Molecular size evaluation of linear and branched paraffins from the gasoline pool by DFT quantum chemical calculations

Impact of the Spatial Organization of Bifunctional Metal–Zeolite Catalysts on the Hydroisomerization of Light Alkanes

“…Regarding the yield of desired C 7 isomers, similar to H‐ZSM‐22‐based catalysts, the Pt‐Al 2 O 3 /H‐MOR‐S exhibited a higher yield of C 7 isomers and lower yield of cracking products than Pt‐H‐MOR‐S/Al 2 O 3 (Figure c). The yield of dibranched isomers over H‐MOR‐S‐based catalysts is much higher than over H‐ZSM‐22‐based catalysts (Figure d and c), because the consecutive skeletal isomerization can take place inside the 12‐MR micropore channels . Specifically, the maximum yield of dibranched isomers over Pt‐Al 2 O 3 /H‐MOR‐S was 9.4 % at a n ‐heptane conversion level of ≈80 %, while the corresponding value over Pt‐Al 2 O 3 /H‐ZSM‐22 is 1.3 %.…”

“…They ield of dibranched isomers over H-MOR-S-based catalysts is much higher than over H-ZSM-22-based catalysts (Figure 2d and 5c), because the consecutive skeletal isomerization can take place inside the 12-MR micropore channels. [25] Specifically,the maximum yield of dibranched isomers over Pt Compared with the two H-MOR-S-based catalysts,t he activities of the two H-MOR-L-based catalysts are lower (Figure 5a,b). Considering that the density of Pt and acid sites are similar for these four catalysts (Table S2 and Figure S12), the difference in activity between H-MOR-S and H-MOR-L should be caused by the accessibility of active sites:t he acid sites deep inside the H-MOR-L crystals do not significantly participate in the isomerization reaction.…”

Pore-throat sizes in sandstones, tight sandstones, and shales

“…The effective molecular diameters for nitrogen gas molecules N 2 are 3.4 Å ; methane CH 4 , 3.8 Å ; water, 3.2 Å ; complex ring structures, 10-30 Å ; and asphaltene molecules, 50-100 Å (Tissot and Welte, 1978, their table III.2.1). For paraffins, combined width-height values range from 4.5 Å for normal paraffins to 7.5 Å for branched-chain paraffins (Jimenez-Cruz and Laredo, 2004). The diameter of mercury as determined by two methods is 3.1 and 3.3 Å (Bondi, 1964); the value of 3.1 Å (0.31 nm) is plotted in Figure 2.…”

From Continuous to Molecular Scale in Modelling Elastohydrodynamic Lubrication: Nanoscale Surface Slip Effects on Film Thickness and Friction

“…Because the film thickness is found to be close to the size of the molecules that compose the fluid (n-octane is 1.3 nm long and 0.5 nm in size according to [14]), the continuous approach becomes questionable: the fluid should in fact be considered as a discrete medium, an assembly of n-octane molecules.…”