Hydrogenation/Hydrodeoxygenation Selectivity Modulation by Cometal Addition to Palladium on Carbon-Coated Supports
Hydrogenation/Hydrodeoxygenation Selectivity Modulation by Cometal Addition to Palladium on Carbon-Coated Supports
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DOI：
10.1021/acssuschemeng.2c02399
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发表时间：
2022-06
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影响因子：
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通讯作者：
Alireza Saraeian;Geet Gupta;R. Johnson;Rick W. Dorn;Alex M. Kauffmann;H. Bateni;J. Tessonnier;Luke T. Roling;Aaron J. Rossini;B. Shanks
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文献类型：
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作者：
Alireza Saraeian;Geet Gupta;R. Johnson;Rick W. Dorn;Alex M. Kauffmann;H. Bateni;J. Tessonnier;Luke T. Roling;Aaron J. Rossini;B. Shanks
合成了一系列碳载钯催化剂，研究了钯-金属二元催化剂对凝相加氢反应选择性的影响。使用实验室规模的活塞流反应器的苯乙酮和1-苯基乙醇的转化被用于评估不同的加氢系统如何改变芳环或羰基的氢化与加氢脱氧之间的反应选择性。在这项研究中，包括碱金属和碱土金属和过渡金属的各种彗星进行了筛选。这些结果表明，与Pd单金属催化剂相比，Pd-金属双金属催化剂导致选择性的显著变化。最值得注意的是，在加入铁的情况下，仅产生作为最终产物的氢化物，而加入锂产生超过80%的苯基氢化产物，几乎没有脱氧。为了研究如何cometal除了改变Pd活性位点的电子状态，采用各种表征技术来比较酸度，氧化态，氧亲和力和电子性质的差异。实验结果和DFT计算表明，锂的掺入到Pd晶格中导致通过更高的形成能相比，表面Pd-H和抑制脱氧的间隙Pd氢化物（Pd-H）的形成的阻塞，而铁的加入导致形成的相具有更高的亲和力对氧，从而增加脱氧的选择性。这项工作的发现提供了一个模型系统，以研究催化剂对碳载体上反应选择性的影响，而不会引入复杂的因素，如孔径和杂原子，这些因素难以用商业过程中使用的传统碳来控制，并提供可应用于其他过程的见解，如生物衍生化学品的选择性氢化。
A series of carbon-supported palladium catalysts were synthesized to study the influence of binary Pd–metal catalysts on the selectivity of condensed-phase hydrogenation reactions. Conversion of acetophenone and 1-phenylethanol using a lab-scale plug flow reactor was used to assess how the different bimetallic systems altered reaction selectivity between hydrogenation of either the aromatic ring or the carbonyl group versus hydrodeoxygenation. A variety of cometals including alkali and alkaline earth metals and transition metals were screened in this study. These results showed that the Pd–metal bimetallic catalysts led to dramatic shifts in selectivity compared to the Pd monometallic catalysts. Most notably, with the addition of iron, ethylbenzene was exclusively produced as the final product, while the addition of lithium yielded more than 80% phenyl hydrogenation products with little deoxygenation. To investigate how cometal addition alters the electronic states of Pd active sites, various characterization techniques were employed to compare differences in acidity, oxidation states, oxygen affinity, and electronic properties. The experimental results and DFT calculations suggest that the incorporation of lithium into the Pd lattice leads to the blockage of interstitial Pd hydride (Pd-H) formation through a higher formation energy compared to surface Pd-H and inhibits deoxygenation, whereas the addition of iron leads to the formation of a phase with higher affinity toward oxygen, thereby increasing the selectivity to deoxygenation. The findings of this work provide a model system to study the influence of bimetallic catalysts on reaction selectivity on carbon supports without introducing complicating factors such as pore size and heteroatoms that are difficult to control with traditional carbons used in commercial processes, and serve to provide insights that could be applied to additional processes such as selective hydrogenation of bioderived chemicals.