Method for oxidative coupling of methane comprising catalytic cracking

A method for oxidative coupling of methane in which a coupling feed gas containing methane and a gas containing oxygen are allowed to react in the presence of a catalyst, and a coupling product gas containing an unsaturated hydrocarbon is produced, said method for oxidative coupling of methane comprising:

• a coupling step, in which a coupling feed gas containing methane and a gas containing oxygen are supplied to a conveying catalyst bed which is formed by an ascending stream which contains a catalyst, and then methane and oxygen are allowed to react so as to produce a coupling product gas accompanied by the catalyst;
• a catalyst separation step for separating said catalyst from said coupling product gas;
• a catalyst cooling step for cooling the separated catalyst to produce a cooled catalyst;
• and
• a catalyst feedback step for feeding back said catalyst which is separated in said catalyst separation step and cooled, to said coupling step;
• wherein said conveying catalyst bed is formed by at least a part of said coupling feed gas and said catalyst;
• the catalyst amount being in a range between 0.5% and 5% by volume with respect to the volume of the entirety of the gas supplied to the coupling step in the conveying catalyst bed;
• and
• the residence time in the coupling reaction zone being between 0.1 to 10 second;
• and
• wherein said method for oxidative coupling of methane further comprises, between said catalyst separation step and said catalyst feedback step, a cracking step in which said catalyst which is separated in said catalyst separation step is brought into contact with a cracking feed gas which contains a saturated hydrocarbon having a carbon number of at least 2, and then a cracking reaction is allowed to occur so as to produce a cracking product gas which contains an unsaturated hydrocarbon.