Advanced Support Structures for Enhanced Catalytic Activity

Stuecker, John N.; Miller, James E.; Ferrizz, Robert E.; Mudd, and Jason E.; Cesarano, Joseph

doi:10.1021/ie030291v

Cited by 118 publications

(74 citation statements)

References 16 publications

(20 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, optimization of heterogeneous catalysts is often performed by selection or design of supports rather than by modifying the structure of the catalytic groups. [2][3][4][5] In addition, homogeneous catalysts typically exhibit superior selectivity and kinetics. Despite these disadvantages, heterogeneous catalysts are valued because they allow easy separation of products and can be reused for extended periods of time.…”

Section: Introductionmentioning

confidence: 99%

Substrate inhibition in the heterogeneous catalyzed aldol condensation: A mechanistic study of supported organocatalysts

Kandel

Althaus

Peeraphatdit

et al. 2012

Journal of Catalysis

137

View full text Add to dashboard Cite

In this study, we demonstrate how materials science can be combined with the established methods of organic chemistry to find mechanistic bottlenecks and redesign heterogeneous catalysts for improved performance. By using solid-state NMR, infrared spectroscopy, surface and kinetic analysis, we prove the existence of a substrate inhibition in the aldol condensation catalyzed by heterogeneous amines. We show that modifying the structure of the supported amines according to the proposed mechanism dramatically enhances the activity of the heterogeneous catalyst. We also provide evidence that the reaction benefits significantly from the surface chemistry of the silica support, which plays the role of a co-catalyst, giving activities up to two orders of magnitude larger than those of homogeneous amines. This study confirms that the optimization of a heterogeneous catalyst depends as much on obtaining organic mechanistic information as it does on controlling the structure of the support. Disciplines Materials Chemistry | Other Chemistry | Physical ChemistryComments NOTICE: this is the author's version of a work that was accepted for publication in Journal of Catalysis. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Catalysis, [291, (2012) AbstractIn this study we demonstrate how materials science can be combined with the established methods of organic chemistry to find mechanistic bottlenecks and redesign heterogeneous catalysts for improved performance. By using solid-state NMR, infrared spectroscopy, surface and kinetic analysis, we prove the existence of a substrate inhibition in the aldol condensation catalyzed by heterogeneous amines. We show that modifying the structure of the supported amines according to the proposed mechanism dramatically enhances the activity of the heterogeneous catalyst. We also provide evidence that the reaction benefits significantly from the surface chemistry of the silica support, which plays the role of a co-catalyst, giving activities up to two orders of magnitude larger than those of homogeneous amines. This study confirms that the optimization of a heterogeneous catalyst depends as much on obtaining organic mechanistic information as it does on controlling the structure of the support.

show abstract

Section: Introductionmentioning

confidence: 99%

Substrate inhibition in the heterogeneous catalyzed aldol condensation: A mechanistic study of supported organocatalysts

Kandel

Althaus

Peeraphatdit

et al. 2012

Journal of Catalysis

137

View full text Add to dashboard Cite

show abstract

“…First tests have been run using common clay paste for modeling (Stuecker et al 2004;Warnier and Verbruggen 2009; Brian 2014). The material is fairly weak and shows high shrinkage during the drying process ([6%) because of high water content.…”

Section: Preliminary Testsmentioning

confidence: 99%

Large-scale 3D printing with cable-driven parallel robots

Izard¹,

Dubor

Hervé³

et al. 2017

Constr Robot

104

View full text Add to dashboard Cite

Gantry robots and anthropomorphic arms of various sizes have already been studied and, while they are in use in some parts of the world for automated construction, a new kind of wide workspace machinery, cable-driven parallel robots (CDPR), has emerged. These robots are capable of automated movement in a very wide workspace, using cables reeled in and out by winches as actuation members, the other elements being easily stacked for easy relocation and reconfiguration, which is critical for on-site construction. The motivation of this paper is to showcase the potential of a CDPR operating solely on motor position sensors and showing limited collisions from the cables for large-scale applications in the building industry relevant for additive manufacturing, without risk of collisions between the cables and the building. The combination of the Cogiro CDPR (Tecnalia, LIRMM-CNRS 2010) with the extruder and material of the Pylos project (IAAC 2013) opens the opportunity to a 3D printing machine with a workspace of 13.6 9 9.4 9 3.3 m. The design patterns for printing on such a large scale are disclosed, as well as the modifications that were necessary for both the Cogiro robot and Pylos extruder and material. Two prints, with different patterns, have been achieved with the Pylos extruder mounted on Cogiro: the first spanning 3.5 m in length, the second, reaching a height of 0.86 m. Based on this initial experiment, plans for building larger parts and buildings are discussed, as well as other possible applications for CDPRs in construction, such as the manipulation of assembly processes (windows, lintels, beams, floor elements, curtain wall modules, etc.) or brick laying.

show abstract

“…The robocast part is designed using CAD software, and the robocasting apparatus then manufactures the part as specified. This process has been described in detail elsewhere [29][30][31][32] . Three differently structured robocast samples were used during this study: the first robocast monolith possesses a face-centered cubic (FCC) geometry, the second has a simple cubic (SC) structure, and the third sample is designed with a "modified" FCC structure that possesses a bulk porosity similar to that of an extruded honeycomb.…”

Section: Monolith Supportsmentioning

confidence: 99%

“…It is possible to construct a robocast monolith, once the relevant slurry processing parameters are determined, from many different materials, including catalysts such as BaMn-hexaaluminates. In fact, one such monolith has already been synthesized, and the results for methane catalytic combustion are very promising 29 .…”

Section: Additional Commentsmentioning

confidence: 99%

Monolithic Supports with Unique Geometries and Enhanced Mass Transfer

Stuecker

Ferrizz

Cesarano

et al. 2004

Ind. Eng. Chem. Res.

Self Cite

View full text Add to dashboard Cite

The catalytic combustion of natural gas has been the topic of much research over the past decade. Interest in this technology results from a desire to decrease or eliminate the emissions of harmful nitrogen oxides (NO X ) from gas turbine power plants. A low-pressure drop catalyst support, such as a ceramic monolith, is ideal for this high-temperature, high-flow application. A drawback to the traditional honeycomb monoliths under these operating conditions is poor mass transfer to the catalyst surface in the straight-through channels. "Robocasting" is a unique process developed at Sandia National Laboratories that can be used to manufacture ceramic monoliths with alternative 3-dimensional geometries, providing tortuous pathways to increase mass transfer while maintaining low pressure drops.This report details the mass transfer effects for novel 3-dimensional robocast monoliths, traditional honeycomb-type monoliths, and ceramic foams. The mass transfer limit is experimentally determined using the probe reaction of CO oxidation over a Pt / γ-Al 2 O 3 catalyst, and the pressure drop is measured for each monolith sample. Conversion versus temperature data is analyzed quantitatively using well-known dimensionless mass transfer parameters. The results show that, relative to the honeycomb monolith support, considerable improvement in mass transfer efficiency is observed for robocast samples synthesized using an FCC-like geometry of alternating rods. Also, there is clearly a trade-off between enhanced mass transfer and increased pressure drop, which can be optimized depending on the particular demands of a given application.4

show abstract

Advanced Support Structures for Enhanced Catalytic Activity

Cited by 118 publications

References 16 publications

Substrate inhibition in the heterogeneous catalyzed aldol condensation: A mechanistic study of supported organocatalysts

Substrate inhibition in the heterogeneous catalyzed aldol condensation: A mechanistic study of supported organocatalysts

Large-scale 3D printing with cable-driven parallel robots

Monolithic Supports with Unique Geometries and Enhanced Mass Transfer

Contact Info

Product

Resources

About