Energetics of cellulose and cyclodextrin glycosidic bond cleavage

Abstract

Thermochemical conversion of lignocellulosic materials for production of biofuels and renewable chemicals utilizes high temperature to thermally decompose long-chain cellulose to volatile organic compounds.

What limits the yield of levoglucosan during fast pyrolysis of cellulose?

“…[38,65,70,71,78,89,168] Pyrolysis reactor. [77] Similar analysis conducted on monosaccharides such as glucose, mannose, and the disaccharide sucrose, lead to activation energies ≤40 kJ mol -1 which are indicative of mass transfer limitations in these tests. For all of these components the hook was covered with char-like residue that presented a macroscopic-scale structure that suggested bubble bursting and gas formation within the liquid intermediate, a case of mass transfer limitation probably due to the high boiling point of the liquid intermediate.…”

“…Another aspect that may have modified the results was the procedure to recuperate and measure the vapors produced from the test, by reheating and collecting the products, after they have condensed in dedicated vessels of the apparatus. [84,99] More recently, Zhu et al [77] used heating pulses in microseconds time scale applied to thin film samples to study the kinetics of model compounds that represent cellulose. wt.% of levoglucosan when using the same reactor [140] meanwhile it is widely known that cellulose yields a minimum of 45 wt.% even at high furnace temperatures of 600°C.…”

“…[76] Although these glucose-forming reactions offer a potential explanation for levoglucosan yields that are no more than 60 wt.% from pyrolysis of pure cellulose, none of the reported experimental work has evidenced the production of glucose as an intermediate product as would be expected. [21,77] Thus, it is premature to assign them as a definitive explanation for the observed yields of levoglucosan from cellulose pyrolysis.…”

“…[94] Experimental apparatus based on fluidized beds, TGA instruments, electrically heated elements, and laser heating have been developed to allow measurement of chemical kinetics during pyrolysis. [3,39,77,78,84,[95][96][97][98][99][100][101][102][103][104] . However, these studies generally report various differences in heat and mass transfer effects as reasons for variations in kinetic parameters reported in the literature.…”

Direct conversion of cellulose to sorbitol via an enhanced pretreatment with ionic liquids

“…Schematic illustration of cellulose dissolution in [Amim]Cl and the process of hydrolytic hydrogenation …”