High-Efficiency Columns for the Analysis of Hydrocarbons by Gas-Liquid Chromatography

Scott, Raymond; Cheshire, Jim

doi:10.1038/180702b0

Cited by 19 publications

(3 citation statements)

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“…The activation of methane was also investigated on Lewis acids bound to anionic sites in the SSZ‐13 periodic unit cell. SSZ‐13 (CHA framework) is a small pore zeolite with 3‐dimensional interconnected pores and a single symmetry‐distinct T‐site among 4, 6, and 8 MR rings that form cages of ∼8 Å in diameter . The SSZ‐13 lattice constants were optimized in a hexagonal unit cell using the same procedure as described for ZSM‐22 and were found to be

a = b =

13.68 Å and

c =

14.9 Å.…”

Section: Resultsmentioning

confidence: 99%

Quantification and Statistical Analysis of Errors Related to the Approximate Description of Active Site Models in Metal‐Exchanged Zeolites

2019

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Metal‐exchanged zeolites are complex catalytic systems with great potential for applications in hydrocarbon conversion processes. The numerous combinations of zeotypes and metal‐based Lewis acid motifs create a vast material space that can only be effectively navigated with robust structure‐function relationships. Exhaustive modeling of extraframework metal sites in all crystallographically distinct framework positions is not practical; thus, we quantified the uncertainties arising from the use of simplified active site representations using the C−H bond activation in methane as a probe reaction. Density functional theory calculations and statistical analysis of associated error ensembles suggest that the Lewis acid identity primarily determines the reactivity of the zeolite towards methane activation, with other factors such as zeolite model characteristics deemed secondary. The error ensemble distributions were used to predict the relative probability of creating active C−H bond scission fragments in metal‐exchanged zeolites, and thus can be used to efficiently screen various metal‐exchange candidates in their efficacy towards hydrocarbon conversion.

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a = b =

13.68 Å and

c =

14.9 Å.…”

Section: Resultsmentioning

confidence: 99%

Quantification and Statistical Analysis of Errors Related to the Approximate Description of Active Site Models in Metal‐Exchanged Zeolites

2019

View full text Add to dashboard Cite

show abstract

“…Generally, it is considered that all practical and theoretical questions are answered by the van Deemter equation (6), which contains very detailed information on the optimal flow rate of carrier gas, particle diameter of the support, and the amount of liquid phase. Scott (18) and Purnell (14), considering these parameters, constructed packed columns of high efficiency with values for the HETP (height equivalent to the theoretical plate) of less than 0.5 mm.…”

mentioning

confidence: 99%

“…These highlights in the literature (13,14,18) obviously discouraged research on a question of prime importance : how to pack columns reproducibly and with a maximum efficiency. Hitherto, experimental knowledge of column packing has been hindered by lack of thorough understanding.…”

mentioning

confidence: 99%