Title
Facile hydrothermal synthesis of Pd, Ir, Pd-Ir particles on CMK-3 for reductive catalytic fractionation of birch wood
Authors
ALEKSANDR S. KAZACHENKO, ROMAN V. BORISOV, ANGELINA V. MIROSHNIKOVA, OLEG V. BELOUSOV, SERGEY V. BARISHNIKOV, ANDREY M. SKRIPNIKOV, OLGA S. SELEZNEVA, MAXIM N. LIKHATSKI and ANATOLY M. ZHIZHAEV

Received April 22, 2025
Published Volume 59 Issue 9-10 October-December
Keywords iridium, palladium, hydrothermal synthesis, mesoporous carbon material, catalysts, RCF

Abstract
Palladium, iridium and iridium-palladium particles were applied to ordered mesoporous carbon material CMK-3 by a simple hydrothermal method. Iridium particles with a diameter of 3-6 nm were formed on the carbon material upon reduction from aqueous solutions of potassium hexachloroiridate(IV) by sodium tetrahydroxoborate in alkaline media at a temperature of 180 °C. Palladium particles had a wide size distribution from 3 to 40 nm and were obtained by decomposition of an alkaline solution of tetraamminepalladium(II) chloride in an autoclave. The corresponding reflections of metal phases were detected by X-ray phase analysis. The proportion of metallic Ir and Pd on the surface was determined by X-ray photoelectron spectroscopy and amounted to 25% and 75%, respectively. After bombardment with argon ions for 1 minute, the surface fraction of iridium was more than 50%, and that of palladium was more than 90%. The obtained catalysts were used in the process of reductive catalytic fractionation (RCF) of birch wood, which allowed to effectively separate lignocellulosic biomass into valuable chemical products. The use of catalysts based on Pd and Pd-Ir led to a significant increase in the yield of liquid products (up to 58.6% by weight) and a decrease in the lignin content in the solid residue (up to 6.0% by weight). The highest wood conversion (60.7% by weight) was achieved using the Pd/CMK-3 catalyst. The results of the work demonstrate the prospects for using the synthesized catalysts for sustainable processing of biomass into valuable chemical products.