Hierarchically porous titanium phosphatenanoparticles: an efficient solid acid catalyst for microwave assisted conversion of biomass and carbohydrates into 5-hydroxymethylfurfural

Abstract

A new hierarchical macro/mesoporous titanium phosphate MTiP-1 has been synthesized through a slow evaporation method by using titanium isopropoxide and orthophosphoric acid as inorganic sources and pluronic P123 as the structure directing agent. Powder X-ray diffraction, FT-IR and electron dispersive spectroscopy (EDS) were used to analyze the framework, structure and composition of the material. The N₂ adsorption/desorption isotherm of this material is of type IV, which is characteristic of a mesoporous material and it shows a Brunauer–Emmett–Teller (BET) surface area of 193 m² g⁻¹ together with an average pore dimension of ca. 7 nm. From scanning electron microscopic (SEM) images it is seen that there is hierarchical porosity in MTiP-1 and the mesoporosity of this material arises due to self-aggregation of tiny spherical particles of dimension ca. 15–20 nm. Transmission electron microscopic (TEM) images show the existence of randomly distributed mesopores in the material. This MTiP-1 material shows very good catalytic activity in the microwave assisted conversion of biomass and carbohydrates into 5-hydroxymethylfurfural (HMF). The catalytic reactions are carried out in different solvents like water, water–methylisobutyl ketone (MIBK), MIBK and dimethylacetamide (DMA)–LiCl. MTiP-1 also catalyzes the direct conversion of cellulose substrates and lignocellulosic biomass, sugarcane bagasse, into HMF.