Synthesis and Characterization of Aluminophosphates Type-5 and 36 Doubly Modified with Si and Zn and Its Catalytic Application in the Reaction of Methanol to Hydrocarbons (MTH)

Abstract

This paper presents a study of the synthesis of AlPO4-5 and AlPO4-36 materials doubly substituted by Si and Zn, as acid function and aromatizing function, respectively. The physicochemical properties of the zeotypes were studied by XRD, adsorption of N2, Temperature Programmed Desorption with NH3, 31P MAS NMR and SEM. The incorporation of Zn and Si has shown an important effect on the acidic, textural and morphological properties of the samples. The particle size has a significant effect on the catalytic activity in the reaction of methanol to hydrocarbons in terms of methanol conversion and selectivity. It was observed that as the particle size decreases, the methanol conversion increases causing the catalyst to deactivate in a shorter time. The incorporation of Zn improved the selectivity to total aromatics by the aromatizing effect of Zn. The SAPO-5 (S5) material having a smaller particle size showed complete conversions of methanol. In contrast, the ZnAPO-5 (Z5) material showed low conversions but a high selectivity to total aromatics (41%). On the other hand, the material S36-2 presented a high selectivity to aromatics (58%) due to the high amount of Zn and Si. Both metals provided a certain acidic character to the materials.