Zirconium oxidation catalysts

Figure Bl.25.9(a) 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 [17]. Note the simultaneous occurrence of single ions (Ff, Si, Zr and molecular ions (SiO, SiOFf, ZrO, ZrOFf, ZrtK. 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 abundance. In addition to the peaks expected from zirconia on silica mounted on an indium foil, the spectrum in figure Bl. 25.9(a)...

The dehydration of 1-hexanol to hexene was conducted over heterogeneous sulfated zirconium oxide catalyst [19, 138]. The zirconia was treated with sulfuric acid and is known as super acid catalyst, having well documented performance for many reactions [19]. The reaction conditions are notably milder as for other acid catalysts, such as silica-alumina. 

A patent was issued to DuPont (US 5,478,549) in 1995 for a zirconium oxide catalyst that can be installed below the gauzes and catchment system. The German company, L C Steinmuller, submitted a patent application (DE 198 05 202 Al) in 1999 for a wide range of N2O abatement catalyst that can be installed below the gauzes222. 

In all cases the mechanism is adsorption of A, reaction on the surface to form adsorbed B, and desorption of B into the gas phase. Sketch the rate of reaction (per unit mass of catalyst) vs total pressure in each of the above three cases. Also, for comparison, include a sketch of the rate of the homogeneous reaction, assuming that it is first order. Sketches should be for constant composition. 9-11. Thodos and Stutzmanstudied the formation of ethyl chloride, using a zirconium oxide catalyst (on silica gel) in the presence of inert methane,... 

J.A. Moreno, G. Poncelet, Isomerization of -butane over sulfated Al- and Ga-promoted zirconium oxide catalysts. Influence of promoter and preparation method, J. Catal. 203 (2001) 453—465. 

C NMR spectra of CH4 in an AIPO4-II molecular sieve have revealed exchange effects between adsorbed and nonadsorbed methane gas. The diffusion of a mixture of methane and xenon in the zeoHte siUcahte has been studied by pulsed field gradient NMR spectroscopy. In situ H MAS NMR studies of the H/D exchange of deuterated propane adsorbed on H-ZSM-5 have been reported. C MAS NMR spectroscopy has been used to study the initial stages of propane activation over H-ZSM-5, and sorption properties of hnear alkanes in ferrierite. Protonated sites on sulfate-promoted zirconium oxide catalysts have been studied using H NMR spectroscopy. NMR relaxation and self-diffusion of pentane, neopentane, dodecane, benzene, cyclohexane, and... 

The equilibrium is more favorable to acetone at higher temperatures. At 325°C 97% conversion is theoretically possible. The kinetics of the reaction has been studied (23). A large number of catalysts have been investigated, including copper, silver, platinum, and palladium metals, as well as sulfides of transition metals of groups 4, 5, and 6 of the periodic table. These catalysts are made with inert supports and are used at 400—600°C (24). Lower temperature reactions (315—482°C) have been successhiUy conducted using 2inc oxide-zirconium oxide combinations (25), and combinations of copper-chromium oxide and of copper and silicon dioxide (26). 

Zirconium tetrafluoride [7783-64-4] is used in some fluoride-based glasses. These glasses are the first chemically and mechanically stable bulk glasses to have continuous high transparency from the near uv to the mid-k (0.3—6 -lm) (117—118). Zirconium oxide and tetrachloride have use as catalysts (119), and zirconium sulfate is used in preparing a nickel catalyst for the hydrogenation of vegetable oil. Zirconium 2-ethyIhexanoate [22464-99-9] is used with cobalt driers to replace lead compounds as driers in oil-based and alkyd paints (see Driers and metallic soaps). 

Reduction. 2,2-Dimeth5lpropanal [630-19-3] can be prepared by the reduction of neopentanoic acid usiag various catalysts, such as iroa (14), tin or zirconium oxides (15,16), iron—chromium (17), and other reagents (18,19). The reduction of neopentanoic acid to 2,2-dimeth5lpropaaol [75-84-3]... 

Cobalt. Without a doubt cobalt 2-ethyIhexanoate [136-52-7] is the most important and most widely used drying metal soap. Cobalt is primarily an oxidation catalyst and as such acts as a surface or top drier. Cobalt is a transition metal which can exist in two valence states. Although it has a red-violet color, when used at the proper concentration it contributes very Httie color to clear varnishes or white pigmented systems. Used alone, it may have a tendency to cause surface wrinkling therefore, to provide uniform drying, cobalt is generally used in combination with other metals, such as manganese, zirconium, lead, calcium, and combinations of these metals. 

OS 80] [R 7] [P 60] The acid-catalyzed dehydration of of 1-hexanol to hexene was conducted in a micro reactor made of PDMS, which also contained a heahng fimc-hon [19, 138], Sulfated zirconium oxide was coated as catalyst on the top plate of the micro reactor. A yield of 85-95% was obtained by-products could not be detected. This performance exceeds those of conventional reactors (30%). 

Zirconium oxide is of interest as a catalyst, as a support for other catalysts and as a diffusion barrier. In the latter application a thin layer of Zr02 prevents the dissolution of rhodium in alumina supports under severe oxidative conditions [32], Here it is essential to apply Zr02 on the support at the highest possible... 

Interpretation of the spectra in Fig. 4.6 is best done by comparison with those of zirconium ethoxide and zirconium oxide reference compounds. Figure 4.7 contains the ZrO+/Zr+ and ZrO/Zr+ ratios from the SIMS spectra of the reference compounds, and of the catalysts as a function of the calcination temperature. The figure clearly shows that catalysts calcined at temperatures up to 200 °C have ZrO+/Zr+ and Zr02+ /Zr+ ratios about equal to those measured from a zirconium ethoxide reference compound. However, samples calcined above 300 °C have intensity ratios close to that of Zr02. 

For the formation of ethyl chloride using a catalyst of zirconium oxide on silica gel in the presence of inert methane, data were taken of the rate, lbmol/(h)(lb catalyst), and partial pressures of the participants in atm. Temperature was 350 F. The equilibrium constant is 35. 

Zirconium monochloride, 26 646, 647 Zirconium organometallic compounds as catalysts, 26 656-657 Zirconium oxide... 

Strangely enough, a combination similar to the ammonia catalyst, iron oxide plus alumina, yielded particularly good results (32). Together with Ch. Beck, the author found that other combinations such as iron oxide with chromium oxide, zinc oxide with chromium oxide, lead oxide with uranium oxide, copper oxide with zirconium oxide, manganese oxide with chromium oxide, and similar multicomponent systems were quite effective catalysts for the same reaction (33). 

Production of HMF from glucose was also evaluated using titanium and zirconium oxides as solid acid catalysts in hot compressed water (473 K) [78-80], Interestingly, it was found that the Zr02 catalyst acts as an acido-basic catalyst. Therefore, Zr02 was able to promote a tandem reaction involving (1) the isomerization of glucose to fructose and (2) the dehydratation to fructose to HMF (yield of HMF = 20% Scheme 8). 

Ermakova and co-workers manipulated the Ni particle size to achieve large CF yields from methane decomposition. The Ni-based catalysts employed for the process were synthesized by impregnation of nickel oxide with a solution of the precursor of a textural promoter (silica, alumina, titanium dioxide, zirconium oxide and magnesia). The optimum particle size (10 0 nm) was obtained by varying the calcination temperature of NiO. The 90% Ni-10% silica catalyst was found to be the most effective catalyst with a total CF yield of 375 gcp/gcat- XRD studies by the same group on high loaded Ni-silica... 

The incorporation of vanadium(V) into the framework positions of silicalite-2 has been reported by Hari Prasad Rao and Ramaswamy469. With this heterogeneous oxidation catalyst the aromatic hydroxylation of benzene to phenol and to a mixture of hydroquinone and catechol could be promoted. A heterogeneous ZrS-1 catalyst, which has been prepared by incorporation of zirconium into a silicalite framework and which catalyzes the aromatic oxidation of benzene to phenol with hydrogen peroxide, is known as well in the literature. However, activity and selectivity were lower than observed with the analogous TS-1 catalyst. 

Mesityl oxide can also be produced by the direct condensation of acetone at higher temperatures. This reaction can be operated in the vapor phase over zinc oxide (182), or zinc oxide—zirconium oxide (183), or in the liquid phase over cation-exchange resin (184) or zirconium phosphate (185). Other catalysts are known (186). 

Dehydration of ethanol has been effected over a variety of catalysts, among them synthetic and naturally occurring aluminas, silica-aluminas, and activated alumina (315—322), hafnium and zirconium oxides (321), and phosphoric acid on coke (323). Operating space velocity is chosen to ensure that the two consecutive reactions,... 

Subsequently, the same authors138 described the preparation of a solid superacid catalyst with acid strength of H0 = —16 with a sulfuric acid-treated zirconium oxide. They exposed Zr(OH)4 to 1A sulfuric acid and calcined it in air at approximately 600°C. The obtained catalyst was able to isomerize (and crack) butane at room temperature. The acidity was examined by the color change method using Hammett indicators added to a powdered sample placed in sulfuryl chloride. The... 

The X-ray photoelectron and IR spectra showed that the catalyst possessed bidentate sulfate ion coordinated to the metal. The specific surface areas were much larger than those of the zirconium oxides, which had not undergone the sulfate treatment. The interesting feature of these catalysts is the high temperature at which they are prepared, which means that they maintain their acidity at temperatures as high as 500°C and should thus be easy to regenerate and reuse. 

Similar to the catalyst of the catalytic thermometry sensor, the catalytic activity of the CTL-based sensor depends not only on the kind of catalyst material and the surface-to-volume ratio of the powder but also on the preparation procedure of the powder. In considering these conditions, a detailed comparison of the CTL catalytic activity has not been reported so far. The present authors and coworkers observed the CTL emission by ethanol vapor on y-aluminum oxide, barium sulfate, calcium carbonate, and zirconium oxide at a few hundred degrees. On the other hand, CTL emission is not observed during the catalytic oxidation on metal and semiconductive materials, e.g., tin oxide, zinc oxide, and copper oxide. 

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