The Dynamics of Adsorption on Clean and Adsorbate-Modified Transition Metal and Metal Oxide Surfaces

PDF Version Also Available for Download.

Description

Research directed toward understanding the dynamical factors governing the adsorption of molecules typically involved in heterogeneous catalytic processes has been continued. Adsorption is the first step in any catalytic process, and predictions of rates of adsorption are fundamental to calculations of rates of catalytic reactions. Dissociative adsorption can occur either directly upon impact with the surface or as the result of the migration of a temporarily trapped species across the surface. Alkane activation exhibits both of these pathways for reaction on metal surfaces. We have focused on the dynamics of dissociative adsorption of low molecular weight alkanes on single crystal ... continued below

Creation Information

Madix, Robert J. March 31, 2006.

Context

This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided by UNT Libraries Government Documents Department to Digital Library, a digital repository hosted by the UNT Libraries. More information about this report can be viewed below.

Who

People and organizations associated with either the creation of this report or its content.

Publisher

Provided By

UNT Libraries Government Documents Department

Serving as both a federal and a state depository library, the UNT Libraries Government Documents Department maintains millions of items in a variety of formats. The department is a member of the FDLP Content Partnerships Program and an Affiliated Archive of the National Archives.

Contact Us

What

Descriptive information to help identify this report. Follow the links below to find similar items on the Digital Library.

Description

Research directed toward understanding the dynamical factors governing the adsorption of molecules typically involved in heterogeneous catalytic processes has been continued. Adsorption is the first step in any catalytic process, and predictions of rates of adsorption are fundamental to calculations of rates of catalytic reactions. Dissociative adsorption can occur either directly upon impact with the surface or as the result of the migration of a temporarily trapped species across the surface. Alkane activation exhibits both of these pathways for reaction on metal surfaces. We have focused on the dynamics of dissociative adsorption of low molecular weight alkanes on single crystal surfaces of platinum group metals. The overall objective of these studies was to make a quantitative comparison of the dissociation probabilities of C{sub 2}-C{sub 4} alkanes on different metals in order to assess the effects of the structures of the different alkanes and the intrinsic differences of the metals on reactivity. First, an unusual and somewhat unexpected difference is observed in the reactivity of linear and branched alkanes. Further, the reactivity of each alkane is significantly higher on Pt(111) than on Pd(111). It has also been observed that the trapping probabilities for the alkanes are higher on Pd(111) due to a larger dissipation of energy to lattice vibrations upon collision, suggesting that energy dissipation in the reaction coordinate into phonons may be involved in dissociative adsorption. We have thus focused on the dynamics of dissociative adsorption of low molecular weight alkanes on single crystal surfaces of platinum, palladium and nickel in order to assess the role of energy dissipation from the incident molecule and the differences of the reactivity of the different metals. We observe that the reactivity of each of the alkanes studied to date differs by only a small amount. On the contrary, due to the dissipation of incident translational energy to lattice vibrations upon collision, the trapping probabilities for the alkanes differ appreciably for the three surfaces. There thus appears to be no correlation between the large differences observed in the trapping probabilities and the reactivity of the surfaces for direct collisional activation of the alkanes, suggesting that no significant amount of the incident kinetic energy of the alkane is dissipated from the reaction coordinate into lattice vibrations. Further, the differences in reactivities of different alkanes on these surfaces appears to originate from steric differences in the accessibility of C-H bonds during the collisional encounter with the surface.

Language

Item Type

Identifier

Unique identifying numbers for this report in the Digital Library or other systems.

  • Report No.: DOE/ER/15511-1 - Final Report
  • Grant Number: FG02-04ER15511
  • DOI: 10.2172/1001764 | External Link
  • Office of Scientific & Technical Information Report Number: 1001764
  • Archival Resource Key: ark:/67531/metadc839538

Collections

This report is part of the following collection of related materials.

Office of Scientific & Technical Information Technical Reports

What responsibilities do I have when using this report?

When

Dates and time periods associated with this report.

Creation Date

  • March 31, 2006

Added to The UNT Digital Library

  • May 19, 2016, 3:16 p.m.

Description Last Updated

  • Dec. 5, 2016, 2:33 p.m.

Usage Statistics

When was this report last used?

Yesterday: 0
Past 30 days: 0
Total Uses: 2

Interact With This Report

Here are some suggestions for what to do next.

Start Reading

PDF Version Also Available for Download.

Citations, Rights, Re-Use

Madix, Robert J. The Dynamics of Adsorption on Clean and Adsorbate-Modified Transition Metal and Metal Oxide Surfaces, report, March 31, 2006; United States. (digital.library.unt.edu/ark:/67531/metadc839538/: accessed September 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.