Lignin is one of the three main structural components of lignocellulosic biomass and is considered as the most abundant source of aromatic and phenolic compounds. Lignin is produced as side-stream in the pulp/paper industry or as residue in the production of second-generation bioethanol. More recently, novel biomass fractionation processes in biorefineries have been developed aiming at the production of high quality/purity lignin towards its more efficient down-stream catalytic conversion to chemicals, monomers, and fuels. Within this context, in this work, we studied the thermal (non-catalytic) and catalytic fast pyrolysis on a Py/GC–MS system and a fixed-bed reactor unit of three types of lignin, all originating from the same biomass (beech wood sawdust) but with different isolation processes: organosolv lignin derived by the organosolv pretreatment/fractionation of biomass, surface extracted lignin derived by the mild Soxhlet extraction (with ethanol or acetone) from the hydrothermally (HT) in pure water pretreated biomass, and the enzymatic hydrolysis lignin derived as a lignin-rich solid residue from the enzymatic hydrolysis of the HT pretreated biomass. Conventional microporous ZSM-5 and mesoporous ZSM-5 zeolites (with intracrystal mesopores, ˜ 9 nm) were used as catalysts in the pyrolysis experiments. Both zeolites were very active in converting the initially produced via thermal pyrolysis methoxy-substituted phenols, benzenes and benzaldehydes mainly towards BTX mono-aromatics, such as 1,3-dimethylbenzene/p- and o-xylenes, toluene and trimethylbenzenes, as well as polycyclic aromatic hydrocarbons (PAHs, mainly naphthalenes). The mesoporous ZSM-5 induced higher dealkoxylation reactivity compared to the microporous ZSM-5 leading to higher concentration of BTX aromatics without a consequent increase of PAHs. The pronounced dealkoxylation/aromatization reactivity of both ZSM-5 zeolites resulted to lower yields (but highly aromatic) organic bio-oils (e.g. from 32−35 wt.% to 15−22 wt.%) compared to thermal pyrolysis, increased non-condensable gases (mainly CO, CO₂, methane, ethylene and propylene) and formation of relatively low amounts of coke on catalysts (e.g. 3−5 wt.% on lignin) in addition to thermal pyrolysis char. The observed moderate variations in the characteristics of the three types of beech wood lignin, i.e. molecular weight (GPC), S/G ratio, inter-unit linkages (2D HSQC NMR) and elemental composition, did not induce a systematic/substantial differentiation in the thermal and catalytic fast pyrolysis product yields and composition.

木质素是木质纤维素生物质的三种主要结构成分之一，被认为是芳香族和酚类化合物最丰富的来源。木质素在纸浆/造纸工业中作为侧流生产，或作为第二代生物乙醇生产中的残留物生产。最近，生物精炼厂开发了新型生物质分馏工艺，旨在生产高质量/纯度的木质素，以实现更有效的下游催化转化为化学品、单体和燃料。在此背景下，在这项工作中，我们研究了 Py/GC-MS 系统和三种木质素固定床反应器装置上的热（非催化）和催化快速热解，所有木质素均来自相同的生物质（山毛榉木屑）但具有不同的分离过程：有机溶剂木质素通过有机溶剂预处理/分馏生物质，表面提取木质素，通过温和的索氏提取（用乙醇或丙酮）从纯水预处理生物质中的水热（HT）中提取，以及酶解木质素来自 HT 预处理生物质的酶促水解的富含木质素的固体残留物。传统的微孔 ZSM-5 和介孔 ZSM-5 沸石（具有晶内介孔，约 9 nm）用作热解实验中的催化剂。这两种沸石在将最初通过热解产生的甲氧基取代苯酚、苯和苯甲醛主要转化为 BTX 单芳烃方面非常活跃，例如 1,3-二甲苯/对和邻二甲苯、甲苯和三甲苯，以及多环芳烃（多环芳烃，主要是萘）。与微孔 ZSM-5 相比，介孔 ZSM-5 诱导更高的脱烷氧基化反应性，导致更高浓度的 BTX 芳烃，而不会随之增加 PAH。₂，甲烷、乙烯和丙烯）以及在催化剂上形成相对少量的焦炭（例如，木质素的 3-5 重量%）以及热裂解炭。观察到的三种类型的山毛榉木质素的特征的适度变化，即分子量 (GPC)、S/G 比、单元间连接 (2D HSQC NMR) 和元素组成，并未引起系统/实质性差异热和催化快速热解产物的产率和组成。