The Synthesis And Application Of Novel Porous Carbon Materials In The Heterogeneous Catalysis

Owing to high specific surface area, large pore volume, good electronic conductivity, well controlled pore size and surface properties, thermal conductivity porous carbon materials have great potential applications in many aspects, such as catalyst, catalyst supports, electrode materials, absorbent and gas storage. Generally, synthesis of porous carbon materials was realized through hard template, soft template methods and other methods; however, these ways suffer from high costs, complex synthetic processes which significantly impeded their wide applications in other areas. Therefore, this thesis attempts to prepare porous carbon materials based on molecular design, and reduces the cost. Moreover, this thesis presents systematic research on N-doping, loading noble metal nanoparticles in the porous carbon materials, and focuses on their applications in catalyst supports.In chapter 3, we used glucose as the carbon source and borax (Na2B4O7) both as a catalyst and structure-directing agent with hydrothermal method to synthesize a kind of hierarchically porous carbons. Then, the materials was used as supports for gold and palladium nanoparticles to catalyze the oxidation of hydrocarbons with O2. The Au-Pd bimetallic catalysts exhibited a marked superiority over their pure metal counterparts in terms of indane conversion, with 76% conversion of indane and 100% selectivity to indanone, suggesting a strong molecular-scale synergy of Au-Pd. Radical intermediates were demonstrated to likely be involved in these transformations. Moreover, the Au-Pd catalyst was highly stable, it could hinder metal agglomeration and leaching and reduce the size of the nanoparticles, maintaining the high activity and selectivity during a number of recycles under the investigated conditions. The combination of high activity and selectivity as well as good stability enables Au-Pd @ MC a potential material for practical applications in liquid-phase aerobic oxidation of hydrocarbons to corresponding alcohol and ketone.In chapter 4, we use the carbon materials in the chapter 3 and dicyandiamide (DCDA) as the nitrogen source, to synthesize a kind of novel nitrogen-doped hierarchically porous carbons (DMC). DCDA has many advantages, such as high nitrogen content, plentiful source and low cost, which can be used as a novel kind of nitrogen. During the pyrolyzation and carbonization, nitrogen-containing functional groups (C-N, N-H and C=N, etc.) were introduced to the edges and onto the basal plane of the porous carbon material, which made the novel N-doped carbon materials exhibit a high solubility without further chemical modifications, and led not only to an electronic activation of the metal nanoparticles but also to an enhancement of the substrates and additional electronic activation of the substrates. Then, the materials was supported on Ir nanoparticles to catalyze the condensation of bio-alcohols. Based on these catalytic results above, Ir-DMC could be considered as a kind of efficient heterogeneous catalysts for the self-condensation of bio-alcohols, with 59.4% conversation of butanol and 94% selectivity to ethylhexanol in aqueous phase. What’s more, the immobilized catalysts are evidenced to be stable and reusable.In chapter 5, we used the materials which had been describered in chapter 3 as the support to synthesize the Pd-DMC, and it also showed much higher activity in the hydrogenation of cyclohexene than the Pd-MC. And at room temperature, both the conversion of cyclohexene and selectivity to cyclohexane could be 100% in a short time. We believe that the nitrogen in the carbon materials can hinder the metal nanoparticles aggregation and leaching from the surface, therefore, it could improve the activity of the reaction.A series of N-doped porous carbons materials were productively synthesized with different additions of dicyandiamide and different carbonization temperatures. The obtained N-doped carbons possess impressive pore volume (0.56 cm3 g-1), high N content (up to 9 wt%) and high surface area (510～20 m2 g-1). The unique feature of large surface area and high N contents is very important in the support of catalysts. This work provides great capacity for the application of the catalyst supports in fine-chemical production with high activity.