Improvement of hydrothermal stability of Pt/SAPO-11 catalyst in hydrodeoxygenation–isomerization–aromatization of vegetable oil

• SAPO-11 in Pt/SAPO-11–Al2O3 has low hydrothermal stability during vegetable oil hydrotreating.
• HDA in crystallization gel increases the amount of Al neighbors of SiO4 tetrahedra.
• SiO4 tetrahedra with 3–4 Al neighbors are resistant to desilication.
• SAPO-11 framework desilication during vegetable oil hydrotreating is partially reversible.

SAPO-11 component of Pt/SAPO-11–Al2O3 catalysts displays relatively low hydrothermal stability in hydrotreating of vegetable oils that produces water during the process. Application of XRD, HRTEM, NH3 TPD, TPO, H2 pulse chemisorptions and 29Si MAS NMR revealed that the reason for hydrothermal deactivation of SAPO-11 is partially reversible desilication of its framework. This results in gradual loss of acidity and catalytic activity in isomerization of normal paraffins – products of oil deoxygenation. Addition of amine surfactant hexadecylamine to SAPO-11 crystallization gel at HDA/Al2O3 ratio of ∼0.6 strongly increases the hydrothermal stability of SAPO-11. This translates in stable operation of Pt/SAPO-11–Al2O3 catalyst in hydrotreating of soybean oil yielding >99% deoxygenation and producing liquid organic product with cloud point < −35 °C containing 15 wt% monoaromatics. The stabilizing effect of HDA is a sequence of increasing the relative content of Si(nAl(4-n)Si) tetrahedra with n = 3–4 displaying higher resistance to hydrothermal desilication.

Figure optionsDownload high-quality image (71 K)Download as PowerPoint slide