Enhanced Dehydrogenative Aromatization of Propane by Incorporating Fe and Pt into the Zn/HZSM-5 Catalyst

Abstract

In this study, an attempt was made to modify the Zn/HZSM-5 aromatization catalyst by successively impregnating Fe and Pt. Multitechniques including NH3 adsorption FT-IR, TEM, HAADF-STEM, XPS, and operando dual beam FT-IR spectroscopy of propane aromatization were employed to investigate the interactions among Zn, Fe, and Pt and the synergetic catalysis among the Brønsted acid sites, Lewis acid sites, and metallic sites of the ZnFePt/HZSM-5 catalyst. Results show that an optimized trimetallic Zn1.0Fe0.3Pt0.1/HZSM-5 catalyst has much lower dry gas production and significantly enhanced propane transformation activity and aromatization selectivity compared with the parent Zn/HZSM-5. The excellent performance of the trimetallic catalyst could be attributed to the high dispersion of metals, the formation of FePt bimetallic dehydrogenation active sites, and the promotion effect of FePt sites for the recombinational desorption of H atoms for the [ZnOZn]2+ sites. The fixed-bed reaction indicates that the trimetallic Zn1.0Fe0.3Pt0.1/HZSM-5 catalyst also has excellent durability which is desirable for practical use.

Mercaptosilane-assisted synthesis of highly dispersed and stable Pt nanoparticles on HL zeolites for enhancing hydroisomerization of n-hexane

“…The peak at 1490 cm À1 refers to the contribution from both the Brønsted acid and Lewis acid. [50][51][52] Similar to the results of NH 3 -TPD, it is demonstrated from the Py-IR results that the amount of the B and L acid sites in the different catalysts are also similar. All the above results indicate that the two preparation methods mercaptosilaneassisted in situ synthesis and the traditional ion-exchange strategy have little effect on the acidic properties of the Pt/HL catalysts.…”

Operando Dual Beam FTIR Study of Hydroxyl Groups and Zn Species over Defective HZSM-5 Zeolite Supported Zinc Catalysts

“…Catalyst samples were pressed into self-supporting thin wafers (1 cm 2 ) and placed in the sample beam of the dual beam IR cell, and the reference beam was left vacant. The experiment procedures and the method to conduct spectrum subtraction were described elsewhere [22,37,40]. In this study, samples were pretreated in the IR-cell reactor at 400 • C for 4 h under vacuum (10 −3 Pa).…”

Transformation of Propane over ZnSnPt Modified Defective HZSM-5 Zeolites: The Crucial Role of Hydroxyl Nests Concentration

“…This phenomenon suggests the formation of SnPt alloy particles on the SnPt/HZ30 catalyst. Based on our previous work [38], there is no hydrogen consumption peak on the Zn/HZ30 catalyst, and a hydrogen consumption peak at a high temperature attributed to strong interaction between the zinc and platinum species of Zn 1.0 Pt 0.1 /HZ30 catalyst. As shown in Figure 4, there are two hydrogen consumption peaks over the ZnSnPt modified defective MFI zeolites: One at around 633 K, which is associated with the formation of SnPt alloys; and the other at a high temperature, which shows strong interaction between zinc and platinum species.…”

“…Operando DB-FT-IR study was applied to unravel the role of Zn, Sn, and Pt in propane transformation under real reaction conditions [28,38,45]. The catalysts were pressed into thin wafers, then pretreated in vacuum (10 −3 Pa) at 673 K for 4 h. After the cell was cooled down to 303 K, the background spectra were recorded in the region of 4000-400 cm −1 with a resolution of 4 cm −1 .…”