Chetty Thashini, Dasireddy Venkata D B C, Callanan Linda H, Friedrich Holger B
Catalysis Research Group, School of Chemistry and Physics, University of KwaZulu-Natal, Westville Campus, Private Bag X54001, Durban 4000, South Africa.
Department of Process Engineering, Stellenbosch University, Stellenbosch 7602, South Africa.
ACS Omega. 2018 Jul 17;3(7):7911-7924. doi: 10.1021/acsomega.7b01993. eCollection 2018 Jul 31.
γ-Alumina-supported catalysts with varying copper loadings (5-25 wt %) were prepared by incipient wet impregnation and characterized by various characterization techniques. These catalysts were tested for the selective hydrogenation of octanal in a mixture containing 10 wt % octanal and 2 wt % octene diluted in octanol. The reactions were carried out in a continuous flow fixed-bed reactor in a down flow mode with varying pressures, liquid hourly space velocities, and hydrogen (H)-to-aldehyde molar ratios. The catalyst activities were assessed over a temperature range between 100 and 180 °C using hydrogen gas as the hydrogen source. The results obtained showed that under these experimental conditions, copper preferentially hydrogenates the aldehyde and the copper content exhibited no significant influence on the catalyst activity or product selectivity. Kinetic modeling revealed that both octanal and octene hydrogenation were first-order reactions, although octene conversion was very low until octanal conversion had reached a significant level. The activation energy for octanal hydrogenation is higher than the octene hydrogenation. A maximum octanal conversion of >99% was obtained at 160 °C, and the best selectivity toward octanol of 99% was achieved at 100 °C (53% conversion). The pressure played a small role with regards to octanal conversion and selectivity toward octanol, whereas it exhibited a significant influence on the octene conversion. Increasing the hydrogen-to-aldehyde ratio was found to have a direct influence on both octanal and octene conversion.
通过初湿浸渍法制备了具有不同铜负载量（5-25重量%）的γ-氧化铝负载型催化剂，并采用多种表征技术对其进行了表征。在含有10重量%辛醛和2重量%辛烯且稀释于辛醇中的混合物中，对这些催化剂进行了辛醛选择性加氢测试。反应在连续流动固定床反应器中以向下流动模式进行，改变压力、液时空速和氢气（H）与醛的摩尔比。使用氢气作为氢源，在100至180°C的温度范围内评估催化剂活性。所得结果表明，在这些实验条件下，铜优先将醛加氢，且铜含量对催化剂活性或产物选择性没有显著影响。动力学建模表明，辛醛和辛烯加氢均为一级反应，尽管在辛醛转化率达到显著水平之前，辛烯转化率非常低。辛醛加氢的活化能高于辛烯加氢。在160°C时获得了>99%的最大辛醛转化率，在100°C（转化率53%）时实现了对辛醇的最佳选择性99%。压力对辛醛转化率和对辛醇的选择性影响较小，而对辛烯转化率有显著影响。发现增加氢气与醛的比例对辛醛和辛烯转化率都有直接影响。
