Synthesis of highly active ETS-10-based titanosilicate for heterogeneously catalyzed transesterification of triglycerides

Muhammad A Zaheer; David Poppitz; Khavar Feyzullayeva; Marianne Wenzel; Jörg Matysik; Radomir Ljupkovic; Aleksandra Zarubica; Alexander A Karavaev; Andreas Pöppl; Roger Gläser; Muslim Dvoyashkin

doi:10.3762/bjnano.10.200

Synthesis of highly active ETS-10-based titanosilicate for heterogeneously catalyzed transesterification of triglycerides

Beilstein J Nanotechnol. 2019 Oct 28:10:2039-2061. doi: 10.3762/bjnano.10.200. eCollection 2019.

Affiliations

¹ Institute of Chemical Technology, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.
² Institute of Analytical Chemistry, Universität Leipzig, Linnéstraße 3, 04103 Leipzig, Germany.
³ Faculty of Science and Mathematics, University of Nis, Visegradska 33, 18000 Nis, Serbia.
⁴ Gubkin Russian State University of Oil and Gas, Leninsky Prospekt 65, 119991 Moscow, Russia.
⁵ Felix-Bloch-Institut, Universität Leipzig, Linnéstraße 5, 04103 Leipzig, Germany.

Abstract

In this contribution, the preparation of hierarchically structured ETS-10-based catalysts exhibiting notably higher activity in the conversion of triolein with methanol compared to microporous titanosilicate is presented. Triolein, together with its unsaturated analog trilinolein, represent the most prevalent triglycerides in oils. The introduction of mesopores by post-synthetic treatment with hydrogen peroxide and a subsequent calcination step results in the generation of an additional active surface with Brønsted basic sites becoming accessible for triolein and enhancing the rate of transesterification. The resulting catalyst exhibits a comparable triolein conversion (≈73%) after 4 h of reaction to CaO (≈76%), which is reportedly known to be highly active in the transesterification of triglycerides. In addition, while CaO showed a maximum conversion of 83% after 24 h, the ETS-10-based catalyst reached 100% after 8 h, revealing its higher stability compared to CaO. The following characteristics of the catalysts were experimentally addressed - crystal structure (X-ray diffraction, transmission electron microscopy), crystal shape and size (scanning electron microscopy, laser diffraction), textural properties (N₂ sorption, Hg porosimetry), presence of hydroxyl groups and active sites (temperature-programmed desorption of NH₃ and CO₂, ²⁹Si magic angle spinning nuclear magnetic resonance (NMR)), mesopore accessibility and diffusion coefficient of adsorbed triolein (pulsed field gradient NMR), pore interconnectivity (variable temperature and exchange spectroscopy experiments using hyperpolarized ¹²⁹Xe NMR) and oxidation state of Ti atoms (electron paramagnetic resonance). The obtained results enabled the detailed understanding of the impact of the post-synthetic treatment applied to the ETS-10 titanosilicate with respect to the catalytic activity in the heterogeneously catalyzed transesterification of triglycerides.

Keywords: CaO; ETS-10; diffusion; nuclear magnetic resonance (NMR); transesterification.