Zirconia-containing catalysts

Raudaskoski R, et al. Catalytic activation of CO2 use of secondary CO2 for the production of synthesis gas and for methanol synthesis over copper-based zirconia-containing catalysts. Catal Today. 2009 144(3 4) 318-23. 

Figure 1. Temperature prograimned reduction of silica- and zirconia-supported catalysts containing nickel and sulfate, a) silica-series b) zirconia-series.

Breen JP, Ross JRH. Methanol reforming for fuel-cell applications development of zirconia-containing Cu-Zn-Al catalysts. Catal Today. 1999 51 (3—4) 521—33. 

Par-Isom [Paraffin Isomerization] A process for isomerizing light naphtha in order to improve the octane number. The catalyst, a sulfated zirconia containing platinum, was developed by Cosmo Oil Company and Mitsubishi Heavy Industries, and the process was developed by UOR The oxide catalyst is claimed to be more efficient than zeolite catalysts currently used for this process. 

As mentioned in Section 10.2 above, both ceria and ceria-zirconia contain relatively weakly-bound oxygen when freshly prepared, e.g., in high-surface-area form. The thermal stability of this oxygen may differ in the two materials, however, as shown in steady-state CO-oxidation measurements performed by Bunluesin et al. [11] on model planar catalysts. In these experiments, films of ceria and ceria-zirconia were subjected to calcination treatments over a wide range of temperature before noble... 

As it can be observed in Fig. 4, when only methane is added to the feed, catalyst A shows the best behaviour, followed by catalysts B and U. According to this, the addition of cerium to the zirconium hydroxide increases the activity of the zirconia-supported palladium catafysts. Comparing the performance of the cerium-containing catalysts, it is remarkable that catalyst B presents a poorer performance, than catalyst A (slightly lower initial conversion and foster deactivation). This result suggests that the interaction between Pd and Ce, revealed in the TPR experiments, does not enhance the activity of the active phase (Pd). In contrast, the interaction Ce-Zr in catalysts A increases the thermal stability, considered as the main foctor for preventing catalyst deactivation in these reactions [9]. 

This is a very active research area. There is a good chance that, with further understanding of just what these catalysts are and how they work, one will be found for the commercial alkylation of isobutane with olefins. At present, the reaction must be run at subambient temperatures to avoid the side reaction of dimerization of the olefin. Perhaps, the catalyst being offered by Hydrocarbon Technologies is of this type and will be suitable. Because sulfated zirconia contains... 

Platinum catalysts are superior for hydrocarbon oxidation [350]. Platinum is usually present as metaDic platinum at temperatures exceeding 400 °C [351]. Besides alumina, zirconia, molecular sieves and metal oxides are applied as supports, amongst others. However, an inhibition effect of oxygen was observed over platinum/alumina for light hydrocarbons [350,352] and other platinum-containing catalysts for methane [353] and propane oxidation [354]. This effect becomes problematic, in particular because full hydrocarbon conversion is usually required for a catalytic burner. The temperature control of catalytic burners also becomes difficult, because this is frequently carried out by regulation of the air feed flow rate to suprastoichiometric values. 

Silica/chromia catalysts have also been modified by the incorporation of other oxides such as alumina" or zirconia," by impregnating a silica support with zirconium acetylacetonate or aluminum sec-butoxide or co-gelling the silica gel with appropriate soluble salts. Zirconia-modified catalysts are similar to those with added titanium in their effect but have not been widely reported. Aluminum-modified catalysts have increased activity and provide lower-molecular-weight polymers, but the procedure for their preparation is complicated. Neither type of catalyst is widely described in the literature but they are reported as containing different active sites." ... 

In the mid-1950s, alumina-silica catalysts, containing 25 percent alumina, came into use because of their higher stability. These synthetic catalysts were amorphous their structure consisted of a random array of silica and alumina, tetrahedrally connected. Some minor improvements in yields and selectivity were achieved by switching to catalysts such as magnesia-silica and alumina-zirconia-silica. 

Figure 4.18 shows the positive SIMS spectrum of a silica-supported zirconium oxide catalyst precursor, freshly prepared by a condensation reaction between zirconium ethoxide and the hydroxyl groups of the support. Note the simultaneous occurrence of single ions (H", SR, 7.r ) and molecular ions (SiO, SiOH, ZrO, Zr02 ). Also, the isotope pattern of zirconium is clearly visible. Isotopes are important in the identification of peaks, because all peak intensity ratios must agree with the natural abundances. In addition to the peaks expected from zirconia on silica mounted on an indium foil, the spectrum of Fig. 4.18 also contains peaks from Na, K, and Ca. This is typical for SIMS Sensitivities vary over several orders of magnitude and elements such as the alkalis are detected when present in trace amounts. 

---