Reactions of methylcyclopentane on Rh–Pt catalyst prepared by underpotential deposition of Rh on Pt/SiO2
Reactions of methylcyclopentane on Rh–Pt catalyst prepared by underpotential deposition of Rh on Pt/SiO2
复制标题
DOI：
10.1007/s11244-007-0315-7
复制
发表时间：
2007-09
影响因子：
3.6
通讯作者：
N. Győrffy;A. Wootsch;S. Szabó;I. Bakos;L. Tóth;Z. Paâl
中科院分区：
文献类型：
--
作者：
N. Győrffy;A. Wootsch;S. Szabó;I. Bakos;L. Tóth;Z. Paâl
采用欠电位沉积法将Rh沉积在表征良好的3.1% Pt/SiO2（InCat-1）母催化剂上，得到模型Rh - Pt双金属催化剂。用TEM和EDS测定了其平均粒径和体积组成：约3 nm的颗粒含有约60%的Pt和40%的Rh。以甲基环戊烷（MCP）为催化剂，在513 ~ 603 K、60 ~ 480 Torr H2pressure （10 Torr MCP）条件下进行反应。还研究了Pt/ sio2母体和5% Rh/ sio2催化剂的对比。在催化运行前，对双金属催化剂进行了4次o2和H2up toT= 673 K的后续处理。所有样品的总体活性均为正氢序，双金属铑铂导致TOF值最低。MCP可生成开环产物和氢解产物以及不饱和烃。Rh - Pt催化剂上开环产物和碎片的选择性介于Pt和Rh之间，而双金属样品对苯形成的选择性最高，特别是在较高温度下。所有样品都发生了“选择性”开环，主要产生2 -甲基戊烷和3-甲基戊烷，己烷较少。不同的h2o2预处理对Rh-Pt样品的分散值和催化行为影响较小。Rh - Pt催化剂的选择性介于Pt/ sio2和Rh/ sio2之间，表明所研究的样品是一种真正的双金属催化剂，与这两种组分相似，同时表现出Pt或Rh特征之外的新性质。
Rh was deposited on to a well-characterized 3.1% Pt/SiO2(InCat-1) parent catalyst by underpotential deposition method to obtain a model Rh–Pt bimetallic catalyst. TEM and EDS was used to determine its mean particle size and bulk composition: the particles of ca. 3 nm contained ca. 60% Pt and 40% Rh. The Rh–Pt catalyst was tested in methylcyclopentane (MCP) reaction between 513 K and 603 K and 60–480 Torr H2pressure (with 10 Torr MCP). The parent Pt/SiO2as well as a 5% Rh/SiO2catalyst were also studied for comparison. Four subsequent treatments with O2and H2up toT= 673 K were applied on the bimetallic catalyst before the catalytic runs. The overall activity showed positive hydrogen order on all samples, bimetallic Rh–Pt resulting in the lowest TOF values. Ring opening and hydrogenolysis products, as well as unsaturated hydrocarbons were formed from MCP. The selectivity of ring opening products and fragments over Rh–Pt catalyst was between the values observed on Pt and Rh, while the selectivity towards benzene formation was highest on the bimetallic sample, especially at higher temperatures. “Selective” ring opening occurred on all samples, resulting mostly in 2 and 3-methylpentane and less hexane. Different pretreatments with H2and O2affected slightly the dispersion values and the catalytic behavior of Rh–Pt sample. The selectivities of the Rh–Pt catalyst being between the values observed for Pt/SiO2and Rh/SiO2indicates that the sample studied represented a real bimetallic catalyst, resembling both components and exhibiting at the same time, new properties in addition to those, characteristic of Pt or Rh.