GB744687A - Improvements in or relating to fluidized hydroforming process - Google Patents

Abstract

<PICT:0744687/III/1> In a hydroforming process wherein hydrocarbon fractions are contacted with a dense fluidized catalyst which is continually withdrawn and regenerated in a fluidized state whereby carbonaceous deposits are burnt therefrom, the spent catalyst particles are maintained under regenerative conditions in the regeneration zone for at least 35 minutes and preferably for 1 to 5 hours. The extended regeneration time can be achieved by enlarging the regenerator to increase holding time or by using a plate column regenerator wherein spent catalyst is supplied to the top of the column and passed via downcomers from plate to plate countercurrent to the regenerating gas which is supplied below the lowest plate at such a velocity as to maintain a dense fluidized bed of catalyst on each plate. Cooling coils may be provided at one or more of the plates to control the temperature. In an alternative regenerator, Fig. 2, spent catalyst suspended in air or other carrier gas is introduced through cone 112 into the upper zone of regenerator vessel 110, the remainder of the regeneration gas being introduced via nozzles in the vicinity of 112 and through distribution cone 115 at a velocity, e.g. 0.6-1.0 ft. per second, sufficient to form a dense fluidized bed of catalyst 116 in said upper zone. The average time of residence in this upper zone is less than 15 minutes and may be as little as 3-5 minutes. The portion of the regenerator below 112 is a low velocity zone, provided with baffles 123 and 124, through which the velocity of regeneration gas is sufficient only to maintain fluidity so as to ensure countercurrent contact between gas and catalyst, and wherein the catalyst is maintained in contact with the said gas for at least 35 minutes. The regeneration temperature in the upper zone may be controlled by passing water or other heat-exchange fluid through cooling jacket 130. Alternatively an arrangement of cooling coils with a primary coil entirely below the dense bed level and a secondary coil partly above and partly below, may be used, permitting adjustment of heat-exchange by variation of bed level. The regenerator is operated at 50-500 lbs. per sq. inch pressure and at temperatures of 1050-1200 DEG F. preferably 1075-1125 DEG F. The regeneration gas may be air but air diluted with flue gas to 1 to 5 per cent O2 concentration is preferred. Suitable catalysts include Group VI metal oxides such as molybdenum, chromium or tungsten oxide, or mixtures thereof, preferably supported on activated alumina or zinc spinel. Minor amounts of promoters such as silica, calcium oxide, ceria or potassium oxide may be included in the catalyst.