scholarly journals First-principles-informed energy span and microkinetic analysis of ethanol catalytic conversion to 1,3-butadiene on MgO

2021 ◽  
Author(s):  
Astrid Boje ◽  
William E Taifan ◽  
Henrik Ström ◽  
Tomáš Bučko ◽  
Jonas Baltrusaitis ◽  
...  
Keyword(s):  
Kinetic Modeling ◽  
Process Design ◽  
First Principles ◽  
Catalytic Conversion ◽  
Single Step

Kinetic modeling of single-step catalytic conversion of ethanol to 1,3-butadiene is necessary to inform accurate process design. This paper uses first-principles-informed energy span and microkinetic analysis to explore the reaction...

Catalytic conversion of furfural to methyl levulinate in a single-step route over Zr/SBA-15 in near-critical methanol

2018 ◽  
Vol 333 ◽  
pp. 434-442 ◽  
Author(s):  
Hao Chen ◽  
Houhang Ruan ◽  
Xilei Lu ◽  
Jie Fu ◽  
Timothy Langrish ◽  
...  
Keyword(s):  
Catalytic Conversion ◽  
Single Step ◽  
Methyl Levulinate

Review and Analysis of Bluff Body Flame Stabilization Data

2008 ◽  
Author(s):  
Sajjad A. Husain ◽  
Ganesh Nair ◽  
Santosh Shanbhogue ◽  
Tim C. Lieuwen
Keyword(s):  
Activation Energy ◽  
Kinetic Modeling ◽  
First Principles ◽  
Bluff Body ◽  
Large Range ◽  
Flame Stabilization ◽  
Local Extinction ◽  
Data Set ◽  
Flame Sheet ◽  
Semi Empirical

This paper compiles and analyzes bluff body stabilized flame blowoff data from the literature. Many of these studies contain semi-empirical blowoff correlations that are, in essence, Damko¨hler number correlations of their data. This paper re-analyzes these data, utilizing various Damko¨hler number correlations based upon detailed kinetic modeling for determining chemical time scales. While the results from this compilation are similar to that deduced from many earlier studies, it demonstrates that a rather comprehensive data set taken over a large range of conditions can be correlated from “first-principles” based calculations that do not rely on empirical fits or adjustable constants (e.g., global activation energy or pressure exponents). The paper then discusses the implications of these results on understanding of blowoff. Near blowoff flames experience local extinction of the flame sheet, manifested as “holes” that form and convect downstream. However, local extinction is distinct from blowoff — in fact, under certain conditions the flame can apparently persist indefinitely with certain levels of local extinction. We hypothesize that simple Damko¨hler number correlations contain the essential physics describing this first stage of blowoff; i.e., they are correlations for the conditions where local extinction on the flame begins, but do not fundamentally describe the ultimate blowoff condition itself. However, such correlations are reasonably successful in correlating blowoff limits because the ultimate blowoff event appears to be correlated to some extent to the onset of this first stage.

scholarly journals First-principles microkinetic study of methane and hydrogen sulfide catalytic conversion to methanethiol/dimethyl sulfide on Mo6S8 clusters: activity/selectivity of different promoters

2019 ◽  
Vol 9 (17) ◽  
pp. 4573-4580 ◽  
Author(s):  
Adam A. Arvidsson ◽  
William Taifan ◽  
Anders Hellman ◽  
Jonas Baltrusaitis
Keyword(s):  
Carbon Dioxide ◽  
Hydrogen Sulfide ◽  
Natural Gas ◽  
First Principles ◽  
Dimethyl Sulfide ◽  
Large Fraction ◽  
Catalytic Conversion ◽  
Sour Gas

A large fraction of the global natural gas reserves is in the form of sour gas, i.e. contains hydrogen sulfide (H2S) and carbon dioxide (CO2), and needs to be sweetened before utilization.

Experimental Determination of the Static Equivalent Pressures of Detonative Explosions of Ethylene/O2/N2-Mixtures and Cyclohexane/O2/N2-Mixtures in Long and Short Pipes

2018 ◽  
Author(s):  
Hans-Peter Schildberg
Keyword(s):  
Process Design ◽  
First Principles ◽  
Pressure Ratio ◽  
Ternary Mixtures ◽  
Detonation Pressure ◽  
Recent Past ◽  
Static Loads ◽  
Detonation Transition ◽  
Typical Variation

In the recent past (PVP2013-97677, PVP2014-28197, PVP2015-45286, PVP2016-63223) we had started to determine the static equivalent pressures (pstat) of the eight detonative pressure scenarios in long and short pipes for different detonable gas mixtures. The pstat-values are of vital importance for process design: by assigning static equivalent pressures to the highly dynamic detonative pressure peaks it is possible to apply the established pressure vessel guidelines, which can only cope with static loads, in the design of detonation pressure resistant pipes. In the previous publications the parameter R was defined as the ratio between pstat at the location where transition from deflagration to detonation occurs and pstat in the region of the stable detonation. One important finding was that R depends on the reactivity of the gas mixture. So far, R cannot be predicted from first principles or from combustion parameters, but can only be determined experimentally. The ratio R has a special significance, because it not only determines pstat for the Deflagration to Detonation Transition (DDT) in long pipes (first detonative pressure scenario), but also gives a good estimate for two of the three scenarios relevant in the design of short pipes: DDT and the coalescence of DDT and reflection. The present paper concludes the test series conducted at BASF during the last 4 years. It presents additional experimental data showing the variation of R over the entire detonative range of Ethylene/O2/N2 mixtures and along the stoichiometric line of Cyclohexane/O2/N2 mixtures. Based on the variation of R for these ternary mixtures and for the mixtures presented in the preceding publications, a typical variation of R for a general combustible/O2/N2-mixture is estimated over the entire explosive range. By means of this estimation the static equivalent pressures of the six design-relevant detonative pressure scenarios of any combustible/O2/N2-mixture can now be derived combining the parameter R with the Chapman-Jouguet pressure ratio, which can be calculated in a straightforward manner from thermodynamic properties.

scholarly journals First-principles-informed energetic span and microkinetic analysis of ethanol catalytic conversion to 1,3-butadiene on MgO

2020 ◽  
Author(s):  
Astrid Boje ◽  
William E. Taifan ◽  
Henrik Ström ◽  
Tomas Bucko ◽  
Jonas Baltrusaitis ◽  
...  
Keyword(s):  
Free Energy ◽  
Gas Phase ◽  
First Principles ◽  
Surface Coverage ◽  
Energy Landscape ◽  
High Surface ◽  
Catalytic Conversion ◽  
Free Energy Landscape ◽  
Catalyst Composition ◽  
The Impact

Kinetic modeling of single-step catalytic conversion of ethanol to 1,3-butadiene is necessary to inform accurate process design. This paper considers the synthesis of 1,3-butadiene on an MgO (100) step-edge using first-principles-informed energetic span and microkinetic analysis to explore the reaction free energy landscapes and kinetic limitations of competing reaction pathways. Previous studies have observed mechanisms proceeding via both dehydrogenation and dehydration of ethanol, and highlighted sensitivity to conditions and catalyst composition. Here, we use the energetic span concept to characterize the theoretical maximum turnover and degree of rate control for states in each reaction pathway, finding dehydrogenation to be more active than dehydration for producing 1,3-butadiene, and suggesting states in the dehydrogenation, dehydration, and condensation steps to be rate-determining. The influence of temperature on the relative rate contribution of each state is quantified and explained through the varying temperature sensitivity of the free energy landscape. A microkinetic model is developed to explore the impact of competition between pathways, interaction with gas-phase species, and high surface coverage of stable reaction intermediates. This suggests that the turnover obtained may be significantly lower than predicted from the free energy landscape alone. The theoretical rate-determining states were found to contribute to high surface coverage of adsorbed ethanol and longer, oxygenated hydrocarbons. The combined energetic span and microkinetic analysis permits investigation of a complex system from two perspectives, each with inherent advantages, and helps elucidate conflicting observations of rate determining steps and product distribution by considering the interplay between the different pathways and the equilibrium with gas-phase products.

scholarly journals First-principles-informed energy span and microkinetic analysis of ethanol catalytic conversion to 1,3-butadiene on MgO

2021 ◽  
Author(s):  
Astrid Boje ◽  
William E. Taifan ◽  
Henrik Ström ◽  
Tomas Bucko ◽  
Jonas Baltrusaitis ◽  
...  
Keyword(s):  
Free Energy ◽  
First Principles ◽  
Surface Coverage ◽  
Reaction Pathway ◽  
Relative Rate ◽  
Energy Landscape ◽  
Catalytic Conversion ◽  
Turnover Frequency ◽  
Catalyst Composition ◽  
The Impact

Kinetic modeling of single-step catalytic conversion of ethanol to 1,3-butadiene is necessary to inform accurate process design. This paper uses first-principles-informed energy span and microkinetic analysis to explore the reaction free energy landscapes and kinetic limitations of competing reaction pathways on a MgO (100) step-edge. Previous studies suggested mechanisms proceeding via both dehydrogenation and dehydration of ethanol, and highlighted sensitivity to conditions and catalyst composition. Here, we use the energy span concept to characterize the theoretical maximum turnover and degree of turnover frequency control for states in each reaction pathway, finding the dehydration route to be less active for 1,3-butadiene, and suggesting rate-determining states in the dehydrogenation, dehydration, and condensation steps. The influence of temperature on the relative rate contribution of each state is quantified and explained through the varying temperature sensitivity of the free energy landscape. A microkinetic model is developed to explore competition between pathways, interaction with gas-phase species, and surface coverage limitations. This suggests that the turnover may be significantly lower than predicted solely based on energetics. Turnover frequency determining states found to have high surface coverage include adsorbed ethanol and two longer, oxygenated hydrocarbons. The combined energy span and microkinetic analysis permits investigation of a complex system from two perspectives and helps elucidate conflicting observations of rate determining steps and product distribution by considering both energetic and kinetic limitations. The impact of uncertainty in the energy landscape is quantified using a correlated error model. While the range of predictions is large, the average performance and trends are similar.

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