Quantification of metal‐acid balance in hydroisomerization catalysts: A step further toward catalyst design

Abstract

A methodology was developed to interpret the results of n‐paraffins hydroisomerization over bifunctional catalysts based on two simple kinetic models used consecutively. First, a macrokinetic model was used to obtain the corresponding turnover frequency over the acid sites and the maximum of C16 isomer yield. Second, a dual‐function model was used to correlate these catalytic descriptors to the ratio of metal to acid sites of the catalyst. To illustrate the methodology, Pt/HBEA and Pt/HUSY catalysts with different Pt loadings were evaluated. The impact of metal‐acid balance on the catalytic turnover frequency and the maximal C16 isomer yield were adequately captured for the bifunctional HUSY and HBEA catalysts. Moreover, the parameters of the dual‐function model revealed to be intrinsic to the catalytic properties of the zeolite under the scope. This methodology is believed to be of interest for information‐driven catalyst design for the hydroisomerization of n‐paraffins. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2864–2875, 2017

From powder to extrudate zeolite-based bifunctional hydroisomerization catalysts: on preserving zeolite integrity and optimizing Pt location

“…The consumption of n-paraffins in hydroconversion reactions has been shown to be first-order in the paraffin concentration [18,61,62]. The first-order plots for the hydroisomerization of nhexadecane over Pt/(HUSY+Al 2 O 3 ) ( Figure S5) reveal an excellent fit regardless of reaction temperature or catalyst confirming the abovementioned observations in literature.…”

“…As the catalytic results for Pt/HUSY series were discussed in detail in a previous work [18], the focus herein will be held at those of Pt/(HUSY+Al 2 O 3 ) series and the pertinent comparisons.…”

“…The ultrastabilized Y (USY) zeolite is the most studied and industrially employed zeolite [3] but BEA zeolite [14][15][16][17][18] as well as some medium-pore frameworks have also revealed promising results [19][20][21][22]. For a given zeolite and operating conditions, the reaction rates are hence determined by the balance between the hydrogenatingdehydrogenating (HDH) and acid functions [18,23,24], and the distance between these functions (Weisz's intimacy criterion) [25,26]. Specifically, most of the studies have shown that maximal intimacy between metal and acid sites enhances the selectivity in feed isomers [25,26].…”

Interplay of the adsorption of light and heavy paraffins in hydroisomerization over H-beta zeolite

“…a well-balanced catalyst (i.e. hydrogenation/de-hydrogenation reactions in equilibria), the apparent reaction rate is firstorder in the reacting alkane [4,5]. This has been also verified experimentally [5][6][7].…”

Hollow Y zeolite single crystals: synthesis, characterization and activity in the hydroisomerization of n-hexadecane

“…In particular, the conversion directly depends on the amount, strength and accessibility of Brønsted acid sites in the zeolite framework. Using a fixed bed reactor and considering global reaction order of 1, the average Turnover Frequency (TOF) of the Brønsted acid sites (mol n-C16 /mol Brøn /s) along the reactor was calculated according to [51]:…”