To address the pressures associated with an increasing energy demand and rising cost of liquid fuel production, alternative feedstocks are being developed. One such potential replacement is bio-oils, which are derived from biomass, however the oil produced is often chemically unstable, corrosive and has low heating values due to the high oxygen content. Thus, an upgrading process is required to lower the oxygen content, with catalytic hydrodeoxygenation being one such technology currently being developed, with mechanistic studies commonly completed utilising model compounds. The current study examines factors that influence catalyst deactivation during hydrodeoxygenation of common bio-oil model compounds over zeolite-supported nickel catalysts, indicating the contribution of functional groups on the formation of condensed-ring products and catalyst deactivation. It was determined that phenolic-hydroxyl groups present in model compounds can facilitate catalyst deactivation through the formation of condensed-ring compounds, identified through decreased cycloalkane yields, causing blockage of catalyst pores. Conversely, when toluene, cyclohexanol and anisole were used as model compound feeds, there were no notable changes in cycloalkane yields, indicating aromatic, alkyl–OH and aromatic–OCH₃ have negligible effect on catalyst deactivation. The effect of catalyst metal loading was also examined, and while increased metal content enhanced cyclohexane yields, so to was the formation of condensed-ring products, suggested to be the result of an increased concentration of surface cyclohexane carbocations. Modifications to reaction conditions was studied, with catalyst activity and stability found to improve with increasing reaction temperatures up to 230 °C. Based on the product distributions observed, a coupling reaction pathway (leading to the formation of condensed-ring products and cycloalkanes) is proposed as the hydrodeoxygenation mechanism.

为了应对与能源需求增加和液体燃料生产成本上升相关的压力，正在开发替代原料。一种这样的潜在替代物是源自生物质的生物油，但是由于高的氧含量，产生的油通常在化学上不稳定，具有腐蚀性并且具有较低的发热量。因此，需要改进工艺以降低氧含量，催化加氢脱氧是目前正在开发的一种这样的技术，通常利用模型化合物完成机理研究。当前的研究探讨了在沸石负载的镍催化剂上，普通生物油模型化合物加氢脱氧过程中影响催化剂失活的因素，表明官能团对稠环产物的形成和催化剂失活的贡献。已确定存在于模型化合物中的酚羟基可通过形成稠环化合物来促进催化剂失活，所述缩环化合物是通过降低环烷烃收率确定的，从而导致催化剂孔堵塞。相反，当使用甲苯，环己醇和苯甲醚作为模型化合物进料时，环烷烃收率没有明显变化，表明芳族，烷基-OH和芳族-OCH₃对催化剂失活的影响可忽略不计。还检查了催化剂金属负载的影响，虽然增加的金属含量提高了环己烷的收率，但稠环产物的形成也被认为是表面环己烷碳正离子浓度增加的结果。研究了对反应条件的修改，发现催化剂活性和稳定性随着反应温度升高至230°C而提高。根据观察到的产物分布，提出了偶联反应途径（导致形成稠环产物和环烷烃）作为加氢脱氧机理。