GB615381A - An improved process for the catalytic synthesis of hydrocarbons - Google Patents

Abstract

<PICT:0615381/III/1> The synthesis of hydrocarbons from carbon monoxide and hydrogen is effected in at least two separate conversion zones containing a fluidized catalyst, the gases being passed therethrough in series, and catalyst being passed from zone to zone in a direction opposite to the flow of reactants, catalyst of high activity being supplied to the last zone and low activity catalyst withdrawn from the first. The conversion zones may be in separate reactors or combined in a single reactor sub-divided by perforated grids into preferably superimposed zones. Reaction products are optionally separated between successive zones by cooling and scrubbing. In the absence of such separation, entrained catalyst is carried from zone to zone. To compensate for this, the rate of circulation of catalyst in the opposite direction is then kept high. This rate is preferably a function of the rate of catalyst de-activation. Where the latter is high, as in production of liquid and solid saturated hydrocarbons using cobalt on silica gel, preferred conditions are 375-450 DEG F., 5-10 atm., molar ratio CO : H2 0.2-0.8 : 1, space velocity 200-500, superficial gas velocity not above 1.5 ft./sec. with a catalyst size of 15-60 per cent through a 325 mesh. Complete catalyst replacement is made in 10-50 days. For synthesis of liquid, unsaturated hydrocarbons with reduced iron sesquioxide of similar particle size, conditions are 550-650 DEG F., 5-25 atm., CO : H2 0.5-1.3 : 1, space velocity 500-1500, and superficial velocity 1-3 ft./sec. Catalyst is replaced in 100-400 days. Where de-activation rate is high, three conversion zones 10, 20, 30 in a single reactor may be used. Standpipes 14, 24, 34 serve for transport and final withdrawal of catalyst fed from hopper 1 to zone 10, reactant gases flowing up through line 40. Entrained catalyst is separated and returned by separators 17, 27, 37. Reduction in the size of the zones permits constant velocities to be maintained. In a modification (Fig. 2, not shown), separate reactors communicate by a catalyst overflow standpipe, and products from the first reactor are separated into liquid hydrocarbons, catalyst which is recycled, and tail gases which pass to the second reactor.ALSO:<PICT:0615381/IV(b)/1> The synthesis of hydrocarbons from carbon monoxide and hydrogen is effected in at least two separate conversion zones containing a fluidized catalyst, the gases being passed therethrough in series, and catalyst being passed from zone to zone in a direction opposite to the flow of reactants, catalyst of high activity being supplied to the last zone, and low activity catalyst withdrawn from the first. The conversion zones may be in separate reactors or combined in a single reactor subdivided by perforated grids into preferably super-imposed zones. Reaction products are optionally separated between successive zones by cooling and scrubbing. In the absence of such separation, entrained catalyst is carried from zone to zone. To compensate for this, the rate of circulation of catalyst in the opposite direction is then kept high. This rate is preferably a function of the rate of catalyst deactivation. Where the latter is high, as in production of liquid and solid saturated hydrocarbons using cobalt on silica gel, preferred conditions are 375-450 DEG F., 5-10 atm., molar ratio CO : H2 0.2-0.8 : 1, space velocity 200-500, superficial gas velocity not above 1.5 ft./sec. with a catalyst size of 15-60 per cent through a 325 mesh. Complete catalyst replacement is made in 10-50 days. For synthesis of liquid, unsaturated hydrocarbons with reduced iron sesquioxide of similar particle size, conditions are 550-650 DEG F., 5-25 atm., CO : H2 0.5-1.3 : 1, space velocity 500-1500, and superficial velocity 1-3 ft./sec. Catalyst is replaced in 100-400 days. Where deactivation rate is high, three conversion zones 10, 20, 30 in a single reactor may be used. Standpipes 14, 24, 34 serve for transport and final withdrawal of catalyst fed from hopper 1 to zone 10, reactant gases flowing up through line 40. Entrained catalyst is separated and returned by separators 17, 27, 37. Reduction in the size of the zones permits constant velocities to be maintained. In a modification (Fig. 2, not shown), separate reactors communicate by a catalyst overflow standpipe, and products from the first reactor are separated into liquid hydrocarbons, catalyst which is recycled, and tail gases which pass to the second reactor.