College of Chemistry and Materials Engineering, Zhejiang A & F University
College of Materials Science and Engineering, Nanjing Forestry University

生物质灰分中的碱和碱土金属（AAEMs）对快速热解生物油的产率和组分分布具有显著影响。本研究选取玉米秸秆为原料，研究梯级脱灰预处理（蒸馏水、醋酸铵和盐酸）对AAEMs的选择性脱除及其生物油组分的影响，研究了碱和碱土金属类别（K、Ca、Na和Mg）、盐质量分数（0.5%、2.5%、5%）和不同钾盐的酸根（${rm{SO}}_{4}^{{2-}} $、${rm{NO}}_{3}^{-} $、${rm{CO}}_{3}^{{2-}} $、${rm{HCO}}_{3}^{-} $、AC−和${rm{PO}}_{4}^{{{3-}}}$）对生物油组分的影响。结果表明，在梯级脱灰预处理过程中，随着脱灰溶液酸性程度加深，AAEMs的脱除率逐渐上升，根据AAEMs在梯级脱灰过程中的选择性脱除规律，可将其在生物质中的赋存形态分为水溶性（K）、离子交换性（Ca和Mg）和酸溶性（Na）等形态。经过碱和碱土金属盐浸渍后，AAEMs将起到催化剂的作用，促进热解中间产物左旋葡聚糖的二次降解，导致其相对含量显著降低，形成更多的呋喃和酮类等轻质含氧化合物，导致2, 3-二氢苯并呋喃、酮类和长链烷烃等组分的含量显著增加。不同钾盐酸根离子对脱水糖的二次裂解反应及木质素芳基醚键和酚羟基的裂解反应具有较大的影响，根据酸根的酸性强弱，对脱水糖裂解反应的影响大小顺序为${rm{HCO}}_{3}^{-} $>${rm{CO}}_{3}^{{{2-}}}$>AC−>${rm{PO}}_{4}^{{{3-}}}$>Cl−>${rm{NO}}_{3}^{-} $>${rm{SO}}_{4}^{{{2-}}}$，而对木质素芳基醚键和酚羟基的裂解反应影响大小顺序为${rm{CO}}_{3}^{{{2-}}}$>Cl−>${rm{HCO}}_{3}^{-} $>${rm{PO}}_{4}^{{{3-}}}$≈AC−>${rm{SO}}_{4}^{{{2-}}}$≈${rm{NO}}_{3}^{-} $。

The alkali and alkaline earth metals (AAEMs) in biomass ash have a significant impact on the yield and component distribution of rapid plytic biooil. In this paper, corn straw is selected as the raw material. First, the effect of cascade deash removal pretreatment (distillation water, ammonium acetate and hydrochloric acid) on the selective removal of AAEMs and its biological oil components is studied, and then the effect of the type of AAEMs (K, Ca, Na and Mg), the concentration of chloride salt (0.5%, 2.5% and 5%), and the acid radical in metal salt（${rm{SO}}_4^{2-} $, ${rm{NO}}_3^- $, ${rm{CO}}_3^{2-} $, ${rm{HCO}}_3^- $, AC− and ${rm{PO}}_4^{3-} $）on the compound distribution of bio-oil was systematically investigated. The results show that in the process of ash removal pretreatment, with the deepening of the acidity of the ash removal solution, the removal rate of AAEMs gradually increases. According to the selective removal law of AAEMs in the process of cascade ash removal, their morphology in biomass can be divided into the following three groups, namely the water-soluble metal (K), the ion-exchanged metals (Ca and Mg), the acid-soluble metal (Na). The removal of AAEMs promoted the formation of levoglucosan (LG), while restrained the formation of ketones and furans. However, the incorporation of AAEMs in biomass presented an opposite variation trend. The AAEMs would act as catalyst during biomass pyrolysis which promoted the secondary cracking of LG, leading to the reduction of LG and increase of ketones and furans. In addition, different acid roots in potassium salt also have remarkable influence on the secondary cracking reaction of LG and the rupture of the aryl ether bond and the phenolic hydroxyl group in lignin. The influence of the acid roots on the secondary cracking reaction of LG was in the order of ${rm{HCO}}_3^- $>${rm{CO}}_3^{2-} $>AC−>${rm{PO}}_4^{3-} $>Cl−>${rm{NO}}_3^- $>${rm{SO}}_4^{2-} $, while the influence of acid roots on the rupture of the aryl ether bond and the phenolic hydroxyl group was in the order of ${rm{CO}}_3^{2-} $>Cl−>${rm{HCO}}_3^- $>${rm{PO}}_4^{3-} $≈AC−>${rm{SO}}_4^{2-} $≈${rm{NO}}_3^- $.

国家自然科学基金（52376214, 52076112），浙江省自然科学基金（LY21E060001）和浙江省 “领雁”研发攻关计划（2022C03092）资助

丁紫霞, 蔡博, 岑珂慧, 陈登宇, 马中青. 灰分中碱和碱土金属对生物质快速热解生物油组分的影响[J]. 燃料化学学报（中英文）, 2024, 52(7): 967-975.

DING Zixia, CAI Bo, CEN Kehui, CHEN Dengyu, MA Zhongqing. The effect of alkali and alkaline earth metals in biomass ash on the bio-oil components derived from biomass fast pyrolysis[J]. Journal of Fuel Chemistry and Technology, 2024, 52(7): 967-975.