Levoglucosan from

Brown, R.C., Radlein, D., Piskorz, J., Pretreatment processes to increase pyrolytic yield of Levoglucosan from herbaceous biomass, chemicals and materials from renewable resources,... 

Fig. 7. The major decomposition products from burning of cellulose. Levoglucosan is the dominant compound, and mannosan and galactosan are formed as well as levoglucosan from burning of hemicelluloses.

Further information on the yield of levoglucosan from difiFerent types of cellulose has been reported by Golova and coworkers this is summarized in Table II. 

Formation of Levoglucosan from Different Types of Cellulose... 

In the earlier literature, jS-D-glucose (3) was considered to be an intermediate compound which, on subsequent dehydration, provides levoglucosan. Experimental evidence against this theory has been adduced by Golova and associates, who obtained small yields of levoglucosan from jS-D-glucose and from cellobiose, as compared to a 54—60% yield from cellulose. 

Venn obtained very little levoglucosan from the pyrolysis of raw cotton, whereas washing with water increased the yield to 28 %, and further prepurification by treatment with dilute alkali and acid provided a yield of 38%. Holmes and Shaw found that a cotton fabric purified by scouring and bleaching provided more tar and less char on vacuum pyrolysis than the reference materials. A Russian patent" claims that the heat resistance of cellulose is greatly increased by lowering the content of alkali metals to 0.03 — 0.05%. 

Quantitative estimations of the yield of levoglucosan from the pyrolysis of cellulose have been made. Schwenker and Pacsu found that, at 350-375°, some 12.5% of levoglucosan was produced when various cellulose samples were pyrolyzed in a limited supply of air. Madorsky and cowork-ers 2 found a 52% yield of anhydro sugar from cotton heated at 280° under vacuum. This proportion was dramatically diminished to about 5%, when the pyrolysis was conducted in the presence of such salts as sodium chloride or sodium carbonate. Comparable results have been obtained by Holmes and coworkers. ... 

Pretreatment Processes to Increase Pyrolytic Yield of Levoglucosan from Herbaceous Feedstocks... 

We are investigating various pretreatment processes to increase the pyrolytic yield of levoglucosan from herbaceous biomass. This work is motivated by our effort to convert lignocellulosic material into simple sugars suitable for fermentation. In particular, we are investigating thermal depolymerization of com stover and switchgrass into anhydrosugars and their subsequent hydrolysis and fermentation to lactic acid. 

Most previous work on production of high sugar pyrolysates has used wood as feedstock, which differs in many respects from the herbaceous material of interest to most agricultural operations. For example, herbaceous materials contain more potassium than woody materials (II). Since the catalytic activity of potassium under conditions of pyrolysis are considerably greater than for calcium (12), it may be more difficult to thermally depolyermerize herbaceous plant materials. However, potassium is also more water soluble than calcium and thus easier to remove. TTiis study investigates various pretreatment options for their ability to increase pyrolytic yields of levoglucosan from herbaceous feedstocks. 

Three pretreatments were evaluated for their effectiveness in enhancing pyrolytic yields of levoglucosan from com stover and switchgrass. These are summarized in Table I. 

Bennet NM, Helle SS, Duff SJB. Extraction and hydrolysis of levoglucosan from pyrolysis oil. Bioresour Technol 2009 100 6059-63. 

Garcia CD, Engling G, Herckes P et al (2005) Determination of levoglucosan from smoke samples using microchip capillary electrophoresis with pulsed amperometric detection. Environ Sci Technol 39 618-623... 

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