title: The cluster beam route to model catalysts and beyond.
abstract: The generation of beams of atomic clusters in the gas phase and their subsequent deposition (in vacuum) onto suitable catalyst supports, possibly after an intermediate mass filtering step, represents a new and attractive approach for the preparation of model catalyst particles. Compared with the colloidal route to the production of pre-formed catalytic nanoparticles, the nanocluster beam approach offers several advantages: the clusters produced in the beam have no ligands, their size can be selected to arbitrarily high precision by the mass filter, and metal particles containing challenging combinations of metals can be readily produced. However, until now the cluster approach has been held back by the extremely low rates of metal particle production, of the order of 1 microgram per hour. This is more than sufficient for surface science studies but several orders of magnitude below what is desirable even for research-level reaction studies under realistic conditions. In this paper we describe solutions to this scaling problem, specifically, the development of two new generations of cluster beam sources, which suggest that cluster beam yields of grams per hour may ultimately be feasible. Moreover, we illustrate the effectiveness of model catalysts prepared by cluster beam deposition onto agitated powders in the selective hydrogenation of 1-pentyne (a gas phase reaction) and 3-hexyn-1-ol (a liquid phase reaction). Our results for elemental Pd and binary PdSn and PdTi cluster catalysts demonstrate favourable combinations of yield and selectivity compared with reference materials synthesised by conventional methods.
authors.affiliation: Johnson Matthey Technology Centre, Blount's Court, Sonning Common, Reading RG4 9NH, UK. r.e.palmer@bham.ac.uk.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Ellis
authors.affiliation: Johnson Matthey Technology Centre, Blount's Court, Sonning Common, Reading RG4 9NH, UK. r.e.palmer@bham.ac.uk.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Brown
authors.affiliation: Johnson Matthey Technology Centre, Blount's Court, Sonning Common, Reading RG4 9NH, UK. r.e.palmer@bham.ac.uk.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Bishop
authors.affiliation: Teer Coatings Ltd., Miba Coating Group, West Stone House, West Stone, Berry Hill Industrial Estate, Droitwich, Worcestershire WR9 9AS, UK.
authors.forename: Jinlong
authors.initials: J
authors.lastname: Yin
authors.affiliation: Teer Coatings Ltd., Miba Coating Group, West Stone House, West Stone, Berry Hill Industrial Estate, Droitwich, Worcestershire WR9 9AS, UK.
authors.forename: Kevin
authors.initials: K
authors.lastname: Cooke
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: William D
authors.initials: WD
authors.lastname: Terry
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Jian
authors.initials: J
authors.lastname: Liu
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Feng
authors.initials: F
authors.lastname: Yin
authors.affiliation: Nanoscale Physics Research Laboratory, School of Physics and Astronomy, University of Birmingham, Birmingham B15 2TT, UK.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Palmer