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Conversion of guaiacol over different Re active phases supported on CeO2-Al2O3
Applied Catalysis A: General ( IF 5.5 ) Pub Date : 2017-09-08 , DOI: 10.1016/j.apcata.2017.09.010
C. Alvarez , K. Cruces , R. Garcia , C. Sepulveda , J.L.G. Fierro , I.T. Ghampson , N. Escalona

The effect of Al2O3 modification by CeO2 addition (14 wt.% to obtain a maximum monolayer coverage) on the catalytic activity of three supported Re active phases (Re, ReOx and ReSx) for guaiacol conversion was studied. A 10 wt.% loading of Re was impregnated into CeO2-Al2O3 support and used to prepare the three rhenium active phases by calcination, reduction or sulfidation steps. The catalysts were characterized by different techniques in order to explain the catalytic behavior of the solids studied. The catalysts were then evaluated in a batch reactor at 300 °C and 5 MPa of H2. The characterization results showed that the addition of CeO2 modified the acidity of the support as well as the metal-support interaction, and consequently the catalytic activity. In fact, CeO2 addition doubled the activity of Re and ReSx catalysts in comparison to the corresponding γ-Al2O3-supported catalysts. These results were attributed to a higher dispersion of active sites in the case of metallic Re catalyst and higher concentration of non-stoichiometric sulfur species (ReS2-x) in the case of ReSx catalyst. On the other hand, a similar catalytic activity was observed over the two supported ReOx catalysts, indicating that the role of ReOx active phase on guaiacol conversion outweighs structural and surface modification induced by CeO2 addition. In relation to products distribution, it was observed that CeO2 addition enhanced phenol formation and generally led to higher degree of deoxygenation which is most likely related to decrease in acidity.



中文翻译:

CeO 2 -Al 2 O 3负载的愈创木酚在不同Re反应相上的转化

研究了通过添加CeO 2(14 wt。%获得最大单层覆盖率)改性Al 2 O 3对三个负载的Re活性相(Re,ReO x和ReS x)进行愈创木酚转化的催化活性的影响。将10重量%的Re含量浸渍到CeO 2 -Al 2 O 3载体中,并用于通过煅烧,还原或硫化步骤制备三个rh活性相。为了解释所研究的固体的催化行为,用不同的技术对催化剂进行了表征。然后在间歇反应器中在300°C和5 MPa的H 2下评估催化剂。表征结果表明,CeO 2的添加改变了载体的酸度以及金属-载体的相互作用,并因此改变了催化活性。实际上,的CeO 2除了一倍Re和RES的活性X相比于对应的γ-Al催化剂2 ö 3 -支持的催化剂。这些结果归因于在金属Re催化剂的情况下活性中心的分散性较高,在ReS x催化剂的情况下非化学计量硫物种(ReS 2-x)的浓度较高。另一方面,在两种负载的ReO x上观察到相似的催化活性催化剂,表明ReO x活性相对愈创木酚转化的作用超过了CeO 2添加引起的结构和表面改性。关于产物分布,观察到CeO 2的添加增强了酚的形成并且通​​常导致较高的脱氧度,这最有可能与酸度的降低有关。

更新日期:2017-09-08
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