Publication: Debottlenecking a Pulp Mill

Authors: Davide Di Francesco, Christian Dahlstrand, Joakim Löfstedt, Alexander Orebom, Johan Verendel, Christopher Carrick, Åsa Håkansson, Sören Eriksson, Henrik Rådberg, Henrik Wallmo, Martin Wimby, Florian Huber (hte), Christopher Federsel (hte), Mattias Backmark and Joseph S. M. Samec

ChemSusChem, April 2021, 14, 1-13

By extracting lignin, pulp production can be increased without heavy investments in a new recovery boiler, the typical bottleneck of a pulp mill. The extraction is performed by using 0.20 and 0.15 weight equivalents of CO₂ and H₂SO₄ respectively. Herein, we describe lignin esterification with fatty acids using benign reagents to generate a lignin ester mixable with gas oils. The esterification is accomplished by activating the fatty acid and lignin with acetic anhydride which can be regenerated from the acetic acid recycled in this reaction. The resulting mass balance ratio is fatty acid/lignin/acetic acid (2:1:0.1). This lignin ester can be hydroprocessed to generate hydrocarbons in gasoline, aviation, and diesel range. A 300-hour continuous production of fuel was accomplished. By recirculating reagents from both the esterification step and applying a water gas shift reaction on off-gases from the hydroprocessing, a favorable overall mass balance is realized.