Magnesium aluminate spinel for

Preparation and Characterization of Magnesium Aluminate Spinel for SOx Abatement in Fluid Catalytic Cracking... 

It is for this reason that we write the solid state diffusion reaction for the magnesium aluminate spinel as follows ... 

Recent studies have demonstrated that cerium containing magnesium aluminate spinels such as MgAl204 and Mg2Al205 are very effective SOx reduction catalysts for FCC units. These magnesium aluminate spinels can be prepared by three different techniques (i) thermal co-condensation... 

Designing a catalyst for effective removal of SOx (S02 + S03) in a fluid catalyst cracking unit regenerator is a challenging problem. One must come up with a particle having physical properties similar to FCC catalysts which will 1) oxidize S02 to S03, 2) chemisorb the S03/ and 3) be able to release it as H2S as it enters the reactor side of the unit. A cerium containing magnesium aluminate spinel was found to be very effective for this purpose (1). The preparation methods and characterization techniques utilized for this spinel catalyst and how the SOx abatement activity of this catalyst is related to the preparative route used are discussed in this paper. 

Krishnan M, Tiwari B, Seema S, Kaha N, Biswas P, Rajeswari K et al (2014) Transparent magnesium aluminate spinel a prospective biomaterial for esthetic orthodontic brackets. J Mater Sci Mater Med 25 2591-2599... 

The integrated planar (IP) SOFC stack concept, for instance, applied by Rolls-Royce Fuel Cell Systems, uses an array of series-connected cells deposited by screen printing onto a flat support tube, a schematic cross section of which is shown Fig. 21.23. The support tube, an inert, porous ceramic, is fabricated from a magnesia magnesium aluminate spinel (MMA), whereby the desired coefficient of thermal expansion is adjusted by the ratio of the base materials [76]. 

Both structure and composition affect phonon conductivity in singlephase crystalline ceramics. Complex structures scatter lattice waves to a greater extent. Hence, thermal conductivity is lower in those structures. For example, magnesium aluminate spinel, consisting of two oxides, has a lower thermal conductivity than the single oxides alumina or magnesia. 

Wang, Y., Zhang, F., Xu, S., Yang, L., Li, D., Evans, D. G., and Duan, X. Preparation of macrospherical magnesia-rich magnesium aluminate spinel catalysts for methano-lysis of soybean oil. Chem Eng Sci 63,4306-4312 (2008). 

Magnesium aluminate spinel, MgAl204, or simply spinel, the actual mineral name for this particular spinel composition, causes a thermal-expansion... 

Spinel is a colorless magnesium aluminate (MgAl204) of cubic structure. It is hard and durable, but, like white sapphire, it is not a good diamond substitute because it has a low refractive index and lacks brilliance. However, it is readily doped to produce other gems of various colors. Artificial ruby, for example, is often natural red spinel, and most synthetic blue sapphires on the market are actually blue spinel. 

The primary reformer consists of a multitude of reformer tubes loaded with the nickel catalyst (15 25% NiO on aluminum oxide, calcium aluminate, or magnesium aluminum spinel support) in a furnace box, in which the heat needed for the reaction is transferred to the tubes by radiation. The heat is generated in burners, generally gas-fired in the furnace box. 

It seems possible, from the results obtained with magnesium aluminate and from x-ray evidence, that a satisfactory catalyst for the Hargreaves reaction will be any compound possessing a spinel-type structure. 

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