Synthesis of small pore SAPO-34 molecular sieve has been achieved under optimum conditions, elucidated by a detailed study of the kinetics of crystallization, in the presence of morpholine a s a template. lncorporation of high silicon content into the framework of SAPO-34 has been observed and corroborated by physico-chemical characterization studies. Magic-angle spinning (MAS) NMR investigation points to the existence of aluminosilicate domains in the SAP0 framework.

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New evidence for the framework substitution of titanium into TiMCM-41 mesoporous molecular sieve is found from electron spin resonance (ESR) studies. TiMCM-41 samples with varying Si/Ti ratios have been synthesized as have titanosilicate TS-1, siliceous MCM-41, AlMCM-41, and Ti−AlMCM-41 in the last of which titanium ions are incorporated by ion exchange. These materials were examined by ESR spectroscopy after a thermal activation treatment followed by γ-irradiation at 77 K. γ-Irradiation at 77 K of TiMCM-41 having a high Si/Ti ratio produces a strong orthorhombic ESR signal due to V centers and an axial signal with g ∥ = 1.971 and g ⊥ = 1.901 best explained as arising from trivalent titanium situated at a framework tetrahedral site. An upper limit for the substitution of titanium into a framework tetrahedral site is observed. As the titanium concentration in the synthesis gel increases, the resulting material contains both tetrahedral and octahedral titanium. γ-Irradiation of ion-exchanged Ti−AlMCM-41 gives an axial ESR signal characterized by reverse g values g ∥ = 1.898 and g ⊥ = 1.967 typical of Ti(III) in distorted octahedral symmetry. Both TiMCM-41 and Ti−AlMCM-41 differ in their behavior toward interaction with various adsorbate molecules. The Ti(III) species observed in TiMCM-41 after adsorption of D2O, CO, NH3, and CD3OH changes its ESR characteristics from that of the original Ti(III) species observed in the absence of these adsorbates. The ESR characteristics of the Ti(III) species in Ti−AlMCM-41 after adsorption of the above adsorbates are different from those of TiMCM-41, indicating that the Ti in these two materials are in different coordination environments. This independently supports the different g tensors for Ti(III) in TiMCM-41 versus Ti−AlMCM-41.

This article presents a novel method for tuning the reactivity of nanoenergetic materials by coating a strong oxidizer nanoparticle (potassium permanganate; approximately 150 nm) with a layer of a relatively mild oxidizer (iron oxide). The measured reactivity for a nano-Al/composite oxidizer could be varied by more than a factor of 10, as measured by the pressurization rate in a closed vessel (psl/micros), by changing the coating thickness of the iron oxide. The composite oxidizer nanoparticles were synthesized by a new aerosol approach in which the nonwetting interaction between iron oxide and molten potassium permanganate aids the phase segregation of a nanocomposite droplet into a core-shell structure.