GB979720A - Process for controlling the production of hydrogen from a hydrocarbon - Google Patents

Abstract

<PICT:0979720/C1/1> Hydrogen is produced by cracking a hydrocarbon wherein the endothermic heat of conversion of the hydrocarbon to hydrogen and carbon at above 650 DEG C. is supplied from a catalyst regeneration zone to the reaction zone by a stream of heated catalyst particles and the carbonized catalyst particles are passed from the reaction zone to said regeneration zone and are therein heated by combustion of carbon from the catalyst particles during contact with a gas containing free oxygen, characterized in that during the substantially constant rate of flow of heated particles to the reaction zone the heat supply to said reaction zone is increased by decreasing the carbon level on the particles by a controlled increase in the rate of oxygen supply to the regeneration zone and said heat supply is decreased by increasing said carbon level by a controlled decrease in the rate of oxygen supply to the regeneration zone. A carbon level of more than 0.5% by weight may be maintained on the heated particles passing from the regeneration zone to the reaction zone. The catalyst may be: Al2O3, SiO2 - Al2O3, SiO2 - MgO and may be mixed with an oxide of Zr, Ti or one of the oxides may be mixed with an oxide of Cr, Mo or V. One or more metals or oxides of Group VIII are preferably used, e.g. Ni, Fe or Co with a refractory base e.g. of SiO2 - Al2O3. In Fig. 1, hydrocarbon in line 1 is mixed with a catalyst from line 3 and admitted to reaction reaction chamber 5. The hydrogen and catalyst are separated in cyclone 8 which returns the catalyst to bed 7 via clip leg 9. The reaction temperature 650-925 DEG C. and the particles leave the regenerator at 675-980 DEG C., and the operating pressure is less than 3.4 atmospheres. Catalyst particles pass through outlet line 11 and control valve 12 to regenerating chamber 13 and air is admitted by pipes 14 and 15. The catalyst particles are separated from the flue gas by cyclone 20 and then having up to 10% of carbon deposit are permitted to descend into stripping section 24, where N2 is used to remove carbon oxides. The flow of catalyst particles is controlled by a temperature sensitive element 27 operating control valve 4, and by means of level control tips 28 and 29 which are connected to control valve 12. In a modification, dense phase bed 7, reaction chamber 5 and level control means LRC are eliminated and the light phase stream in line 2 is passed directly to a separating means and then to dense phase zone in regenerator 13.ALSO:Hydrogen is produced by cracking a hydrocarbon, e.g. natural gas, methane, or light hydrocarbon, wherein the endothermic heat of conversion of the hydrocarbon to hydrogen and carbon at above 650 DEG C. is supplied from a catalyst <PICT:0979720/C4-C5/1> regeneration zone to the reaction zone by a stream of heated catalyst particles and the carbonized catalyst particles are passed from the reaction zone to said regeneration zone and are therein heated by combustion of carbon from the catalyst particles during contact with a gas containing free oxygen, characterized in that during the substantially constant rate of flow of heated particles to the reaction zone the heat supply to said reaction zone is increased by decreasing the carbon level on the particles by a controlled increase in the rate of oxygen supply to the regeneration zone and said heat supply is decreased by increasing said carbon level by a controlled decrease in the rate of oxygen supply to the regeneration zone. A carbon level of more than 0.5% by weight may be maintained on the heated particles passing from the regeneration zone to the reaction zone. The catalyst may be: Al2O3, SiO2-Al2O3, SiO2-MgO and may be mixed with an oxide of Zr, Ti or one of the oxides may be mixed with an oxide of Cr, Mo or V. One or more metals or oxides of Group VIII are preferably used, e.g. Ni, Fe or Co, with a refractory base, e.g. of SiO2-Al2O3. In Fig. 1, hydrocarbon in line 1 is mixed with a catalyst from line 3 and admitted to reaction chamber 5. The hydrogen and catalyst are separated in cyclone 8 which returns the catalyst to bed 7 via dip leg 9. The reaction temperature is 650-925 DEG C. and the particles leave the regenerator 13 at 675-980 DEG C., and the operating pressure is less than 3.4 atmospheres. Catalyst particles pass through outlet line 11 and control valve 12 to regenerating chamber 13 and air is admitted by pipes 14 and 15. The catalyst particles are separated from the flue gas by cyclone 20 and then having up to 10% of carbon deposit are permitted to descend into stripping section 24, where N2 is used to remove carbon oxides. The flow of catalyst particles is controlled by a temperature sensitive element 27 operating control valve 4 and by means of level control tips 28 and 29 which are connected to control valve 12. In a modification, dense phase bed 7, reaction chamber 5 and level control means LRC are eliminated and the light phase stream in line 2 is passed directly to a separating means and then to dense phase zone in regenerator 13.