Effect of Pectin and Copper Modification on the Performance of Pd/ZnO Catalyst in Liquid-Phase Hydrogenation and Photocatalytic Hydrogen Evolution
Kenzheyeva A.M. Zharmagambetova A.K. Talgatov E.T. Zamanbekova A.T. Jumekeyeva A.I. Auyezkhanova A.S. Myltykbayeva Z.K. Koca A.
September 2025Multidisciplinary Digital Publishing Institute (MDPI)
Molecules
2025#30Issue 18
This study investigates the influence of pectin and copper incorporation on the catalytic properties of Pd/ZnO catalysts in the liquid-phase hydrogenation of 2-hexyn-1-ol and photocatalytic hydrogen evolution. A series of monometallic Pd/ZnO catalysts with varying pectin contents (0–8.1 wt%) and bimetallic PdCu-Pec/ZnO catalysts with different Pd to Cu mass ratios (3:1, 1:1, 1:3) were synthesized via sequential adsorption of the polymer and metal ions onto ZnO. The catalysts were characterized using TGA, EDX, IR spectroscopy, XRD, TEM, UV–Vis DRS, and XPS. Characterization confirmed successful modification and changes in surface properties. Pectin modification improved the distribution of Pd nanoparticles on the surface of ZnO, resulting in the enhanced catalytic performance of Pd-Pec/ZnO in both hydrogenation and hydrogen evolution reactions compared to unmodified Pd/ZnO. In contrast, copper addition led to a deterioration of catalytic properties in both processes, likely due to the inhibited reduction of Pd caused by Pd–Cu interactions. Among the catalysts studied, Pd-Pec/ZnO with low pectin content (1.8 wt%) exhibited the highest activity in both reactions. The hydrogenation of 2-hexyn-1-ol to cis-2-hexen-1-ol proceeded with high selectivity (96%) at a rate (WC≡C) of 3.3 × 10−6 mol/s, and the catalyst retained its activity over 30 consecutive runs. In the photocatalytic hydrogen evolution reaction, the rate reached 1.11 mmol/(h·gcat) and the catalyst maintained ~94% of its initial activity after three consecutive runs. These findings demonstrate the potential of biopolymer-modified ZnO composites for the design of multifunctional catalysts combining hydrogenation and photocatalytic activity.
2-hexyn-1-ol hydrogenation , biopolymer-modified catalysts , catalyst modification , copper , Pd/ZnO catalyst , pectin , photocatalytic hydrogen production
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Laboratory of Organic Catalysis, D.V. Sokolskiy Institute of Fuel, Catalysis, and Electrochemistry, Kunaev Str. 142, Almaty, 050010, Kazakhstan
Faculty of Natural Sciences and Geography, Abai Kazakh National Pedagogical University, Almaty, 050010, Kazakhstan
Research Institute of New Chemical Technologies and Materials, Al-Farabi Kazakh National University, Almaty, 050040, Kazakhstan
Department of Chemical Engineering, Faculty of Engineering, Marmara University, Istanbul, 34854, Turkey
Laboratory of Organic Catalysis
Faculty of Natural Sciences and Geography
Research Institute of New Chemical Technologies and Materials
Department of Chemical Engineering
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