活性不受影响。对制备的Pt/SBA-15催化剂的形貌、表面化学性质、介孔结构以及催化性能进行表征与测试。透射电子显微镜结果表明:Pt纳米颗粒均匀而分散地分布于SBA-15的介孔结构之中,平均粒径为4.99 nm。X射线光电子能谱和红外光谱等数据证明煅烧后的Pt/SBA-15催化剂表面干净,PVP被成功去除。该催化剂对于肉桂醛加氢反应活性较高,但对于目标产物的选择性较差。对于CO氧化反应,反应初期速率较高,随着反应的进行反应速率逐渐下降。

Utilizing colloidal method with polyvinylpyrrolidone(PVP)as capping agent to synthesize Pt/SBA-15 could not only prevent aggregation and growth of Pt nanoparticles,but also led Pt nanoparticles into pores of SBA-15.Moreover,calcination under O_(2)can remove PVP,so catalytic performance of Pt/SBA-15 would not be affected.Morphology,surface properties,mesoporous structures and catalytic performance of the as-synthesized catalysts were characterized.Transmission electron microscope(TEM)results show that Pt nanoparticles are well-dispersed in the pores of SBA-15,with average diameter of 4.99 nm.X-ray photoelectron spectroscopy(XPS)and fourier transform infrared spectroscopy(FTIR)spectra are confirmed that Pt/SBA-15 surface is clean and PVP is removed after calcination.Pt/SBA-15 shows excellent activity toward hydrogenation of cinnamaldehyde reaction,but poor selectivity of desired product.For CO oxidation reaction,reaction rate is high at initial stage,while the reaction rate is decreasing as the reaction is going on.