石油卟啉电子结构和光谱性质的量子化学研究  

QUANTUM CHEMISTRY STUDY OF ELECTRONIC STRUCTURE AND SPECTRAL PROPERTIES OF PETROPORPHYRINS

作　　者：浦宁 任强 王薇 霍佳宁 贾燕子 胡大为 聂红 Pu Ning;Ren Qiang;Wang Wei;Huo Jianing;Jia Yanzi;Hu Dawei;Nie Hong(SINOPEC Research Institute of Petroleum Processing Co.,Ltd.,Beijing 100083)

机构地区：[1]中石化石油化工科学研究院有限公司,北京100083

出　　处：《石油炼制与化工》2024年第11期68-73,共6页Petroleum Processing and Petrochemicals

基　　金：国家重点研发计划项目(2021YFA1501204);北京市科协青年人才托举工程项目(BYESS2024225);中石化石油化工科学研究院有限公司院控课题(PR20232509)。

摘　　要：石油卟啉通常是卟啉和Ni、V形成的化合物,种类和形态较多且十分复杂。通过量子化学计算方法,使用PBE泛函对Ni^(2+)和VO^(2+)的初卟啉(ETIO)型化合物的几何结构、电子结构和光谱性质进行了计算,得到的相关结论和文献中发表的规律一致。ETIO卟啉环通过4个N原子和Ni^(2+)或VO^(2+)配位,分别形成具有D 4h对称性和C_(4V)对称性的化合物。轴向配位O原子的竞争作用使得V—N键弱于Ni—N键,因而渣油加氢过程中V比Ni更容易进行渣油加氢脱金属反应。解析了Ni^(2+)/VO^(2+)-ETIO化合物的电子结构,卟啉环具有显著的共轭效应,形成的共轭π轨道与Ni/V的3d轨道发生明显的轨道重叠。因此,卟啉和Ni或V的相互作用十分强烈。使用含时密度泛函理论计算了Ni^(2+)-ETIO和VO^(2+)-ETIO化合物的价层电子跃迁,得到了石油卟啉分子的紫外-可见光吸收光谱。理论计算得到强吸收的Soret带和弱吸收的Q带,从电子跃迁角度解释了石油卟啉的紫外-可见光谱存在的特征吸收带。Petroporphyrins are usually porphyrins-coordinated nickel vanadium compounds.The types and forms of petroporphyrins are very complex.In this work,the geometry structure,electronic structure and spectral properties of of Ni^(2+)and VO^(2+)primary porphyrin(ETIO)type compounds were calculated by using PBE density functional,and the simulated results were in line with experimental results.The ETIO porphyrin ring is coordinated with Ni^(2+)or VO^(2+)via four nitrogen atoms to form molecules with D 4H symmetry and C_(4V) symmetry,respectively.The V—N bond is weaker than Ni—N bond because of the competition of axial coordination O atoms,therefore,V is mor subject to hydrodemetallization(HDM)than Ni during residue hydrotreating.The electronic structure of Ni^(2+)/VO^(2+)-porphyrin compounds was analyzed.The resuts showed that the porphyrin ring has a remarkable conjugation effect,and the conjugatedπorbitals were formed by the porphyrin ring overlaps with the 3d orbitals of Ni or V.Therefore,the interaction between porphyrin and Ni or V is very strong.The valence electron transitions of Ni^(2+)-ETIO and VO^(2+)-ETIO compounds were calculated by using time-dependent density functional theory(TDDFT),and the characteristic UV-Vis absorption was obtained.The Soret band with strong absorption and the Q band with weak absorption were calculated theoretically,which was consistent with the spectral characteristics reported in literature.These characteristic absorption in UV-Vis spectrum was explained theoretically.

关 键 词：石油卟啉 电子结构 紫外-可见光谱 含时密度泛函理论 

分 类 号：TE622[石油与天然气工程—油气加工工程]