Kevin R. Franklin

Piperazine Silicate (EU 19): the Structure of a Very Small Crystal Determined with Synchrotron Radiation

Single-crystal diffraction data have been recorded for a very small crystal of dimensions 8 x 18 × 175 ~rn 3. From these data the structure of piperazine silicate (EU 19) has been determined and refined to R = 0.094 for 490 observed reflections. Data collection for such a crystal has been made practicable by the high intensity of the Daresbury Synchrotron Radiation Source and the Enraf-Nonius FAST area detector diffractometer. The potential of this synchrotron radiation method for other small crystals including proteins is discussed. Crystal data: 2+ • 2

Hydrothermal crystallization of (hexane-1,6-diamine)-silicalite-1

The hydrothermal crystallization of HEXDM-silicalite and HEXDM-ZSM-48 (HEXDM = hexane-1,6-diamine) from the reaction mixtures xHEXDM /Na 2 O zTPABr 20 SiO 2 w H 2 0 ( x = 20, 50; y = 0; z = 0; w = 250, 1000; TPA = tetrapropylammonium) has been carried out at 95°, 120°, 150°, 180°C. The crystallization of HEXDM-silicalite is favored by low temperatures and high HEXDM/SiO 2 mole ratios, whereas HEXDM-ZSM-48 is the only product at 150° and 180°C. The reaction rates are increased by the addition of alkali ( y = 0.25, 0.5), and the temperature range for the formation of silicalite is extended by the addition of TPA ions ( z = 0.1, 0.5).

Preparation and properties of gel particle silicalite

Abstract A procedure for the pseudomorphic transformation of particles of silica gel to silicalite-1 is described. Examination of the product by scanning electron microscopy reveals that the particles are composed of large (∼5 μm) loosely packed crystals surrounded by a dense crust of smaller (∼1 μm) crystals. X-ray powder diffraction and thermal analysis suggest that the particles also contain a small proportion of amorphous material.

Zeolite map: The new detergent zeolite

This paper describes the physical and chemical properties of a new zeolite, MAP, which have led to its commercialisation for use as a detergent builder. Its advantageous calcium exchange selectivity and water sorption properties are the result of unusual flexibility of the Zeolite P framework; these are delivered through engineering the framework composition and the size and porosity of the finished particles.

Crystallization of silica molecular sieves from piperazine-quaternary ammonium bromide-silica-water systems

Crystallization from reaction mixtures containing piperazine, silica, water, and each of 11 quaternary ammonium salts at 120°, 150°, and 180°C has been investigated. In many cases, especially at 180°C, no crystalline material was obtained even though the corresponding quaternary-free reaction mixtures gave ZSM-39 or EU-19. Silicalite precursors were formed with tetrapropylammonium, tetrabutylammonium, tetrapentylammonium, tributylpentylammonium, and tributylheptylammonium bromide at 120° and 150°C. These precursors were characterized by X-ray powder diffraction, scanning electron microscopy, and thermal analysis.

Sorption of butan-1-ol from aqueous solution by silica molecular sieves

The sorption of butan-1-ol from dilute aqueous solution by Nu-10, ZSM-48, and three different silicalites has been investigated. All materials show a strong affinity for the alcohol; however, Nu-10 and ZSM-48 have much lower maximum capacities. A form of the Langmuir equation has been used to represent the sorption of butan-1-ol by ZSM-48 and Nu-10. The separation of water and butan-1-ol by thermal desorption is satisfactorily achieved only with ZSM-48 and the silicalite samples.

Synthesis and characterization of diethylamine-silica-Nu-10 and diethylamine-silicalite-1

The synthesis of DEA-silica-Nu-10 and DEA-silicalite-1 (DEA = diethylamine) from the reaction mixture /DEA xNaOH 20 SiO2wH2O (w = 250, 1000; x = 0, 1, 3, 5; y = 20, 50, 100) is described. The formation of DEA-silicalite-1 is favored by static conditions, high DEA concentrations, and low temperature (120°C), whereas DEA-silica-Nu-10 requires lower DEA concentrations and is the only molecular sieve to form at 150° and 180°C, DEA-silica-Nu-10 is obtained as lath-shaped crystals that aggregate in a variety of ways, and DEA-silicalite-1 is crystallized as hexagonal blocks. Thermal analysis shows that the amount of DEA present in both materials varies markedly between samples.

Preparation and properties of piperazine silicate (EU-19) and a silica polymorph (EU-20)

The hydrothermal crystallisation of a piperazine (pipz) silicate (EU-19) from the reaction mixture (p– 2y)pipz–yM2CO3–20SiO2–wH2O (p= 15, 20, or 25; y= 0–2.5; w= 250 or 1 000; M = Na, K, or Cs) at 120 and 150 °C is described. Dependent on w, plate-like or lath-like morphologies are observed. The chemical and physical properties of EU-19 are those of a layer structured material. On calcination the EU-19 crystals are pseudomorphically converted into a thermally stable silica polymorph (EU-20).

Hydrothermal crystallization of piperazine-ZSM-39

The crystallization of PIP-ZSM-39 from the reaction mixtures (15−x)PIP xNaA 20SiO2 250H2O at 180°C is reported for x=0, 0.5, 1, 2, 5, and A=OH−, SO42− or CO32−. For x=0 large (200 μm) octahedral crystals are formed in 16 days; for x≠0 crystallization is faster but the crystals are smaller and less well-formed. At higher pH values the reactions overrun to quartz.

Hydrothermal Crystallisation of Silica Molecular Sieves and Clathrasils from Amine Containing Reaction Mixtures

Abstract The results of an investigation into the crystallisation of silica molecular sieves and clathrasils from the amine-SiO 2 –H 2 O and amine-Na 2 O–SiO 2 –H 2 O systems are summarised. The most commonly obtained products were silica-ZSM-48 (13 amines), silica-ZSM-39 (10 amines), and EU-4 (7 amines). The formation of silicalite-1, silica-Nu-10, and silica-ZSM-23 was favoured by low temperatures, static conditions, and high amine concentrations.