Conversion of dihydroxyacetone to carboxylic acids on pretreated clinoptilolite modified with iron, copper, and cobalt

In this paper, we present the conditions for modifying the natural clinoptilolite zeolite and giving it catalytic properties by embedding in its structure active centers in the form of metals, such as iron, copper, and cobalt. Clinoptilolite as a catalyst matrix was subjected to ammonium exchange (Me-H-CLI) and hierarchization with hydrochloric acid (Me-da-CLI). Clinoptilolite was also used without modification of its structure (Me-0-CLI). The obtained zeolite catalysts were characterized by means of XRD, BET, DRS UV-VIS and FT-IR analyzes as well as Raman spectroscopy. Zeolite catalysts were used for the conversion of dihydroxyacetone (DHA) based biomass. The catalytic process was carried out by the one-pot method. On the basis of the analysis with the use of high- performance liquid chromatography (HPLC), the reaction products were determined together with their selectivity, yield and also conversion of raw material. During the conversion of DHA, the following organic acids were obtained: lactic acid (LAC), formic acid (FA), pyruvic acid (PAC), acetic acid (AD), and levulinic acid (LA). The highest lactic acid yield (66.2%) was achieved with Co-0-CLI, formic acid (93.6%) with Cu-H-CLI and 87.4% acetic acid with Fe-da-CLI.