Characterization of shape selective properties of zeolites via hydroisomerization of n-hexane

Facile Synthesis, Characterization, and Catalytic Behavior of a Large‐Pore Zeolite with the IWV Framework

“…When comparing the shape selectivities of these zeolites in a catalytic test reaction, it is always important to refer the catalytic properties to a certain reaction parameter at the same or similar value level. We found that the distributions of the branched isomers of n ‐hexane at the maximum isomer yields (in contrast to e.g., 10 or 20 mol % conversion of n ‐hexane) provide a very useful platform for correlating the shape selective properties of n ‐hexane hydroisomerization with the effective pore/channel structures of zeolites . Therefore, such results from ITQ‐27 and some selected zeolites are summarized in Table , together with the thermodynamic equilibrium distributions of isomers calculated according to reference .…”

“…The reactions were carried out in a flow‐type fixed bed reactor with pure n ‐hexane as a feed at temperatures between 170 and 310 °C, pressure of 1480 kPa, LHSV (Liquid Hourly Space Velocity) of 1 h −1 and molar H 2 to n ‐hexane ratio of 6:1. More details about the catalyst preparations and pretreatment and catalytic testing are described in our previous publications …”

“…More details about the catalyst preparations and pretreatment and catalytic testing are described in our previous publications. [26,27] Each experiment was started at 170 8Ca nd the reaction temperature was then incrementally increased by 5.6 8C( = 108F) toward an end temperature of up to 310 8C. At least five data points for each temperature were collected to make sure that the results were reproducible and the catalyst was stable.…”

“…The hydroisomerization of n-hexane was selected as at est reaction to probe the effective pore-size of the materials. As described in references [26,27], n-hexanec racks only slowly under the conditions applied in this work by secondary carbenium ions due to its short carbon-carbon chain, leadingt o ah igh selectivityt oh ydroisomerization of n-hexane (kinetic diameter: 4.3 ) to form only four paraffinic isomerso fd ifferent molecular sizes, that is, 2-methylpentane (5.0 ), 3-methylpentane (5.0), 2,2-dimethylbutane (6.2 ), and 2,3-dimethylbutane (5.8 ). This provides ar elativelys imple case for studying the shape-selectivep ropertieso fz eolites that have effective pore sizes close to the molecular kinetic dimensions of these C 6 isomers.…”

“…We found that the distributionso ft he branchedi somerso fn-hexane at the maximum isomer yields (in contrastt oe .g.,1 0o r2 0mol %c onversion of n-hexane) provideavery useful platform for correlating the shape selective properties of n-hexane hydroisomerizationw ith the effective pore/channel structures of zeolites. [26,27] Therefore, such results from ITQ-27 and somes elected zeolitesa re summarized in Ta ble 2, togetherw ith the thermodynamic equilibrium distributionso fi somerscalculated accordingt or eference [28].…”