Production of unsaturated hydrocarbon, e.g. ethylene or propylene, involves thermal cleavage of optionally unsaturated hydrocarbon with injection of hot gas containing alkyl radicals and-or hydrogen atoms

摘要

A method for the production of unsaturated hydrocarbons by thermal cleavage of saturated and/or unsaturated hydrocarbons involves injecting into the reaction space a hot gas containing alkyl radicals and/or hydrogen atoms obtained by the thermal or non-thermal cleavage of suitable precursors. A method (M1) for the production of unsaturated hydrocarbons (I) by thermal cleavage of saturated and/or unsaturated hydrocarbons (II) involves: (a) passing a starting stream containing hot gaseous (II) into a reactor fitted with gas inlet(s); (b) passing in (through these inlet(s)) hot gas containing alkyl radicals and/or hydrogen atoms obtained by the thermal or non-thermal cleavage of corresponding precursors (III) (in the case of thermal cleavage, the temperature of this hot gas is at least that of the reaction mixture at the reactor inlet; for non-thermal cleavage, the temperature of the hot gas is at least the dew point temperature of the reaction mixture at the reactor inlet); and (c) adjusting the pressure and temperature in the reactor to promote thermal cleavage of (II) to form hydrogen and (I). In the case of radical generation by thermal decomposition, this is achieved by heating a gas containing (III) or by passing a gas containing (III) over a source of heat the surface of which is purged with inert gas. The claimed method does not include the production of halogen-containing aliphatic (I) from halogen-containing aliphatic (II). Independent claims are included for (1) a method (M2) for the production of (I) by thermal cleavage of (II), by (a) passing (II) as above into a reactor with an inlet for hot gas containing (III), (d) thermal or non-thermal generation of alkyl radicals and/or H atoms from (III) by means of a suitable device inside a predetermined volume (PV) of the reactor, (e) passing the hot gas containing (III) into this volume (PV) at a temperature subject to the conditions in M1 and (c) setting the pressure and temperature as above (halogenated compounds again excluded) (2) a reactor for M1, comprising: (i) an inlet for gas containing (II); (ii) a hot gas inlet inside the reactor; (iii) a source of (III) connected to the inlet; (iv) a generator of alkyl radicals and/or H atoms from (III) inside the inlet pipe; (v) optionally a heater for the gas in the inlet; (vi) a heater for the gas in the reactor; and (vii) a take-off pipe for the product containing (I) (3) a reactor as above for M1, in which (viii) the radical generator is situated at the reactor end of the feed pipe (4) a reactor for M2 comprising elements (i), (iii), (v), (vi) and (vii) as above, plus (ix) a radical/H atom generator inside PV and (x) an inlet for hot (III) opening into PV inside the reactor.