RESUMO
A temperature-programmed reduction method was developed to stabilize SAPO-37 and molybdenum-(oxy)-carbide-loaded SAPO-37 (SAP-37MoCR). The inorganic framework (Faujasite type SAPO-37) was retained for the first time even after treatment at 550 °C and was confirmed through powder XRD and SEM analysis. SAP-37MoCR exhibits strong acidic sites and is a promising catalyst for MTBE synthesis. Furthermore, the catalyst is stable and recyclable.
RESUMO
Ultra-fine crystallites of Mn(1-x)Zn(x)Fe2O4 series (0 ≤ x ≤ 1) were synthesized through wet chemical co-precipitation method followed by calcination at 200 °C for 4 hours. Formation of ferrites was confirmed by X-ray diffraction, TEM selected area diffraction (SAD) and Fourier Transform Infra-red Spectroscopy (FTIR). Nanocrystallites of different compositions in the series were coated with biocompatible chitosan in order to investigate their possible application as contrast agent for magnetic resonance imaging (MRI). Chitosan coating examined by FTIR, revealed a strong bonding of chitosan molecules to the surface of the ferrite nanocrystallites. Spin-spin, τ2 relaxivities of nuclear spins of hydrogen protons of the solutions for different ferrites were measured from concentration dependence of relaxation time by nuclear magnetic resonance (NMR). All the compositions Mn(1-x)Zn(x)Fe2O4 of series possess higher values of τ2 relaxivity thus making them suitable as contrast agents for τ2 weighted imaging by MRI.
