Catalytic cracking of oil residues on catalysts based on activated aluminium alloys

Abstract

A study has been made of the two-stage process of catalytic cracking of straight-run residual oil on nickel-alumina alloys. It has been shown taht in stage I - cracking of residual oil - the yield of white petroleum products is higher (32·04 wt.%) and their quality is better (benzine fractions contain fewer unsaturated hydrocarbons) compared with similar processes using iron oxide catalysts. Stage II - steam gasification of the coked catalyst - proceeds at a temperature of 800°C with the formation of synthesis gas containing up to 83·57 vol.% H 2. The phase composition of the support and the nickel-containing catalyst based on it was studied. The phase composition of the initial support specimen comprised γ-Al 2O 3, In and In 2O 3. After cracking, breakdown of the crystal structure of metallic In and In 2O 3 and transition of low-temperature γ-Al 2O 3 to a high-temperature crystallized modification of γ-Al 2O 3 occur. The composition of the support after gasification is identical to the composition of the support after cracking. With low cracking temperatures (450, 500°C) crystalline Ni and NiO phases are formed on the nickel-alumina catalyst. It was shown that increase in the cracking temperature leads to reduction of NiO to Ni, and then to breakdown of the crystal structure of the catalyst and subsequent formation of Ni and Ni 3S 2 phases. The γ-Al 2O 3 and metallic Ni phases are stable in relation to gasification and regeneration processes.