The Experts below are selected from a list of 66 Experts worldwide ranked by ideXlab platform
Cyril T. O'connor - One of the best experts on this subject based on the ideXlab platform.
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Effect of stirring, extrusion and pelletisation on high pressure propene oligomerisation and xylene isomerisation over ZSM-5
Applied Catalysis, 2001Co-Authors: S. Schwarz, M. Kojima, Cyril T. O'connorAbstract:Abstract The effect of stirring a ZSM-5 synthesis mixture was to decrease the crystal size. Mechanical stirring was more effective than magnetic stirring. Static synthesis conditions yielded a number average crystal size of 2.4 μm, and stirring decreased the crystal size to as low as 0.4 μm. The decrease in crystal size improved Catalyst lifetime and activity for propene oligomerisation at 250°C, WHSV ca. 12 h-1 and 5 MPa, with the CUV (Catalyst Utilisation value in g liquid produced/g Catalyst) increasing from 110 g/g for an unstirred sample to about 400 g/g for a mechanically stirred sample. Extrusion had no detrimental effect on lifetime and activity for propene oligomerisation, while activity and lifetime decreased with the wt.-% coke deposited in ZSM-5 by ca. 50%. Extrudates yielded heavier liquid products than powder during oligomerisation, probably due to better temperature control in extrudate Catalyst beds. The cetane numbers computed for the hydrogenated liquid fractions obtained with powdered and extruded Catalysts were similar to that obtained for a sample of commercial diesel. However, product obtained from pelletised Catalysts yielded higher cetane numbers. For xylene isomerisation, powdered Catalyst was more active than extrudates and pellets.
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Effect of tetraalkylammonium, alcohol and amine templates on the synthesis and high pressure propene oligomerisation activity of ZSM-type zeolites
Applied Catalysis, 1991Co-Authors: S. Schwarz, M. Kojima, Cyril T. O'connorAbstract:Abstract Various tetraalkylammonium ions (alkyl = methyl, ethyl, propyl, butyl), amines and alcohols have been used to synthesise ZSM-type zeolites under identical conditions. The TMA, TEA, TPA and TBA ions yielded amorphous material, ZSM-8, ZSM-5 and ZSM-11, respectively. X-ray diffraction showed that amine templates produced ZSM-5/ZSM-11 intergrowths with relative crystallinities between 80 and 100%, while alcohols yielded ZSM-5 with ca. 60% crystallinity. Only ZSM-11 and the C6-diamine-based zeolites had very similar characteristics to those of TPA-based ZSM-5, viz. ca. 100% crystallinity, a number average crystal size of ca. 1 μm and a morphology of spherical aggregates. Amine-based zeolites with lower carbon numbers exhibited crystal sizes between 3 and 5 μm, while all alcohol-based zeolites had crystal sizes ranging from 4 to 6 μm. It was observed that only Catalysts that had similar characteristics to TPA-ZSM-5 performed well as propene oligomerisation Catalysts at 250°C, 5 MPa and a weight hourly space velocity of about 12 h−1. The Catalyst Utilisation values for TPA-based ZSM-5, ZSM-11 1,6-hexanediamine and 1,2-cyclohexanediamine-based zeolites were approximately 300 g liquid/g Catalyst. All other Catalysts performed relatively poorly and an inverse relationship between crystal size and Catalyst performance was observed.
S. Schwarz - One of the best experts on this subject based on the ideXlab platform.
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Effect of stirring, extrusion and pelletisation on high pressure propene oligomerisation and xylene isomerisation over ZSM-5
Applied Catalysis, 2001Co-Authors: S. Schwarz, M. Kojima, Cyril T. O'connorAbstract:Abstract The effect of stirring a ZSM-5 synthesis mixture was to decrease the crystal size. Mechanical stirring was more effective than magnetic stirring. Static synthesis conditions yielded a number average crystal size of 2.4 μm, and stirring decreased the crystal size to as low as 0.4 μm. The decrease in crystal size improved Catalyst lifetime and activity for propene oligomerisation at 250°C, WHSV ca. 12 h-1 and 5 MPa, with the CUV (Catalyst Utilisation value in g liquid produced/g Catalyst) increasing from 110 g/g for an unstirred sample to about 400 g/g for a mechanically stirred sample. Extrusion had no detrimental effect on lifetime and activity for propene oligomerisation, while activity and lifetime decreased with the wt.-% coke deposited in ZSM-5 by ca. 50%. Extrudates yielded heavier liquid products than powder during oligomerisation, probably due to better temperature control in extrudate Catalyst beds. The cetane numbers computed for the hydrogenated liquid fractions obtained with powdered and extruded Catalysts were similar to that obtained for a sample of commercial diesel. However, product obtained from pelletised Catalysts yielded higher cetane numbers. For xylene isomerisation, powdered Catalyst was more active than extrudates and pellets.
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Effect of tetraalkylammonium, alcohol and amine templates on the synthesis and high pressure propene oligomerisation activity of ZSM-type zeolites
Applied Catalysis, 1991Co-Authors: S. Schwarz, M. Kojima, Cyril T. O'connorAbstract:Abstract Various tetraalkylammonium ions (alkyl = methyl, ethyl, propyl, butyl), amines and alcohols have been used to synthesise ZSM-type zeolites under identical conditions. The TMA, TEA, TPA and TBA ions yielded amorphous material, ZSM-8, ZSM-5 and ZSM-11, respectively. X-ray diffraction showed that amine templates produced ZSM-5/ZSM-11 intergrowths with relative crystallinities between 80 and 100%, while alcohols yielded ZSM-5 with ca. 60% crystallinity. Only ZSM-11 and the C6-diamine-based zeolites had very similar characteristics to those of TPA-based ZSM-5, viz. ca. 100% crystallinity, a number average crystal size of ca. 1 μm and a morphology of spherical aggregates. Amine-based zeolites with lower carbon numbers exhibited crystal sizes between 3 and 5 μm, while all alcohol-based zeolites had crystal sizes ranging from 4 to 6 μm. It was observed that only Catalysts that had similar characteristics to TPA-ZSM-5 performed well as propene oligomerisation Catalysts at 250°C, 5 MPa and a weight hourly space velocity of about 12 h−1. The Catalyst Utilisation values for TPA-based ZSM-5, ZSM-11 1,6-hexanediamine and 1,2-cyclohexanediamine-based zeolites were approximately 300 g liquid/g Catalyst. All other Catalysts performed relatively poorly and an inverse relationship between crystal size and Catalyst performance was observed.
M. Kojima - One of the best experts on this subject based on the ideXlab platform.
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Effect of stirring, extrusion and pelletisation on high pressure propene oligomerisation and xylene isomerisation over ZSM-5
Applied Catalysis, 2001Co-Authors: S. Schwarz, M. Kojima, Cyril T. O'connorAbstract:Abstract The effect of stirring a ZSM-5 synthesis mixture was to decrease the crystal size. Mechanical stirring was more effective than magnetic stirring. Static synthesis conditions yielded a number average crystal size of 2.4 μm, and stirring decreased the crystal size to as low as 0.4 μm. The decrease in crystal size improved Catalyst lifetime and activity for propene oligomerisation at 250°C, WHSV ca. 12 h-1 and 5 MPa, with the CUV (Catalyst Utilisation value in g liquid produced/g Catalyst) increasing from 110 g/g for an unstirred sample to about 400 g/g for a mechanically stirred sample. Extrusion had no detrimental effect on lifetime and activity for propene oligomerisation, while activity and lifetime decreased with the wt.-% coke deposited in ZSM-5 by ca. 50%. Extrudates yielded heavier liquid products than powder during oligomerisation, probably due to better temperature control in extrudate Catalyst beds. The cetane numbers computed for the hydrogenated liquid fractions obtained with powdered and extruded Catalysts were similar to that obtained for a sample of commercial diesel. However, product obtained from pelletised Catalysts yielded higher cetane numbers. For xylene isomerisation, powdered Catalyst was more active than extrudates and pellets.
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Effect of tetraalkylammonium, alcohol and amine templates on the synthesis and high pressure propene oligomerisation activity of ZSM-type zeolites
Applied Catalysis, 1991Co-Authors: S. Schwarz, M. Kojima, Cyril T. O'connorAbstract:Abstract Various tetraalkylammonium ions (alkyl = methyl, ethyl, propyl, butyl), amines and alcohols have been used to synthesise ZSM-type zeolites under identical conditions. The TMA, TEA, TPA and TBA ions yielded amorphous material, ZSM-8, ZSM-5 and ZSM-11, respectively. X-ray diffraction showed that amine templates produced ZSM-5/ZSM-11 intergrowths with relative crystallinities between 80 and 100%, while alcohols yielded ZSM-5 with ca. 60% crystallinity. Only ZSM-11 and the C6-diamine-based zeolites had very similar characteristics to those of TPA-based ZSM-5, viz. ca. 100% crystallinity, a number average crystal size of ca. 1 μm and a morphology of spherical aggregates. Amine-based zeolites with lower carbon numbers exhibited crystal sizes between 3 and 5 μm, while all alcohol-based zeolites had crystal sizes ranging from 4 to 6 μm. It was observed that only Catalysts that had similar characteristics to TPA-ZSM-5 performed well as propene oligomerisation Catalysts at 250°C, 5 MPa and a weight hourly space velocity of about 12 h−1. The Catalyst Utilisation values for TPA-based ZSM-5, ZSM-11 1,6-hexanediamine and 1,2-cyclohexanediamine-based zeolites were approximately 300 g liquid/g Catalyst. All other Catalysts performed relatively poorly and an inverse relationship between crystal size and Catalyst performance was observed.
Philip Holdway - One of the best experts on this subject based on the ideXlab platform.
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High-Utilisation Nanoplatinum Catalyst (Pt@cPIM) Obtained via Vacuum Carbonisation in a Molecularly Rigid Polymer of Intrinsic Microporosity
Electrocatalysis, 2017Co-Authors: Yuanyang Rong, Daping He, Richard Malpass-evans, Mariolino Carta, Neil B. Mckeown, Murilo F. Gromboni, Lucia H. Mascaro, Geoffrey W. Nelson, John S. Foord, Philip HoldwayAbstract:Polymers of intrinsic microporosity (PIM or here PIM-EA-TB) offer a highly rigid host environment into which hexachloroplatinate(IV) anions are readily adsorbed and vacuum carbonised (at 500 °C) to form active embedded platinum nanoparticles. This process is characterised by electron and optical microscopy, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and electrochemical methods, which reveal that the PIM microporosity facilitates the assembly of nanoparticles of typically 1.0 to 2.5-nm diameter. It is demonstrated that the resulting carbonised “Pt@cPIM” from drop-cast films of ca. 550-nm average thickness, when prepared on tin-doped indium oxide (ITO), contain not only fully encapsulated but also fully active platinum nanoparticles in an electrically conducting hetero-carbon host. Alternatively, for thinner films (50–250 nm) prepared by spin coating, the particles become more exposed due to additional loss of the carbon host. In contrast to Catalyst materials prepared by vacuum-thermolysed hexachloroplatinate(IV) precursor, the platinum nanoparticles within Pt@cPIM retain high surface area, electrochemical activity and high Catalyst efficiency due to the molecular rigidity of the host. Data are presented for oxygen reduction, methanol oxidation and glucose oxidation, and in all cases, the high Catalyst surface area is linked to excellent Catalyst Utilisation. Robust transparent platinum-coated electrodes are obtained with reactivity equivalent to bare platinum but with only 1 μg Pt cm^−2 (i.e. ~100% active Pt nanoparticle surface is maintained in the carbonised microporous host). Graphical Abstract ᅟ
Dmitri Bessarabov - One of the best experts on this subject based on the ideXlab platform.
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Advances in structural and chemical analysis of Catalystcoated membranes for hydrogen fuel cell applications
Membrane Technology, 2009Co-Authors: Dmitri Bessarabov, Adam P. HitchcockAbstract:Catalyst-coated membranes are a key element of advanced membrane electrode assembly designs for automotive, hydrogen-based fuel cell systems. The morphology of the Catalyst layers of these membranes should provide a structure that is optimised for maximum Catalyst Utilisation; water management at a wide range of operational temperatures and relative humidity; fuel (hydrogen) and oxidant (oxygen in air) mass-transfer; and optimum electronic conductivity. Because of the multi-component nature of the layers (Catalyst, ionomer and Catalyst support) and resulting hierarchy in the layered structure at different spatial scales, new tools for their characterisation are required. Such a development should lead to an improved understanding of the links between fuel cell performance and structure of the Catalyst layers under various operating conditions. This feature article presents soft X-ray spectromicroscopy as a tool for such studies and shows how it can probe the structural and chemical properties of the membrane and the Catalyst layers of membrane electrode assemblies.
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Advances in structural and chemical analysis of Catalystcoated membranes for hydrogen fuel cell applications
Membrane Technology, 2009Co-Authors: Dmitri Bessarabov, Andrew HitchcockAbstract:Catalyst-coated membranes are a key element of advanced membrane electrode assembly designs for automotive, hydrogen-based fuel cell systems. The morphology of the Catalyst layers of these membranes should provide a structure that is optimised for maximum Catalyst Utilisation; water management at a wide range of operational temperatures and relative humidity; fuel (hydrogen) and oxidant (oxygen in air) mass-transfer; and optimum electronic conductivity. Because of the multi-component nature of the layers (Catalyst, ionomer and Catalyst support) and resulting hierarchy in the layered structure at different spatial scales, new tools for their characterisation are required. Such a development should lead to an improved understanding of the links between fuel cell performance and structure of the Catalyst layers under various operating conditions. This feature article presents soft X-ray spectromicroscopy as a tool for such studies and shows how it can probe the structural and chemical properties of the membrane and the Catalyst layers of membrane electrode assemblies. © 2009 Elsevier Ltd. All rights reserved.