Mixed oxide

About: Mixed oxide is a research topic. Over the lifetime, 5224 publications have been published within this topic receiving 115567 citations.

Isomerization of n-hexane over mono- and bimetallic Pd–Pt catalysts supported on ZrO2–Al2O3–WOx prepared by sol–gel

Abstract: The catalytic performance of mono- and bimetallic Pd (0.6, 1.0 wt.%)–Pt (0.3 wt.%) catalysts supported on ZrO2 (70, 85 wt.%)–Al2O3 (15, 0 wt.%)–WOx (15 wt.%) prepared by sol–gel was studied in the hydroisomerization of n-hexane. The catalysts were characterized by N2 physisorption, XRD, TPR, XPS, Raman, NMR, and FT-IR of adsorbed pyridine. The preparation of ZrW and ZrAlW mixed oxides by sol–gel favored the high dispersion of WOx and the stabilization of zirconia in the tetragonal phase. The Al incorporation avoided the formation of monoclinic-WO3 bulk phase. The catalysts increased their SBET for about 15% promoted by Al2O3 addition. Various oxidation states of WOx species coexist on the surface of the catalysts after calcination. The structure of the highly dispersed surface WOx species is constituted mainly of isolated monotungstate and two-dimensional mono-oxotungstate species in tetrahedral coordination. The activity of Pd/ZrW catalysts in the hydroisomerization of n-hexane is promoted both with the addition of Al to the ZrW mixed oxide and the addition of Pt to Pd/ZrAlW catalysts. The improvement in the activity of Pd/ZrAlW catalysts is ascribed to a moderated acid strength and acidity, which can be correlated to the coexistence of W6+ and reduced-state WOx species (either W4+ or W0). The addition of Pt to the Pd/ZrAlW catalyst does not modify significantly its acidic character. Selectivity results showed that the catalyst produced 2MP, 3MP and the high octane 2,3-dimethylbutane (2,3-DMB) and 2,2-dimethylbutane (2,2-DMB) isomers.

Pt nanoparticles over TiO2–ZrO2 mixed oxide as multifunctional catalysts for an integrated conversion of furfural to 1,4-butanediol

Abstract: 1,4-butanediol (BDO) is an important commodity chemical for manufacturing many basic chemicals and valuable polymers. Its current manufacturing processes are exclusively based on feedstocks derived from oil and natural gas. The biomass-to-BDO chemical transformation is via furfural, a key platform molecule from glucose and xylose. The integrated conversion involves two sequent reaction steps: selective oxidation of furfural to furanones and hydrogenation of the mixture of furanones to BDO. Platinum nanoparticles supported over TiO 2 –ZrO 2 perform well for both oxidation and hydrogenation steps and the total yield of BDO reaches 85.2%. The chemical composition and crystallinity of the mixed oxide support significantly affect the catalytic performance. The best catalyst is platinum supported over TiO 2 –ZrO 2 mixed oxide (Ti/Zr, 1:1) calcined at 823 K, which also exhibits good recoverability and recyclability in the five-run test.

Nitrogen oxide storage material and nitrogen oxide storage catalyst prepared therefrom, process for its preparation and use thereof

Abstract: of EP0982066The carrier material is selected from a group doping/donating cerium oxide, cerium/zircon-mixed oxide, calcium titanate, strontium titanate, barium titanate, barium stannate, barium zirconate, magnesium oxide, lanthan oxide, praseodymium oxide, samarium oxide, neodymium oxide, yttrium oxide, yttrium barium cuprate, lead titanate, bismuth titanate, lanthan cobaltate, lanthan manganate and barium cuprate or a mixture. The particles of the storage components has particle diameter of at least 1.5 micronmeter. Nitrogen oxide-storage material comprises at least a storage component for nitrogen oxide in the form of particles of oxide(s), carbonate(s), or hydroxide(s) of earth metals magnesium calcium, strontium and barium as well as alkali metals potassium and caesium on a carrier material. Independent claims are include for the production of storage material and use of nitrogen oxide-storage.