Increasingly, bio-sourced products derived from biomass are gaining attention in the pulp and paper industry. For hardwood kraft-dissolving pulp mills, the production of furfural would not only enhance the use of biomass, but also generate additional revenue, and create a reliable source of furfural in North America.
Symposium on Biotechnology for Fuels and Chemicals
That idea was put forth in a recent presentation Naceur Jemaa, an FPInnovations senior scientist, gave at the Symposium on Biotechnology for Fuels and Chemicals, held in Seattle, Washington. He co-authored the presentation titled, ”Furfural from Pulp Mill Prehydrolysates,” with FPInnovations colleagues, post-doctorate fellow Adil Mazar, and senior scientist Waleed Wafa Al Dajani.
Demand for furfural, a colourless organic liquid compound, is growing partly due to its increased use in petroleum refining, agricultural formulations, paints and coatings, pharmaceuticals, and a rise in the overall demand for environmentally sustainable biomass-based chemicals, according to the market research and consulting firm, Allied Market Research. There are no furfural plants in North America.
Five-carbon sugars (C5 sugars)
Currently, prior to the production of dissolving pulp, mills extract hemicelluloses from hardwood chips during a steam prehydrolysis step. A significant amount of five-carbon sugars (C5 sugars) is present in this stream but is burned along with black liquor and lignin. According to Jemaa, valorizing a waste stream to convert the C5 sugars to furfural can be done competitively, reducing the need for imported furfural. This would offload the evaporators and the recovery boiler at kraft-dissolving pulp mills, which would allow for more dissolving pulp production.
The researchers propose that instead of burning C5 sugars, they would be sent to a furfural reactor where the solution would be heated by steam to a temperature of between 200 to 240 degrees Celsius, then adding sulfuric acid. The mixture would then be distilled to refine the stream into pure furfural.
There are several challenges to be addressed in turning mills into furfural refineries. The volume of C5 sugars extracted from wood chips is large. Some pulp mills currently generate up to three tonnes of diluted furfural per day. Market competitiveness depends on the availability of steam, which contributes up to 70 per cent of the production cost of furfural. And, additional equipment, such as a furfural reactor and a distillation system, would require a capital investment.
“Kraft dissolving pulp mills should take advantage of sugars present in the prehydrolysate stream to produce bioproducts, whether it’s furfural, xylitol, or others. These sugars are presently wasted and burned. There is a need to convert these sugars to bioproducts to enhance the utilization of biomass and increase the profitability of pulp mills,” says Jemaa. “We’re getting one step closer to turning mills into biorefineries.”