The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Michael F. Doherty - One of the best experts on this subject based on the ideXlab platform.
-
ultimate Reaction Selectivity limits for intensified reactor separators
Industrial & Engineering Chemistry Research, 2019Co-Authors: Jeffrey A. Frumkin, Lorenz Fleitmann, Michael F. DohertyAbstract:The Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison, proves that any and every Reaction/mixing/separation process is equivalent to a process comprising at most R+1 CFSTRs and a perfect mixer–separator, where R is the number of linearly independent chemical Reactions. Frumkin and Doherty showed that the CFSTR Equivalence Principle can be used together with global optimization to find the maximum Selectivity of a chemistry independent of process design. These Selectivity targets are useful in the context of process intensification because they represent ultimate Selectivity improvements that can be achieved by combining multiple unit operations into a single device. In this work, the model is reformulated as a mixed-integer nonlinear program to solve this nonlinear and nonconvex optimization problem. We implement a more robust, deterministic global optimization using a spatial branch-and-bound algorithm (BARON) to investigate the Selectivity limits for p...
-
Ultimate bounds on Reaction Selectivity for batch reactors
Chemical Engineering Science, 2019Co-Authors: Jeffrey A. Frumkin, Michael F. DohertyAbstract:Abstract Targets and benchmarks are useful in chemical process design as they provide an objective, quantitative assessment of a proposed process flowsheet. In addition, with target bounds on Reaction Selectivity one can also explore the sustainability limits for a chemistry of interest. Unfortunately, targets for Reaction Selectivity are difficult to obtain using conventional design methods. In 2001, Feinberg and Ellison developed the Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, providing a methodology to obtain ultimate bounds on steady-state productivity for a chemistry of interest entirely independent of process design. In previous articles, we showed how the CFSTR Equivalence Principle can be used to obtain bounds on Reaction Selectivity independent of process design for steady-state processes. In this article we prove that the CFSTR Equivalence Principle is also applicable to batch and semi-batch processes, thus providing a unifying framework to obtain an ultimate target for Reaction Selectivity applicable to all candidate processes for a chemistry of interest. This limit also applies to systems with periodic and chaotic operations. We demonstrate the method with an example for the production of lactic acid through the alkaline conversion of fructose.
-
Ultimate Reaction Selectivity Limits for Intensified Reactor–Separators
Industrial & Engineering Chemistry Research, 2018Co-Authors: Jeffrey A. Frumkin, Lorenz Fleitmann, Michael F. DohertyAbstract:The Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison, proves that any and every Reaction/mixing/separation process is equivalent to a process comprising at most R+1 CFSTRs and a perfect mixer–separator, where R is the number of linearly independent chemical Reactions. Frumkin and Doherty showed that the CFSTR Equivalence Principle can be used together with global optimization to find the maximum Selectivity of a chemistry independent of process design. These Selectivity targets are useful in the context of process intensification because they represent ultimate Selectivity improvements that can be achieved by combining multiple unit operations into a single device. In this work, the model is reformulated as a mixed-integer nonlinear program to solve this nonlinear and nonconvex optimization problem. We implement a more robust, deterministic global optimization using a spatial branch-and-bound algorithm (BARON) to investigate the Selectivity limits for p...
-
Target bounds on Reaction Selectivity via Feinberg's CFSTR equivalence principle
AIChE Journal, 2017Co-Authors: Jeffrey A. Frumkin, Michael F. DohertyAbstract:In this work, we show that the Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison,1 can be used to obtain practical upper bounds on Reaction Selectivity for any chemistry of interest. The CFSTR Equivalence Principle allows one to explore the attainable Reaction region by decomposing any arbitrary, steady-state reactor-mixer-separator system with total Reaction volume V > 0 into a new system comprising R + 1 CFSTRs (where R is the number of linearly independent chemical Reactions) with the same total Reaction volume and a perfect separator system. [1, 2] This work further refines the allowable selectivities by incorporating capacity constraints into the CFSTR Equivalence Principle to prevent arbitrarily large recycle streams between the CFSTRs and the separators and infinitesimally small CFSTR conversions. These constraints provide practical upper bounds on Reaction selectivities of chemistries completely independent of reactor design. We present the methodology and the results for a selection of realistic chemistries. This article is protected by copyright. All rights reserved.
Jeffrey A. Frumkin - One of the best experts on this subject based on the ideXlab platform.
-
ultimate Reaction Selectivity limits for intensified reactor separators
Industrial & Engineering Chemistry Research, 2019Co-Authors: Jeffrey A. Frumkin, Lorenz Fleitmann, Michael F. DohertyAbstract:The Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison, proves that any and every Reaction/mixing/separation process is equivalent to a process comprising at most R+1 CFSTRs and a perfect mixer–separator, where R is the number of linearly independent chemical Reactions. Frumkin and Doherty showed that the CFSTR Equivalence Principle can be used together with global optimization to find the maximum Selectivity of a chemistry independent of process design. These Selectivity targets are useful in the context of process intensification because they represent ultimate Selectivity improvements that can be achieved by combining multiple unit operations into a single device. In this work, the model is reformulated as a mixed-integer nonlinear program to solve this nonlinear and nonconvex optimization problem. We implement a more robust, deterministic global optimization using a spatial branch-and-bound algorithm (BARON) to investigate the Selectivity limits for p...
-
Ultimate bounds on Reaction Selectivity for batch reactors
Chemical Engineering Science, 2019Co-Authors: Jeffrey A. Frumkin, Michael F. DohertyAbstract:Abstract Targets and benchmarks are useful in chemical process design as they provide an objective, quantitative assessment of a proposed process flowsheet. In addition, with target bounds on Reaction Selectivity one can also explore the sustainability limits for a chemistry of interest. Unfortunately, targets for Reaction Selectivity are difficult to obtain using conventional design methods. In 2001, Feinberg and Ellison developed the Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, providing a methodology to obtain ultimate bounds on steady-state productivity for a chemistry of interest entirely independent of process design. In previous articles, we showed how the CFSTR Equivalence Principle can be used to obtain bounds on Reaction Selectivity independent of process design for steady-state processes. In this article we prove that the CFSTR Equivalence Principle is also applicable to batch and semi-batch processes, thus providing a unifying framework to obtain an ultimate target for Reaction Selectivity applicable to all candidate processes for a chemistry of interest. This limit also applies to systems with periodic and chaotic operations. We demonstrate the method with an example for the production of lactic acid through the alkaline conversion of fructose.
-
Ultimate Reaction Selectivity Limits for Intensified Reactor–Separators
Industrial & Engineering Chemistry Research, 2018Co-Authors: Jeffrey A. Frumkin, Lorenz Fleitmann, Michael F. DohertyAbstract:The Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison, proves that any and every Reaction/mixing/separation process is equivalent to a process comprising at most R+1 CFSTRs and a perfect mixer–separator, where R is the number of linearly independent chemical Reactions. Frumkin and Doherty showed that the CFSTR Equivalence Principle can be used together with global optimization to find the maximum Selectivity of a chemistry independent of process design. These Selectivity targets are useful in the context of process intensification because they represent ultimate Selectivity improvements that can be achieved by combining multiple unit operations into a single device. In this work, the model is reformulated as a mixed-integer nonlinear program to solve this nonlinear and nonconvex optimization problem. We implement a more robust, deterministic global optimization using a spatial branch-and-bound algorithm (BARON) to investigate the Selectivity limits for p...
-
Target bounds on Reaction Selectivity via Feinberg's CFSTR equivalence principle
AIChE Journal, 2017Co-Authors: Jeffrey A. Frumkin, Michael F. DohertyAbstract:In this work, we show that the Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison,1 can be used to obtain practical upper bounds on Reaction Selectivity for any chemistry of interest. The CFSTR Equivalence Principle allows one to explore the attainable Reaction region by decomposing any arbitrary, steady-state reactor-mixer-separator system with total Reaction volume V > 0 into a new system comprising R + 1 CFSTRs (where R is the number of linearly independent chemical Reactions) with the same total Reaction volume and a perfect separator system. [1, 2] This work further refines the allowable selectivities by incorporating capacity constraints into the CFSTR Equivalence Principle to prevent arbitrarily large recycle streams between the CFSTRs and the separators and infinitesimally small CFSTR conversions. These constraints provide practical upper bounds on Reaction selectivities of chemistries completely independent of reactor design. We present the methodology and the results for a selection of realistic chemistries. This article is protected by copyright. All rights reserved.
Robert M Rioux - One of the best experts on this subject based on the ideXlab platform.
-
addition of sulfonic acids to terminal alkynes catalyzed by a rhodium complex ligand concentration controlled Reaction Selectivity
Chemcatchem, 2013Co-Authors: Yong Yang, Eric G Moschetta, Robert M RiouxAbstract:A Rh-catalyzed process for the regioselective formation of vinyl sulfonate esters in moderate to high yields through the hydrosulfonation of alkynes with sulfonic acids has been developed. Our synthetic approach is capable of adding a variety of alkynes to a set of sulfonic acids and is amenable to different phosphorus ligands, solvents, and Rh precursors. We control the chemo- and regioSelectivity of the Reaction to the Markovnikov vinyl sulfonate ester by tuning the concentration of the exogenous ligand, PPh3, which forms the active RhP species in situ. At lower PPh3 concentrations, the Reaction favors the formation of vinyl sulfonate esters, whereas at higher PPh3 concentrations, the Reaction favors the formation of vinylphosphonium salts. We perform Hammett analyses and kinetic isotope effect experiments to determine the steps of the catalytic mechanism. Reaction data for substituted acetylenes indicates syn and anti addition occur across the triple bond. Experiments performed with the vinylphosphonium salt as the exogenous ligand determined that the formation of the salt was not a necessary step in the catalytic mechanism for the direct formation of the vinyl sulfonate esters.
-
Addition of Sulfonic Acids to Terminal Alkynes Catalyzed by a Rhodium Complex: Ligand Concentration‐Controlled Reaction Selectivity
Chemcatchem, 2013Co-Authors: Yong Yang, Eric G Moschetta, Robert M RiouxAbstract:A Rh-catalyzed process for the regioselective formation of vinyl sulfonate esters in moderate to high yields through the hydrosulfonation of alkynes with sulfonic acids has been developed. Our synthetic approach is capable of adding a variety of alkynes to a set of sulfonic acids and is amenable to different phosphorus ligands, solvents, and Rh precursors. We control the chemo- and regioSelectivity of the Reaction to the Markovnikov vinyl sulfonate ester by tuning the concentration of the exogenous ligand, PPh3, which forms the active RhP species in situ. At lower PPh3 concentrations, the Reaction favors the formation of vinyl sulfonate esters, whereas at higher PPh3 concentrations, the Reaction favors the formation of vinylphosphonium salts. We perform Hammett analyses and kinetic isotope effect experiments to determine the steps of the catalytic mechanism. Reaction data for substituted acetylenes indicates syn and anti addition occur across the triple bond. Experiments performed with the vinylphosphonium salt as the exogenous ligand determined that the formation of the salt was not a necessary step in the catalytic mechanism for the direct formation of the vinyl sulfonate esters.
-
Influence of Particle Size on Reaction Selectivity in Cyclohexene Hydrogenation and Dehydrogenation over Silica-Supported Monodisperse Pt Particles
Lawrence Berkeley National Laboratory, 2009Co-Authors: Robert M RiouxAbstract:Influence of particle size on Reaction Selectivity in cyclohexene hydrogenation and dehydrogenation over silica-supported monodisperse Pt particles R. M. Rioux † , B. B. Hsu § , M. E. Grass, H. Song ‡ , and G. A. Somorjai* Department of Chemistry, University of California, Berkeley and Lawrence Berkeley National Laboratory, Materials and Chemical Sciences Division, Berkeley, CA 94720 Running title: Influence of particle size on Selectivity for C 6 H 10 conversion Keywords: cyclohexene, hydrogenation, dehydrogenation, platinum, particle size, Selectivity Correspondences should be addressed to somorjai@berkeley.edu Current address: Department of Chemical Engineering, Pennsylvania State University, University Park, PA 16802 Current address: Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139 Current address: Department of Chemistry and School of Molecular Science (BK21), Korea Advanced Institute of Science and Technology, Daejeon, 305-701, Korea
Lorenz Fleitmann - One of the best experts on this subject based on the ideXlab platform.
-
ultimate Reaction Selectivity limits for intensified reactor separators
Industrial & Engineering Chemistry Research, 2019Co-Authors: Jeffrey A. Frumkin, Lorenz Fleitmann, Michael F. DohertyAbstract:The Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison, proves that any and every Reaction/mixing/separation process is equivalent to a process comprising at most R+1 CFSTRs and a perfect mixer–separator, where R is the number of linearly independent chemical Reactions. Frumkin and Doherty showed that the CFSTR Equivalence Principle can be used together with global optimization to find the maximum Selectivity of a chemistry independent of process design. These Selectivity targets are useful in the context of process intensification because they represent ultimate Selectivity improvements that can be achieved by combining multiple unit operations into a single device. In this work, the model is reformulated as a mixed-integer nonlinear program to solve this nonlinear and nonconvex optimization problem. We implement a more robust, deterministic global optimization using a spatial branch-and-bound algorithm (BARON) to investigate the Selectivity limits for p...
-
Ultimate Reaction Selectivity Limits for Intensified Reactor–Separators
Industrial & Engineering Chemistry Research, 2018Co-Authors: Jeffrey A. Frumkin, Lorenz Fleitmann, Michael F. DohertyAbstract:The Continuous Flow Stirred Tank Reactor (CFSTR) Equivalence Principle, developed by Feinberg and Ellison, proves that any and every Reaction/mixing/separation process is equivalent to a process comprising at most R+1 CFSTRs and a perfect mixer–separator, where R is the number of linearly independent chemical Reactions. Frumkin and Doherty showed that the CFSTR Equivalence Principle can be used together with global optimization to find the maximum Selectivity of a chemistry independent of process design. These Selectivity targets are useful in the context of process intensification because they represent ultimate Selectivity improvements that can be achieved by combining multiple unit operations into a single device. In this work, the model is reformulated as a mixed-integer nonlinear program to solve this nonlinear and nonconvex optimization problem. We implement a more robust, deterministic global optimization using a spatial branch-and-bound algorithm (BARON) to investigate the Selectivity limits for p...
Gabor A. Somorjai - One of the best experts on this subject based on the ideXlab platform.
-
atomic scale foundation of covalent and acid base catalysis in Reaction Selectivity and turnover rate
Topics in Catalysis, 2015Co-Authors: Gabor A. Somorjai, Nathan MusselwhiteAbstract:Modern industrial catalysts are highly engineered multi-component materials, which are optimized to be highly efficient for the given Reaction. The key components of every catalyst are: (1) the active metal and (2) the support. The former is active through the formation of covalent bonds with surface species, activating the bonds in the targeted molecule. In many systems the support is a metal oxide, which can promote charged intermediates in acid–base type catalytic chemistry. When the covalent chemistry of the metal catalyst and the acid–base chemistry of the support work together, the overall catalytic productivity can be much greater than the sum of the parts. This synergic interaction also works in favor of changes in the Selectivity of complex Reactions. This intent of this article is to analyze covalent metal catalysis both alone and in tandem with acid–base heterogeneous catalysis.
-
Size and Shape Control of Metal Nanoparticles for Reaction Selectivity in Catalysis
ChemCatChem, 2012Co-Authors: Gabor A. SomorjaiAbstract:A nanoparticle with well-defined surfaces, prepared through colloidal chemistry, enables it to be studied as a model heterogeneous catalyst. The colloidal synthetic approach provides versatile tools to control the size and shape of nanoparticles. Traditional nucleation and growth mechanisms have been utilized to understand how nanoparticles can be uniformly synthesized and unprecedented shapes can be controlled. Now, the size of metal particles can be controlled to cluster regimes by using dendrimers. By using seeds and foreign atoms, specific synthetic environments such as seeded growth and crystal overgrowth can be induced to generate various shaped mono- or bi-metallic, core/shell, or branched nanostructures. For green chemistry, catalysis in 21st century is aiming for 100 % Selectivity to produce only one desired product at high turnover rates. Recent studies on nanoparticle catalysts clearly demonstrate size and shape dependent Selectivity in many catalytic Reactions. By combining in situ surface characterization techniques, real-time monitoring of nanoparticles can be performed under Reaction environments, thus identifying several molecular factors affecting catalytic activity and Selectivity.
-
Reaction Selectivity in Heterogeneous Catalysis
Lawrence Berkeley National Laboratory, 2010Co-Authors: Gabor A. SomorjaiAbstract:Reaction Selectivity in Heterogeneous Catalysis Gabor A. Somorjai* and Christopher J. Kliewer Department of Chemistry, University of California, Berkeley, California 94720, and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 E-mail: somorjai@socrates.berkeley.edu TITLE RUNNING HEAD: Selectivity in Heterogeneous Catalysis CORRESPONDING AUTHOR FOOTNOTE: Gabor A. Somorjai, Tel: 510-642-4053. Fax: 510- 643-9668. E-mail: somorjai@socrates.berkeley.edu. Review for Reaction Kinetics and Catalysis Letters
-
Reaction Selectivity in heterogeneous catalysis
Reaction Kinetics and Catalysis Letters, 2009Co-Authors: Gabor A. Somorjai, Christopher J. KliewerAbstract:The understanding of Selectivity in heterogeneous catalysis is of paramount importance to our society today. In this review we outline the current state of the art in research on Selectivity in heterogeneous catalysis. Current in-situ surface science techniques have revealed several important features of catalytic Selectivity. Sum frequency generation vibrational spectroscopy has shown us the importance of understanding the Reaction intermediates and mechanism of a heterogeneous Reaction, and can readily yield information as to the effect of temperature, pressure, catalyst geometry, surface promoters, and catalyst composition on the Reaction mechanism. DFT calculations are quickly approaching the ability to assist in the interpretation of observed surface spectra, thereby making surface spectroscopy an even more powerful tool. HP-STM has revealed three vitally important parameters in heterogeneous Selectivity: adsorbate mobility, catalyst mobility and selective site-blocking. The development of size controlled nanoparticles from 0.8 to 10 nm, of controlled shape, and of controlled bimetallic composition has revealed several important variables for catalytic Selectivity. Lastly, DFT calculations may be paving the way to guiding the composition choice for multi-metallic heterogeneous catalysis for the intelligent design of catalysts incorporating the many factors of Selectivity we have learned.
-
The 13th International Symposium on Relations Between Homogeneous and Heterogeneous Catalysis—An Introduction
Topics in Catalysis, 2008Co-Authors: Gabor A. SomorjaiAbstract:Over 40 years, there have been major efforts to aim at understanding the properties of surfaces, structure, composition, dynamics on the molecular level and at developing the surface science of heterogeneous and homogeneous catalysis. Since most catalysts (heterogeneous, enzyme and homogeneous) are nanoparticles, colloid synthesis methods were developed to produce monodispersed metal nanoparticles in the 1–10 nm range and controlled shapes to use them as new model catalyst systems in two-dimensional thin film form or deposited in mezoporous three-dimensional oxides. Studies of Reaction Selectivity in multipath Reactions (hydrogenation of benzene, cyclohexene and crotonaldehyde) showed that Reaction Selectivity depends on both nanoparticle size and shape. The oxide-metal nanoparticle interface was found to be an important catalytic site because of the hot electron flow induced by exothermic Reactions like carbon monoxide oxidation.
