Magnesia metal oxide catalysts

In the vapor phase, acetone vapor is passed over a catalyst bed of magnesium aluminate (206), 2iac oxide—bismuth oxide (207), calcium oxide (208), lithium or 2iac-doped mixed magnesia—alumina (209), calcium on alumina (210), or basic mixed-metal oxide catalysts (211—214). Temperatures ranging... 

Dehydration and dehydrogenation combined utilizes dehydration agents combined with mild dehydrogenation agents. Included in this class of catalysts are phosphoric add, silica-magnesia, silica-alumina, alumina derived from aluminum chloride, and various metal oxides. 

Many of the catalysts for the hydrodesulfurization process are produced by combining (Table 5-5) a transition metal (or its salt) with a solid support. The metal constituent is the active catalyst. The most commonly used materials for supports are alumina, silica, silica-alumina, kieselguhr, magnesia (and other metal oxides), as well as the zeolites. The support can be manufactured in a variety of shapes or may even be crushed to particles of the desired size. The metal constituent can then be added by contact of the support with an aqueous solution of the metal salt. The whole is then subjected to further treatment that will dictate the final form of the metal on the support (i.e., the metal oxide, the metal sulfide, or even the metal itself). 

Reaction 1.1 is known as steam reforming. The reaction conditions are fairly severe (>1000°C),and the structural strength of the catalyst is an important point of consideration. The catalyst employed is nickel on alumina, or magnesia, or a mixture of them. Other non-transition metal oxides such as CaO, Si02, and K20 are also added. 

Suitable catalysts for dehydrative amination are alumina, silica-alumina, alumina-magnesia [13], aluminum phosphate [14], binary transition metal oxides... 

Other alkaline earth metal oxides and related Group II metal oxides were screened for activity. Tests indicated that magnesia-zinc oxide combinations were about as efficient as magnesia alone. Calcium oxide, zinc oxide, and cadmium oxide were all catalysts for the reaction but were not as effective as magnesium oxide. Efficiencies of these oxides were increased by supporting them on activated alumina. In addition, it was found that sodium and lithium compounds deposited on activated alumina were active cat-... 

Anosovite (type II) [12065-65-5] P-TijO, M = 223.0070 64.1 wt.% Ti 35.9 wt.% 0 (Oxides and hydroxides) Orthorhombic Distorded pseudobrookite TiO 191-210 pm mC32(Z=4) S.G. C2/m Biaxial ( ) n.a. 4900 Habit acicular cry als. Color bhie-daik. Diaphaneity opaque. Luster metallic. Streak black. Type II can be prepared by the hydrogen r uction of solid TiO, at temperature around 1500 Cwith magnesia as a catalyst. Anosovite type 11 is similar to that found in artiftcial titania dags and it is stabilized at room ten erature with small amount of iron. This oxide is dimorphic with a rapid phase transition from semiconductor to metal occuring at roughly 120 C. 

Concerning gaseous catalyst poisons, a distinction should be made between permanent poisons causing an irreversible loss of catalytic activity and temporary poisons which lower the activity while present in the synthesis gas. For a review of poisoning of synthesis catalysts, see [1,2]. Permanent poisons accumulate on the surface and may be detected by chemical analysis of the poisoned catalysts, whereas temporary poisons cause a partial coverage of the catalyst surface. Since oxygen is the most common temporary poison, it is difficult to detect the amount on the spent catalyst by analysis since the promoter phases are difficulty reducible metal oxides like alumina, magnesia, silica, and potassium oxide. 

Extensive research has been conducted on catalysts that promote the methane—sulfur reaction to carbon disulfide. Data are pubhshed for sihca gel (49), alurnina-based materials (50—59), magnesia (60,61), charcoal (62), various metal compounds (63,64), and metal salts, oxides, or sulfides (65—71). Eor a sihca gel catalyst the rate constant for temperatures of 500—700°C and various space velocities is (72)... 

The catalysts used in the process are essentially nickel metal dispersed on a support material consisting of various oxide mixtures such as alumina, silica, lime, magnesia, and compounds such as calcium aluminate cements. When the catalyst is made, the nickel is present as nickel oxide which is reduced in the plant converter with hydrogen, usually the 3 1 H2 N2 synthesis gas ... 

Catalysts. - Group VIII metals, conventional base metal catalysts (Ni, Co, and Fe) as well as noble metal catalysts (Pt, Ru, Rh, Pd) are active for the SR reaction. These are usually dispersed on various oxide supports. y-Alumina is widely used but a-alumina, magnesium aluminate, calcium aluminate, ceria, magnesia, pervoskites, and zirconia are also used as support materials. The following sections discuss the base metal and noble metal catalysts in detail, focusing on liquid hydrocarbon SR for fuel cell applications. 

Alkali oxides such as K2O are used to minimize carbon formation on the Ni catalyst. The alkali may evaporate at elevated reaction temperatures however, its loss can be controlled by adding acidic components, such as silica.Oxides of alkali earth metals, such as magnesia or calcia are also added to the support to neutralize highly acidic sites, which are mainly responsible for the carbon forming reactions. Compositions of various commercial Ni-based SR catalysts are listed in Table 4. 

---