Combinatorial discovery of oxidative dehydrogenation catalysts within the Mo-V-Nb-O system

Abstract

Combinatorial methodologies were used for the synthesis and screening of mixed metal oxide heterogeneous catalysts. Primary screening at low reactant conversions at a throughput of greater than 10,000 catalyst compositions per month was performed by using simultaneous MS and photothermal def lection spectroscopy on spatially separated thick film catalysts with Ϸ200 g per catalyst prepared by using automated liquid dispensing. Secondary screening under realistic operating conditions was performed at a throughput of greater than 3,000 catalyst compositions per month on Ϸ50 mg of catalyst in an array of fixed bed microreactors with gas chromatograph detection. The approach was validated by the discovery of catalysts with superior performance to those previously described for the oxidative dehydrogenation of ethane to ethylene. We show the full implementation and integration of combinatorial methodologies for synthesis, screening, discovery, and optimization of multicomponent heterogeneous catalysts.Although combinatorial methodologies are practiced routinely for drug discovery (1, 2), this general approach is compelling in other fields where predictive abilities also are restricted. Recently, combinatorial methods have been applied within several different areas of materials science, where increasing compositional or structural complexity often results in unique or otherwise improved properties (1-12). Structural and compositional complexity may result in systems consisting of several components functioning cooperatively. In these combinations, the synergy of the multicomponent system results in performance characteristics that are particularly difficult to predict à priori. Presently, the vast majority of complex inorganic solids and multicomponent materials remain unexplored (13), in part because composition-structure-property relationships for such systems are limited. The utility of combinatorial chemistry, i.e., the ability both to prepare and to screen vast numbers of compounds in a rapid fashion, may be most productively realized within such systems. Here, we describe an integrated combinatorial program that has resulted in the discovery of improved multicomponent heterogeneous catalysts for the oxidative dehydrogenation of ethane to ethylene. Bringing combinatorial methodologies to bear on this application is particularly appealing because catalyst discovery has relied traditionally on an iterative trial-and-error synthesis and characterization strategy that is both tedious and time consuming.The parallel synthesis of catalytic materials by the use of automation and miniaturization techniques is most efficient when preparing very small quantities (Ͻ1 mg) of catalysts. The characterization of such small amounts of catalytic materials frequently is hindered by the lack of sensitive high throughput screening methodologies, particularly for reactions of low probability such as the partial oxidation of hydrocarbons. These obstacles have been overcome in our laboratories, and an integrated combinatorial d...

Catalysis Research of Relevance to Carbon Management: Progress, Challenges, and Opportunities

“…For example, X-ray microbeam techniques based on synchrotron radiation including X-ray fluorescence, X-ray diffraction, and nearedge X-ray absorption spectroscopy have been used to determine chemical compositions, crystal structures, and metal valence states in combinatorial arrays. 228,229 …”

Kombinatorische und Hochdurchsatz‐Techniken in der Materialforschung

“…MateriAbbildung 9. a) Zusammensetzungsraum der katalytischen Aktivität zur oxidativen Dehydrierung von Ethan (aus Lit. [124] Datensätze, die experimentell zur Abbildung von Parameterräumen gewonnen werden, sind ebenfalls als Basis für die direkte Modellierung eines solchen QCAR geeignet. [129] Sieg et al zeigten mithilfe der systematischen Erfassung von katalytischen Aktivitäten in quaternären Zusammensetzungsräumen, dass sich sowohl SVM, Multilevel-B-Spline oder Kriging (Abbildung 11) für die mathematische Modellierung solcher Korrelationen eignen.…”

“…[222][223][224][225] Die Verwendung der Gaschromatographie in HTE wurde ebenfalls bereits vor vielen Jahren in der Katalyseforschung beschrieben. [124,226] Der Einsatz von HT-GC und HT-MS bei größeren Bibliotheken wurde detailliert von Weiss et al beschrieben. [227] Hier haben die Autoren sich die kurzen MSAnalysezeiten der konventionellen Instrumente zunutze gemacht, die viele MS-Scans innerhalb von Sekunden durchführen und die Daten sammeln.…”

“…[355] In einer Serie von Publikationen berichteten Wissenschaftler bei Symyx über die Entwicklung von Katalysatorsystemen für die oxidative Dehydrierung von Ethan zu Ethen. [124,356] Die Ni-Ta-Nb-und Ni-Co-Nb-Systeme enthalten Katalysatoren, die die Leistung der derzeitig besten Mo-V-Katalysatoren bei Weitem übertreffen. Bei nur 300 8C wurden mit Ni 62 Ta 10 Nb 28 O x Ethan-Umsätze von über 20 % bei Ethenselektivitäten von bis zu 82 % erzielt.…”

Parallel Solution Combustion Synthesis for Combinatorial Materials Studies

“…Among them, sol-gel, coprecipitation, and hydrothermal synthesis have been successfully applied to combinatorial studies of catalyst, zeolite, etc. [6][7][8][9][10] The solution combustion (SC) method is an important wet chemical synthesis technique which was first proposed by J. J. Kingsley and K. C. Patil in 1988. 11 This method has the advantage of instantaneous high temperature.…”