Method for producing butadiene from butanediols

A method for producing 1,3-butadiene from butanediol, which method comprises at least:

• a) esterifying the butanediol by a carboxylic acid in a mixture comprising the butanediol, the carboxylic acid and a liquid pyrolysis effluent, in a reactive distillation column, in the presence of a homogeneous or heterogeneous acid catalyst, and at a pressure of between 0.01 and 1 MPa to form the corresponding diester, thereby producing at least a carboxylic acid effluent and a diester effluent;
• b) pyrolyzing the diester effluent obtained from a) in a reaction section at a temperature of between 500° C. and 650° C. thereby producing a reaction-section effluent, cooling said reaction-section effluent to a temperature that is less than 100° C., and feeding the cooled reaction-section to a separation section and separating at least a liquid pyrolysis effluent comprising at least 50% by weight of carboxylic acid and a vapor pyrolysis effluent comprising more than 90% by weight of butadiene, said liquid pyrolysis effluent feeding the esterification in a);
• c) distilling at least the carboxylic acid effluent obtained from a), in a distillation column at a pressure that is less than or equal to 1 MPa, at a temperature at the top of the column between 0 and 110° C. and a temperature at the bottom of the column between 100° C. and 120° C., and producing an aqueous distillate comprising the by-products of a) and b), and a carboxylicacid residue;
• d) drying the carboxylic acid residue obtained from c) and producing a water effluent and a carboxylic acid recycle that is fed to esterification in a).