Pyrolysis reaction networks for lignin model compounds: unraveling thermal deconstruction of β-O-4 and α-O-4 compounds

Abstract

Although lignin is one of the main components of biomass, its pyrolysis chemistry is not well understood due to complex heterogeneity.

Measuring biomass fast pyrolysis kinetics: State of the art

“…With a cleavage of α‐O‐4 bond a radical with aromatic core is formed that is resonantly stabilized, in contrast to the β‐O‐4 bond cleavage of the trimer molecule. Therefore, the molecules with β‐O‐4 decompose predominantly via concerted mechanisms (Choi et al, ).…”

“…Besides, these studies can also help in designing a suitable catalyst to improve the selectivity towards desired products (Butler et al, ; Li et al, ). Numerous studies have been performed over the years to decode the kinetic mechanisms of biomass fast pyrolysis (Agarwal, Dauenhauer, Huber, & Auerbach, ; Bai et al, ; Bai & Brown, ; Banyasz, Li, Lyons‐Hart, & Shafer, ; Bradbury, Sakai, & Shafizadeh, ; Branca, Di Blasi, Mango, & Hrablay, ; Broido & Nelson, ; Choi et al, ; Chu, Subrahmanyam, & Huber, ; Custodis, Hemberger, Ma, & van Bokhoven, ; Debiagi et al, ; Faravelli, Frassoldati, Migliavacca, & Ranzi, ; Gai et al, ; Huang, Liu, Tong, Li, & Wu, ; Huang, Liu, Wei, Huang, & Li, ; Kawamoto, Murayama, & Saka, ; Kawamoto & Saka, ; Khachatryan, Xu, Wu, Pechagin, & Asatryan, ; Kim, Bai, & Brown, ; Lou, Wu, & Lyu, ; Mayes & Broadbelt, ; Mayes, Nolte, Beckham, Shanks, & Broadbelt, ; Mettler, Mushrif, et al, 2012; Miller & Bellan, ; Norinaga, Shoji, Kudo, & Hayashi, ; Nowakowska, Herbinet, Dufour, & Glaude, ; Patwardhan, Dalluge, Shanks, & Brown, ; Patwardhan, Satrio, Brown, & Shanks, ; Piskorz, Majerski, Radlein, Vladars‐Usas, & Scott, ; Piskorz, Radlein, & Scott, ; Ranzi et al, , ; Ranzi, Debiagi, & Frassoldati, , ; Ronsse, Dalluge, Prins, & Brown, ; Scheer et al, ; Scheer, Mukarakate, Robichaud, Nimlos, & Ellison, ; Shafizadeh & Fu, ; Shen & Gu, ; Shen, Gu, & Bridgwater, ; Shen, Xiao, Gu, & Luo, ; Varhegyi, Jakab, & Antal, ; Vasiliou et al, ; Vinu & Broadbelt, ; Wang, Ru, Lin, & Luo, ; Werner, Pommer, & Broström, ; Zhang, Li, Yang, & Blasiak, ; Zhang, Nolte, & Shanks, ; Zhou, Li, Mabon, & Broadbelt, ; Zhou, Nolte, Mayes, Shanks, & Broadbelt,…”

“…Alternatively, model compounds of the three biomass constituents have been used to derive the details of intermediate species generated during their thermal decomposition. Pyrolysis of model compounds also provides insights on the influence of the substituent functional groups or bond linkages on the product distribution (Asatryan et al, ; Asmadi, Kawamoto, & Saka, ; Buckingham et al, ; Choi et al, ; Custodis et al, ; Jarvis et al, ; Kawamoto & Saka, ; Khachatryan et al, ; Lou et al, ; Nowakowska et al, ; Patwardhan et al, ; Robichaud, Nimlos, & Ellison, ; Scheer et al, ; Scheer et al, ; Scheer, Mukarakate, Robichaud, Ellison, & Nimlos, ; Vasiliou et al, ; Wang, McDonald, et al, ; Xu et al, ; Zhou, Nolte, et al, ).…”

Unravelling Some of the Key Transformations in the Hydrothermal Liquefaction of Lignin

“…[3] Lignin constitutes 25-35 %o ft he organic matrix of lignocellulosic biomass, adding strength and rigidity to cell walls. [10] The hydrothermal conversion of benzylp henyle ther,asimple model compound reminiscent of a-O-4 linkages, has been studied by Siskin et al [11] and Lercher and co-workers. Of these,t he b-O-4 linkage predominates, accounting foro ver5 0% of the cross-links.…”

“…[8] The chemistry of lignin under hydrothermalc onditions is comparatively less well understood [2,9] than that under pyrolysis conditions when linkages such as b-O-4 and a-O-4 are broken down through free radicalc hemistrya nd react further in pericyclic reactions. [10] The hydrothermal conversion of benzylp henyle ther,asimple model compound reminiscent of a-O-4 linkages, has been studied by Siskin et al [11] and Lercher and co-workers. [12] They demonstrated that the ether hydrolyzed to benzyl alcohol and phenol.…”