准东煤灰中钙镁黄长石形成及其反应活性的微观机理分析  

Microscopic Mechanism Analysis of Formation and Reactivity of Akermanite in Zhundong Coal Ash

作　　者：何兰珍 买尔哈巴·阿不都热合曼 魏博[1] HE Lanzhen;MAIERHABA Abudoureheman;WEI Bo(State Key Laboratory of Chemistry and Utilization of Carbon Based Energy Resources,Xinjiang Key Laboratory of Clean Conversion and Chemical Engineering Process,School of Chemical Engineering and Technology,Xinjiang University,Urumqi 830017,China)

机构地区：[1]省部共建碳基能源资源化学与利用国家重点实验室,新疆煤炭清洁转化与化工过程重点实验室,新疆大学化工学院,新疆维吾尔自治区乌鲁木齐830017

出　　处：《材料科学与工程学报》2024年第5期790-796,共7页Journal of Materials Science and Engineering

基　　金：国家自然科学基金项目(22178298,51966017)。

摘　　要：采用密度泛函理论对煤灰中硅灰石和钙镁黄长石的能级差、态密度及HOMO与LUMO等性质进行计算,从前线分子轨道等理论揭示其形成过程及反应活性机理。HOMO与LUMO统称为前线分子轨道,其轨道上分子反应活性最高,反应时外加电子会占据反应物的LUMO轨道,物质发生电离时电子会从反应物的最高HOMO轨道转移至LUMO轨道。研究结果表明:硅灰石和钙镁黄长石的能级差值为5.029和5.133 eV,前者反应活性高,优先发生发应。硅灰石的价带顶部主要由O的2p轨道组成,且电子态密度的峰值为28.021 State/eV.atom,电子活跃性最强,表明O的活性最高,电子易发生转移参与其他体系成键。当Mg^(2+)作为电子接受体进入硅灰石晶格时,O1、O3的电子发生转移使结构重组生成钙镁黄长石。钙镁黄长石的HOMO轨道由O1、O8、O15、O22组成,发现Si1-O1、Si4-O8的布居数最小,分别为0.47、0.45,键长最长,分别为1.656A、1.661A,表现出共价性最弱,离子性最强,易发生键断裂,与其他矿物质反应生成低温共熔体,加剧了准东煤的结渣沾污现象。Density Functional Theory(DFT)is used to calculate the energy difference,density of states,HOMO and LUMO properties of wollastonite and akermanite in coal ash.The formation process and reaction activity mechanism are explained by the frontier molecular orbital theory.HOMO and LUMO are collectively referred to as frontier molecular orbitals,in which the molecular reaction activity is the highest.During the reaction,the external electron will occupy the LUMO orbital of the reactant.And the electron will be transferred from the highest HOMO orbital of the reactant to the LUMO orbital when the substance is ionized.The results show that the energy difference between wollastonite and akermanite are 5.029 and 5.133 eV,and the former has high reactivity and preferentially responds.The top of the valence band of wollastonite is mainly composed of O 2p orbitals,and the peak value of electronic density of states is 28.021 State/eV.atom.The electron activity is the strongest,which indicate that O has the strongest reaction activity and the electron is easy transferred to participate in the bonding of other systems.When Mg^(2+)enters the wollastonite lattice as electron acceptor,the structure recombines to form akermanite by the electron transfer of O1 and O3.The HOMO orbit of akermanite is made up of O1,O8,O15 and O22.It is found that the minimum population of Si1-O1 and Si4-O8 are 0.47 and 0.45,respectively.The maximum bond lengths are 1.656A and 1.661A,showing the weakest covalence and the strongest ionic property.The Si1-O1 and Si4-O8 bonds are easy react with other minerals to form low-temperature eutectic compound,which aggravate the slagging and fouling of Zhundong coal.

关 键 词：密度泛函理论 准东煤灰 硅灰石 钙镁黄长石 

分 类 号：TQ536[化学工程—煤化学工程]