Ultrafast 2D-IR spectroscopy of intensely optically scattering pelleted solid catalysts

ACKNOWLEDGMENTS This work was supported by a UKRI Future Leaders Fellowship grant (Grant No. MR/S015574/1), STFC-UKRI program access to CLF-ULTRA (Grant No. LSF1828), direct access to CLF-ULTRA (Grant Nos. Apps 17330043 and 19130012), and a group residency in the Research Complex at Harwell (RCaH). The authors are grateful to Kathryn Welsby, Ivalina Minova, and Santhosh Matam for support early in the project with samples and the Linkam cell. Mr. John Still of the School of Geosciences, University of Aberdeen is thanked for the SEM images, and Kieran Farrell/Martin Zanni is thanked for the discussion about the polarizations of the beams creating the thermal transientsPeer reviewedPublisher PD

Investigation of the dynamics of 1-octene adsorption at 293 K in a ZSM-5 catalyst by inelastic and quasielastic neutron scattering

The properties of 1-octene adsorbed in zeolite ZSM-5 at 293 K are studied by means of inelastic and quasielastic neutron scattering (INS and QENS) in order to investigate interactions relevant to the zeolite solid acid catalysis of fluidised catalytic cracking reactions. The INS spectrum is compared to that recorded for the solid alkene and reveals significant changes of bonding on adsorption at ambient temperatures; the changes are attributed to the oligomerization of the adsorbed 1-octene to form a medium chain n-alkane or n-alkane cation. QENS analysis shows that these oligomers are immobilised within the zeolite pore structure but a temperature-dependant fraction is able to rotate around their long axis within the pore channels

Studies of propene conversion over H-ZSM-5 demonstrate the importance of propene as an intermediate in methanol-to-hydrocarbons chemistry

Funding Information: Johnson Matthey plc. is thanked for supplying the ZSM-5 zeolite and for financial support through the provision of industrial CASE studentships in partnership with the EPSRC (APH (EP/P510506/1), AZ (EP/N509176/1)). Experiments at the ISIS Neutron and Muon Source were made possible by a beam time allocation from the Science and Technologies Facilities Council. 53 The resources and support provided by the UK Catalysis Hubviamembership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1 are gratefully acknowledged. This research has been performed with the use of facilities and equipment at the Research Complex at Harwell; the authors are grateful to the Research Complex for this access and support.Peer reviewedPublisher PD

The Methyl Torsion in Unsaturated Compounds

The STFC Rutherford Appleton Laboratory is thanked for funding and access to neutron beam facilities. Computing resources (time on the SCARF compute cluster for the CASTEP calculations) was provided by STFC’s e-Science facility. Dr John Tomkinson (ISIS) is thanked for generously providing the INS spectra of the toluene isotopomers. A.Z. and A.P.H. would like to thank Johnson Matthey plc. For financial support through the provision of industrial CASE studentships in partnership with the EPSRC. The UK Catalysis Hub is kindly thanked for resources and support provided via our membership of the UK Catalysis Hub Consortium and funded by EPSRC grant: EP/R026939/1, EP/R026815/1, EP/R026645/1, EP/R027129/1 or EP/M013219/1(biocatalysis).Peer reviewedPublisher PD

Onset of propene oligomerization reactivity in ZSM-5 studied by inelastic neutron scattering spectroscopy

The techniques of quasi-elastic and inelastic neutron scattering (QENS and INS) are applied to investigate the oligomerization of propene over a ZSM-5 zeolite. Investigations are performed at low temperatures, allowing identification of the onset of the oligomerization reaction and observation of the low-energy spectral changes due to intermediate formation that are difficult to observe by optical methods. Oligomerization proceeds via formation of a hydrogen-bonded precursor by an interaction of the propene with an internal acid site followed by protonation and chain growth with protonation being the rate-limiting step. The use of quasi-elastic neutron scattering to observe changes in system mobility with temperature via the elastic window scan technique allows identification of the active temperature range where catalyst activity commences and permits targeting of the more time-consuming INS investigations to conditions of interest. From examination of the product’s spectrum, the structure of the resulting oligomer is deduced to be primarily linear

New Spectroscopic Insight into the Deactivation of a ZSM-5 Methanol-to-Hydrocarbons Catalyst

Funding Information: Johnson Matthey plc. is thanked for supplying the ZSM‐5 zeolite and for financial support through the provision of industrial CASE studentships in partnership with the EPSRC (APH (EP/P510506/1), AZ (EP/N509176/1)). Experiments at the ISIS Neutron and Muon Source were made possible by a beam time allocation from the Science and Technologies Facilities Council. The resources and support provided by the UK Catalysis Hub membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1 are gratefully acknowledged. This research has been performed with the use of facilities and equipment at the Research Complex at Harwell; the authors are grateful to the Research Complex for this access and support. Dr Andrea Sauerwein and Dr Jonathan Bradley (Johnson Matthey) are thanked for their help in acquiring the Si and Al NMR spectra using the Bruker Avance Neo spectrometer.Peer reviewedPublisher PD

Cluster-Cluster Microlensing as a Probe of Intracluster Stars, MACHOs, and Remnants of the First Generation Stars

The galaxy cluster Abell 2152 is recently found to be forming a cluster-cluster system with another, more distant cluster whose core is almost perfectly aligned to that of A2152. We discuss the detectability of microlensing events where a single star in the source cluster behind A2152 is extremely magnified by an intracluster compact object in A2152. We show that a search with an 8m-class telescope with a wide field of view, such as the Subaru/Suprime-Cam, can probe intracluster compact objects with a wide mass range of m_{co} ~ 10^{-5}-10^{10} M_sun, including ranges that have not yet been constrained by any past observations. We expect that the event rate is biased for the background cluster than the foreground cluster (A2152), which would be a unique signature of microlensing, making this experiment particularly powerful. The sensitivity of this experiment for the mass fraction of compact objects would be 1-10% in the total dark matter of the cluster, which is roughly constant against m_{co}, with a reasonable telescope time for large telescopes (~10 nights). Therefore any compact objects in this mass range can be detected or rejected as the dominant component of the dark matter. About 10 events are expected if 20% of the cluster mass is in a form of compact objects with M ~ 1 M_sun, as claimed by the MACHO collaboration for the Milky Way halo. Other possibly detectable targets include intracluster stars stripped by galaxy interactions, and hypothetical very massive black holes (M >~ 100 M_sun) produced as remnants of the first generation stars, which might be responsible for the recently reported excess of the cosmic infrared background radiation that seems impossible to explain by normal galactic light.Comment: 14 pages, 6 figures, to appear in ApJ. Some minor corrections, and references adde

Inelastic neutron scattering studies of propene and 1-octene oligomerisation in HZSM-5

Neutron scattering methods (quasielastic neutron scattering (QENS) and inelastic neutron scattering (INS)) have been used to study the reactivity of propene and 1-octene over the acid zeolite catalyst H-ZSM 5. The high activity of the catalyst causes the alkenes to form linear oligomers below room temperature. INS has shown that the reaction proceeds through a hydrogen-bonded intermediate. Studies using propane as an inert analogue for propene have found that the adsorbed C3 molecules spend the majority of their time undergoing short jumps within the pore channels of the zeolite. Hydrothermal de-alumination plays an important role in determining the activity of zeolite catalysts. De-alumination was found to delay the onset of catalytic activity for oligomerization to higher temperatures and increase the mobility of hydrocarbons within the zeolite, both due to reduced acid-hydrocarbon interactions

Counting the Acid Sites in a Commercial ZSM-5 Zeolite Catalyst

This work was funded by Johnson Matthey plc. through the provision of industrial CASE studentships in partnership with the EPSRC (AZ (EP/N509176/1), APH (EP/P510506/1)). Experiments at the ISIS Neutron and Muon Source were made possible by beam time allocations from the Science and Technologies Facilities Council.45,46 Resources and support were provided by the UK Catalysis Hub via membership of the UK Catalysis Hub consortium and funded by EPSRC grants EP/R026815/1 and EP/R026939/1Peer reviewedPublisher PD