Montmorillonite-Alumina Composite

2 M AICI3 was adjusted to pH 4.2 with 0.1 M NaOH. Na-montmorillonite was aged with Al solution for different times, with or without discarding the supernatant (6 different procedures). 

37 Mordenite (Synthetic Zeoeite) erom Huber NaAISi-O 2 3H2O Properties BET specific surface area 340 m /g [851], 149 m-/g [877,858], 

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The low H/C-ratio of FCC feed derived from liquefied biomass led to low conversion and poor gasoline selectivity. Addition of alumina to the matrix resulted in a catalyst more active for heavy oil cracking but with a poor selectivity. Alumina-montmorillonite catalysts showed activities for heavy oil cracking comparable to that of a conventional, zeolite based, cracking catalyst. Effects of matrix composition and zeolite type on the heavy oil cracking performance are discussed. 

SiO system under conditions of one atmosphere pressure and 80°C. It was found that the trioctahedral phase had a variable alumina content which was the result of variations in the composition of the chemical system of the experiment. Variations in pH (4-6) and the additions of Na or K ions did not seriously affect the phase relations of the montmorillonites. 

Sepiolite and palygorskite have a rather special composition and seem to be related to specific mineral parageneses. They appear to be stably associated with montmorillonite, corrensite, serpentine, chert, sulfates, carbonates and various salts. They are found in deposits typified by processes of chemical precipitation or solution-solid equilibria (Millot, 1964) and are therefore rarely associated in sediments with large quantities of detrital minerals. Their chemical environment of formation is in all evidence impoverished in alumina and divalent iron. Their frequent association with evaporites, carbonates and cherts indicate that they came from solutions with high chlorinity. 

Preferred bentonite clays are those whose chief constituent is mont-morillonite, a mineral of the composition corresponding to the empirical formula, 4Si02-Al203 H20. The principal sources of raw clay for the manufacture of the presently most widely used natural catalyst (Filtrol Corporation) are deposits in Arizona and Mississippi. The clay from these deposits contains appreciable amounts of impurities, principally CaO, MgO, and Fe203, which replace part of the A1203 in the ideal montmorillonite structure. The catalyst is prepared by leaching the raw clay with dilute sulfuric acid until about half of the alumina and associated impurities is removed. The resulting product is then washed, partially dried, and extruded into pellets, after which it is activated by calcination. A typical analysis of the finished catalyst is as follows (Mills, 12). 

The microparticles that make up the coating can be of any desired substance composition wise which can be reduced to a colloidal state of subdivision however, they must be dispersible in a medium as a colloidal dispersion. Water is the best medium for dispersions of particles of varying ionic charges. Examples of suitable aqueous sols are amorphous silica, iron oxide, alumina, thoria, titania, zirconia, zircon, and alumina sihcates, including colloidal clays such as montmorillonite, colloidal kaolin, attapul-gite, and hectorite. Silica is preferred material because of its low order of chemical activity, its ready dispersibility, and the easy availabihty of aqueous sols of various concentrations. 

Montmorillonite is the name given to day found near MontmoriUonin in France, whereit was identified by Knight in 1896 (Utracki, 2004). Montmorillonite is a 2 1 layered hydrated aluminosilicate, with a triple-sheet sandwich structure consisting of a central, hydrous alumina octahedral sheet, bonded to two silica tetrahedral sheets by shared oxygen ions (Fig. 3). The unit cell of this ideal structure has a composition [Al2(0H)2(Si205)2]2 with a molar... 

The natural montmorillonite clays consist of several hundred individual platelike particles of dimensions 1 jum x 1 jum x 1 nm, held together by electrostatic forces with a gap of approximately 0.3 nm between two adjacent particles. The structure at the atomic level is shown in Figure 13.28 (77). The sodium montmorillonite layer is a crystalline 2 1 layered clay mineral in which a central alumina octahedral sheet is sandwiched between two silica tetrahedral sheets. These structures are sometimes called smectite clays, because of their layered structure see Figure 7.1. Note that this clay mineral comprises silicate layers in which the fundamental unit is planar. In the gap between the silicate layers are sodium ions. The gap is widely known as a gallery or an interlayer. The density of montmorillonite clays vary slightly with composition, but is generally near 2.5 g/crn (78). 

Chemical characterization of fines implies the elemental and mineral compositional analysis of migratory fines in porous media. Khilar and Fogler (1998) presented the range in chemical composition of migratory clays primarily of kaolinite, illite, montmorillonite, and chlorite particles in Table 5.6. We observe from this table that silica, Si02, and alumina are the major minerals. 

The montmorillonite pillared with alumina, Al-CLM, as well as that containing alumina and lanthanum, Al(La)-CLH, were prepared according to the method described by Yamanaka and Brindley (8). Hydroxyalumlnum solutions of composition ratio 0H/A1= 1.84 were prepared by adding a 0.0IH NaOH solution to another one 0. IM Al(NO ). In the case of Al(La)-CLM, the precursor solution of AI(III) contained 4% of La(Ill). The final pH values were 4.32 and 4.77, respectively. These solutions were aged at reflux temperature (85"-95°C) for 10 h, which appears to have a beneficial effect on the subsequent pillaring process in accordance with data reported by Tokarz et al.(3). 

The chemical composition of the Zr-pillared clays as well as the Na montmorillonite are reported in table 2. Silica, alumina and zirconia have been analyzed by X-Ray fluorescence the other elements by atomic absorption spectroscopy after sulfofluorhydric dissolution of the clay (6). 

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