## 4 HPS-Based Catalysts for the Synthesis and Transformation of Platform Chemicals
### Magnetic Catalysts Based on HPS in the Conversion of Plant Polysaccharides  
Despite the advantages of homogeneous catalysts, such as high catalytic activity, high selectivity, etc., when creating new industrial catalysts, preference is often given to heterogeneous catalytic systems, which have an important advantage of relatively easy separation from the reaction mixture for subsequent regeneration and reuse [134]. However, existing methods of separation (filtration, centrifugation, decantation, etc.) are laborious, time consuming, and may lead to losses in the catalysts [57], especially if their particles are small in size and density [135]. These problems can be avoided, or at least their impact on production costs can be significantly reduced, if the catalyst particles have magnetic properties [136; 137]. Over the past 10-15 years, a large number of magnetic catalysts have been developed and successfully applied for hydrogenation, oxidation, carbon-carbon coupling, click reactions, Suzuki-Miyaura reactions, chiral and enzyme catalysis, photocatalysis [138; 139], in transesterification and esterification reactions for the production of biodiesel fuel [140], etc. Magnetic catalyst separation has the following advantages: fast and efficient separation (the process of separating the catalyst by a magnetic field takes seconds or minutes and the catalyst is completely removed); low energy consumption of separation process (by both a permanent magnet and an electromagnet); the catalyst remains inside the reactor and the process can be quickly restarted with minimal catalyst losses after removing the reaction mixture and introducing a new portion of the substrate into the reactor; magnetic catalysts exhibit their properties only in the presence of a magnetic field and there are thus no additional requirements for the storage, handling, and use of such catalytic systems; sampling and product separation are greatly simplified if the reaction takes place in an inert atmosphere; solvent consumption and waste generation are minimized; the process is easily scaled from laboratory to industrial volumes; and magnetic properties can be imparted to any catalysts (based on enzymes, metals, solid acids, etc.) [57]. Magnetic catalysts are currently being actively developed and have great potential for practical applications in industrial catalytic processes [141]. However, they are not yet used on an industrial scale for a number of reasons. First, the synthesis of magnetic metal and metal oxide nanoparticles often requires expensive precursors and toxic organic solvents, which limits large-scale production [139]. Since HPS has proven to be a suitable catalytic support, we have developed a method for the synthesis of magnetic Ru-containing catalysts based on commercial HPS sorbent MN2/70 (Purolite, UK). The catalyst was prepared using a two-stage procedure. First, magnetite nanoparticles were synthesized in the pores of HPS through the thermal decomposition of iron (III) acetate. At the second stage, Ru-containing nanoclusters were synthesized on the surface of the composite. To achieve this, the composite powder was impregnated with a solution of ruthenium (IV) hydroxochloride in a complex solvent, dried and kept in hydrogen at 300 \({}^{\circ}\)C for 2 h. The resulting magnetic catalysts were tested in the conversion of plant polysaccharides, namely in the process of direct conversion of microcrystalline cellulose into glycools: ethylene glycol (EG) and propylene glycol (PG) [142; 143]. EG and PG are the most important raw materials for the production of drugs, fuels, surfactants, antifreezes, lubricants and solvents, lactic acid, etc. [144; 145]) and in the hydrolytic hydrogenation of inulin to mannitol [146; 147]. The process of conversion of cellulose Into EG and PG is quite complex (Figure 3) and includes several types of reactions, like hydrolysis, isomerization, retro-aldol condensation, hydrogenation, and hydrodeoxygenation [107].