## 3 Results  
### XRD Analysis  
Phase composition of the samples was determined by XRD. Figure 1 shows X-ray diffraction patterns of the samples depending on the calcination temperature. All XRD patterns were refined by the Rietveld method. Lattice parameters for all observed phases remain practically unchanged with the variation of the calcination temperature and, within the error bars, correspond to anatase (ICDD PDF-2 # 21-1272), rutile (ICDD PDF-2 # 21-1276) and brookite (ICDD PDF -2 # 29-1360) phases (Table 1). X-ray diffraction data show that the Pt/Ti-PLA-400 catalyst contains a mixture of TiO\({}_{2}\) phases including anatase (66%), rutile (19%) and brookite (15%) (Table 1). The Pt/Ti-P25-400 catalyst contains only two titanium dioxide phases: anatase (84%) and rutile (16%) (Table 1). An increase of the calcination temperature leads to an increase of the amount of the more stable TiO\({}_{2}\)-rutile phase. Only the TiO\({}_{2}\)-rutile phase is observed in the Pt/Ti-P25-800 sample. For the Pt/Ti-PLA samples, calcination at 600 \({}^{\circ}\)C leads to disappearance of the TiO\({}_{2}\)-brookite phase but the TiO\({}_{2}\)-anatase phase remains stable even after calcination at 800 \({}^{\circ}\)C.  
Table 1 shows that, for the catalysts calcined at 400 \({}^{\circ}\)C, crystallite sizes of the TiO\({}_{2}\)-anatase phase, estimated from the coherent scattering region (D), are quite similar: 19-22 nm. The surface areas of the Pt/Ti-PLA 400 and Pt/Ti-P25-400 samples are also similar: 79 and 64 m\({}^{2}\)/g, respectively. However, in the case of PLA-produced support the rutile particles are significantly smaller: 7 nm compared to 29 nm. The brookite phase has an even lower D value of about 5 nm. An increase in the calcination temperature leads to an increase in the D values for the TiO\({}_{2}\)-rutile and TiO\({}_{2}\)-anatas phases for all samples, but the commercial support is more prone to sintering. Thus, the support obtained by the PLA method is more thermally stable with respect to phase transitions and sintering. No reflections corresponding to Pt phases were observed for the samples calcined at 400 \({}^{\circ}\)C implying that the samples contain platinum in a highly dispersed or an amorphous state. Metallic Pt phase (ICDD PDF-2 # 04-0802) is observed upon calcination of the samples at 600 \({}^{\circ}\)C and higher. The crystallite sizes of metallic Pt in the Pt/Ti-PLA and Pt/Ti-P25 samples calcined at 600 \({}^{\circ}\)C are 16 nm and 11 nm, respectively. This is comparable to data reported in [16] for samples aged under air in presence of water. An increase in the calcination temperature leads to a change in the size of Pt crystallites (Table 1). For the support obtained by PLA, the size of Pt crystallites is slightly larger. The amount of platinum observed by XRD is lower than the actual platinum loading in the catalysts even after their calcination at 800 \({}^{\circ}\)C. Hence, approximately one third of the platinum in both samples remains in an X-ray amorphous or highly dispersed state. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & **BET Surface** & \multicolumn{2}{c}{**TiO\({}_{2}\)-Anatase**} & \multicolumn{2}{c}{**TiO\({}_{2}\)-Rutile**} & \multicolumn{2}{c}{**TiO\({}_{2}\)-Brookite**} & \multicolumn{2}{c}{**Pt**} \\ \cline{2-10}  & **Area, m\({}^{2}\)/g** & **D, nm** & **wt. \%** & **D, nm** & **wt. \%** & **D, nm** & **wt. \%** & **D, nm** & **wt. \%** \\ \hline Pt/Ti-PLA 400 & 79 & 21.6 & 66 & 7.3 & 19 & 5 & 15 & - & 0 \\ Pt/Ti-PLA 600 & 64 & 30 & 68 & 13 & 26 & 7 & 5 & 16 & 0.8 \\ Pt/Ti-PLA 800 & - & 60 & 11.8 & 62 & 86.8 & - & 0 & 48 & 1.4 \\ Pt/Ti-P25-400 & 63 & 18.8 & 84 & 29 & 16 & - & 0 & - & 0 \\ Pt/Ti-P25-600 & 29 & 22.4 & 38.8 & 44 & 61 & - & 0 & 11 & 0.2 \\ Pt/Ti-P25-800 & 1.6 & - & 0 & 114 & 98.7 & - & 0 & 36 & 1.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Phase composition and percentage in Pt/Ti-PLA and Pt/Ti-P25 samples by XRD data.