Advances in Upgrading Lignin Pyrolysis Vapors by Ex Situ Catalytic Fast Pyrolysis

Abstract

Lignin, a highly branched, substituted, mononuclear aromatic polymer, is one of the principal components of lignocellulosic biomass. Its valorization is considered an important part of the modern biorefinery scheme. However, as a result of the natural complexity and high stability of lignin, its depolymerization and the following conversion are challenging. The unique structure and composition of lignin offer many possible routes to produce liquid fuels and chemicals. Recognized as an efficient and feasible process, ex situ catalytic fast pyrolysis (CFP) has attracted much attention for upgrading lignin and lignin pyrolysis vapors. The main challenge of this process is the development of active and stable catalysts that can effectively break the C−O bond of lignin and decompose the intermediates. In this Review, we aim to provide an overview of recent advances on a related topic. The Review introduces ex situ CFP, the reactions and pathways of lignin vapors in the ex situ CFP process, and summarizes in detail recent progress in experimental studies on upgrading lignin‐derived model phenols, lignin, and lignin pyrolysis vapors to hydrocarbons by the ex situ CFP process over different catalysts.

Co-processing of wood and wheat straw derived pyrolysis oils with FCC feed—Product distribution and effect of deoxygenation

“…While non-basic nitrogen compounds and condensed aromatics contribute to coke formation on the external surface of zeolite crystallites and pore blockage [54], the poisoning ability of bulkier nitrogen bases is even higher [52,55]. Xu et al [56][57][58][59][60] demonstrated that N-heterocycles (pyridines, pyrroles, anilines and indoles) can be produced via reaction of biomass derived oxygenates and ammonia. Even though not measured directly, some ammonia may be produced from the FP of wheat straw containing ∼1 wt% N (d.b.)…”

Alternatives for Chemical and Biochemical Lignin Valorization: Hot Topics from a Bibliometric Analysis of the Research Published During the 2000–2016 Period

“…The high number of papers that cover lignin valorization, which have been identified by this work, introduces the research advances in the whole processing: the improvements in isolation, recovery, and characterization of lignin from biomass, the posterior depolymerization of lignin into monomers by chemical and biological means, and the final upgrading of the depolymerized lignin monomers to industrially relevant chemicals [41]. All these aspects have been deeply described by several reviews [42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57], and, therefore, the purpose of this section is just to summarize the most The most frequently selected keyword was Lignin, with 245 appearances. As Lignin was one of the words employed in the search engine, it is quite logical to find it among the most common keywords.…”

Technical Lignin Valorization in Biodegradable Polyester-Based Plastics (BPPs)

“…Lignin, the second most abundant biomacromolecule next to cellulose, is proven to be synthesized through specific biosynthesis pathways. , As a complicated three-dimensional network polymer, lignin plays a significant role in plant cell walls between cellulose and hemicellulose by lignin–carbohydrate complex (LCC) linkages, , providing mechanical strength and structural support, as shown in Figure a . Lignin exhibits heterogeneous chemical structures depending on the types and amounts of phenylpropane subunits ( p -hydroxyphenyl, guaiacyl, and syringyl) and interunit linkages (ether linkage and C–C bonds), such as β- O -4, β-β, β-5, and β-1 linkages in Figure b, c. − Nevertheless, the native structure of lignin has been confirmed by ceaselessly intensive research using state-of-the-art analytical technology, especially nuclear magnetic resonance (NMR) technology. − …”