Hydrothermal synthesis of nanosized SAPO-34 molecular sieves by different combinations of multi templates

• SAPO-34 nanoparticles are synthesized by conventional hydrothermal method.
• Different combinations and concentrations of four templates are investigated.
• Particles in nanoscale are observed in the multi template synthesized SAPO-34.
• The large surface areas of SAPO-34 are obtained by using three or four templates.

In the present study, the silicoaluminophosphate (SAPO-34) nanoparticles were synthesized under hydrothermal conditions in the presence of a single or a mixture of tetraethyl ammonium hydroxide (TEAOH), morpholine, diethylamine (DEA) and triethylamine (TEA) as structure-directing agents (SDAs). The effects of different types, amounts and combinations of templates on the structure and morphology of SAPO-34 molecular sieves were investigated by XRD, SEM, EDX and BET analyses. Compared with the single template synthesized, using two, three and four SDAs leads to the crystallinity increase, the crystallite size reduction and the morphology change to spherical aggregates of several cubic nanosized crystals. Furthermore, decreasing molar ratio of TEAOH in initial gel from 2 to 0.4 do not change the purity of SAPO-34, but affect its crystallinity and particle size. Small SAPO-34 particles and large BET surface area are obtained when three or four templates are used as SDAs.

Particles of nanosized SAPO-34 were synthesized hydrothermally with multiple templates to a detailed study concerning the different combinations and ratios of four organic templates. The results show that the particle size decreases and the surface area increases by using three or four templates.Figure optionsDownload as PowerPoint slide