Earth abundant metal catalysts stabilized by porous N-doped carbon

近年来，在均相催化剂中已经成功地证明了用富含稀土的金属替代稀有贵金属。可重复使用的和纳米结构的氢化和脱氢催化剂，基于丰富的可获得的金属，具有广泛的有机合成范围已经开发到小得多的程度。主要的批评来自于这样的观察，即与贵金属相比，地球上丰富的金属在纳米结构催化剂中的活性要低得多。基于聚合物的SiCN和SiC材料结合了联合收割机材料的特定特性，例如热鲁棒性和耐腐蚀性，易于加工，并且可以在不同的有机溶剂中在低温下成型或结构化。在四篇已发表的论文中，在“Angewandte Chemie”，“Nature Communication”（2x）和“Nature Catalysis”中，金属-SiCN纳米复合材料作为可重复使用的催化剂的潜力以及我们在3d金属催化（多相）方面的专业知识已经得到了证明。在这个项目中，我们计划表明，纳米结构的三维金属催化剂可以是上级的活性和选择性相比，贵金属催化剂，并提出1。新型多孔N掺杂SiC载体的开发; 2.用于氢化和脱氢反应的活性和选择性3D金属催化剂的设计。由于载体合成是开发新型高活性催化剂的基础，因此这两个目标密切相关。SiCN和SiC作为金属催化剂的多孔载体具有材料特定的优点和缺点。SiCN给出了显著更小和更反应性的金属纳米颗粒，而高比表面积的产生是一个问题。特别小的和反应性的金属纳米颗粒的稳定化可以通过在载体中存在N原子来解释。它们在合成和催化过程中通过配位稳定金属离子和簇或颗粒，以抑制较大聚集体的生长。SiC更容易合成，因为前体聚合物对水解不敏感，并且可以产生更高的比表面。不幸的是，不存在使非常小且高度反应性的金属纳米团簇或颗粒稳定的N原子。这些优点的组合将是多孔N掺杂SiC。初步工作支持这一假设。关于2.：在这个子项目中，我们感兴趣的是：a）在温和条件下钴催化还原胺化合成伯胺，B）在存在易失活官能团的情况下腈的氢化，和c）迄今很少或从未使用的3d金属的选择性（脱）氢化催化剂的设计。

The replacement of rare noble metals by earth abundant metals has been demonstrated successfully for homogenous catalysts in recent years. Reusable and nano-structured hydrogenation and dehydrogenation catalysts, based on abundantly available metals, with a broad scope in organic synthesis have been developed to a much lesser extent. The main criticism arose from the observation that earth abundant metal are much less active in nanostructured catalyst in comparison to noble metals. Polymer based SiCN and SiC materials combine material specific characteristics such as thermal robustness and corrosion resistance with easy processing and possible shaping or structuring at low temperatures in diverse organic solvents. This easy processing also permits the synthesis of highly active catalysts.In four published manuscripts, in “Angewandte Chemie”, in “Nature Communication” (2x), and in “Nature Catalysis”, the potential of metal-SiCN nanocomposites as reusable catalysts and our expertise in 3d-metal catalysis (heterogeneous) have been demonstrated. In this project, we plan to show that nanostructured 3d-metal catalysts could be superior in activity and selectivity compared to noble metal catalysts and propose 1. the development of novel porous N-doped SiC supports and 2. the design of active and selective 3d-metal catalysts for hydrogenation and dehydrogenation reactions. Both aims are strongly linked since the support synthesis is the basis for developing novel highly active catalysts.Regarding 1.: SiCN and SiC have material specific advantages and disadvantages as porous supports for metal catalysts. SiCN gave significantly smaller and more reactive metal nanoparticles while the generation of high specific surfaces is a problem. The stabilization of especially small and reactive metal nanoparticles can be explained by the presence of N-atoms in the supports. They stabilize metal ions and clusters or particles via coordination during synthesis and catalysis to suppress growth of larger aggregates. SiC is easier to synthesize since the precursor polymers are not hydrolysis sensitive and higher specific surfaces can be generated. Unfortunately, the N-atoms which stabilize very small and highly reactive metal nanoclusters or particles are not present. A combination of the advantages would be porous N-doped SiC. Preliminary works support this hypothesis. Regarding 2.: In this subproject, we are interested in: a) the cobalt catalyzed reductive amination for the synthesis of primary amines under mild conditions, b) the hydrogenation of nitriles in the presence of functional groups easily to hydrogenate, and c) the design of selective (de)hydrogenation catalysts of so far rarely or never used 3d metals.