聚氯乙烯是世界上产量最大的通用塑料,在日常生活的诸多领域具有广泛应用.按照原料来源划分,聚氯乙烯的工业生产方法主要有基于煤炭的电石法和基于石油的“平衡法”.我国有丰富的煤炭资源,因此,电石乙炔法是合成聚氯乙烯的主要途径.该方法采用乙炔与氯化氢在活性炭担载氯化汞催化剂上进行氢氯化反应得到聚氯乙烯的单体氯乙烯.然而,由于汞催化剂的挥发性以及毒性,开发汞替代催化剂迫在眉睫.乙炔与二氯乙烷耦合反应是将煤炭与石油资源共同利用来制备聚氯乙烯的一条极具吸引力的途径.相对于研究相对成熟的氢氯化反应,目前耦合反应的研究较少,所开发的催化剂活性与氢氯化体系相比仍有数量级的差距,反应机制仍存在较大争议.争议的焦点在于:二氯乙烷是通过先裂解产生氯化氢,后者再与乙炔发生氢氯化反应,还是二氯乙烷活化后直接与乙炔进行耦合反应.本文报道了一种通过结合预氧化-热裂解的新方法用于制备高活性、高稳定性氮化碳基催化剂,并且将其应用到二氯乙烷裂解反应中,获得较好的活性.表征结果表明,通过改变预氧化温度能够调控不同氮物种缺陷的分布,并发现较高的吡啶氮含量更有利于提高催化剂催化催化裂解反应的活性.进一步添加金属组分(金、铂和钌)修饰上述氮化碳催化剂构建了一系列M/C3N4/AC (M=Au,Pt,Ru)双金属催化剂.结合多种表征技术、稳态反应性能测试以及动力学研究发现,金属组分主要以氯化物的形式单原子分散在载体上,且金属的存在造成两种反应物分子在金属位点上的竞争吸附,因此催化剂在强化氢氯化反应的同时,也减弱了脱氯化氢反应性能,其催化耦合反应总体性能呈现如下趋势:Au/C3N4/AC＞Pt/C3N4/AC＞Ru/C3N4/AC.基于上述结论,通过装填C3N4/AC和单原子催化剂Au/C3N4/AC的串联反应器,实现了耦合反应的过程强化.综上可见,二氯乙烷脱氯化氢反应是乙炔与二氯乙烷耦合反应的必要步骤,未来催化剂的设计需要考虑到乙炔与二氯乙烷的活化需要不同的活性位点.“,”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 dehydrochlorina-tion 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 hy-drochlorination activity but weakens the dehydrochlorination ability due to competitive adsorption between the two reactants at the metal sites.Superior coupling performance was achieved over C3N4/AC and single-atom Au/C3N4/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.