大比表面三维介孔MCM-48分子筛负载Pt催化氧化甲苯  

Pt supported by three-dimensional mesoporous MCM-48 with large specific surface area for toluene catalytic oxidation

作　　者：于庆君 高巍 庄瑞杰 易红宏 唐晓龙 YU Qingjun;GAO Wei;ZHUANG Ruijie;YI Honghong;TANG Xiaolong(Department of Environmental Science and Engineering,School of Energy and Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,China;Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants,Beijing 100083,China)

机构地区：[1]北京科技大学能源与环境工程学院环境科学与工程系,北京100083 [2]工业典型污染物资源化处理北京市重点实验室,北京100083

出　　处：《材料工程》2023年第4期29-38,共10页Journal of Materials Engineering

基　　金：中央高校基本科研业务费专项资金项目(FRF-IDRY-20-004);重质油国家重点实验室开放基金资助(SKLOP202002001);国家自然科学基金联合基金项目重点支持项目(U20A20130);国家环境保护食品链污染防治重点实验室开放课题基金资助(FC2021YB05)。

摘　　要：采用自合成大比表面三维有序介孔分子筛MCM-48(≈1400 m^(2)/g)为载体,其上负载Pt,获得负载型Pt/MCM-48,应用于甲苯催化燃烧,与微孔分子筛Silicalite-2、介孔分子筛材料SBA-15和MCM-41以及商用SiO_(2)等硅基载体相比,展示出优异的低温催化氧化性能。在此基础上,考察不同Pt负载量对负载型Pt/MCM-48催化燃烧甲苯性能的影响,筛选出的1%(质量分数)理论负载量的催化剂具备最佳催化氧化性能。对等体积浸渍法、原位合成法、甲醇法、乙二醇法等不同引入方式的考察发现,等体积浸渍法与原位合成法向载体上引入Pt的实际负载量接近于理论添加量,相比之下,甲醇法、乙二醇法等溶剂法获得Pt实际负载量远低于理论负载量。转化频率(turnover frequency, TOF)计算结果表明,甲醇法获得的Pt/MCM-48中Pt转化效率以及Pt原子利用率最高。BET,XPS,STEM以及H_(2)-TPR等表征充分证明,MCM-48超大的比表面为Pt的分散提供了有利条件,有助于获得高比例Pt^(0);有序的三维介孔结构则大大提高活性位点的可接近性,并减小甲苯分子的扩散阻力,因此呈现出优异的催化氧化甲苯性能。此外,GC-MS研究表明甲苯在Pt/MCM-48上首先转化为醛/酚/酸类中间产物,最终实现深度催化氧化成为二氧化碳。Supported catalyst Pt/MCM-48 was prepared by using MCM-48 with large specific surface area of≈1400 m^(2)/g as a support and applied for catalytic combustion of toluene.Compared with using microporous Silicalite-2,mesoporous molecular sieves SBA-15 and MCM-41 as well as commercial SiO_(2) as a support,the catalyst with MCM-48 as a support exhibits the best catalytic performance for toluene oxidation,demonstrating the highest catalytic performance for toluene oxidation.Then,the effect of various Pt loading amount on toluene oxidation was investigated and it was found that Pt/MCM-48 with 1%(mass fraction)Pt exhibits the best catalytic performance.Various introduction ways of Pt into support materials were compared among incipient-wetness impregnation method,in-situ synthesis method,methanol method and ethylene glycol method.The results indicate that the actual amount of Pt introduced in MCM-48 is similar to the theoretical amount via impregnation method and in-situ synthesis method,while is much less than the theoretical amount by using the solvent method.Nevertheless,both highest toluene conversion efficiency of Pt and the utilization rate of Pt atom are obtained over the Pt/MCM-48 by using methanol method.However,how to improve the actual Pt loading amount despite of keeping the high utility of single Pt atom is what we should focus on in the near future.Several characterizations,i.e.,BET,XPS,STEM and H_(2)-TPR etc.,provide solid proofs that the MCM-48 with large specific surface area provide favorable condition for the high dispersion and good distribution of Pt in the support,which is beneficial for obtaining high proportion of Pt^(0).Meanwhile,the ordered three-dimensional mesoporous structure greatly improves the accessibility of the active sites and decreases the diffusion resistance of toluene,hence,greatly contributes to the superior toluene oxidation ability.In addition,GC-MS results show that toluene is firstly converted to the intermediates of aldehydes/phenols/acids,etc.on Pt/MCM-48,and finally conver

关 键 词：大比表面 MCM-48 PT 甲苯 催化氧化 

分 类 号：X511[环境科学与工程—环境工程]