Method and apparatus for producing aldehyde

A method for the production of a C2n unsaturated aldehyde, wherein n is in the range of and including 3 to 6, the method comprising:

• (i) feeding an olefin stream comprising a Cn-1 alkene to a hydroformylation reactor, and contacting the olefin stream with a hydroformylation gas stream comprising hydrogen and carbon monoxide to effect a hydroformylation reaction to provide a crude aldehyde stream comprising a Cn aldehyde, Cn-1 alkane(s), and Cn-1 alkene(s);
• (ii) feeding the crude aldehyde stream to a crude aldehyde distillation zone operated under distillation conditions to form a bottom stream comprising the Cn aldehyde, Cn-1 alkane(s), and Cn-1 alkene(s) and comprising an increased concentration of the Cn aldehyde relative to the crude aldehyde stream and an overhead stream comprising an increased concentration of Cn-1 alkane(s), and Cn-1 alkene(s) relative to the crude aldehyde stream;
• (iii) feeding the bottom stream from the crude aldehyde distillation column to an aldolisation reactor under condensation and dehydration conditions to effect an aldolisation reaction of the Cn aldehyde to provide a crude aldol stream comprising an aldol product C2n unsaturated aldehyde, unreacted Cn aldehyde, Cn-1 alkane(s), Cn-1 alkene(s), water and heavies;
• (iv) passing the crude aldol stream to a crude aldol distillation column operated under distillation conditions to form a bottom stream having an increased concentration of the C2n unsaturated aldehyde, water and heavies as compared to the crude aldol stream, and an overhead stream comprising unreacted Cn aldehyde, Cn-1 alkane(s), Cn-1 alkene(s) and a reduced concentration of the C2n unsaturated aldehyde, water and heavies as compared to the crude aldol stream;
• (v) passing the overhead stream from the crude aldol distillation column to a first condenser zone, the first condenser zone being configured to provide a first condensed stream comprising an increased concentration of unreacted Cn aldehyde and water as compared to the overhead stream from the crude aldol distillation column and an overhead stream comprising Cn-1 alkane(s), Cn-1 alkene(s) and a reduced concentration of unreacted Cn aldehyde and water as compared to the overhead stream from the crude aldol distillation column;
• (vi) passing the overhead stream from the first condenser zone to a second condenser zone, the second condenser zone being configured to condense at least a portion of the overhead stream from the first condenser zone to provide Cn/Cn-1 condensate;
• and
• wherein at least a portion of the Cn/Cn-1 condensate is recovered and returned to upstream of the crude aldehyde distillation column or to the crude aldehyde distillation column.