METHOD OF OBTAINING CARBAMIDE-FORMALDEHYDE CONCENTRATE Russian patent published in 2015 - IPC C08G12/12 C07C47/55 

FIELD: chemistry.

SUBSTANCE: invention relates to method of obtaining carbamide-formaldehyde concentrate with mole ratio carbamide:formaldehyde 1:(4.9-5). Method includes oxidative dehydration of methanol in formaldehyde on silver or iron-molybdenum catalyst in one or several tubular or shelf-type reactors and chemical absorption of formaldehyde-containing gas in two successively placed column apparatuses. Abgas from first column apparatus is divided into two parts with ratio 1:4 with supply of smaller one to catalytic after-burning, and larger one into second column apparatus for chemical absorption by 15-25% carbamide solution with formation of prepolymer with molar ratio carbamide:formaldehyde, equal (0.1-0.5):1, mixed with 50-65% water solution of carbamide in flow mixer and supplied further for chemical absorption of formaldehyde-containing gas into upper section of first column apparatus.

EFFECT: invention makes it possible to optimise scheme of obtaining carbamide-formaldehyde concentrate in order to increase efficiency of production and reduce formaldehyde content in abgas, supplied into reactor of oxidative methanol dehydration.

1 dwg, 1 ex