Chemical yields from low-temperature pyrolysis of CCA-treated wood

Abstract

Low-temperature pyrolysis offers a feasible option for wood-waste management and the recovery of a variety of useful chemicals. The effect of chromated copper arsenate (CCA) wood preservative on the yield and composition of various pyrolysis products was investigated in the present research. A novel quantitative ³¹P nuclear magnetic resonance (NMR) spectroscopy methodology has been developed to quantify levoglucosan and levoglucosenone from the pyrolysate of CCA-treated and untreated wood. The CCA treatment of wood had a notable effect on the characteristics of the carbohydrate-derived degradation products of tar. In particular, yields of the important pharmaceutical precursors levoglucosan and levoglucosenone were elevated by 3 and 4.5 times, respectively, when compared with those from untreated wood. Phosphoric acid has proven to be an efficient catalyst to favor levoglucosenone formation. The pyrolysis of CCA-treated wood in the presence of phosphoric acid gave rise to high yields of levoglucosenone, demonstrating the potential for a new pathway in the rational use of CCA-treated wood waste. Pretreatment of wood with metal compounds has demonstrated that K₂Cr₂O₇ and CuSO₄ salts promote the formation of levoglucosan. The CrO₃ treatment was found to favor the formation of levoglucosenone. A kinetic study of the pyrolysis of CCA-treated wood by thermogravimetric analysis has shown that CCA components have a significant influence on the thermal decomposition behavior of CCA-treated wood and accelerate the weight loss of wood and the oxidation of the char.

Citation

Fu, Qirong; Argyropolous, Dimitris S.; Lucia, Lucian A.; Tilotta, David C.; Lebow, Stan T. 2009. Chemical yields from low-temperature pyrolysis of CCA-treated wood. Research Paper FPL-RP-652. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 18 p.