Catalytic effects of copper(II) chloride and aluminum chloride on the pyrolytic behavior of cellulose

The cellulose without and with catalyst (CuCl2, AlCl3) was subjected to pyrolysis at temperatures from 350 to 500 °C with different heating rate (10 °C/min, 100 °C/s) to produce bio-oil and selected chemicals with high yield. The pyrolytic oil yield was in the range of 37–84 wt% depending on the temperature, the heating rate and the amount of metal chloride. The non-catalytic fast pyrolysis at 500 °C gives the highest yield of bio-oil. The mixing cellulose with both metal chlorides results with a significant decrease of the liquid product. The non-catalytic pyrolysis of cellulose gives the highest mass yield of levoglucosan (up to 11.69 wt%). The great influence of metal chloride amount on the distribution of bio-oil components was observed. The copper(II) chloride and aluminum chloride addition to cellulose clearly promotes the formation of levoglucosenone (up to 3.61 wt%), 1,4:3,6-dianhydro-α-d-glucopyranose (up to 3.37 wt%) and unidentified dianhydrosugar (MW = 144; up to 1.64 wt%). Additionally, several other compounds have been identified but in minor quantities. Based on the results of the GC–MS, the effect of pyrolysis process conditions on the productivity of selected chemicals was discussed. These results allowed to create a general model of reactions during the catalytic pyrolysis of cellulose in the presence of copper(II) chloride and aluminum chloride.

► Pyrolysis of cellulose with and without CuCl2 and AlCl3 as catalysts.
► Mixing cellulose and metal chloride changes the products distribution and the composition of bio-oil.
► The higher addition of CuCl2 or AlCl3, the deeper transformation of levoglucosan and the productivity of levoglucosenone and 1,4:3,6-dianhydro-a-d-glucopyranose.
► High selectivity of both catalysts was observed.