Carbon dioxide capture and use as a carbon feedstock presents both environmental and
industrial ... more Carbon dioxide capture and use as a carbon feedstock presents both environmental and
industrial benefits. Here we report the discovery of a hybrid oxide catalyst comprising
manganese oxide nanoparticles supported on mesoporous spinel cobalt oxide, which
catalyses the conversion of carbon dioxide to methanol at high yields. In addition, carbon–
carbon bond formation is observed through the production of ethylene. We document the
existence of an active interface between cobalt oxide surface layers and manganese oxide
nanoparticles by using X-ray absorption spectroscopy and electron energy-loss spectroscopy
in the scanning transmission electron microscopy mode. Through control experiments, we
find that the catalyst’s chemical nature and architecture are the key factors in enabling
the enhanced methanol synthesis and ethylene production. To demonstrate the industrial
applicability, the catalyst is also run under high conversion regimes, showing its potential as a
substitute for current methanol synthesis technologies.
When pure mesoporous silica (MCF-17) was modified with
aluminum (Al modified MCF-17), Lewis acid si... more When pure mesoporous silica (MCF-17) was modified with aluminum (Al modified MCF-17), Lewis acid sites were created, but this material was inactive for the catalytic conversion (reforming) of n-hexane to isomers. When colloidally synthesized platinum nanoparticles were loaded onto traditional MCF-17, the catalyst showed very low activity toward isomer production. However, when Pt nanoparticles were loaded onto Al modified MCF-17, isomerization became the dominant catalytic pathway, with extremely high activity and selectivity (>90%), even at high temperatures (240−360 °C). This highly efficient catalytic chemistry was credited to the tandem effect between the acidic Al modified MCF-17 and the Pt metal.
The effect of acidic properties of mesoporous zeolites on the control of
product selectivity durin... more The effect of acidic properties of mesoporous zeolites on the control of product selectivity during the hydrogenative isomerization of methylcyclopentane has been investigated. A series of mesoporous zeolites with controlled acidic properties were prepared by postdealumination process with hydrochloric acid under hydrothermal conditions, and the resultant zeolites used for supporting colloidal Pt nanoparticles (NPs) with a mean size of 2.5 nm (±0.6 nm). As compared to the pure Pt NPs supported on catalytically inert mesoporous silica (MCF-17) as the reference catalyst that can produce isomers most selectively (∼80%), the Pt NPs supported on mesoporous zeolites produced C 6 ,†,‡ -cyclic hydrocarbons (i.e., cyclohexane and benzene) most dominantly. The type and strength of the Bro ̈ nsted (B) and Lewis (L) acid sites of those zeolites with a controlled Al amount are analyzed by using FT-IR after the adsorption of pyridine and NH temperature-programmed desorption measurements, and they are correlated with the selectivity change between cyclohexane and benzene. From this investigation, we found a linear relationship between the number of Bro ̈ nsted acid sites and the formation rate for cyclohexane. In addition, we revealed that more Lewis acidic zeolite having relatively smaller B/L ratio is effective for the cyclohexane formation, whereas more Bro ̈ nsted acidic zeolite having relatively larger B/L ratio is effective for the benzene formation.
Analysis of catalytic organic transformations in flow reactors
and detection of short-lived interm... more Analysis of catalytic organic transformations in flow reactors and detection of short-lived intermediates are essential for optimization of these complex reactions. In this study, spectral mapping of a multistep catalytic reaction in a flow microreactor was performed with a spatial resolution of 15 μm, employing micrometer-sized synchrotron-based IR and X-ray beams. Two nanometer sized Au nanoclusters were supported on mesoporous SiO , packed in a flow microreactor, and activated toward the cascade reaction of pyran formation. High catalytic conversion and tunable products selectivity were achieved under continuous flow conditions. In situ synchrotron-sourced IR microspectroscopy detected the evolution of the reactant, vinyl ether, into the primary product, allenic aldehyde, which then catalytically transformed into acetal, the secondary product. By tuning the residence time of the reactants in a flow microreactor a detailed analysis of the reaction kinetics was performed. An in situ micrometer X-ray absorption spectroscopy scan along the flow reactor correlated locally enhanced catalytic conversion, as detected by IR microspectroscopy, to areas with high concentration of Au(III), the catalytically active species. These results demonstrate the fundamental understanding of the mechanism of catalytic reactions which can be achieved by the detailed mapping of organic transformations in flow reactors .
Carbon dioxide capture and use as a carbon feedstock presents both environmental and
industrial ... more Carbon dioxide capture and use as a carbon feedstock presents both environmental and
industrial benefits. Here we report the discovery of a hybrid oxide catalyst comprising
manganese oxide nanoparticles supported on mesoporous spinel cobalt oxide, which
catalyses the conversion of carbon dioxide to methanol at high yields. In addition, carbon–
carbon bond formation is observed through the production of ethylene. We document the
existence of an active interface between cobalt oxide surface layers and manganese oxide
nanoparticles by using X-ray absorption spectroscopy and electron energy-loss spectroscopy
in the scanning transmission electron microscopy mode. Through control experiments, we
find that the catalyst’s chemical nature and architecture are the key factors in enabling
the enhanced methanol synthesis and ethylene production. To demonstrate the industrial
applicability, the catalyst is also run under high conversion regimes, showing its potential as a
substitute for current methanol synthesis technologies.
When pure mesoporous silica (MCF-17) was modified with
aluminum (Al modified MCF-17), Lewis acid si... more When pure mesoporous silica (MCF-17) was modified with aluminum (Al modified MCF-17), Lewis acid sites were created, but this material was inactive for the catalytic conversion (reforming) of n-hexane to isomers. When colloidally synthesized platinum nanoparticles were loaded onto traditional MCF-17, the catalyst showed very low activity toward isomer production. However, when Pt nanoparticles were loaded onto Al modified MCF-17, isomerization became the dominant catalytic pathway, with extremely high activity and selectivity (>90%), even at high temperatures (240−360 °C). This highly efficient catalytic chemistry was credited to the tandem effect between the acidic Al modified MCF-17 and the Pt metal.
The effect of acidic properties of mesoporous zeolites on the control of
product selectivity durin... more The effect of acidic properties of mesoporous zeolites on the control of product selectivity during the hydrogenative isomerization of methylcyclopentane has been investigated. A series of mesoporous zeolites with controlled acidic properties were prepared by postdealumination process with hydrochloric acid under hydrothermal conditions, and the resultant zeolites used for supporting colloidal Pt nanoparticles (NPs) with a mean size of 2.5 nm (±0.6 nm). As compared to the pure Pt NPs supported on catalytically inert mesoporous silica (MCF-17) as the reference catalyst that can produce isomers most selectively (∼80%), the Pt NPs supported on mesoporous zeolites produced C 6 ,†,‡ -cyclic hydrocarbons (i.e., cyclohexane and benzene) most dominantly. The type and strength of the Bro ̈ nsted (B) and Lewis (L) acid sites of those zeolites with a controlled Al amount are analyzed by using FT-IR after the adsorption of pyridine and NH temperature-programmed desorption measurements, and they are correlated with the selectivity change between cyclohexane and benzene. From this investigation, we found a linear relationship between the number of Bro ̈ nsted acid sites and the formation rate for cyclohexane. In addition, we revealed that more Lewis acidic zeolite having relatively smaller B/L ratio is effective for the cyclohexane formation, whereas more Bro ̈ nsted acidic zeolite having relatively larger B/L ratio is effective for the benzene formation.
Analysis of catalytic organic transformations in flow reactors
and detection of short-lived interm... more Analysis of catalytic organic transformations in flow reactors and detection of short-lived intermediates are essential for optimization of these complex reactions. In this study, spectral mapping of a multistep catalytic reaction in a flow microreactor was performed with a spatial resolution of 15 μm, employing micrometer-sized synchrotron-based IR and X-ray beams. Two nanometer sized Au nanoclusters were supported on mesoporous SiO , packed in a flow microreactor, and activated toward the cascade reaction of pyran formation. High catalytic conversion and tunable products selectivity were achieved under continuous flow conditions. In situ synchrotron-sourced IR microspectroscopy detected the evolution of the reactant, vinyl ether, into the primary product, allenic aldehyde, which then catalytically transformed into acetal, the secondary product. By tuning the residence time of the reactants in a flow microreactor a detailed analysis of the reaction kinetics was performed. An in situ micrometer X-ray absorption spectroscopy scan along the flow reactor correlated locally enhanced catalytic conversion, as detected by IR microspectroscopy, to areas with high concentration of Au(III), the catalytically active species. These results demonstrate the fundamental understanding of the mechanism of catalytic reactions which can be achieved by the detailed mapping of organic transformations in flow reactors .
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Papers by Selim Alayoglu
industrial benefits. Here we report the discovery of a hybrid oxide catalyst comprising
manganese oxide nanoparticles supported on mesoporous spinel cobalt oxide, which
catalyses the conversion of carbon dioxide to methanol at high yields. In addition, carbon–
carbon bond formation is observed through the production of ethylene. We document the
existence of an active interface between cobalt oxide surface layers and manganese oxide
nanoparticles by using X-ray absorption spectroscopy and electron energy-loss spectroscopy
in the scanning transmission electron microscopy mode. Through control experiments, we
find that the catalyst’s chemical nature and architecture are the key factors in enabling
the enhanced methanol synthesis and ethylene production. To demonstrate the industrial
applicability, the catalyst is also run under high conversion regimes, showing its potential as a
substitute for current methanol synthesis technologies.
aluminum (Al modified MCF-17), Lewis acid sites were created, but this material
was inactive for the catalytic conversion (reforming) of n-hexane to isomers. When
colloidally synthesized platinum nanoparticles were loaded onto traditional MCF-17,
the catalyst showed very low activity toward isomer production. However, when Pt
nanoparticles were loaded onto Al modified MCF-17, isomerization became the
dominant catalytic pathway, with extremely high activity and selectivity (>90%), even
at high temperatures (240−360 °C). This highly efficient catalytic chemistry was
credited to the tandem effect between the acidic Al modified MCF-17 and the Pt
metal.
product selectivity during the hydrogenative isomerization of methylcyclopentane has
been investigated. A series of mesoporous zeolites with controlled acidic properties were
prepared by postdealumination process with hydrochloric acid under hydrothermal
conditions, and the resultant zeolites used for supporting colloidal Pt nanoparticles (NPs)
with a mean size of 2.5 nm (±0.6 nm). As compared to the pure Pt NPs supported on
catalytically inert mesoporous silica (MCF-17) as the reference catalyst that can produce
isomers most selectively (∼80%), the Pt NPs supported on mesoporous zeolites
produced C
6
,†,‡
-cyclic hydrocarbons (i.e., cyclohexane and benzene) most dominantly. The type and strength of the Bro
̈
nsted (B)
and Lewis (L) acid sites of those zeolites with a controlled Al amount are analyzed by using FT-IR after the adsorption of
pyridine and NH
temperature-programmed desorption measurements, and they are correlated with the selectivity change
between cyclohexane and benzene. From this investigation, we found a linear relationship between the number of Bro
̈
nsted acid
sites and the formation rate for cyclohexane. In addition, we revealed that more Lewis acidic zeolite having relatively smaller B/L
ratio is effective for the cyclohexane formation, whereas more Bro
̈
nsted acidic zeolite having relatively larger B/L ratio is effective
for the benzene formation.
and detection of short-lived intermediates are essential for optimization of
these complex reactions. In this study, spectral mapping of a multistep
catalytic reaction in a flow microreactor was performed with a spatial
resolution of 15 μm, employing micrometer-sized synchrotron-based IR and
X-ray beams. Two nanometer sized Au nanoclusters were supported on
mesoporous SiO
, packed in a flow microreactor, and activated toward the
cascade reaction of pyran formation. High catalytic conversion and tunable
products selectivity were achieved under continuous flow conditions. In situ synchrotron-sourced IR microspectroscopy detected
the evolution of the reactant, vinyl ether, into the primary product, allenic aldehyde, which then catalytically transformed into
acetal, the secondary product. By tuning the residence time of the reactants in a flow microreactor a detailed analysis of the
reaction kinetics was performed. An in situ micrometer X-ray absorption spectroscopy scan along the flow reactor correlated
locally enhanced catalytic conversion, as detected by IR microspectroscopy, to areas with high concentration of Au(III), the
catalytically active species. These results demonstrate the fundamental understanding of the mechanism of catalytic reactions
which can be achieved by the detailed mapping of organic transformations in flow reactors .
industrial benefits. Here we report the discovery of a hybrid oxide catalyst comprising
manganese oxide nanoparticles supported on mesoporous spinel cobalt oxide, which
catalyses the conversion of carbon dioxide to methanol at high yields. In addition, carbon–
carbon bond formation is observed through the production of ethylene. We document the
existence of an active interface between cobalt oxide surface layers and manganese oxide
nanoparticles by using X-ray absorption spectroscopy and electron energy-loss spectroscopy
in the scanning transmission electron microscopy mode. Through control experiments, we
find that the catalyst’s chemical nature and architecture are the key factors in enabling
the enhanced methanol synthesis and ethylene production. To demonstrate the industrial
applicability, the catalyst is also run under high conversion regimes, showing its potential as a
substitute for current methanol synthesis technologies.
aluminum (Al modified MCF-17), Lewis acid sites were created, but this material
was inactive for the catalytic conversion (reforming) of n-hexane to isomers. When
colloidally synthesized platinum nanoparticles were loaded onto traditional MCF-17,
the catalyst showed very low activity toward isomer production. However, when Pt
nanoparticles were loaded onto Al modified MCF-17, isomerization became the
dominant catalytic pathway, with extremely high activity and selectivity (>90%), even
at high temperatures (240−360 °C). This highly efficient catalytic chemistry was
credited to the tandem effect between the acidic Al modified MCF-17 and the Pt
metal.
product selectivity during the hydrogenative isomerization of methylcyclopentane has
been investigated. A series of mesoporous zeolites with controlled acidic properties were
prepared by postdealumination process with hydrochloric acid under hydrothermal
conditions, and the resultant zeolites used for supporting colloidal Pt nanoparticles (NPs)
with a mean size of 2.5 nm (±0.6 nm). As compared to the pure Pt NPs supported on
catalytically inert mesoporous silica (MCF-17) as the reference catalyst that can produce
isomers most selectively (∼80%), the Pt NPs supported on mesoporous zeolites
produced C
6
,†,‡
-cyclic hydrocarbons (i.e., cyclohexane and benzene) most dominantly. The type and strength of the Bro
̈
nsted (B)
and Lewis (L) acid sites of those zeolites with a controlled Al amount are analyzed by using FT-IR after the adsorption of
pyridine and NH
temperature-programmed desorption measurements, and they are correlated with the selectivity change
between cyclohexane and benzene. From this investigation, we found a linear relationship between the number of Bro
̈
nsted acid
sites and the formation rate for cyclohexane. In addition, we revealed that more Lewis acidic zeolite having relatively smaller B/L
ratio is effective for the cyclohexane formation, whereas more Bro
̈
nsted acidic zeolite having relatively larger B/L ratio is effective
for the benzene formation.
and detection of short-lived intermediates are essential for optimization of
these complex reactions. In this study, spectral mapping of a multistep
catalytic reaction in a flow microreactor was performed with a spatial
resolution of 15 μm, employing micrometer-sized synchrotron-based IR and
X-ray beams. Two nanometer sized Au nanoclusters were supported on
mesoporous SiO
, packed in a flow microreactor, and activated toward the
cascade reaction of pyran formation. High catalytic conversion and tunable
products selectivity were achieved under continuous flow conditions. In situ synchrotron-sourced IR microspectroscopy detected
the evolution of the reactant, vinyl ether, into the primary product, allenic aldehyde, which then catalytically transformed into
acetal, the secondary product. By tuning the residence time of the reactants in a flow microreactor a detailed analysis of the
reaction kinetics was performed. An in situ micrometer X-ray absorption spectroscopy scan along the flow reactor correlated
locally enhanced catalytic conversion, as detected by IR microspectroscopy, to areas with high concentration of Au(III), the
catalytically active species. These results demonstrate the fundamental understanding of the mechanism of catalytic reactions
which can be achieved by the detailed mapping of organic transformations in flow reactors .