Bimetallic Cr-In/H-SSZ-13 zeolites were prepared by wet impregnation and investigated for selective catalytic reduction of nitric oxide by methane(CH4-SCR).Reduction-oxidation treatments led to close contact and interaction between Cr and In species in these zeolites,as revealed by transmission electron microscopy and X-ray photoelectron spectroscopy.Compared to monometallic Cr/H-SSZ-13 and In/H-SSZ-13,the bimetallic catalyst system exhibited dramatically enhanced CH4-SCR performance,i.e.,NO conversion greater than 90%and N2 selectivity greater than 99%at 550°C in the presence of 6%H2O under a high gas hourly space velocity of 75 000/h.The bimetallic Cr-In/H-SSZ-13 showed very good stability in CH4-SCR with no significant activity loss for over 160 h.Catalytic data revealed that CH4 and NO were activated on the In and Cr sites of Cr-In/H-SSZ-13,respectively,both in the presence of O2 during CH4-SCR.
Jun YangYupeng ChangWeili DaiGuangjun WuNaijia GuanLandong Li
1,3‐Dienes are a class of easily accessible and versatile feedstock chemicals that can participate in a wide range of reactions to facilitate the synthesis of various valuable allylic compounds.In the past decades,radical methodology has emerged as a powerful tool for organic synthesis by virtue of the fact that diverse highly reactive radical species can usually be generated under mild,neutral and controlled conditions,and allow for rapid generation of molecular complexity.In this review,we critically illustrate the recent advances in the field of radical‐mediated transformations of 1,3‐dienes based on the different radical precursors and working modes.Wherever possible,particular emphasis is also put on the related mechanistic studies and synthetic applications.
The active sites of monodisperse transition metal Ni-clusters were anchored on carbon nitride(CN)by an in situ photoreduction deposition method to promote the efficient separation of photogenerated charges and achieve high-efficiency photocatalytic activity for hydrogen evolution.The Ni-cluster/CN exhibited a photocatalytic hydrogen production rate of 16.5 mmol·h^(-1)·g^(-1) and a total turnover frequency(TOF(H_(2)))value of 461.14 h^(-1).X-ray absorption spectroscopy based on synchrotron radiation indicated that CN had two reaction centers to form stable interface interactions with monodispersed Ni-clusters,in which carbon can act as an electron acceptor,while nitrogen can act as an electron donor.Meanwhile,the hybrid electronic structure of the Ni-cluster/CN system was constructed,which was favorable for photocatalytic activity for hydrogen production.An in-depth understanding of the interfacial interaction between CN and Ni-clusters will have important reference significance on the mechanistic study of development based on the cocatalyst.
