title: A high precision gas flow cell for performing in situ neutron studies of local atomic structure in catalytic materials.
abstract: Gas-solid interfaces enable a multitude of industrial processes, including heterogeneous catalysis; however, there are few methods available for studying the structure of this interface under operating conditions. Here, we present a new sample environment for interrogating materials under gas-flow conditions using time-of-flight neutron scattering under both constant and pulse probe gas flow. Outlined are descriptions of the gas flow cell and a commissioning example using the adsorption of N2by Ca-exchanged zeolite-X (Na78-2xCaxAl78Si144O384,x ≈ 38). We demonstrate sensitivities to lattice contraction and N2adsorption sites in the structure, with both static gas loading and gas flow. A steady-state isotope transient kinetic analysis of N2adsorption measured simultaneously with mass spectrometry is also demonstrated. In the experiment, the gas flow through a plugged-flow gas-solid contactor is switched between N215 and N214 isotopes at a temperature of 300 K and a constant pressure of 1 atm; the gas flow and mass spectrum are correlated with the structure factor determined from event-based neutron total scattering. Available flow conditions, sample considerations, and future applications are discussed.
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Daniel
authors.identifier: 0000000246114113
authors.initials: D
authors.lastname: Olds
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Katharine
authors.identifier: 0000000290713383
authors.initials: K
authors.lastname: Page
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Arnold
authors.identifier: 0000000341801923
authors.initials: A
authors.lastname: Paecklar
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Peter F
authors.identifier: 0000000213530348
authors.initials: PF
authors.lastname: Peterson
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Jue
authors.initials: J
authors.lastname: Liu
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: Rucker
authors.affiliation: Spallation Neutron Source, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Mariano
authors.identifier: 000000029368766X
authors.initials: M
authors.lastname: Ruiz-Rodriguez
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: Michael
authors.identifier: 0000000322614823
authors.initials: M
authors.lastname: Olsen
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Michelle
authors.initials: M
authors.lastname: Pawel
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, One Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Overbury
authors.affiliation: Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Neilson