Acetylene coupling with ethylene dichloride, which uses both coal and oil resources, is attractive for sustainable PVC manufacturing. Herein, highly active and stable carbon nitride-based catalysts were developed by a novel pre-oxidation-pyrolysis process, affording unprecedented dehydrochlorination activity with good durability. The best-performing system was further modified with different precious metals (Au, Pt, and Ru) to promote the hydrochlorination chemistry between the in-situ formed hydrogen chloride and acetylene co-feed. The presence of metal centers intensifies the hydrochlorination activity but weakens the dehydrochlorination ability due to competitive adsorption between the two reactants at the metal sites. Superior coupling performance was achieved over C 3 N 4 /AC and single-atom Au/C 3 N 4 /AC catalysts in cascade reactors. Our results strongly suggest that dehydrochlorination is an essential step in the coupling reaction, and the activation of acetylene and ethylene dichloride molecules requires different active sites that should be engineered in future work.
Nitrogen-doped carbons (NC) and carbon nitride (C 3 N 4 ) belong to the two fundamental pillars of functionalized carbon materials that have broad applications in different fields. The synthesis of NC and C 3 N 4 often starts from different precursors, and a general approach that can offer both architectures is still highly sought. Herein, a facile Triton X-100-assisted copolymerization-carbonization strategy is reported to fulfill this task. By moderating the weight ratios of Triton X-100 and several conventional precursors of C 3 N 4 ( e.g ., dicyandiamide, urea, and cyanamide), a series of both types of N-functionalized carbons with controllable N dopants is successfully afforded. The yielded solids transform from graphitic C 3 N 4 with low surface areas to porous NC when the weight ratio reaches the critical values. This phenomenon might be attributed to the intensified copolymerization between the intermediates of both starting precursors during the carbonization, resulting in increased oxygen content and decreased N:C ratio in the products. Both the bulk and activated carbon-supported materials are then designed and used as metal-free catalysts in the dehydrochlorination of ethylene dichloride, a key reaction in polyvinyl chloride manufacture. It is found that NC is significantly more active than C 3 N 4 , but the corresponding supported catalysts exhibit an opposing trend. The structure-activity correlations suggest both the number of different N defects and the surface areas might play key roles in determining the dehydrochlorination chemistry.
危险品化学品经营许可证（带存储）