Constructing Pyridinic N-Rich Aromatic Ladder Structure Catalysts from Industrially Available Polyacrylonitrile Resin for Acetylene Hydrochlorination

摘要

N-doped carbon material is a promising alternative to mercury catalyst for acetylene hydrochlorination. Herein, we present an innovative strategy to synthesize pyridinic N-rich aromatic ladder structure material through controlling the self-assembly of polyacrylonitrile polymer chains. The prepared material gave similar to 93% conversion of acetylene with >99% selectivity for vinyl chloride and exhibited a satisfying stability during 200 h lifetime test. Characterizations and density functional theory calculations demonstrated that the activity of the catalyst likely originates from three types of active pyridinic N sites in the ladder structure. Particularly, the pyridinic N sites with one H atom nearby are more active because the H atom can stabilize the transition state through H center dot center dot center dot Cl bond, thereby reducing the energy barrier. The energy barriers on these pyridinic N sites were calculated to be 29.8 and 47.4 kcal mol(-1), much lower than 83.2 and 84.4 kcal mol(-1) on those sites without H atom nearby. The facile and highly effective strategy for the synthesis of a specific N species with defined formation mechanism is expected to be helpful in the design of other green catalysts for acetylene hydrochlorination.