## 4 HPS-Based Catalysts for the Synthesis and Transformation of Platform Chemicals
### Hydrolytic Oxidation of Cellobiose to Glucaric Acid
The average size of platinum nanoclusters was 2.8 nm; palladium--3.4 nm; and ruthenium--1.8 nm. The diameter of gold nanoclusters turned out to be approximately an order of magnitude larger, 32.1 nm. It should be noted that nanoparticles of all metals were uniformly distributed within the catalyst volume, and there was no metal crust on the surface of the polymer. We hypothesize that the large size of gold nanoparticles is likely due to the nature of the precursor, interaction with the hydrophobic polymer matrix of the support, and the tendency of gold nanoparticles to aggregate. In our recent work, large gold particles (19.3 \(\pm\) 8.7 nm) were also obtained using a similar method for the synthesis of the 0.5%-PdAu/HPS-R catalyst [171]. In [172], with a gold content of 1 wt.% in the catalyst, the size of Au-containing nanoparticles was also relatively large (10.9 nm or more). Since our catalyst contains significantly more gold (3 wt.%), the particles formed are larger. The synthesized catalysts were tested in the hydrolytic hydrogenation of cellobiose. The results obtained are presented in Table 9. The maximum yield of gluconic and glucaric acids was observed with the 3% Pt/MN270 catalyst and attained 16.1% and 41.5% at 100% conversion of cellobiose. Such a high efficiency of the catalyst can be attributed to a much larger number of active centers on its surface as compared to other catalysts [170]. The 3% Au/MN270 catalyst was less effective in the cellobiose oxidation reaction. After the end of the experiment, a fairly large amount of glucose and cellobionic acid, as well as a small amount of gluconic acid, were found in the catalyst. Glucaric acid was present in trace quantities. The conversion of cellobiose was 86.2%. The low activity of the Au-containing catalyst could be due to the large particle size of the active phase. Catalysts containing Pd and Ru showed the worst results: low conversion of the initial substrate and extremely low yields of gluconic and glucaric acids. The experiment without a catalyst \begin{table}
\begin{tabular}{c c c} \hline \hline \multirow{2}{*}{**Catalyst**} & \multirow{2}{*}{**M Loading, wt.\%**} & **M Content from Elemental Analysis, wt.\%** \\ \hline
3\% Pt/MN270 & 3.00 & 2.91 \\
3\% Pd/MN270 & 3.00 & 2.95 \\
3\% Au/MN270 & 3.00 & 2.87 \\
3\% Ru/MN270 & 3.00 & 2.70 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Results of X-ray fluorescence analyses of the synthesized catalysts. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **BET** & **Langmuir** & **t-Plot** \\ \cline{2-5}  & **S\({}_{\text{BET}}\), m\({}^{2}\)/g** & **S\({}_{\text{L}}\), m\({}^{2}\)/g** & **S\({}_{\text{tr}}\), m\({}^{2}\)/g** & **V, cm\({}^{3}\)/g** \\ \hline HPS MN270 & 1075 & 1191 & 265 1, 807 2, 1072 3 & 0.37 \\
3\% Pt/MN270 & 863 & 944 & 184 1, 678 2, 862 3 & 0.31 \\
3\% Pd/MN270 & 649 & 758 & 94 1, 553 2, 647 3 & 0.22 \\
3\% Au/MN270 & 738 & 810 & 141 1, 593 2, 734 3 & 0.25 \\
3\% Ru/MN270 & 839 & 921 & 151 1, 699 2, 856 3 & 0.28 \\ \hline \hline \end{tabular}  
* Specific surface area surface of meso- and macropores. 2 Specific surface area of micropores. 3 Total specific surface area. \(\text{S}_{\text{L}}\)—specific surface area (Langmuir model); \(\text{S}_{\text{BET}}\)—specific surface area (BET model); \(\text{S}_{\text{t}}\)—specific surface area (t-plot); V—volume of micropores.  
\end{table} 
Table 8: Results of the studies of the initial sample of HPS and the catalysts via the low-temperature nitrogen adsorption. showed that the catalyst plays the main role in the cellobiose hydrolysis reaction and that the degree of hydrolysis obviously depends on the nature of the metal in the catalyst. The process conditions were optimized (temperature of 145 \({}^{\circ}\)C, an O\({}_{2}\) pressure of 5 bar, and a substrate/catalyst mass ratio of 4/1), and the obtained yields of gluconic and glucaric acids reached 21.6 and 63.4%, respectively, at 100% of cellobiose conversion.