Simulations of the thermodynamics and kinetics of NH 3 at the RuO 2 (110) surface

Erdtman, Edvin; Andersson, Mike; Spetz, Anita Lloyd; Ojamäe, Lars

doi:10.1016/j.susc.2016.10.006

Cited by 6 publications

(4 citation statements)

References 38 publications

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“…The total Gibbs free energy (ΔG) of the system was minimized with respect to the distribution of the species in order to obtain the most thermodynamically stable (i.e. the equilibrium) composition of the system 30 :…”

Section: Catalytic Activity Testmentioning

confidence: 99%

Time evolution of the CO2 hydrogenation to fuels over Cu-Zr-SBA-15 catalysts

Atakan

Erdtman

Mäkie

et al. 2018

Journal of Catalysis

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The self-archived postprint version of this journal article is available at Linköping University Institutional Repository (DiVA): http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-147297 N.B.: When citing this work, cite the original publication.Atakan, A., Erdtman, E., Mäkie, P., Ojamäe, L., Odén, M., (2018) ABSTRACT: Time evolution of catalytic CO2 hydrogenation to methanol and dimethyl ether (DME) has been investigated in a hightemperature high-pressure reaction chamber where products accumulate over time. The employed catalysts are based on a nano-assembly composed of Cu nanoparticles infiltrated into a Zr doped SiOx mesoporous framework (SBA-15): Cu-Zr-SBA-15. The CO2 conversion was recorded as a function of time by gas chromatography-mass spectrometry (GC-MS) and the molecular activity on the catalyst's surface was examined by diffuse reflectance in-situ Fourier transform infrared spectroscopy (DRIFTS). The experimental results showed that after 14 days a CO2 conversion of 25% to methanol and DME was reached when a DME selective catalyst was used which was also illustrated by thermodynamic equilibrium calculations. With higher Zr content in the catalyst, greater selectivity for methanol and a total 9.5 % conversion to methanol and DME was observed, yielding also CO as an additional product. The time evolution profiles indicated that DME is formed directly from methoxy groups in this reaction system. Both DME and methanol selective systems show the thermodynamically highest possible conversion.

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Section: Catalytic Activity Testmentioning

confidence: 99%

Time evolution of the CO2 hydrogenation to fuels over Cu-Zr-SBA-15 catalysts

Atakan

Erdtman

Mäkie

et al. 2018

Journal of Catalysis

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“…The DFT-based surface reaction rates together with the gas-phase reaction mechanism and the rate for C 2 H 6 formation from CH 3 from the literature − were employed in the kinetic model. The simulation of the kinetics was performed using the MATLAB SimBiology module. , The simulations of the amount of surface species as a function of time start from the surface fully covered by methyl groups (4CH 3 (s)) at a pressure of 100 Pa and a temperature of 773 K. The pressure was held constant by the presence of noninteracting gas molecules (e.g., N 2 ) plus molecules formed after desorption. The number of gas molecules was assumed to be much larger than the number of surface sites; that is, the initial molar ratio of gas molecules/CH 3 (s) was set to 50.…”

Section: Methodsmentioning

confidence: 99%

Reduction of Carbon Impurities in Aluminum Nitride from Time-Resolved Chemical Vapor Deposition Using Trimethylaluminum

et al. 2020

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Aluminum nitride (AlN) is a semiconductor with a wide range of applications from light-emitting diodes to high-frequency transistors. Electronic grade AlN is routinely deposited at 1000 °C by chemical vapor deposition (CVD) using trimethylaluminum (TMA) and NH3, while low-temperature CVD routes to high-quality AlN are scarce and suffer from high levels of carbon impurities in the film. We report on an atomic layer deposition-like CVD approach with time-resolved precursor supply where readsorption of methyl groups from the AlN surface is suppressed by the addition of an extra pulse, H2, N2, or Ar, between the TMA and NH3 pulses. The suppressed readsorption allowed deposition of AlN films with a carbon content of 1 at. % at 480 °C. Kinetic and quantum-chemical modeling suggests that the extra pulse between TMA and NH3 prevents readsorption of desorbing methyl groups terminating the AlN surface after the TMA pulse.

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“…The DFT-based surface reaction rates together with the gas phase reaction mechanism and rate for C2H6 formation from CH3 from literature 27,28,29,30,31 were employed in the kinetic model. The simulation of the kinetics was performed using the MATLAB SimBiology module 32,33 . The simulations of the amount of surface species as a function of time start from the surface fully covered by methyl groups (4CH3(s)) at the pressure 100 pascal and the temperature 773 Kelvin.…”

Section: Computational Detailsmentioning

confidence: 99%

Reduction of carbon impurities in aluminium nitride from time-resolved chemical vapour deposition using trimethylaluminum

Rouf¹,

Sukkaew²,

Ojamäe³

et al. 2020

Preprint

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Aluminium nitride (AlN) is a semiconductor with a wide range of applications from light emitting diodes to high frequency transistors. Electronic grade AlN is routinely deposited at 1000 °C by chemical vapour deposition (CVD) using trimethylaluminium (TMA) and NH3 while low temperature CVD routes to high quality AlN are scarce and suffer from high levels of carbon impurities in the film. We report on an ALD-like CVD approach with time-resolved precursor supply where thermally induced desorption of methyl groups from the AlN surface is enhanced by the addition of an extra pulse, H2, N2 or Ar between the TMA and NH3 pulses. The enhanced desorption allowed deposition of AlN films with carbon content of 1 at. % at 480 °C. Kinetic- and quantum chemical modelling suggest that the extra pulse between TMA and NH3 prevents re-adsorption of desorbing methyl groups terminating the AlN surface after the TMA pulse.

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Simulations of the thermodynamics and kinetics of NH 3 at the RuO 2 (110) surface

Cited by 6 publications

References 38 publications

Time evolution of the CO2 hydrogenation to fuels over Cu-Zr-SBA-15 catalysts

Time evolution of the CO2 hydrogenation to fuels over Cu-Zr-SBA-15 catalysts

Reduction of Carbon Impurities in Aluminum Nitride from Time-Resolved Chemical Vapor Deposition Using Trimethylaluminum

Reduction of carbon impurities in aluminium nitride from time-resolved chemical vapour deposition using trimethylaluminum

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