The influence of the cobalt-containing component (Co-Al2O3/SiO2, Co-Re/Al2O3 and Co-Re/TiO2) of a composite catalyst was studied in the Fischer – Tropsch combined process for synthesis and hydrotransformation of hydrocarbons. A flow fixed-bed reactor was used for characterization of the catalytic properties at 2 MPa, flow rate 1000 h–1, 240–280 °C for 40–90 hours of continuous operation. The highest productivity and selectivity to C5+ hydrocarbons equal to 106 kg/(m3 cat·ч) and 67.1 %, respectively, was characteristic of the composite catalyst Co-Al2O3/SiO2(35%)/ZSM-5(30%)/Al2O3(30%) at 240 °C. The comparable activities were observed with the catalysts Co-Re/Al2O3 and Co-Al2O3/SiO2 but the former provided the formation of unsaturated hydrocarbons in a lower proportion in the products. The use of the Co-Re/TiO2 catalyst at elevated temperature (up to 280 °C) allowed the molecular mass distribution of the products to be shifted towards the formation of the gasoline fraction. The rate of the catalyst deactivation was established to increase in the series Co-Al2O3/SiO2 > Co-Re/Al2O3 > Co-Re/TiO2.
A composite Co-Al2O3/SiO2/HZSM-5 catalyst has been developed for one-step synthesis of fuel series hydrocarbons from CO and H2. The catalyst was obtained by mixing and forming powders with a Co-Al2O3/SiO2 catalyst, zeolite HZSM-5, and boehmite Al(O)OH?H2O. The physicochemical methods XRD, PEM, BET established the phase composition of the catalyst, the particle size of cobalt (8.2 ± 1 nm), its specific surface area (286 m2/g). Tests were carried out in the synthesis of hydrocarbons from CO and H2 for 60 hours at a temperature of 240 ° C, a pressure of 2.0 MPa, and a gas flow rate of 1000 h-1. It is shown that synthesis gas diluted by 40% with nitrogen can produce liquid C5+ hydrocarbons with a selectivity of 69% and a productivity of 81 kg/(m3?h). The yield of С5+ hydrocarbons was 70 g/m3 of the leaked synthesis gas and 135 g/m3 of the converted synthesis gas. Synthetic oil has a molecular mass distribution close to monomodal (the probability of chain growth is 0.81), 88% consists of gasoline and diesel fractions and 12% of long-chain C19+ hydrocarbons. The ratio of isomeric hydrocarbons to normal hydrocarbons (iso/n) is 1,26, and the ratio of olefinic hydrocarbons to paraffinic hydrocarbons is 0,97. In the gasoline fraction of hydrocarbons (C5-C10), a high content of alkenes of normal and branched structure (76,3%) is noted, the proportion of iso-alkanes and n-alkanes is 10,8 and 12,9%, respectively. The catalyst showed stable operation, the rate of its deactivation is comparable to the rate of deactivation of a commercial bifunctional catalyst.
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