Activated carbon (AC) prepared by chemical activation with H 3 PO 4 (named AC-P) was employed for catalytic fast pyrolysis of cellulose and biomass to selectively produce levoglucosenone (LGO). The catalytic pyrolysis behaviors and product distributions were revealed via both analytical pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) and lab-scale experiments. Moreover, the performance of AC-P catalyst was compared with previously reported strong acid catalysts and other ACs prepared by different activation methods. In addition, reusability and stability of the AC-P catalyst have been examined via recycling experiments. The results indicated that the AC-P catalyst was effective for selectively preparing LGO from both cellulose and biomass and performed better than other catalysts. Among the three biomass materials (pine wood, poplar wood, and bagasse), pine wood showed the best selectivity for producing LGO. The maximal LGO yields of 18.1 and 9.1 wt % were obtained from cellulose and pine wood, respectively, in Py-GC/MS experiments under a catalyst-to-feedstock ratio of 1:3 at 300 °C, whereas the lab-scale setup obtained the highest LGO yields of 14.7 and 7.8 wt % from cellulose and pine wood with selectivities of 76.3 and 43.0%, respectively, based on organic liquid products. Furthermore, granular AC-P catalyst exhibited good reusability and stability in the recycling experiments. Stable yields of LGO above 12.5 wt % from cellulose were obtained in six consecutive runs without any regeneration of the recycled granular AC-P catalyst.
Fast
pyrolysis of bagasse catalyzed by activated carbon (AC) at
low temperatures offered a new and promising way to produce the valuable
4-ethyl phenol (4-EP) compound in high selectivity. In this study,
the technique of pyrolysis-gas chromatography/mass spectrometry
(Py-GC/MS) was first applied to investigate several factors
on the 4-EP production, including biomass type, fast pyrolysis temperature,
AC-to-bagasse ratio, and catalytic pattern (in situ or ex situ catalysis).
Moreover, fast pyrolysis experiments by using AC catalyst were conducted
in a lab-scale setup to quantitatively determine the pyrolytic products.
The experimental results indicated that, among these five herbaceous
biomass materials, bagasse was the best material to produce 4-vinylphenol
(4-VP) from the noncatalytic process and 4-EP from the catalytic fast
pyrolysis process, respectively. 4-VP and its precursors could be
catalytically hydrogenated into 4-EP with high selectivity under the
catalysis of AC catalyst. Both catalytic pyrolysis temperature and
AC-to-bagasse ratio affected the 4-EP selectivity significantly, whereas
the catalytic pattern had minor effects on the 4-EP production. The
highest yield of 4-EP from bagasse in Py-GC/MS experiments
was 2.13 wt %, obtained at the pyrolysis temperature of 300 °C
and AC-to-bagasse ratio of 4 from the in situ catalytic pattern. Moreover,
lab-scale fast pyrolysis of bagasse catalyzed by AC catalyst obtained
the maximal 4-EP yield of 2.49 wt %, with the selectivity of 10.71%.
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