Title: PROCESS FOR PREPARING POLYISOCYANATES FROM BIOMASS

 Number/Link: US2012302786

Applicant/Assignee: BASF

Publication date: 29-11-2012

“Gist”: Lignin is reduced to hydroxy- or alkoxy monocyclic aromatics by pyrolysis (e.g.), condensed with formaldehyde, aminated and subsequently phosgenated to produce isocyanates.

Why it is interesting: The use of renewable raw materials has been a steeply rising trend in the polyurethane science- and patent literature of the last few years. Up to now the research has almost always been related to renewable polyols usually based on ‘vegetable’ oils like castor oil, soy oil and a host of other naturally occuring materials. BASF is the first to succeed in making -the economically most important- aromatic isocyanates from renewable raw materials, viz. lignin, which is an abundant and cheap by-product from the paper industry.  The lignin is first broken down to monocyclic aromatics containing hydroxyl groups, then condensed with formaldehyde to di- or poly-hydroxyaromatics which are then turned into amines. The amines can be phosgenated to yield isocyanates.  In the first claim the renewable aromatic amines are defined by their C14 to C12 ratio – establishing their non-fossil origin.  Very clever.