Obtaining value prior to pulping with diethyl oxalate and oxalic acid

Abstract

Pulp and paper are converted to paper products with yields of paper dependent on the wood and the process used. Even with high yield pulps there are conversion losses and with chemical pulps the yields approach 50%. The portions of the wood that do not provide product are either combusted to generate power and steam or incur a cost in waste water treatment. Value prior to pulping is an approach to pulping that tries to recover the carbohydrate components that do not enter the paper product before the pulping process has been started. We describe here an approach that releases hemicellulosic sugars from wood chips (both softwoods and hardwoods). Treatment of wood chips with oxalic acid solutions or diethyl oxalate in a vapor phase deposits oxalic acid within the wood chip where it will hydrolyze the hemicellulose. Solutions of these hydrolysates are readily fermented with Saccharomyces cerevisiae, Pichia stipitis or Escherichia coli. The treated wood chips are improved sources for pulp and paper production. The high yield thermomechanical pulps require 30-50% less electrical refiner energy and result in a stronger paper product. Chips treated prior to kraft pulping have similar yields of pulp, but decreased kappa values for the same cooking conditions. The pretreatments described hold promise for the generation of new products from existing manufacturing infrastructure while improving traditional processes.

Citation

Kenealy, W.R.; Horn, E.; Houtman, C.J.; Laplaza, J.; Jeffries, T.W. 2007. Obtaining value prior to pulping with diethyl oxalate and oxalic acid. Proceedings of the 10th International Congress on Biotechnology in the Pulp and Paper Industry, 2007 June 10-15, Madison, WI. Madison, WI : Omni Press, 2007: Pages 25-26