纳米碳催化乙炔氢氯化反应机理的DFT研究
发布时间：2018-10-10 06:54
【摘要】：聚氯乙烯作为五大工程塑料之一,其单体氯乙烯(VCM)的合成是聚氯乙烯工业生产中的重要环节,其中催化剂扮演着至关重要的角色。目前工业化生产VCM中使用的主要为汞基催化剂,而由于汞的高温易挥发性造成严重的汞污染以及我国严峻的汞资源形势和国际禁汞的趋势,新型无汞催化剂的开发应用已迫在眉睫。本论文基于密度泛函理论,采用计算化学的手段研究乙炔氢氯化反应在两种非金属碳基催化剂上的反应机理。分别探索了C原子掺杂的B_(12)N_(12)笼(B11N12C、B12N11C)和三种缺陷石墨烯(单空位石墨烯MVG、双空位石墨烯DVG和Stone-wales缺陷石墨烯SWDG)上的反应机理,从而为实验提供理论依据,促进低成本,高稳定性的新型非金属催化剂的开发。研究结果表明,C掺杂后的B11N12C和B12N11C笼相较于掺杂前对反应物C2H2和HCl的吸附均得到明显增强,且C2H2在B11N12C上有顺式和反式两种吸附形态,掺杂笼对C2H2的吸附能力远远高于对于HCl的吸附,C2H2的吸附能大小顺序为B12N11CB11N12C(反式)B11N12C(顺式),吸附能依次为-27.58、-25.87和-25.70kcal/mol;HCl的吸附强度顺序为B11N12CB12N11C,吸附能依次为-3.06和-1.58 kcal/mol;前线分子轨道理论(FMO)分析结果表明掺杂后,掺杂位点的前线轨道发生电子云的明显富集,有利于吸附的发生;C2H2的吸附形态引发的B11N12C上的两种反应路径R1(反式)、R2(顺式)和B12N11C上的反应路径中,R1的活化能最低,为36.08kcal/mol,R2和R3分别为49.63和41.41kcal/mol,三种路径的速率控制步骤均为共吸附态转变为过渡态时HCl分子的解离。缺陷石墨烯中缺陷位的形成改变了石墨烯表面均匀的电子分布,并使电子在缺陷位附近发生聚集,较完美石墨烯PG增强了石墨烯与反应物的相互作用,特别是DVG对两种反应物的吸附均强于其他缺陷石墨烯,吸附能大小顺序为DVGMVGSWDG。C2H2的吸附能分别为-13.25、-6.22和-1.92kcal/mol,HCl的吸附能分别为-5.08、-4.43和-3.28kcal/mol;三种缺陷石墨烯反应机理十分相似,速率控制步骤均为共吸附态向过渡态转变时HCl的分解,MVG、DVG和SWDG活化能分别为39.46、41.55和41.16kcal/mol,反应活性位点在两个相连的5元环和6元环共有的碳碳键上。MVG上的活化能更低,更有利于催化乙炔氢氯化反应的发生。
[Abstract]:As one of the five engineering plastics, the synthesis of vinyl chloride monomer (VCM) is an important part in the industrial production of PVC, in which the catalyst plays a crucial role. At present, mercury-based catalysts are mainly used in the industrial production of VCM, and the severe mercury pollution caused by the high temperature and volatility of mercury, the severe situation of mercury resources in China and the trend of international mercury ban. The development and application of new mercury-free catalysts is imminent. Based on density functional theory (DFT), the mechanism of hydrogen-chlorination of acetylene over two non-metallic carbon-based catalysts was studied by computational chemistry. The reaction mechanisms of C atom doped B _ (12) N _ (12) cage (B _ (11) N _ (12) C) and three kinds of defective graphene (single vacancy graphene MVG, double vacancy graphene DVG and Stone-wales defect graphene SWDG) were investigated respectively, which provided theoretical basis for experiment and promoted low cost. Development of new non-metallic catalysts with high stability. The results show that the adsorption of C2H2 and HCl in the B11N12C and B12N11C cages after doping with C is obviously enhanced compared with that before doping, and C2H2 has two kinds of adsorption forms on B11N12C: cis and trans-type. The adsorption ability of the doped cages to C2H2 is much higher than that of the adsorbed C _ 2H _ 2 of HCl in the order of B12N11CB11N12C (trans-B11N12C), -27.58 ~ 25.87 and -25.70 kcal / mol 路mol ~ (-1) h ~ (-1), respectively, and the order of adsorption energy is B11N12CB12N11C, and the adsorption energy is -3.06 and -1.58 kcal/mol;, respectively, and the order of adsorption energy is B11N12CB12N11C, and the order of adsorption energy is B11N12CB12N11C and -1.58 kcal/mol;. The results of channel theory (FMO) analysis show that after doping, The electron cloud enrichment occurred in the frontier orbit of the doping site, which is beneficial to the activation energy of the two reaction pathways R1 (trans) R2 (cis) and R1 (cis) on B11N12C initiated by the adsorptive form of C _ 2H _ 2 and the lowest activation energy of R1 in the reaction path on B12N11C, which is beneficial to the adsorption formation of C _ 2H _ 2. The values of R2 and R3 were 49.63 and 41.41 kcal / mol, respectively. The rate control steps of the three paths were the dissociation of HCl molecules when the coadsorption state was transformed into transition state. The formation of defect sites in graphene changed the uniform electron distribution on the surface of graphene and made the electrons gather near the defect site. The perfect graphene PG enhanced the interaction between graphene and reactants. In particular, the adsorption of the two reactants by DVG was stronger than that of other graphene defects, and the adsorption energy of DVGMVGSWDG.C2H2 was -13.25 ~ 6.22 and -1.92 kcal / mol 路mol ~ (-1), respectively, and the adsorption energy of DVGMVGSWDG.C2H2 was -5.08 ~ 4.43 and -3.28 kcal / mol, respectively, and the reaction mechanism of three kinds of defective graphene was very similar. The activation energy of HCl decomposed into transition state is 39.46 渭 g 41.55 and 41.16 kcal / mol, respectively, and the activation energy of the active sites is lower on the carbon / carbon bond shared by the two connected five-member and six-member rings, respectively, when the rate control step is the transition from the co-adsorption state to the transition state, and the activation energy of DVG and SWDG are even lower than that of MVG, and the activation energy of MVG is much lower than that of MVG, and the activation energy of the active sites is even lower. It is more favorable to catalyze the hydrogen chlorination of acetylene.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ222.423;O643.36
本文编号：2261056
[Abstract]:As one of the five engineering plastics, the synthesis of vinyl chloride monomer (VCM) is an important part in the industrial production of PVC, in which the catalyst plays a crucial role. At present, mercury-based catalysts are mainly used in the industrial production of VCM, and the severe mercury pollution caused by the high temperature and volatility of mercury, the severe situation of mercury resources in China and the trend of international mercury ban. The development and application of new mercury-free catalysts is imminent. Based on density functional theory (DFT), the mechanism of hydrogen-chlorination of acetylene over two non-metallic carbon-based catalysts was studied by computational chemistry. The reaction mechanisms of C atom doped B _ (12) N _ (12) cage (B _ (11) N _ (12) C) and three kinds of defective graphene (single vacancy graphene MVG, double vacancy graphene DVG and Stone-wales defect graphene SWDG) were investigated respectively, which provided theoretical basis for experiment and promoted low cost. Development of new non-metallic catalysts with high stability. The results show that the adsorption of C2H2 and HCl in the B11N12C and B12N11C cages after doping with C is obviously enhanced compared with that before doping, and C2H2 has two kinds of adsorption forms on B11N12C: cis and trans-type. The adsorption ability of the doped cages to C2H2 is much higher than that of the adsorbed C _ 2H _ 2 of HCl in the order of B12N11CB11N12C (trans-B11N12C), -27.58 ~ 25.87 and -25.70 kcal / mol 路mol ~ (-1) h ~ (-1), respectively, and the order of adsorption energy is B11N12CB12N11C, and the adsorption energy is -3.06 and -1.58 kcal/mol;, respectively, and the order of adsorption energy is B11N12CB12N11C, and the order of adsorption energy is B11N12CB12N11C and -1.58 kcal/mol;. The results of channel theory (FMO) analysis show that after doping, The electron cloud enrichment occurred in the frontier orbit of the doping site, which is beneficial to the activation energy of the two reaction pathways R1 (trans) R2 (cis) and R1 (cis) on B11N12C initiated by the adsorptive form of C _ 2H _ 2 and the lowest activation energy of R1 in the reaction path on B12N11C, which is beneficial to the adsorption formation of C _ 2H _ 2. The values of R2 and R3 were 49.63 and 41.41 kcal / mol, respectively. The rate control steps of the three paths were the dissociation of HCl molecules when the coadsorption state was transformed into transition state. The formation of defect sites in graphene changed the uniform electron distribution on the surface of graphene and made the electrons gather near the defect site. The perfect graphene PG enhanced the interaction between graphene and reactants. In particular, the adsorption of the two reactants by DVG was stronger than that of other graphene defects, and the adsorption energy of DVGMVGSWDG.C2H2 was -13.25 ~ 6.22 and -1.92 kcal / mol 路mol ~ (-1), respectively, and the adsorption energy of DVGMVGSWDG.C2H2 was -5.08 ~ 4.43 and -3.28 kcal / mol, respectively, and the reaction mechanism of three kinds of defective graphene was very similar. The activation energy of HCl decomposed into transition state is 39.46 渭 g 41.55 and 41.16 kcal / mol, respectively, and the activation energy of the active sites is lower on the carbon / carbon bond shared by the two connected five-member and six-member rings, respectively, when the rate control step is the transition from the co-adsorption state to the transition state, and the activation energy of DVG and SWDG are even lower than that of MVG, and the activation energy of MVG is much lower than that of MVG, and the activation energy of the active sites is even lower. It is more favorable to catalyze the hydrogen chlorination of acetylene.
【学位授予单位】：石河子大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ222.423;O643.36
【参考文献】
相关期刊论文 前10条
1 骆雁;蒋琨;;我国PVC行业发展现状及市场分析[J];聚氯乙烯;2016年06期
2 程晓光;赵基钢;王雷;沈本贤;;AuCl_3-CuCl_2/γ-Al_2O_3乙炔氢氯化催化剂的失活原因分析及再生性能研究[J];石油炼制与化工;2014年12期
3 任若凡;沈本贤;王雷;杨恒华;赵基钢;;Au-Cu-K三组元无汞催化剂活性下降原因[J];化工进展;2014年10期
4 王丰;朱沛叶;王吉德;;用于乙炔氢氯化反应的活性炭负载铋无汞催化剂(英文)[J];化学通报;2014年09期
5 王雷;沈本贤;任若凡;赵基钢;;UDH多组元无汞催化剂的制备、表征及其与HgCl_2催化剂的乙炔氢氯化反应活性对比[J];石油炼制与化工;2014年05期
6 王丰;马磊;王吉德;;用于乙炔氢氯化的磷酸预处理活性炭负载Pd催化剂(英文)[J];新疆大学学报(自然科学版);2014年01期
7 ;联合国《水俣公约》正式签署[J];中国石油和化工;2013年11期
8 刘建楠;程党国;陈丰秋;詹晓力;郑礼平;;乙炔氢氯化制氯乙烯Pt/C催化剂的性能[J];工业催化;2013年08期
9 邴涓林;;2012年中国PVC产业状况分析[J];聚氯乙烯;2013年05期
10 张云洁;;氯化汞触媒在聚氯乙烯行业中的应用[J];聚氯乙烯;2013年03期
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