Lanthanum phosphate as catalyst in the reaction of 5-HMF formation

¹ Institut Teknologi Sepuluh Nopember, Department of Chemistry, Surabaya, Jawa Timur, Indonesia, 60111
² Universitas Indonesia, Department of Chemistry, Depok, Jawa Barat, Indonesia, 16424
³ Universitas Airlangga, Department of Chemistry, Surabaya, Jawa Timur, Indonesia, 60115
⁴ Universitas Maritim Raja Ali Haji, Department of Chemistry Education, Tanjungpinang, Kepulauan Riau, Indonesia, 29111

Abstract

Lanthanum phosphate (LP) has been synthesized by sol-gel method at room temperature. The synthesized catalyst was characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), pyridine adsorption FTIR, N₂ adsorption-desorption and SEM-EDX. The XRD results show that LP has a hexagonal structure. The FTIR spectra of LP showed O=P-O bending vibrations, P-O vibrations (from phosphate tetrahedral distortion), P-O symmetrical strain vibrations and PO₄^3- bending vibrations, each of which was characterized by the appearance of a peak at 613, 530-620, 950 and 538-621 cm^-1. The presence of the OH functional group was indicated by a peak at 3450-3700 cm^-1, which was strengthened by the H-O-H bending vibration that appeared at 1629 cm^-1. The surface area, pore volume and pore diameter of LP are 51.04 m²/g, 0.21 cm³/g and 13.31 nm, respectively. SEM image showed that agglomerated solids with irregular shapes were obtained from the synthesis. Catalytic testing indicates that the acidity of the catalyst has main role in the formation of 5-HMF.