Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours
Ga/HZSM-5 Catalysed Acetic Acid Ketonisation for Upgrading of Biomass Pyrolysis Vapours
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DOI：
10.3390/catal9100841
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发表时间：
2019-10
期刊：
影响因子：
3.9
通讯作者：
Hessam Jahangiri;Amin Osatiashtiani;M. Ouadi;A. Hornung;A. Lee;K. Wilson
中科院分区：
文献类型：
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作者：
Hessam Jahangiri;Amin Osatiashtiani;M. Ouadi;A. Hornung;A. Lee;K. Wilson
热解生物油含有大量的羧酸，这限制了它们作为生物燃料的效用。生物质热解蒸气中羧酸的酮化是提升所得生物油冷凝物的能量含量和稳定性的潜在途径，但需要活性、选择性和抗结焦的固体酸催化剂。在这里，我们探讨了气相酮化乙酸在Ga掺杂的HZSM-5。弱刘易斯酸位点被鉴定为负责在350 °C和400 °C下乙酸酮化成丙酮的活性物质。转换频率与Ga负载成比例，对于10 Ga/HZSM-5，在400 °C下达到约6 min−1。对所需丙酮产物的选择性与弱：强酸位点比相关，比弱刘易斯酸位点更有利，并且对于10 Ga/HZSM-5达到30%。强布朗斯特酸性促进竞争性非选择性反应和碳沉积。10 Ga/HZSM-5催化剂在乙酸酮化反应中表现出良好的稳定性，反应时间可达5 h以上。
Pyrolysis bio-oils contain significant amounts of carboxylic acids which limit their utility as biofuels. Ketonisation of carboxylic acids within biomass pyrolysis vapours is a potential route to upgrade the energy content and stability of the resulting bio-oil condensate, but requires active, selective and coke-resistant solid acid catalysts. Here we explore the vapour phase ketonisation of acetic acid over Ga-doped HZSM-5. Weak Lewis acid sites were identified as the active species responsible for acetic acid ketonisation to acetone at 350 °C and 400 °C. Turnover frequencies were proportional to Ga loading, reaching ~6 min−1 at 400 °C for 10Ga/HZSM-5. Selectivity to the desired acetone product correlated with the weak:strong acid site ratio, being favoured over weak Lewis acid sites and reaching 30% for 10Ga/HZSM-5. Strong Brønsted acidity promoted competing unselective reactions and carbon laydown. 10Ga/HZSM-5 exhibited good stability for over 5 h on-stream acetic acid ketonisation.