Synthesis of large crystals

M. Morris, A. Dixon, A. Sacco, and R. Thompson, Investigation on the Relative Effectiveness of some Tertiary Alkanolamines in the Synthesis of Large-crystal Zeolite NaA. Zeolites, 1993, 13, 113-121. 

Fig. 6. The effect of varying the concentration of triethanolamine on the size of the largest crystals of zeolite A. Synthesis at 95 °C, composition 0.84 Si02 AI2O3 1.94 Na20 194 H20 y TEA. The x-axis represents the number of moles of triethanolamine y in the composition. Reprinted with permission from Zeolites, vol. 13, Morris M, Dixon AG, Sacco A, Thompson RW, Investigations on the relative effectiveness of some tertiary alkanolamines in the synthesis of large-crystal zeolite NaA, (1993) pp. 113-21, Elsevier Science Inc.

Nadimi S, Oliver S, Kuperman A, Lough A, Ozin G A, Garces J M, Olken M M and Rudolf P 1994 Nonaqueous synthesis of large zeolite and molecular sieve crystals Stud. Surf. Sol. Catal. 84 93-100... 

Synthesis procedures to obtain large zeolite crystals are well developed (1,2). In particular much attention has been paid to the synthesis of ZSM-5 crystals (3-6). Elongated prismatic (Fig. la) and cubic-shaped orthorhombic (Fig. lb) ZSM-5 crystals of sizes between 2-50 /tm were reported in the first recipes (7) in the patent literature. Later on, systematic studies have led to excellent synthesis prescriptions for the growth of large crystals of the prismatic (8) as well as of the orthorhombic form (9). The synthesis parameters which are dominant in the crystallization of pure ZSM-5 single crystals, are still under study (10,11). 

Synthesis of large AFI-tvpe crystals. For these studies of the crystallization of large AFI-type aluminophosphate crystals, the reaction temperature T, the concentration of tripropylamine Pr3N, and the amount of water were chosen as operational variables. Synthesis runs were performed with each of these "factors" at a high (+) and a low (-) level, for molar compositions with b Pr,N - A1 0-, - P203 - c H20 as indicated in Table I ... 

Synthesis of large ZSM-5 Crystals. Preliminary studies led to the investigation of a synthesis mixture with a molar composition expressed in oxide ratio 6.5 (TPA)oO - b (NH4)20 - c Al20o - Si02 -a H20. Table IV illustrates the factors which were examined ... 

The amount of water present during the synthesis of large AFI-type aluminophosphate crystals was found to be of significant importance. However, yield of AlP0 -5 and crystal size were countercurrently influenced. It follows tnat at least with tripropyl amine, either few large crystals or maximum conversions into small particle AlP0 -5 is possible. 

C. Shao, X. Li, S. Qiu, and F. Xiao, The Role of Pyrocatechol as a Complex Agent for Silicon in the Synthesis of Large Single Crystals of Silica-sodalite Zeolite. Microporous Mesoporous... 

For growing single crystals from solution, the methodology is similar to that used in normal hydrothermal synthesis, except that the solution is typically supersaturated and the vessels are cooled very slowly (1 °C per min) to facilitate slow growth of large crystals. 

Reviews of general interest in this area highlights microreactors that can be used for a variety of photochemical reactions such as the synthesis of large ring ketones. Interest in the control that can be exercised on the outcome of photochemical reactions in constrained environments continues to increase and reviews dealing with the enantioselective photoreactions of achiral compounds in chiral crystals and inclusion crystals have been published. ... 

The catalysts used in the aforementioned studies were always titanium silicates of MFI structure prepared by hydrothermal synthesis. Ti can, however, be inserted in the silica lattice by post-synthesis treatment of a dealuminated H-ZSM-5 with TiCl4 vapor [11]. Titanium silicalite-2 (TS-2), with the MEL structure of ZSM-11, was prepared shortly after the first synthesis of TS-1 [15]. Both catalysts have been used for the hydroxylation of phenol. Kraushaar-Czarnetzki and van Hooff showed that no major catalytic differences resulted from the method of synthesis of TS-1 [11]. The slow rate of reaction they observed was probably the result of large crystal size and low titanium content [7]. Tuel and Ben Taarit demonstrated there was no perceptible difference between the catalytic activity of TS-2 and TS-1 [8]. This was predictable, because of the close similarity of the Ti-site structure, chemical composition, and pore dimensions of the two titanium silicates. 

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