Phenol is its own selectivity promoter in low-temperature liquid-phase hydrogenation

Phenol hydrogenation is widely studied for selective production of the chemical intermediate cyclohexanone. A plethora of studies in the literature have reported catalysts aiming to achieve high selectivity compared to Pd/C. However, we demonstrate that selective and high-yielding reactions are inherent features of liquid-phase phenol hydrogenation using conventional Pd/C catalysts. We also show there is a very strong dependance of selectivity upon conversion, with high selectivity being maintained until near complete consumption of the phenol, after which subsequent reaction to the unwanted, fully hydrogenated cyclohexanol occurs rapidly. Furthermore, through competitive reactions with other aromatic molecules it is demonstrated that the phenol molecule effectively self-poisons the onwards reaction of weakly bound cyclohexanone, likely by virtue of its relative adsorption strength, and this is the source of the intrinsic selectivity. The implications of this to the reaction mechanism, and in turn to the rational design of catalysts, especially for obtaining chemicals from phenolic bio-oils, are discussed

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

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

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

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

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

The effects of MTG catalysis on methanol mobility in ZSM-5

The UK Catalysis Hub is thanked for resources and support provided via our membership of the UK Catalysis Hub Consortium and funded by EPSRC (grants EP/I038748/1, EP/I019693/1, EP/K014706/1, EP/K014668/1, EP/K014854/1, EP/ K014714/1 and EP/M013219/1). A. J. O. M. would like to acknowledge the Ramsay Trust for provision of the Ramsay Trust Memorial Fellowship. The STFC Rutherford Appleton Laboratory is thanked for access to neutron beam facilities.Peer reviewedPublisher PD

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

Mutations in the PP2A regulatory subunit B family genes PPP2R5B, PPP2R5C and PPP2R5D cause human overgrowth

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