Effect of Sulfate Ions on Activity of TiO2, Fe2O3 and ZrO2 for the 2-Pinene Isomerization Reaction

Ohnishi, Ryuichiro; Morikawa, Toshiyuki; Hiraga, Yoshizumi; Tanabe, Kozo

doi:10.1524/zpch.1982.130.2.205

Cited by 4 publications

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“…The addition of 0.5 wt 'YO SO:increased the conversion from 58 to 84% at 573 K [68]. For the isomerization of 2-pinene to camphene and tricyclene, SOi-/TiO2 showed the highest activity and SOi-/ZrO2 the lowest activity, SOi-/Fe203 being intermediate [70]. The selective catalytic reduction of NO with NH3 at higher temperatures (673-798 K) is achieved by use of SOi-/Ti02 [69].…”

Section: Catalyst Amount Reaction Time Yieldmentioning

confidence: 98%

Solid Superacids

Tanabe

Hattori

1999

Preparation of Solid Catalysts

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A solid superacid is defined as a solid material which shows an acid strength higher than the acid strength (Ho = -1 1.9) of 100% sulfuric acid [l]. The acid strength is measured by use of basic indicators having different pK, values [2]. However, this method is not suitable for colored materials and may have some problems when pore sizes of a solid are too small for large molecules of the indicators and if there exist any interactions between the indicators and any sites (basic or redox sites) other than acid sites. The catalytic activity for the skeletal isomerization of n-butane is a measure of superacidity, since the reaction does not take place in the presence of 100?40 sulfuric acid at room temperature. Superacidity can be estimated also by utilizing the temperature-programmed desorption (TPD) method using ammonia or pyridine, provided that the relative value in TPD is related to the absolute value (Ho) and the interaction of ammonia or pyridine with basic sites on solid surfaces is confirmed to be negligible.Recently, various kinds of solid superacids have been developed. The first group is metal oxides and mixed oxides containing a small amount of sulfate ion, and those modified with platinum. The second group is metal oxides, mixed oxides, graphite, metal salts, etc. treated or combined with antimony fluoride or aluminum chloride. The third group is perfluorinated polymer sulfuric acid (Nafion-H). The fourth and fifth groups are H-ZSM-5 and a type of heteropolyacids, respectively. The last group is simply mixed oxides.The solid superacids of the second group which have a possibility of leaching or evaporating of halogen compounds seem to be environmentally undesirable as catalysts. These superacids and Nafion-H have been extensively reviewed [ 1-51. Therefore, the superacids of the first group for which many papers have been contributed recently and the industrial application of which is promising, are mainly described here and the other superacids are dealt with only briefly.

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Section: Catalyst Amount Reaction Time Yieldmentioning

confidence: 98%