Analytical study on the pyrolytic behaviour of cellulose in the presence of MCM-41 mesoporous materials

摘要

The effect of different mesoporous materials of the MCM-41 type on the pyrolytic behaviour of cellulose was evaluated by off-line analytical pyrolysis followed by GC-MS analysis of the evolved products trapped onto a XAD-2 resin. Siliceous MCM-41 (Si-MCM-41) and Me-MCM-41 catalysts containing different metals, namely Al, Mg, Ti, Sn or Zr, were synthesised and investigated utilising the same catalyst/cellulose mass ratio 1:3. The effect of the catalysts was evaluated by quantifying the yields of the following pyrolysis products: (2H)-furan-3-one, 2-furaldehyde, 5-methyl-2-furaldehyde, 4-hydroxy-5,6-dihydro-pyran-2-one, levoglucosenone, 1-hydroxy-3,6-dioxabicyclo[3.2.1]octan-2-one (LAC), 1,4:3,6-dianhydro-α-D-glucose and levoglucosan. All the examined mesostructured solids decreased the yields of levoglucosan with respect to uncatalysed cellulose, and increased the production of levoglucosenone and LAC. The effect was higher with doped MCM-41 in comparison to Si-MCM-41. The formation of other pyrolysis products was less influenced by the catalyst. The activity of Sn-MCM-41 was further investigated by preparative pyrolysis with a fixed bed quartz reactor. This catalyst gave rise to a pyrolytic liquid enriched in LAC and depleted in levoglucosan, and could be re-used six times after regeneration without apparent loss of activity.