Preparation, Characterization, and Isomerization Catalytic Performance of Palladium Loaded Zirconium Hydroxide/Sulfated Zirconia

Abstract

A series of zirconium hydroxide and sulfated zirconia were prepared by a facile hydrothermal method without a template. The catalysts were characterized by XRD, BET, SEM, TEM, TG-DSC, Raman, NH 3 TPD, and pyridine IR spectroscopy, and the reactivity was evaluated by the isomerization of n-hexane. The results indicated that a colloidal network structure could be formed by the condensation of the surface hydroxyl group under hydrothermal atmosphere, and it had an impact on the crystal form, surface properties, crystallization, and thermostability. Based on this, a crystallization model was deduced. The amounts of sulfates decreased with decreasing hydroxyl groups, so the acid distribution and strength have been changed. Ammonia ions and alumina also had an obvious effect on the surface structure and acidity of zirconium hydroxide and sulfated zirconia. Finally, isomerization of n-hexane indicated that a catalyst modified by ammonia hydrothermal treatment and alumina showed better reactivity and stability.

Acid‐free and highly efficient one‐step nitration of naphthalene with NO2 promoted by O2‐Ac2O in Fe‐ and Cu‐modified S2O82−/ZrO2 catalyst to 1,5‐dinitronaphthalene under mild conditions

“…with the S 2 O 8 2À group have similar NH 3 desorption peaks (acid strength), one at 172 C and another at 507 C, which is higher than those (175 and 351 C) in S 0:5 F 2:0 C 0:5 Z catalyst (Figure 7A). [40] The obtained results confirm that the sulphur sources and metal promoters not only affect the acid content but also change the nature of the acid strength. In other words, the incorporation of S 2 O 8 2À groups, Fe, and Cu metal into ZrO 2 can increase its acidity and create a strong acidic site, which will improve ZrO 2 catalytic activity.…”

Transesterification of Glycerol to Glycerol Carbonate over Mg-Zr Composite Oxide Prepared by Hydrothermal Process

“…As can be seen from Table 4 that the Mg1Zr2-HT-used catalyst has a larger specific surface area than the Mg1Zr2-CP-used catalyst, and more active sites can be retained. This may be because the colloidal network structure formed in the hydrothermal process is more stable through dissolution-deposition, which alleviates the collapse of the structure and the sintering of particles, so that it still maintains a large specific surface area in the reaction process [43]. Since the catalytic reaction occurs on the surface of active components, the agglomeration and growth of grains lead to the decrease of active surface area, the decrease of active sites, and the reduction in catalytic activity [44].…”

Effective Catalyst for Removing Trace Olefins from Reforming Aromatics: Sulfated Zirconia with High Sulfur Content Synthesized by Sulfonation with Chlorosulfonic Acid

“…Through our efforts in previous studies, − it has been found that sulfated zirconia exhibits excellent catalytic performance for removing trace olefins from aromatics, and its good thermal stability allows carbon deposition to be removed by calcination at high temperature to regenerate the catalyst. Additionally, sulfated zirconia has aroused the interest of many researchers due to its strong acidic properties, simple preparation process, environmental friendliness, and excellent reactivity in various acid-catalytic reactions, such as isomerization, − acylation, esterification, , alkylation, , and condensation . However, it has been recognized by most researchers that the undesired deactivation and the need for enhanced reusability of conventional sulfated zirconia, resulting from limited acidity and the leach of sulfur species, ,, become challenges that restrict its industrial application.…”