氮掺杂石墨烯负载金属双原子催化剂对合成气合成C_(2)氧化物性能调控  

The Regulation of Catalytic Performance for C_(2) Oxygenates Synthesis from Syngas over the Nitrogen-Doped Graphene-Supported Metaldiatomic Catalysts

作　　者：常泽海 王宝俊[1] 凌丽霞[1] 章日光[1] CHANG Zehai;WANG Baojun;LING Lixia;ZHANG Riguang(State Key Laboratory of Clean and Efficient Coal Utilization,Taiyuan University of Technology,Taiyuan 030024,China)

机构地区：[1]太原理工大学,省部共建煤基能源清洁高效利用国家重点实验室,山西太原030024

出　　处：《化学反应工程与工艺》2021年第6期534-547,共14页Chemical Reaction Engineering and Technology

基　　金：国家自然科学基金重点项目(21736007)。

摘　　要：负载型金属催化剂的催化性能主要取决于金属活性中心的设计。本工作采用密度泛函理论计算研究了氮掺杂石墨烯(NC)负载不同金属活性中心,即同核双原子(Cu Cu@NC,Rh Rh@NC和Co Co@NC)和异核双原子催化剂(Cu Rh@NC,Rh Co@NC和Cu Co@NC)上合成气合成C_(2)氧化物反应。结果表明:6类双原子催化剂均具有较好的稳定性;CH_(x)生成活性顺序为Cu Rh@NC>Rh Co@NC>Cu Co@NC>Cu Cu@NC>Rh Rh@NC>CoCo@NC,CH_(x)生成选择性顺序为RhCo@NC>CoCo@NC>RhRh@NC>CuCo@NC>CuRh@NC>CuCu@NC。进一步,一旦生成有利CH_(x)中间体,CHO插入CH_(x)能够高活性高选择性地生成C_(2)氧化物。综合考虑催化活性和选择性,RhCo@NC是合成气合成C_(2)氧化物的最佳催化剂,Rh抑制甲醇形成,Co促进C—O键断裂生成CH_(x)。Rh和Co协同催化利于CH_(x)生成,并促进C—C链增长生成C_(2)氧化物。电子性质分析表明活性组分适中的电荷转移量有利于提高催化性能。在525 K下,从头算分子动力学(AIMD)模拟显示RhCo@NC催化剂具有高的热稳定性。The catalytic performance of the supported metal catalysts mainly depends on the design of metal active center.In this study,C_(2)oxygenates synthesis from syngas over the nitrogen-doped grapheme(NC)-supported metal diatomic catalysts had been investigated using the density functional theory calculations,the homonuclear diatomic catalysts(CuCu@NC,RhRh@NC and Co Co@NC)and heteronuclear diatomic catalysts(CuRh@NC,RhCo@NC and CuCo@NC)were considered.The results showed that six kinds of diatomic catalysts have good stability,meanwhile,CH_(x) formation activity followed the order of CuRh@NC>RhCo@NC>CuCo@NC>CuCu@NC>RhRh@NC>CoCo@NC,and the order of CH_(x) selectivity was RhCo@NC>CoCo@NC>RhRh@NC>CuCo@NC>CuRh@NC>[e-mail],once the most favored CH_(x) intermediate was formed,CHO insertion into CH_(x) could easily generate C_(2)oxygenates with high activity and selectivity.Considering the catalytic activity and selectivity,RhCo@NC was screened out to be the best catalyst for C_(2)oxygenates synthesis from syngas,in which the metal Rh inhibits methanol formation,and Co promoted the C—O bond cleavage to generate CH_(x).The synergetic effect of Rh and Co co-catalyzes the formation of CH_(x) and promoted the C—C chain formation of C_(2)oxygenates.The electronic property analysis showed that the moderate charge transfer of the active component was beneficial to the improvement of catalytic performance.The ab initio molecular dynamics(AIMD)simulation of RhCo@NC catalyst at 525 K showed that the catalyst had better thermal stability.This study clearly elucidated the essential attribute about the influence of adjacent bimetallic active centers on catalytic performance and provided reasonable guidance for the design of highly efficient catalysts.

关 键 词：合成气 C_(2)氧化物 氮掺杂石墨烯 金属双原子催化剂 密度泛函理论 

分 类 号：TQ013.1[化学工程]