Catalytic cracking of gas oils in electromagnetic fields: reactor design and performance

The application of dielectric heat transfer in the catalytic cracking and hydrocracking of gas oils has been investigated. A three-phase spouted-bed catalytic reactor has been designed and operated using dielectric radio frequency (RF) heating. The electromagnetic power was transferred to the reactor by a 27.12 MHz RF generator acting through two capacitor plates. In this technique, heat is generated to the catalyst held in the electromagnetic field and thermal energy dissipated to the surroundings of the catalyst volume preventing carbon formation by eliminating secondary reactions. Energy transfer from the RF filed to the reaction was solely dependent on the dielectric properties of solids in the reactor, effectively the catalyst or transient carbon. Three zeolitic catalysts have been tested. These catalysts were 13X, 5A and Ammonium Y Zeolite. Two different gas oils have been used as feedstocks for the experiments. Saudi Light Vacuum Gas Oil (SALVGO) supplied by Saudi Aramco Oil and North Sea Light Gas Oil (BPLGO) supplied by BP Oil. A comparative study of the two gas oils cracked over 13X zeolitic catalyst has been presented. The analysis of the feedstocks have shown that SALVGO contains hydrocarbons in the range C-11-C-30 with average molecular weight of 294, while BPLGO contains hydrocarbons in the range C-11-C-25 with average molecular weight of 243. The analysis of cracked products have shown a production of lower olefins such as propene and butene with hydrogen sulphide from SALVGO at a conversion of 87% and aromatics such as benzene and toluene from BPLGO at a conversion of 72%. The successful use of zeolitic catalyst in producing lower olefins and aromatics with an RF dielectric reactor suggests exploring this type of reactor for objectives such as the production of reformulated gasoline, in which butene is used as feedstock for production of high-octane gasoline components such as MTBE and alkylate. (C) 2002 Elsevier Science B.V. All rights reserved.