{"title":"MOR-Type Titanosilicate with Specific Ti Location in Defective T3 Sites for Efficient Cyclohexanone Ammoximation","authors":"Zhipeng Wan, Jingyi Tan, Wei Chen, Longkang Zhang, Xianchen Gong, Chengwei Zhai, Hao Xu*, Anmin Zheng* and Peng Wu*, ","doi":"10.1021/acscatal.4c01914","DOIUrl":null,"url":null,"abstract":"<p >Controlling the location and microenvironment of active centers in the zeolite framework is critical for understanding the in-depth structure–performance relationships of catalytic systems and constructing highly efficient catalysts. Herein, we have developed an <b>MOR</b>-type titanosilicate (denoted as 6M-Ti-M360) with an extremely low framework Ti content (Si/Ti = 300), exhibiting not only ultrahigh catalyst weight-based conversion (81%) but also a record-breaking turnover number (TON = 5845) per Ti site in batchwise ammoximation of cyclohexanone. Its highly isolated and active Ti species took the specific position of defective T3 sites within the eight-member ring side pockets of the <b>MOR</b> topology, evidenced by molecular dimension-dependent shape-selective experiments and theoretical evaluation of the catalytic activation ability of the different crystallographic Ti sites at the molecular level. Despite an extremely low Ti content but with the most active Ti on the defective T3 sites, the 6M-Ti-M360 catalyst maintained the cyclohexanone conversion and cyclohexanone oxime selectivity both as high as 99% for a long lifetime (314 h) in a continuous slurry bed reactor, capable of producing 1100 kg of oxime per gram of Ti. The clarification of the location and local microenvironment of Ti active sites may provide new insights into the exploration and construction of highly active sites in zeolitic catalysts.</p>","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":null,"pages":null},"PeriodicalIF":11.3000,"publicationDate":"2024-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Catalysis ","FirstCategoryId":"92","ListUrlMain":"https://pubs.acs.org/doi/10.1021/acscatal.4c01914","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Controlling the location and microenvironment of active centers in the zeolite framework is critical for understanding the in-depth structure–performance relationships of catalytic systems and constructing highly efficient catalysts. Herein, we have developed an MOR-type titanosilicate (denoted as 6M-Ti-M360) with an extremely low framework Ti content (Si/Ti = 300), exhibiting not only ultrahigh catalyst weight-based conversion (81%) but also a record-breaking turnover number (TON = 5845) per Ti site in batchwise ammoximation of cyclohexanone. Its highly isolated and active Ti species took the specific position of defective T3 sites within the eight-member ring side pockets of the MOR topology, evidenced by molecular dimension-dependent shape-selective experiments and theoretical evaluation of the catalytic activation ability of the different crystallographic Ti sites at the molecular level. Despite an extremely low Ti content but with the most active Ti on the defective T3 sites, the 6M-Ti-M360 catalyst maintained the cyclohexanone conversion and cyclohexanone oxime selectivity both as high as 99% for a long lifetime (314 h) in a continuous slurry bed reactor, capable of producing 1100 kg of oxime per gram of Ti. The clarification of the location and local microenvironment of Ti active sites may provide new insights into the exploration and construction of highly active sites in zeolitic catalysts.
控制沸石骨架中活性中心的位置和微环境对于深入理解催化体系的结构-性能关系和构建高效催化剂至关重要。在此,我们开发了一种框架 Ti 含量极低(Si/Ti = 300)的 MOR 型钛硅酸盐(记为 6M-Ti-M360),在批量氨基化环己酮的过程中,不仅表现出超高的催化剂重量转化率(81%),而且每个 Ti 位点的周转次数(TON = 5845)也打破了记录。通过分子维度依赖性形状选择实验以及对不同晶体学 Ti 位点在分子水平上的催化活化能力的理论评估,证明了其高度分离和活性 Ti 物种在 MOR 拓扑结构的八元环侧袋中占据了有缺陷的 T3 位点的特定位置。尽管 6M-Ti-M360 催化剂的 Ti 含量极低,但在有缺陷的 T3 位点上的 Ti 活性最高,因此在连续浆料床反应器中,环己酮转化率和环己酮肟选择性在较长的使用寿命(314 小时)内均保持在 99% 以上,每克 Ti 可生产 1100 公斤肟。澄清钛活性位点的位置和局部微环境可为探索和构建沸石催化剂中的高活性位点提供新的见解。
期刊介绍:
ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels.
The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.