杨梅单宁接枝胶原纤维负载Pt催化剂的制备及其催化硝基苯加氢的研究

Preparation of Pt nanoparticle catalyst supported by bayberry tannin grafted collagen fiber and its catalytic hydrogenation of nitrobenzene

以杨梅单宁接枝胶原纤维为载体,制备了新型负载铂(Pt)纳米催化剂。杨梅单宁作为桥分子,通过其邻位酚羟基与Pt(IV)形成五元螯合环并固定在胶原纤维上。还原过程中,杨梅单宁能有效地抑制Pt纳米颗粒的团聚。通过扫描电镜(SEM)、透射电镜(TEM)、X-射线光电子分光光谱(XPS)以及X-射线衍射(XRD)等分析手段对该催化剂的物化性能进行了表征,结果表明该催化剂具有规整的纤维结构,且在胶原纤维的外表面形成了具有高分散性、平均粒径在2.8±0.5nm的Pt(0)纳米颗粒。该催化剂用于硝基苯催化加氢反应中,在较温和的条件下显示出了较高的催化活性(TOF=1097mol/(molPt·h))、高选择性(98%)以及较低的活化能(Ea=30.49kJ/mol)。通过改变胶原纤维表面杨梅单宁的接枝度,可以有效控制催化剂对硝基苯的催化反应速率。该催化剂重复使用5次后,催化活性没有降低,表明该催化剂具有良好的重复使用特性。

A novel heterogeneous Pt nanoparticle catalyst was synthesized using bayberry tannin grafted collagen fiber as supporting material.Bayberry tannin was selected as a bridge molecule to chelate with Pt （Ⅳ） ions with its adjacent hydroxyls to form five members ring,which were immobilized on the outer surface of collagen fiber.Bayberry tannin subsequently can prevent the coalescing of Pt nanoparticles during the chemical reduction.The main physical and chemical properties of the catalyst were characterized by scanning electron microscopy （SEM）,X-ray photoelectron spectroscopy （XPS）,transmission electron microscopy （TEM） and X-ray diffraction （XRD）.It was found that the catalyst is in highly ordered fibrous state,and the supported Pt nanoparticles with average diameter of 2.8 ± 0.5 nm are uniformly dispersed on the outer surface of collagen fiber.The catalytic hydrogenation of nitrobenzene of the catalyst was investigated.It was found that Pt nanoparticles supported on bayberry tannin grafted collagen fiber exhibited outstanding activity （TOF=1097 mol/（mol Pt·h））,high selectivity （98%） and low activation energy （Ea=30.49 kJ/mol）.The catalyst has been reused for five times without decrease of ability,which suggests the high recyclability and stability of the catalyst.