GB732537A - Improvements in or relating to hydrocarbon conversion - Google Patents

Abstract

Hydroforming of naphtha is carried out in the presence of a fluidized bed of MoO3 and SiO2 on alumina gel catalyst at a temperature of about 950 DEG F. and a pressure of about 500 p.s.i.g.; catalyst is circulated through a regeneration zone in which the velocity of regeneration gas is increased from below 5 feet per second to above 10 feet per second in order to carry an entrained stream of catalyst to an upper collection zone (see Group III). Circulation of the catalyst is effected by pressure differences and fluistatic pressure in the transfer lines.ALSO:Catalyst which has been used as a dense fluidized bed in reactor 18 for the conversion of hydrocarbons is transferred in the dense phase via line 32 to combustion zone 30A where, in order to remove deactivating deposits, <PICT:0732537/III/1> it is treated in the dense phase with regeneration gas introduced at 58 and having a superficial velocity of below about 5 feet per sec.; the gas velocity increases to above about 10 feet per sec. in zone 30B, so that the regenerated catalyst is entrained and carried to collection zone 30C, where the gas velocity is reduced and catalyst separates as a dense phase and is returned via line 64 to the reactor. Circulation of the catalyst is effected by pressure differences and fluistatic pressure in the transfer lines. Catalyst is removed from the reactor at various points through lines 34, 36, 38, 40; safety valve 50 is automatically closed when the pressure difference across valves 50, 52 falls, and valve 52 is regulated according to the carbon content of the catalyst in line 32. The flue gas from collection zone 30C passes through porous filters 56 to cooler 84; part is discharged through line 74, and the remainder flows through line 88 to compressor 94, being divided into two streams, one passing through line 108 and heater 110 for blowing back the filters 56, and the other passing through line 106 to mix with regeneration air; auxiliary filter 96 is brought into use if there is a breakdown of the filters 56. Regeneration temperature is controlled (e.g. at 750-1150 DEG F.) by varying the relative proportions of air and recycled flue gas. Catalyst return line 64 includes safety valve 66, operating similarly to valve 50, and valve 68 which is regulated according to the bed level 60 in the collection zone. Controller 70 operates flue gas outlet valve 72 in order to maintain a desired pressure differential between the reactor and regenerator. Time controller 78 regulates the blowing back of filters 56 in sequence. In Fig. 2 (not shown), acceleration of the flue gas takes place in a series of parallel tubes surrounded by a cooler, and part of the regenerated catalyst is recirculated from the collector to the bottom of the regeneration zone. The amount of catalyst recirculated provides an additional control of the regeneration temperature. In Fig. 3 (not shown), the flue gas is not recirculated, heated air being used for blowing back the filters. The process is described with reference to the hydroforming of naphthas (see Group IV (b)), using a catalyst consisting of MoO3 and SiO2 on alumina gel, but is also applicable in hydrodesulphurization, hydrogenation, and hydrocracking.