Combinatorial approaches as a component of high-throughput experimentation (HTE) in catalysis research

Inkjet printing assisted synthesis of multicomponent mesoporous metal oxides for ultrafast catalyst exploration

We describe an inkjet printing assisted cooperative-assembly method for high-throughput generation of catalyst libraries (multicomponent mesoporous metal oxides) at a rate of 1,000,000-formulations/hour with up to eight-component compositions. The compositions and mesostructures of the libraries can be well-controlled and continuously varied. Fast identification of an inexpensive and efficient quaternary catalyst for photocatalytic hydrogen evolution is achieved via a multidimensional group testing strategy to reduce the number of performance validation experiments (25,000-fold reduction over an exhaustive one-by-one search).

Development of a high-throughput methodology for screening coking resistance of modified thin-film catalysts

A high-throughput optical technique has been developed for the rapid screening of coking resistant composition-spread promoted-catalyst libraries during hydrocarbon cracking, in particular for Jet Propellant 8(JP-8) cracking. The libraries are screened by measuring changes in the catalyst's surface color due to the accumulation and burnoff of coke from the surface during JP-8 exposure and catalyst regeneration via oxygen burnoff. This rapid screening method was validated through a comparison of the coking properties of high-surface area powder cracking catalysts, and sputter deposited samples. Experiments on bimetallic (Pt-Gd) catalysts showed systematic trends consistently illustrating the superiority of Pt-Gd alloys to coking due to the presence of gadolinium.

Imaging Reflection IR Spectroscopy as a Tool to Achieve Higher Integration for High-Throughput Experimentation in Catalysis Research

FTIR spectroscopy in reflection mode combined with a focal plane array (FPA) detector was employed for high-throughput screening of activity of catalysts in n-pentane hydroisomerization. The reactor system was evaluated using reference catalysts Pt-MOR and gamma-alumina of known catalytic activity. By using the reflection setup, a higher degree of parallelization was possible, as compared to previous reports, in which transmission cells had been used. The 49-channel parallel reactor in combination with the FPA-IR optical setup was able to provide reliable information about the activity of different catalysts with relative data error of less than +/-20%.

Fluorescence spectroscopy and multivariate spectral descriptor analysis for high-throughput multiparameter optimization of polymerization conditions of combinatorial 96-microreactor arrays

Selection of optimum process conditions in combinatorial microreactors is essential if the combinatorial synthesis process is to be correlated with the synthesis process on a more conventional scale and the materials are to have the desired chemical properties. We have developed a new methodology for the high-throughput multiparameter optimization of polymerization reaction conditions in arrays of microreactors. Our strategy is based on the application of nondestructive spectroscopic techniques to measure chemical properties of polymers directly in individual microreactors followed by the multivariate spectral descriptor analysis for rapid determination of the optimal process conditions. We have demonstrated our strategy in the high-throughput multiparameter optimization of process conditions in thin-film melt polymerization reactions performed in 96-microreactor arrays for combinatorial screening of new polymerization catalysts. The combinatorial polymerization system was optimized for the best processing parameters using a set of input variables that included reactant parameters (relative amounts of starting components and catalyst loading) and processing variables (reaction time, reaction temperature, and inert gas flow rate). The measured output parameters were the chemical properties of materials and reproducibility of the material formation in replicate polymerizations in microreactors. Spatially resolved nondestructive evaluation of polymer formation was performed directly in individual microreactors and provided information about the spatial homogeneity of polymers in microreactors. It showed to be another powerful indicator of the reproducible polymerization process on the combinatorial scale. Although the methodology described here was implemented for high-throughput optimization of polymerization conditions, it is more general and can be further implemented for a variety of applications in which optimization of process parameters can be studied in situ or off-line using spectroscopic and other tools.

Application of a new color detection based method for the fast parallel screening of DeNO(x) catalysts

A new fast parallel detection method for stage I screening of solid catalysts has been developed. This method is based on the color change of organic dyes in the presence of either educts or reaction products in a reaction gas flow. As an example, NO decomposition and NO reduction with propylene under lean or rich conditions were studied. The presence of NO in a gas stream was detected by the color change from colorless to blue-green of filter paper impregnated with an organic dye, 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), which was placed in the gas stream after the catalyst bed. The catalyst library was made up of mixed metal oxides, synthesized by impregnation of activated carbon with metal oxide precursor solutions and subsequent combustion of the carbon matrix. Catalytic activity of these metal oxides was compared to platinum on gamma-alumina as a reference catalyst. The most active compounds were then studied in detail for their DeNO(x)properties in a high precision parallel flow test rig under a stationary and cyclic lean/reach operation. A new promising NO(x) storage catalyst was discovered.

Development of combinatorial chemistry methods for coatings: high-throughput optimization of curing parameters of coatings libraries

An automated analytical system has been implemented for the high-throughput optimization of processing conditions such as curing parameters in fabrication of UV-cured automotive organic protective coatings. Selection of optimum process conditions of combinatorial arrays of coatings is essential to correlate the high-throughput screening and conventional processes and to achieve the desired physical properties of coatings. For monitoring of curing conditions of each coating in the array, a viscosity-sensitive fluorophore 4,4'-bis(2-benzoxazolyl)stilbene was incorporated into coating formulations. This fluorescence tagging approach permitted us to combine a gradient temperature heater and a UV curing system with the full capabilities of our high-throughput screening system, including generation of spectroscopic data and its analysis. This investigation demonstrated the possibility of rapid decoupling of temperature and radiation effects in curing of UV-curable coating formulations by using multiple coatings and process conditions at once. While the system described here was implemented for high-throughput optimization of temperature conditions of radiation curing of arrays of organic protective coatings for automotive applications, this system can be further applied for a variety of other applications where optimization of process parameters can be studied in situ or off-line using optical spectroscopic tools.