Saponite synthetic

Polyimide-clay nanocomposites constitute another example of the synthesis of nanocomposite from polymer solution [70-76]. Polyimide-clay nanocomposite films were produced via polymerization of 4,4 -diaminodiphenyl ether and pyromellitic dianhydride in dimethylacetamide (DMAC) solvent, followed by mixing of the poly(amic acid) solution with organoclay dispersed in DMAC. Synthetic mica and MMT produced primarily exfoliated nanocomposites, while saponite and hectorite led to only monolayer intercalation in the clay galleries [71]. Dramatic improvements in barrier properties, thermal stability, and modulus were observed for these nanocomposites. Polyimide-clay nanocomposites containing only a small fraction of clay exhibited a several-fold reduction in the... 

FIG. 13 Reduction of the relative permeability coefficient is dependent on the clay platelet aspect ratio in the system of polyimide-clay hybrid with water vapor as the permeate. Each hybrid contains 2 wt% clay. The aspect ratios for hectorite, saponite, montmorillonite, and synthetic mica are 46, 165, 218, and 1230, respectively. (From Ref. 71.)... 

Smectites are 2 1 charged layered silicates from natural (montmorillonite, hectorite, beidellite, saponite etc.) or synthetic (synthetic fluorohectorites, such as... 

Mesostructured clay catalysts a new porous clay heterostructure (PCH) derived from synthetic saponite... 

Here we report the synthesis and catalytic application of a new porous clay heterostructure material derived from synthetic saponite as the layered host. Saponite is a tetrahedrally charged smectite clay wherein the aluminum substitutes for silicon in the tetrahedral sheet of the 2 1 layer lattice structure. In alumina - pillared form saponite is an effective solid acid catalyst [8-10], but its catalytic utility is limited in part by a pore structure in the micropore domain. The PCH form of saponite should be much more accessible for large molecule catalysis. Accordingly, Friedel-Crafts alkylation of bulky 2, 4-di-tert-butylphenol (DBP) (molecular size (A) 9.5x6.1x4.4) with cinnamyl alcohol to produce 6,8-di-tert-butyl-2, 3-dihydro[4H] benzopyran (molecular size (A) 13.5x7.9x 4.9) was used as a probe reaction for SAP-PCH. This large substrate reaction also was selected in part because only mesoporous molecular sieves are known to provide the accessible acid sites for catalysis [11]. Conventional zeolites and pillared clays are poor catalysts for this reaction because the reagents cannot readily access the small micropores. 

M. Polverejan, Y. Liu, and T. J. Pinnavaia. Mesostructured clay catalysts a new porous clay heterostructure(PCH) derived from synthetic saponite. Stud Surf. Sci. Catal., 129(2000), pp.401-408. 

Bergaoui, L. et al.. Porosity of synthetic saponites with variable layer charge pillared by A1j3 polycations, Langmuir, 11, 2849, 1995. 

The necessity to develop hydrotreating catalysts with enhanced activity stimulates the search for alternative catalyst supports. It was shown that clay-supported transition metal sulfides can efficiently catalyze hydrodesulfurization (HDS) of thiophene [1-3]. However, the large scale application of the catalysts based on natural clays is still hampered, mainly due to the difficulties in controlling the chemical composition and textural properties. Synthetic clays do not suffer from these drawbacks. Recently, a novel non-hydrothermal approach was proposed for the synthesis of some trioctahedral smectites, namely saponite... 

P-15 - Synthesis of mesoporous aluminosilicate FSM-materials derived from synthetic and natural Saponite. 

Fig. 2 Intensity of the second harmonic signal versus the amount of PDDA offered in solution (Cpdda in moles/L) for the film glass/clay/PDDA/NAMO. Lap= laponite Hec= hectorite Sme= synthetic saponite APTS=3-aminopropyltrimethoxysilane and TMSPA=trimethoxysilylpropyltrimethymammonium.

Other than montmorillonite, synthetic mica, saponite and hectorite were used to synthesize a nylon 6-clay hybrid. The nano composites fabricated by using each of these types of clay were called NCH, NCHM, NCHP and NCHH. 

Silicate layers were uniformly dispersed in nylon 6 in NCH, NCHM, NCHP and NCHH at the molecular level. The thicknesses of the silicate layers were 1 nm in all of these nanocomposites, but their widths varied depending on the type of clay used. An examination of each photograph revealed that the width of the nano composites fabricated using montmorillonite and synthetic mica were about 100 nm and those of the nanocomposites fabricated using saponite and hectorite were about 50 nm. 

It was inferred from all of these results that montmorillonite in all types of clay can bond most strongly with nylon 6 and that the bond strength weakens in the order of synthetic mica > saponite hectorite. Figure 12 shows the N-NMR chemical shift as an indicator of bond strength and the flexural... 

Preparation and Properties of Pillared Synthetic Boron-Containing Saponite... 

Pillaring selected synthetic clay minerals with suitable pillaring agents may lead to a breakthrough in the theory and application of pillared clays. This chapter reports on the preparation and characterization of a novel pillared synthetic heteroatom-containing clay, that is, pillared synthetic boron-containing saponite. 

Characterization of the pillared synthetic (boron-containing) saponites... 

Figure 4-1 shows the X-ray pattoms of synthetic boron-containing saponite (0)... 

FIGURE 4-1. X-ray diffraction patterns of (a) synthetic boron-containing saponite (0) (b) alumina-pillared synthetic boron-containing saponite (0) (c) synthetic boron-containing saponite (3.0) and (d) alumina-pillared synthetic boron-containing saponite (3.0). 

---