TiO_2纳米管负载铂催化剂催化完全氧化甲醛

Complete catalytic oxidation of formaldehyde over Pt-supported TiO_2 nanotubes

采用阳极氧化法制备了管径均匀、排列规整的TiO2纳米管阵,负载Pt之后直接用于动态条件下60mg/m3甲醛的催化氧化脱除.实验结果表明在空速为60000h-1以及100℃条件下,该纳米管催化剂对甲醛转化率高达98%,并且100%转化为二氧化碳和水.采用SEM、XRD和TPR对TiO2纳米管及纳米管催化剂进行了分析.结果表明TiO2纳米管管径约为130nm,经过450℃煅烧2h后由无定形转化成锐钛矿型,负载质量分数为1%的Pt不会改变纳米管的晶型,但是出现了氧化铂的晶相峰,表明Pt在纳米管上没有得到充分的分散,进而说明有望通过进一步提高Pt在纳米管上的超微分散以提高其催化性能;Pt负载在纳米管上使得催化剂表面活性氧物种增多,同时导致Ti—O键减弱,晶格氧的流动性有所增加,进而促进了纳米管表面氧的活性.通过本文的研究我们得出:1%Pt/TiO2在温和条件下对甲醛催化氧化反应具有良好的催化效果,有望通过进一步的研究,实现在更为温和的条件下对室内甲醛的完全催化氧化脱除.

Highly-ordered and uniform TiO2 nanotube arrays are fabricated by anodization and after supporting Pt they are applied directly in the catalytic oxidation of 60 mg/m3 formaldehyde under dynamic conditions. Experiment results indicate that the as-prepared nanotube catalyst exhibits excellent activity towards formaldehyde oxidation,with 98% conversion of HCHO and 100% conversion to CO2 and H2O under 60000 h-1 GHSV and 100 ℃. SEM,XRD and TPR are used for the characterization of TiO2 nanotubes and the corresponding catalyst. The diameter of the resulting TiO2 nanotubes is about 130nm and it changes from amorphous to anatase after 2h＇s calcination at 450 ℃. Supporting 1% Pt does not change the crystal structure of nanotubes,but the peaks corresponding to platinum oxide appear in XRD patterns. This finding indicates Pt is not highly dispersed on TiO2 nanotubes,which further indicates the catalytic acitivity may be promoted by enhancing Pt dispersion on nanotubes. From TPR result,supported Pt not only brings out more surface oxygen species,but also weakens Ti—O bond and enhances the mobility of crystal oxygen,which furter promote the activity of surface oxygen over nanotubes. Therefore,we come to the conclusion that 1% Pt/TiO2-NT exhibits excellent activity in the oxidation of formaldehyde under ambient conditions and that the complete catalytic oxidation of indoor formaldehyde under even more ambient conditions may be achieved through further investigation.