New developments in catalysts for key reactions in petroleum/hydrocarbon processing

A one-step sol-gel technique was used to synthesize alumina-supported platinum and platinum-rhenium catalysts. Transmission electron microscopy, X-ray diffraction, and surface area/pore volume measurements show that the addition of Re2(CO)10 to the synthesis sol results in smaller average platinum particle diameters (35 A vs. 110 A), slightly lower surface area (150 m2/g vs. 160 m2/g), and slightly reduced pore volumes (0.15 ml/g vs. 0.16 ml/g) over the platinum catalyst synthesized without rhenium.; KLTL zeolite-supported platinum catalysts were synthesized from aqueous tetraammineplatinum(II) nitrate solutions and non-acidic KLTL zeolite crystallites with different and well-defined morphologies and channel lengths. The catalytic performance for the dehydrocyclization of n-hexane to form benzene was virtually independent of the zeolite channel length, but the catalyst activity, selectivity, and resistance to deactivation were correlated with the ratio of platinum clusters supported on extracrystalline surfaces to that supported within the intracrystalline pores.; The H-D exchange reaction between CD4 and the following solid acids (HZSM-5, sulfated zirconia, iron- and manganese-promoted sulfated zirconia (FMSZ), and AlCl3/sulfonic acid resin) was investigated with a batch recirculation flow reactor, and the products were analyzed for CD 3H by mass spectrometry. The extrapolated results show that the reaction is 103 times faster with the AlCl3/sulfonated resin than with HZSM-5 or FMSZ. These data, combined with literature results showing that the catalytic activities of FMSZ and the AlCl3/sulfonic acid resin are markedly greater than those of the other solid acids for n-butane isomerization, indicate that the mechanism of the n-butane isomerization catalyzed by FMSZ is different from that catalyzed by AlCl3/sulfonic acid resin. In-situ electron spin resonance and UV-Vis spectroscopy measurements of the FMSZ catalyst between periods of exposure to n-pentane indicate that Fe3+ and Mn 3+ are reduced during the isomerization and disproportionation reactions. Our observations support the published hypothesis that there is an oxidation/reduction function in addition to a proton-donor function involved in the reactions catalyzed by FMSZ. The addition of Pt to the FMSZ catalyst and the addition of hydrogen to the 1% n-pentane feed increases the catalyst's active life and the selectivity for the desired isopentane isomerization product at temperatures from 0 to 50°C.