This is the first review of titanium dioxide‐zirconium dioxide (TiO2‐ZrO2) mixed oxides, which are frequently employed as catalysts and catalyst supports. In this review many details pertaining to the synthesis of these mixed oxides by various conventional and nonconventional methods and their characterization by several techniques, as reported in the literature, are assessed. These mixed oxides have been synthesized by different preparative analogies and were extensively characterized by employing various spectroscopic and nonspectroscopic techniques. The TiO2‐ZrO2 mixed oxides are also extensively used as supports with metals, nonmetals, and metal oxides for various catalytic applications. These supported catalysts have also been thoroughly investigated by different techniques. The influence of TiO2‐ZrO2 on the dispersion and surface structure of the supported active components as examined by various techniques in the literature has been contemplated. A variety of reactions catalyzed by TiO2‐ZrO2 and su...

Recent Advances on TiO2‐ZrO2 Mixed Oxides as Catalysts and Catalyst Supports

Activities of a series of metals (Pt, Pd, Rh, Cu, Mn) supported on TiO2 were investigated for the catalytic oxidation of formaldehyde. Among them, Pt/TiO2 was found to be the most promising catalyst. Nitrogen adsorption, hydrogen chemisorption, X-ray diffraction (XRD), transmission electron microscopy (TEM) and temperature programmed reduction (TPR) by H2 were used to characterize the platinum catalysts. Using Ce0.8Zr0.2O2, Ce0.2Zr0.8O2, SiO2 as supports instead of TiO2, the activity sequence of 0.6 wt.% platinum with respect to the supports is TiO2 > SiO2 > Ce0.8Zr0.2O2 > Ce0.2Zr0.8O2, and this appears to be correlated with the dispersion of platinum on supports rather than the specific surface areas of the catalysts. Platinum loading on TiO2 has a great effect on the catalytic activity, and 0.6 wt.% Pt/TiO2 catalyst was observed to be the most active, which could be attributed to the well-dispersed platinum surface phase. The reduction temperature greatly affects the particle size and, consequently, the catalytic activity. The smaller particle size of platinum, due to its high dispersion on support, has a positive effect on catalytic performance. Increasing formaldehyde concentration and space velocity exhibits an inhibiting effect on the catalytic activity.

Performance and characterization of supported metal catalysts for complete oxidation of formaldehyde at low temperatures

CuO catalysts supported on ZrO 2 -doped TiO 2 (hereafter denoted as TZ) and pure anatase TiO 2 were characterized by HRTEM, XRD, UV–vis DRS, TPR, XPS, in situ FT-IR and activity test for the removal of NO by CO. The results indicate that: (1) CuO species can be highly dispersed on the surface of TZ support, and the dispersion capacity (DC) is about 1.1 mmol/100 m 2 TZ, which can be explained by the incorporation model. (2) The reduction temperature of CuO supported on TZ is lower than that supported on pure anatase TiO 2 , ZrO 2 and ZrO 2 surface-modified anatase TiO 2 supports. Furthermore, the activity of Cu-TZ is also the highest among them measured by a relative turn over frequency (TOF) value of NO. (3) The ZrO 2 doping into TiO 2 improves the adsorption stability of NO x (especially the bridged nitrate/nitro) and decreases the active temperature of Cu + –CO species, both of which are the key intermediates for NO conversion. On the other hand, the ZrO 2 doping into TiO 2 promotes the formation of Cu + /Cu 0 species at high temperatures, which has a crucial effect on N 2 O reduction.

Dispersion, reduction and catalytic performance of CuO supported on ZrO2-doped TiO2 for NO removal by CO

Bimetallic catalysts supported over TiO2-ZrO2 binary oxides were prepared by co-impregnation methods and used for catalyzing liquid-phase hydrogenation of furfural Highly selective hydrogenation catalysts can be developed based on bimetallic synergistic effect The coexistence of small proportion of palladium with supported nickel species greatly improves the catalytic performance and transfer the reaction selectivity from partial hydrogenation to total hydrogenation The catalyst with Ni-Pd mole ratio of 5:1 shows the best performance The yield of tetrahydrofurfuryl alcohol (THFA) reaches 934% Ni-Pd synergistic effect is interpreted through XPS measurement and a hydrogen-transfer mechanism is proposed Pt-Re bimetallic catalyst is an excellent partial hydrogenation catalyst for furfural conversion Furfural can be totally converted and the selectivity of partial hydrogenation product (FA) reaches 957% When rhenium oxide species are located on the Pt surface, the hydrogen species on Pt are transferred to adsorbed C = O bond to achieve selective hydrogenation (C) 2015 Elsevier BV All rights reserved

Tuning catalytic selectivity of liquid-phase hydrogenation of furfural via synergistic effects of supported bimetallic catalysts

Characteristics of Al-MCM-41 supported Pt catalysts: effect of Al distribution in Al-MCM-41 on its catalytic activity in naphthalene hydrogenation

Vapor-phase naphthalene hydrogenation over various supported Pt catalysts was studied in a continuous fixed-bed micro-reactor Experimental results indicated that the catalytic activity of the catalyst strongly depended on the nature of the support and the pre-reduction temperature Reaction order was independent of the support as the reaction was pseudo-first-order with respect to naphthalene in the temperature range studied By comparing the apparent rate constant over various supported Pt catalysts, Pt supported on TiO2–ZrO2 (1 : 1) reduced at a low temperature showed the highest activity For higher pre-reduction temperatures, Pt/TiO2–ZrO2 (1 : 1) exhibited the least suppression of H2 uptake, due to a stabilization effect exerted by ZrO2, which prevents the migration of TiOx moieties and the blockage of the Pt surface However, the apparent depression of the hydrogenation activity of high-temperature reduced Pt/TiO2–ZrO2 (1 : 1) was significantly greater than the suppression of its hydrogen uptake Furthermore, the decreasing value of the hydrogenation activity relative to the hydrogen uptake demonstrates electron perturbations between the support and the Pt metal

Chun-Mei Lu

Papers

Naphthalene hydrogenation over Pt/TiO2-ZrO2 and the behavior of strong metal-support interaction (SMSI)