2.2.2. Catalysts and Adsorbents

Based on the preliminary experimental results with various kinds of catalysts, Pt/Al2O3/Cl and Pt/H-Mordenite/Al2O3 catalysts were selected for quality improvement of feedstock "A" and "B", respectively. The main properties of the catalysts are summarized in Table 2.


**Table 2.** The main properties of catalysts used in the experiments.

During the pre-selection of the catalysts, Pt/Al2O3/Cl showed the highest isomerization activity at favorably low temperatures. However, this catalyst is very sensitive to the water and sulfur content of the feedstock; thus, these impurities were removed from feedstock "B" to obtain feedstock "A" by commercial Molecular Sieves 4A and 13X purchased from Sigma-Aldrich. Hydrogenation and isomerization of feedstock "A" over the Pt/Al2O3/Cl catalyst were carried out in the reactor system where both reactors were operated in serial. Halogen content of the Pt/Al2O3/Cl in case of Reactor I was lower than that of Reactor II to ensure sufficiently available active sites for the hydrogenation of benzene and for the isomerization reactions. The catalyst volume in Reactor I (40 cm3) was half of the volume used in Reactor II (80 cm3) to avoid significant increases in temperature in Reactor I. This heat releases during the fast hydrogenation reaction of benzene to cyclohexane, and during isomerization reactions, which are also exothermic.

The catalytic isomerization of feedstock "B" over Pt/H-Mordenite/Al2O3 was carried out on one side of the same catalytic test apparatus. Compared to the commercial light gasoline isomerization catalysts (Pt-content: 0.30–0.34 %) used in industry, platinum content was slightly increased to 0.38%; this value was determined in previous experiments. Higher platinum content increases the number of available active metal sites of the catalyst for the hydrogenation of benzene, as well as the other hydrogenation/dehydrogenation reactions. A volume of 80 cm<sup>3</sup> of catalyst was placed in the middle of the reactor and treated before the experiments as follows: dried at 150 ◦C for 2 h in nitrogen, heated to 300 ◦C at 25–30 ◦C/h in hydrogen atmosphere (40 dm3/h), temperature was held for 3 h, and then increased to 400 ◦C and held for 1 h.
