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首页> 外文期刊>Catalysis science & technology >Zirconia catalysed acetic acid ketonisation for pre-treatment of biomass fast pyrolysis vapours
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Zirconia catalysed acetic acid ketonisation for pre-treatment of biomass fast pyrolysis vapours

机译：氧化锆催化乙酸-酮化预处理生物质快速热解的蒸气

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摘要

Crude pyrolysis bio-oil contains significant quantities of carboxylic acids which limit its utility as a biofuel. Vapour phase ketonisation of organic acids contained within biomass fast-pyrolysis vapours offers a potential pre-treatment to improve the stability and energy content of resulting bio-oils formed upon condensation. Zirconia is a promising catalyst for such reactions, however little is known regarding the impact of thermal processing on the physicochemical properties of zirconia in the context of it's corresponding reactivity for the vapour phase ketonisation of acetic acid. Here we show that calcination progressively transforms amorphous Zr(OH)(4) into small tetragonal ZrO2 crystallites at 400 degrees C, and subsequently larger monoclinic crystallites 600 degrees C. These phase transitions are accompanied by an increase in the density of Lewis acid sites, and concomitant decrease in their acid strength, attributed to surface dehydroxylation and anion vacancy formation. Weak Lewis acid sites (and/or resulting acid-base pairs) are identified as the active species responsible for acetic acid ketonisation to acetone at 350 degrees C and 400 degrees C, with stronger Lewis acid sites favouring competing unselective reactions and carbon laydown. Acetone selectivity is independent of acid strength.
机译：原油热解生物油包含意义重大限制其大量的羧酸作为生物燃料的功能。生物质中所含的有机酸fast-pyrolysis蒸汽提供了可能预处理,提高稳定性和能量内容生成的生物形成的凝结。这样的反应,然而所知甚少关于热处理的的影响氧化锆的物理化学性质它的相应的反应汽相酮化醋酸。表明,煅烧逐步转换非晶态锆(OH)(4)成小正方锆微晶在400摄氏度,随后大单斜微晶在600摄氏度。这些相变伴随着一个路易斯酸的密度增加网站,伴随他们的酸强度的降低,归因于表面脱羟基和阴离子空位的形成。产生的酸碱双)被确定为活跃的物种负责醋酸酮化丙酮在350摄氏度和400年度,更强的路易斯酸的网站有利于unselective反应和竞争碳沉积作用。独立的酸强度。

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