## 4 HPS-Based Catalysts for the Synthesis and Transformation of Platform Chemicals
### Hydrolytic Hydrogenation of Cellulose to Hexitols
This is the reason why ruthenium is part of the majority of catalytic systems proposed for the hydrolytic hydrogenation of cellulose and its oligomers with high potential for practical application [119; 120; 121; 122; 123; 124]. Based on the results obtained in the hydrogenation of mono- and disaccharides with HPS-based catalysts [95; 96], our group proposed the use of Ru/HPS catalysts in the hydrolytic hydrogenation of microcrystalline cellulose to produce sorbitol and mannitol [124]. The catalysts were synthesized using the following procedure: HPS was impregnated according to incipient wetness impregnation with the solution of the calculated amount of ruthenium (IV) hydroxochloride in a complex solvent consisting of tetrahydrofuran, methanol, and water at a volume ratio 4:1:1 at room temperature. Then, the catalyst was dried at 70 \({}^{\circ}\)C, consecutively treated with solutions of NaOH and H\({}_{2}\)O\({}_{2}\), and then washed with water until the absence of chloride anions in the washing water. The catalyst was then dried at 85 \({}^{\circ}\)C, reduced by hydrogen at 300 \({}^{\circ}\)C and atmospheric pressure for 2 h, cooled in nitrogen and kept under air. The catalyst particle size was controlled by sieving (mesh size 60 \(\upmu\)m) the initial powdered support. Commercial sorbents HPS MN270 (without functional groups), MN100 (functionalized with amino groups), and MN500 (functionalized with sulfo groups), were purchased from Purolite, UK, and used for the synthesis. The main characteristics of these sorbents and their structure are indicated in Table 1.  
The obtained catalysts were tested in the reaction of hydrolytic hydrogenation of cellulose and the results are presented in Table 2.  
It was found that the catalyst based on HPS MN270 has the maximum catalytic activity in this process. Its functionalized analogues showed much worse results. Comparing the results of nitrogen physical adsorption (Table 3), one can see that the 1% Ru/MN500 catalyst during the reduction in hydrogen at 300 \({}^{\circ}\)C underwent significant structural changes, leading to a more than fivefold decrease in the specific surface area and a huge decrease in the surface of micropores. This is due to a desulfurization of MN500 at temperatures of 100-150 \({}^{\circ}\)C [125] affecting the HPS structure. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Specification**} & \multicolumn{2}{c}{**HPS**} \\ \hline  & **MN270** & **MN100** & **MN500** \\ \hline  & & Tertiary amine & Sulfonic acid \\  & & \(\sim\)1400 m\({}^{2}\)/g & \(\sim\)900 m\({}^{2}\)/g & \(\sim\)600 m\({}^{2}\)/g \\  & micro-mesoporous with a & micro-mesoporous with a & micro-mesoporous with a \\  & predominance of micropores & predominance of micropores & predominance of micropores \\  & \(\sim\)0.4 mL/g & \(\sim\)0.4 mL/g & \(\sim\)0.3 mL/g \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Main characteristics of MN type sorbents. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Catalyst**} & \multicolumn{2}{c}{**Cellulose**} & \multirow{2}{*}{\(\eta_{hex.}\) \%} & \multicolumn{2}{c}{**Selectivity, \%**} \\ \cline{3-5}  & **Conversion, \%** & & **S** & **M** \\ \hline
1.0\% Ru/MN270 & 84.3 & 50.4 & 50.5 & 9.3 \\
1.0\% Ru/MN100 & 77.0 & 12.7 & 14.9 & 1.6 \\
1.0\% Ru/MN500 & 80.6 & 1.8 & 1.8 & 0.4 \\ Without a catalyst & 55.6 & 0.5 & 0.6 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Dependences of the cellulose conversion, total yield of hexitols (\(\eta_{hex. }\)) and selectivity to sorbitol (S) and mannitol (M).