Shape Selective Catalysts
Shape Selective Catalysts - Related Videos
10:38
Electrochemical Measurements of Supported Catalysts Using a Potentiostat/Galvanostat
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2023
Source: Laboratory of Dr. Yuriy Román — Massachusetts Institute of Technology A potentiostat/galvanostat (often referred to as simply a potentiostat) is an instrument that measures current at an applied potential (potentiostatic operation) or measures potential at an applied current (galvanostatic operation) (Figure 1). It is the most commonly used instrument in the electrochemical characterization of anode and cathode materials for fuel cells, electrolyzers, batteries, and supercapacitors.
11:15
HKUST-1 as a Heterogeneous Catalyst for the Synthesis of Vanillin
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Cited by 12 •
2016
The conversion of trans-ferulic acid to vanillin was achieved by heterogeneous catalysis. HKUST-1 was employed in this synthesis and the essential step in the catalytic process was the generation of unsaturated metal sites. Thus, when the catalyst was activated under vacuum, full vanillin conversion (yield of 95%) was obtained.
09:53
Predicting Catalyst Extrudate Breakage Based on the Modulus of Rupture
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Cited by 3 •
2018
Here we present a protocol to measure the modulus of rupture of an extruded catalyst and the breakage of said catalyst extrudates by collision against a surface or by compression in a fixed bed.
08:15
Temperature-programmed Deoxygenation of Acetic Acid on Molybdenum Carbide Catalysts
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Cited by 1 •
2017
Presented here is a protocol for the operation of a micro-scale temperature-programmed reactor for evaluating the catalytic performance of molybdenum carbide during acetic acid deoxygenation.
10:19
Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation
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2017
A convenient method for the synthesis of 2 nm supported bimetallic nanoparticle Pt-Cu catalysts for propane dehydrogenation is reported here. In situ synchrotron X-ray techniques allow for the determination of the catalyst structure, which is typically unobtainable using laboratory instruments.
FAQs
Selectivity arises at several stages inside a porous catalyst. Pore dimensions can determine whether a reactant reaches an active site, whether molecules can adopt a suitable transition-state geometry, and whether products can leave. These restrictions favor some reaction pathways over others, linking molecular fit directly to the product distribution observed after the reaction.
Diffusion controls how readily molecules move through channels and cavities, while steric interactions reflect the spatial difficulty of placing molecules or reaction structures within those spaces. Together, they can limit access, alter the progress of competing reactions, and influence which products escape the porous environment. These effects help explain why pore structure affects both selectivity and catalyst efficiency.
A confined catalytic environment can make one pathway more accessible than another by accommodating its reactants or transition-state geometry more effectively. Molecules associated with competing pathways may experience greater steric restriction or limited access to active sites. Suppressing those alternatives can improve the product distribution, making the selected chemical transformation more useful for practical processing.
Zeolite channels and cavities provide the structured spaces in which molecular access and movement are constrained. Their dimensions influence entry to active sites, the formation of transition states, and product exit, while their geometry also affects diffusion and steric interactions. Consequently, changing the available pore environment can change which molecules react and which products are favored.
Important applications include petroleum refining, hydrocarbon conversion, and the production of valuable chemicals. In these settings, molecular constraints help direct reactions toward preferred products while limiting competing transformations. The resulting control over product distributions can support more efficient processing and make better use of the catalyst during chemical conversion.
Precisely engineered microporous environments can provide control over reactant access, reaction-pathway preference, product release, and molecular diffusion. This control may suppress competing reactions and improve the distribution of desired products. In chemistry, those outcomes are relevant because they can increase efficiency and catalyst utilization during refining, hydrocarbon conversion, and valuable-chemical production.