Johnson Matthey Public Limited Company

Thomas Davison

John David Pach

Sam Barker

A process for the production of formaldehyde-stabilised urea is described comprising the steps of: (a) generating a synthesis gas; (b) subjecting the synthesis gas to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (c) cooling the shifted gas to below the dew point and recovering condensate to form a dried shifted gas; (d) recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas; (e) synthesising methanol from the carbon dioxide-depleted synthesis gas in a methanol synthesis unit and recovering the methanol and a methanol synthesis off-gas; (f) subjecting at least a portion of the recovered methanol to oxidation with air to form formaldehyde in a stabiliser production unit; (g) subjecting the methanol synthesis off-gas to methanation in a methanation reactor containing a methanation catalyst to form an ammonia synthesis gas; (h) synthesising ammonia from the ammonia synthesis gas in an ammonia production unit and recovering the ammonia; (i) reacting a portion of the ammonia and at least a portion of the recovered carbon dioxide stream in a urea production unit to form a urea stream; and (j) stabilising the urea by mixing the urea stream and a stabiliser prepared using the formaldehyde produced in the stabiliser production unit, wherein the carbon dioxide removal unit operates by means of absorption using a liquid absorbent and comprises an absorbent regeneration unit, wherein the process includes recovering a carbon dioxide-containing gas stream from the absorbent regeneration unit, compressing at least a portion of the recovered carbon dioxide-containing gas stream to form a compressed carbon dioxide-containing gas stream and passing the compressed carbon dioxide-containing gas stream to the methanol synthesis unit.

Process for the production of formaldehyde-stabilized urea

An integrated process for the production of a formaldehyde-stabilised urea is described comprising the steps of: (a) generating a synthesis gas comprising hydrogen, nitrogen, carbon monoxide, carbon dioxide and steam in a synthesis gas generation unit; (b) dividing the synthesis gas into a first synthesis gas stream and a smaller second synthesis gas stream; (c) subjecting the first synthesis gas stream to one or more stages of water-gas shift in one or more water-gas shift reactors to form a shifted gas; (d) cooling the shifted gas to below the dew point and recovering condensate to form a dried shifted gas; (e) recovering carbon dioxide from the dried shifted gas in a carbon dioxide removal unit to form a carbon dioxide-depleted synthesis gas; (f) subjecting the carbon dioxide-depleted synthesis gas to a stage of methanation in one or more methanation reactors to form an ammonia synthesis gas; (g) synthesising ammonia from the ammonia synthesis gas in an ammonia production unit and recovering the ammonia; (h) reacting a portion of the ammonia and at least a portion of the recovered carbon dioxide stream in a urea production unit to form a urea stream; and (i) stabilising the urea by mixing the urea stream and a stabiliser prepared using formaldehyde to form a stabilised urea, wherein the formaldehyde is generated by steps comprising; (1) passing the second portion of synthesis gas through a scrubber to remove contaminants therefrom and form a scrubbed synthesis gas; (2) synthesising methanol from the scrubbed synthesis gas in a methanol synthesis unit, and recovering the methanol and a methanol synthesis off-gas; (3) combining the methanol synthesis off-gas with the shifted gas and (4) subjecting at least a portion of the recovered methanol to oxidation with air in a formaldehyde stabiliser production unit to produce formaldehyde.

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Billingham, United Kingdom

Thomas Davison