Alkaline earth metal ion-exchanged β zeolite supported Pt catalysts for hydroisomerization of n-heptane

Abstract

Alkaline earth metal (Mg, Ca, Sr and Ba) ions were exchanged into Hb zeolite, which were used as the supports to load the noble metal Pt to prepare bifunctional catalysts for hydroisomerization of n-heptane. The catalysts were characterized by ICP, XRD, BET, NH 3 -TPD, H 2 -TPR and H 2 -chemisorption techniques, and evaluated in an atmospheric fixed bed reactor. The catalysts promoted by the alkaline earth metals are revealed to present much higher selectivity to isomerization than the counterpart Pt/Hb. Moreover, the Ba-bearing catalyst loaded with 0.4 wt% Pt and 5:1 molar ratio of Ba to Pt gives a very high selectivity to iso-heptanes 95.4% with a considerable high conversion of n-heptane 61.7%. The promotion effect of alkaline earth metals is briefly discussed in relation to characterization data.Keywords Hydroisomerization of paraffin Á b zeolite Á Alkaline earth metal Á Bifunctional catalyst Á Pt

Pt-promoted and Hβ zeolite-supported Ni2P catalysts for hydroisomerisation of n-heptane

“…The supports used for the bifunctional catalysts include SAPO (a kind of molecular sieves combined by Silicon, Aluminum, Phosphorus and Oxygen) [4,5], Y zeolite [6,7], β zeolite [8,9], SO 4 2− /ZrO 2 [10,11] and heteropolyacid [12,13], among which the three-dimensional 12-membered-ring β-zeolite is known as one of the most effective supports for hydroisomerisation of n-heptane. Chao et al [14] revealed that Pt-loaded β-zeolite showed higher selectivity to isomerisation and conversion than the one-dimensional 12-membered-ring mordenitesupported Pt catalyst.…”

Combined influence of alkaline earth metals and CO2 on performance of hierarchical zeolite Beta in n-hexane isomerization

“…Liu et al showed the increase in number of acid sites of Pt-H-Beta zeolites as Mg < Ca < Sr < Ba. Lack of agreement in acidity pattern reported in references 6 and 7 should be noticed [7]. Seddigi obtained decreased number of acid sites with higher acid strength (than that of zeolites HY) when the zeolites were modified with Ba [8].…”

“…In addition, Ca-Pt/deSi Beta was found to afford the highest isomer yields. Conversion sequence among these four metals was the same in the reaction of n-heptane isomerization reaction who reported Mg to yield the least acidic and Ba the highest acidic zeolites [7]. This suggested order may not be convincing while going down the Group from Mg to Ba, and basicity increases or acidity decreases making Mg most acidic.…”

“…The advantage of the presence of CO 2 is evident from the fact that a mixture of CO 2 + H 2 affords higher conversion and isomer selectivity (67 and 96%, respectively, column 7) than that in the presence of only H 2 (47 and 93%, respectively, column 8) over Ca-Pt/deSi Beta. Liu et al obtained 61.7% n-heptane conversion and 95.4% isomer selectivity on 1.41 wt % Ba (calculated by us)/0.4 wt % Pt on zeolites Beta (their best performing catalyst) at 230 °C and the WHSV of 2.7 h −1 [7]. Whereas in the present study, Ba-Pt/deSi Beta renders 51% conversion and 82% selectivity at 350 °C and 4.8 h −1 WHSV (column 10).…”

Using β-MCM41 composite molecular sieves as supports of bifunctional catalysts for the hydroisomerization of n-heptane

“…Based on the above considerations, together with the fact that b zeolite is one of the most promising supports of the bifunctional catalysts for the hydroisomerization of n-heptane [18,19], it is adequate to attempt the composite molecular sieve b-MCM41 as the catalyst support, which has been seldom reported [20]. In this work, we synthesized b-MCM41 composite molecular sieves by a hydrothermal approach, and prepared Pt/b-MCM41 bifunctional catalysts for the hydroisomerization of n-heptane, observing a highly improved selectivity to isomerization with a considerably high conversion.…”