Abstract This study aims to report on the feasibility of enhancing light olefins production from ex-situ catalytic fast pyrolysis (CFP) of biomass by co-feeding with steam and determine the role of steam. Effects of steam on catalyst and pyrolysis/catalysis reactions in ex-situ CFP were investigated using a two-stage fluidized-bed/fixed-bed reactor. Carbon yield of olefins + monocyclic aromatic hydrocarbons (MAHs) increased by 23.80% after proper steam dealumination of HZSM-5 framework, which suggests that HZSM-5 can be activated at the initial exposure to steam. For activated HZSM-5, olefins carbon yield increased by 35.65% and olefins to MAHs (O/M) ratio boosted from 0.83 to 1.60 as steam concentration in carrier gas increased from 0% to 40%, while the total carbon yield of olefins and MAHs still kept at the same level. Steam enhanced olefins production by: (1) promoting the formation of light compounds in bio-oil, which are the main precursors of hydrocarbons, during pyrolysis; (2) inhibiting aromatization reactions during catalysis. It provides a possibility for the control of O/M ratio of hydrocarbon products and the enhancement of light olefins production from CFP of biomass.

中文翻译：

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蒸汽对促进生物质异位催化快速热解轻烯烃生产的影响

摘要 本研究旨在报告通过与蒸汽共同进料来提高生物质异位催化快速热解 (CFP) 生产轻质烯烃的可行性，并确定蒸汽的作用。使用两级流化床/固定床反应器研究了蒸汽对非原位 CFP 中催化剂和热解/催化反应的影响。对HZSM-5骨架进行适当的蒸汽脱铝后，烯烃+单环芳烃（MAHs）的碳产率提高了23.80%，这表明HZSM-5在最初接触蒸汽时可以被活化。对于活化的 HZSM-5，随着载气中蒸汽浓度从 0% 增加到 40%，烯烃碳产率增加了 35.65%，烯烃与 MAHs (O/M) 比从 0.83 提高到 1.60，而烯烃和MAH 仍保持在同一水平。蒸汽增强烯烃的生产通过： (1) 在热解过程中促进生物油中轻质化合物的形成，这是烃的主要前体；(2)抑制催化过程中的芳构化反应。它为控制烃类产品的 O/M 比和提高生物质 CFP 生产轻质烯烃提供了可能。