Recently, the use of plant-origin materials has become especially important due to the aggravation of environmental problems and the shortage and high cost of synthetic materials. One of the potential candidates among natural organic compounds is polysaccharides, characterized by a number of advantages over synthetic polymers. In recent years, natural polysaccharides have been used to design composite catalysts for various organic syntheses. This review is devoted to the current state of application of polysaccharides (chitosan, starch, pectin, cellulose, and hydroxyethylcellulose) and composites based on their catalysis. The article is divided into four main sections based on the type of polysaccharide: (1) chitosan-based nanocomposites; (2) pectin-based nanocomposites; (3) cellulose (hydroxyethylcellulose)-based nanocomposites; and (4) starch-based nanocomposites. Each section describes and summarizes recent studies on the preparation and application of polysaccharide-containing composites in various chemical transformations. It is shown that by modifying polysaccharides, polymers with special properties can be obtained, thus expanding the range of biocomposites for catalytic applications.

The development of effective bifunctional catalysts demonstrating high performance in both photocatalytic hydrogen evolution and selective hydrogenation of unsaturated compounds is of great interest for photocatalytic transfer hydrogenation. In this work, TiO₂ and Pd@TiO₂ catalysts were studied in two separate processes: photocatalytic H₂ evolution and conventional hydrogenation reactions. Photocatalytic properties of titanium dioxide synthesized by a simple precipitation method were compared with those of commercial ones. Commercial anatase with a lower agglomeration degree showed better activity in H₂ evolution. Further modification of the commercial anatase with Pd resulted in increasing its activity, achieving an H₂ evolution rate of 760 μmol/h g_cat. The Pd catalysts supported on different TiO₂ samples were tested in hydrogenation of acetylenic compounds. The activity of the Pd@TiO₂ catalysts was found to be dependent on the photocatalytic properties of TiO₂ supports. XPS studies of Pd catalysts indicated that commercial anatase with better photocatalytic properties provided easier reduction of Pd²⁺ to active Pd⁰ particles. The Pd catalyst supported on commercial anatase demonstrated the highest activity in the hydrogenation process. The W_C≡C rate achieved 2.6 × 10⁻⁶, 9.0 × 10⁻⁶ and 35.7 × 10⁻⁶ mol/s for hydrogenation of 2-hexyne-1-ol, 5-hexyne-1-ol and 2-hexyne, respectively. The selectivity of the catalyst to target olefinic compounds was 94–96%. In addition, the hydrogenation rate was found to be significantly affected by reaction conditions such as hydrogen concentration and solvent composition. The W_C≡C rate decreased linearly with decreasing hydrogen concentration in a H₂:He gas mixture (30–100 vol%). Performing the reaction in 0.10 M NaOH ethanolic solution resulted in increasing the W_C≡C rate and selectivity of the process. The Pd catalyst was reused in an alkali medium (NaOH in ethanol) for 35 runs without significant degradation in its catalytic activity. Thus, the results obtained in this work can be useful in photocatalytic transfer hydrogenation.

The proposed paper describes a simple and environmentally friendly method for the synthesis of three-component polymer–inorganic composites, which includes the modification of zinc oxide or montmorillonite (MMT) with chitosan (CS), followed by the immobilization of palladium on the resulting two-component composites. The structures and properties of the obtained composites were characterized by physicochemical methods (IRS, TEM, XPS, SEM, EDX, XRD, BET). Pd–CS species covered the surface of inorganic materials through two different mechanisms. The interaction of chitosan polyelectrolyte with zinc oxide led to the deprotonation of its amino groups and deposition on the surface of ZnO. The immobilization of Pd on CS/ZnO occurred by the hydrolysis of [PdCl₄]²⁻, followed by forming PdO particles by interacting with amino groups of chitosan. In the case of CS/MMT, protonated amino groups of CS interacted with negative sites of MMT, forming a positively charged CS/MMT composite. Furthermore, [PdCl₄]²⁻ interacted with the –NH³⁺ sites of CS/MMT through electrostatic force. According to TEM studies of 1%Pd–CS/ZnO, the presence of Pd nanoclusters composed of smaller Pd nanoparticles of 3–4 nm in size were observed on different sites of CS/ZnO. For 1%Pd–CS/MMT, Pd nanoparticles with sizes of 2 nm were evenly distributed on the support surface. The prepared three-component CS–inorganic composites were tested through the hydrogenation of 2-propen-1-ol and acetylene compounds (phenylacetylene, 2-hexyn-1-ol) under mild conditions (T—40 °C, P_H2—1 atm). It was shown that the efficiency of 1%Pd–CS/MMT is higher than that of 1%Pd–CS/ZnO, which can be explained by the formation of smaller Pd particles that are evenly distributed on the support surface. The mechanism of 2-hexyn-1-ol hydrogenation over an optimal 1%Pd–CS/MMT catalyst was proposed.

Recently, Pd catalysts supported on magnetic nanoparticles (MNPs) have attracted a great attention due to their ability of easy separation with an external magnet. Modification of MNPs is successfully used to obtain Pd magnetic catalysts with enhanced catalytic activity. In this work, we discussed the effect of titania content in TiO₂/MNPs support materials on catalytic properties of Pd@TiO₂/MNPs catalysts in phenylacetylene hydrogenation. TiO₂/MNPs composites were prepared by simple ultrasound-assisted mixing of TiO₂ and MNPs, synthesized by co-precipitation method. This was followed by deposition of palladium ions on the mixed metal oxides using NaOH as precipitant. The supports and catalysts were characterized using XRD, BET, STEM, EDX, XPS, and a SQUID magnetometer. Pd nanoparticles (5–6 nm) formed were found to be homogeneously distributed on support materials representing the well-mixed metal oxides with TiO₂ content of 10, 30, 50, or 70%wt. Testing of the catalysts in phenylacetylene hydrogenation showed that their activity increased with increasing TiO₂ content, and the process was faster in alkali medium (pH = 10). The hydrogenation rates of triple and double C–C bonds on Pd@70TiO₂/MNPs achieved 9.3 × 10⁻⁶ mol/s and 23.1 × 10⁻⁶ mol/s, respectively, and selectivity to styrene was 96%. The catalyst can be easily recovered with an external magnet and reused for 12 runs without significant degradation in the catalytic activity. The improved catalytic properties of Pd@70TiO₂/MNPs can be explained by the fact that the surface of the support is mainly composed of TiO₂ particles, affecting the state and size of Pd species.

The global depletion of fossil resources, combined with accelerating climate change and environmental concerns, is driving intensive research into alternative, sustainable sources of energy and raw materials. Particular attention is being paid to lignocellulosic biomass as the most abundant and renewable organic resource. The catalytic conversion of biomass-derived carbohydrates into high-value-added products (fuels and chemicals) aligns with the principles of sustainable development and offers a viable alternative to petroleum-based feedstocks. This review provides a product-oriented perspective on the deep valorization of carbohydrates, focusing on catalytic strategies that enable the production of renewable fuels and chemicals. It highlights two key stages in the valorization of lignocellulosic biomass: (1) the acid-catalyzed conversion of carbohydrates into platform molecules (furfural, 5-hydroxymethylfurfural, and levulinic acid); and (2) the selective hydrogenation and hydrogenolysis of these intermediates to obtain target end products. These target products fall into two major categories: (i) biofuels and fuel additives; and (ii) green chemicals, such as solvents, pharmaceuticals, agrochemicals, cosmetics, and intermediates for the synthesis of biobased polymeric materials, including polyesters, resins, and polyurethanes. Particular emphasis is placed on recent advances in the development of heterogeneous catalysts. Solid acid catalysts used in the synthesis of platform molecules are discussed, along with ruthenium-based catalysts employed in the subsequent hydrogenation and hydrogenolysis steps. Recent efforts toward integrating both catalytic stages into a single one-pot processes using bifunctional metal–acid catalysts and dual catalytic systems based on ruthenium are also reviewed, as they represent a promising route to simplify biomass valorization schemes and improve product selectivity toward fuels and chemicals.

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 (W_C≡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·g_cat) 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.