GB1007423A - Pyrolysis of hydrocarbons - Google Patents

Abstract

Acetylene and hydrogen are obtained by the pyrolysis of methane at subatmospheric pressure at a space velocity (volumes of gas at S.T.P. per volume of reactor space per second) of 0.05-20 sec.-1 in which the reaction zone is heated to maintain the inlet and exit temperatures at at least 1250 DEG C. and the maximum temperature at at least 1500 DEG C. but not more than 250 DEG C. above the minimum temperature and quenching immediately. In a modification a mixture of hydrogen and methane in a mole ratio of 1-39: 1 is pyrolysed at 1-5 atmospheres with a minimum temperature of at least 1200 DEG C. and a maximum temperature in the range 1450-2000 DEG C. but not more than 250 DEG C. above the minimum with an effective space velocity (the space velocity divided by the total pressure in atmospheres) of 0.5-100 sec.-1 atm.-1 Where methane is not mixed with hydrogen the pressure may be 50-115 mm./Hg. and where it is mixed with hydrogen other gases, e.g. nitrogen, may also be present. Heating is preferably effected electrically. The product is substantially a mixture of hydrogen acetylene and unchanged methane. Multistage operation may be used where methane alone is pyrolysed at a methane conversion to give maximum efficiency of conversion to acetylene and after removing the acetylene the hydrogen-methane mixture is again pyrolysed and the process repeated if necessary.ALSO:Acetylene and hydrogen are obtained by the pyrolysis of methane at subatmospheric pressure at a space velocity (volumes of gas at S.T.P. per volume of reactor space per second of 0.05-20 sec.-1 in which the reaction zone is heated to maintain the inlet and exit temperatures at at least 1250 DEG C. and the maximum temperature at at least 1500 DEG C. but not more than 250 DEG C. above the minimum temperature and quenching immediately. In a modification a mixture of hydrogen and methane in a mole ratio of 1-39 : 1 is pyrolysed at 1-5 atmospheres with a minimum temperature of at least 1200 DEG C. and a maximum temperature in the range 1450-2000 DEG C. but not more than 250 DEG C. above the minimum with an effective space velocity (the space velocity divided by the total pressure in atmospheres) of 0.5-100 sec.-1 atm.-1 Where methane is not mixed with hydrogen the pressure may be 50-115 mm. Hg. and where it is mixed with hydrogen other gases, e.g. nitrogen may also be present. Heating is preferably effected electrically. The product is substantially a mixture of hydrogen acetylene and unchanged methane. Multistage operation may be used where methane alone is pyrolysed at a methane conversion to give maximum efficiency of conversion to acetylene and after removing the acetylene the hydrogen-methane mixture is again pyrolysed and the process repeated if necessary.