Vanadosilicates isostructural to ETS-10 and AM-6 microporous materials were synthesized hydrothermally using derivatives of cis-and trans-3,5-dimethyl-piperidine as organic structure directing agents (SDAs) and were subsequently tested as heterogeneous catalysts for the oxidehydration of glycerol to acrylic acid. The best performances were obtained with vanadosilicates prepared with 1,1,3,5-tetramethyl piperidinum cations, which were capable of converting 93.6% of glycerol to acrylic acid in one step, with 85.4% selectivity. Other important chemicals such as acrolein (3.8%), propanal (2.3%), acetaldehyde (3.2%), acetic acid (2.5%), and propionic acid (1.4%) were produced in smaller amounts. The results clearly indicated that these vanadosilicates are potential multifunctional catalysts capable of performing the oxidehydration of glycerol to acrylic acid in a single step. Spectroscopic data obtained from 51 VMAS-NMR, UV-Vis, XPS, and Raman scattering analyses suggested that the selectivity of these vanadosilicates for the oxidative dehydration of glycerol to acrylic acid could be attributed to the capacity of the vanadium species for dynamic adoption of multiple oxidation states during the catalytic reaction.

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Synthesis of a microporous cobalt silicate was achieved by using 6,10-dimethyl-5-azoniaspiro[4, 5]decane bromide as structure directing agent. And physicochemical characterization was carried out using XRD, SEM, HTEM, TGA, FT-IR, BET-N2, ICP-OES and EDS. ETS-10 like structure framework was present as a competitive phase. Calcination of the cobalt silicate at 500oC leads to a new structure. The possibility of this material be cobalt oxide was excluded since Bragg reflections at 2θ = 19.2º; 30.3º; 36.9º; 43.7º; 59.2º were absent (JCPDS#80-1538). Both the indexation of the XRD data for the calcined material which has resulted in a tetragonal unit cell (a = b = 10.39 Å and c = 12.21 Å, α = β = γ = 90°, V= 1317.4 Å3) and HTEM data indicated the cobalt silicate can be used as a precursor for the preparation of double perovskite cobalt materials.

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