Pillaring solutions, preparation

Lower dilution levels did not allow sufficient depolymerlzatlon and higher dilution caused excessive depolymerlzatlon In the aged solutions. Pillared clays prepared from aged dilute solutions had an enhanced microstructure which showed an Increased activity for selectively cracking large molecules to the light cycle oil range. This microstructure Is lost In the presence of steam which also reduces the formation of catalytic coke. Addition of rare earth zeolite to pillared clay can partially overcome the effects of this loss of microstructure. 

The surface areas of pillared clays prepared from dilute Chlorhyd-rol solution depend on the extent of dilution and age of the dilute solution. Dilution produces polycations favorable to the production of pillared clays by depolymerizing larger polycations present in the Chlorhydrol solution. Aging is the reequilibration of these depolymerized solutions. 

Iron impurities in clays have been thought responsible for these type of catalysts low carbon selectivity (4,5). The purpose of this paper is to investigate and report the influence that the location, chemical state and environment of iron impurities have on the cracking properties of pillared clays prepared by reacting several smectites with aluminum chlorhydroxide solutions. 

Pillaring solutions. Conventional Al203-pillared montmorillonite and interstratified illite/montmorillonites were prepared using an aluminum chlorohydrate (ACH) solution having an Al-concentration of 0.25 M and an OH/Al-ratio of 2.5, prepared by dilution of a commercial ACH-solution (Locron L, Hoechst). The solution was aged for 20 hr. after dilution, prior to use for preparation of pillared products. 

Silicon oxide / Aluminum oxide pillared smectites. Si02/Al203-pillared smectites were prepared using two different methods (6). The surface areas of the pillared products decreased with increasing Si/Al-ratio in the pillaring solution while the basal spacings were essentially independent of this ratio. 

In this work, zirconium acetate solution was used in order to increase the pH of the pillaring solution and the content of sulfate ions introduced. Different preparation parameters and their effect on the structural and textural properties have been investigated. The resulting materials present a best zirconium-sulfate intercalation with higher sulfate rate and develop very high thermal stability of sulfur even at about 830 °C. 

All samples were prepared using 0.1 mol/L zirconium acetate solution at 15 °C with 42 hours intercalation reaction. The clay suspension pH was fixed at the same value as that of the intercalation solution. The X-ray diffraction patterns of zirconium sulfate pillared clays prepared with different sulfate to zirconium ratios are shown in Fig. 4. This figure shows a shoulder at about 19.5 A for the sample prepared using a S04 Zr ratio equal to 0.125. The 19.5 A spacing corresponds to the intercalation of non sulfated zirconium polycations [13]. Non-drastic loss in surface area is observed when the sulfate to zirconium ratio increases. But the use of zirconyl chloride solution shows a drastic loss of surface area when the SOarZr ratio increases (more than 50 %) [13]. 

Zirconium-sulfate pillared clay prepared with reaction time of 140 hours and using 0.1 mol /L zirconium acetate solution has been analyzed with mass spectrometry. When the sample was heated in air, masses of 17, 18, 44, 48, 64 and 80 were recorded, corresponding, respectively, to OH+, H2O+, COz, SO+, S02" and SO3+. Figs. 7, 8 and 9 show the variation of the different masses with heating temperature. 

The titanium pillaring solution is prepared from TiCU and HCl diluted in distilled water, the TiCU and HCl concentration being respectively 0.82M and... 

Besides AI13 several other species might be present in the pillaring solution, depending on the preparation conditions [Al(0H)x(H20)g.x] " monomers, [Al2(OH)x(H20)io dimers and also higher polymeric forms (Alpoiy) [42]. 

Pillaring solutions of Al and Zr have been prepared. In the method of Lahav et al., 0.2 M AICI3 is hydrolyzed with 0.2 M NaOH, leading to an OH/Al ratio of 2.33 and a pH of 4 [54]. The final concentration of the Absolution is 0.07 M. The aging process is performed under reflux conditions for 24 h. An alternative and less complicated synthesis simply includes the dilution of the commercially available Locron L solution. This highly concentrated Absolution (4.6 M) is diluted with demineralized water to obtain the same concentration, OH/Al and pH as in the first method. 

Fig. 2. X-ray diffraction patterns of La/Al-, Ce/Al-, and RE/Al-pillared montmorillonites prepared from solutions autoclaved at 120 C for 12-96 h.

Al-pillared montmorillonite prepared using a RE-free ACH-solution. 

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