{"title":"Hydrogenolysis of guaiacol and lignin to phenols over Ni/Nb2O5HZSM-5 catalyst","authors":"Xiaohong Ren, Zeming Rong, Xiaoqiang Yu","doi":"10.1016/j.mcat.2024.114559","DOIUrl":"10.1016/j.mcat.2024.114559","url":null,"abstract":"<div><p>Selective hydrogenolysis of C<sub>Ar</sub>-O bonds in lignin to produce aromatic compounds typically necessitates severe conditions. We developed a Ni/Nb<sub>2</sub>O<sub>5</sub><img>HZSM-5 catalyst that facilitates direct cleavage of guaiacol's aryl ether bonds at reduced temperatures (200 °C) and pressure (0.1 MPa H<sub>2</sub>), achieving a conversion of 89.5 % with the selectivity of phenol at 81.7 %, while retaining its activity after five cycles. The Ni/Nb<sub>2</sub>O<sub>5</sub><img>HZSM-5 exhibits a higher yield of phenol (49.1 mmol<sub>phenol</sub>·g<sub>Ni</sub><sup>−1</sup>·<em>h</em><sup>−1</sup>), currently achieving the highest phenol yield among Ni-based catalysts. The addition of Nb<sub>2</sub>O<sub>5</sub> enhances the dispersion of Ni and augments the effective surface area. In addition, the strong interaction of Nb with the HZSM-5 changed the electronic state of Nb and enhanced the resistance of the catalyst to high temperature and mechanical stress. Employing this catalyst for lignin depolymerization in an aqueous medium led to a 17.0 wt% yield of alkyl phenolic compounds. This approach represents an advancement in biomass resource conversion, circumventing the dependency on high-pressure and precious-metal catalysts, and signaling a new trajectory for sustainable biomass utilization in scientific research.</p></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114559"},"PeriodicalIF":3.9,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270428","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Anil Malik , Nitish Saini , Ranjita S. Das , Anupama Kumar , Suman L. Jain
{"title":"Light-induced, metal free, and green synthetic approach for N-methylation via coupling of benzylamine, benzaldehyde and CO2 at atmospheric pressure","authors":"Anil Malik , Nitish Saini , Ranjita S. Das , Anupama Kumar , Suman L. Jain","doi":"10.1016/j.mcat.2024.114562","DOIUrl":"10.1016/j.mcat.2024.114562","url":null,"abstract":"<div><p>Herein, we report a combination of experimental and computational studies for the photochemical synthesis of <em>N,N’-</em>dibenzyl<em>-N-</em>methylamine <em>via</em> three component coupling of benzylamine, benzaldehyde, and CO<sub>2</sub> assisted by 1-butyl-3-methylimidazolium chloride ionic liquid at atmospheric pressure. The theoretical investigation revealed the formation of imine and two reaction intermediates (I & II) through the coupling reaction of CO<sub>2</sub> with benzaldehyde and benzylamine in excess phenyl saline. The Molecular electrostatic potential and activation energy calculations depicted the formation of Intermediate I (formoxysilane) formation by inserting CO<sub>2</sub> into the Si<img>H bond of the phenyl silane <em>via</em> hydrogen bonding. Furthermore, Intermediate I converted to Intermediate II by reacting with phenyl saline (PhSiH<sub>3</sub>) and imine, followed by the final methylated product <em>via</em> the C<img>N bond between the carbon of CO<sub>2</sub> and nitrogen of the imine group.</p></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114562"},"PeriodicalIF":3.9,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Qian Wang , Mingqin Xing , Liping Wang , Zhiyuan Gong , Muhammad Asif Nawaz , Rubén Blay-Roger , T. Ramirez-Reina , Zhong Li , Fanhui Meng
{"title":"CO2 hydrogenation to light olefins over highly active and selective Ga-Zr/SAPO-34 bifunctional catalyst","authors":"Qian Wang , Mingqin Xing , Liping Wang , Zhiyuan Gong , Muhammad Asif Nawaz , Rubén Blay-Roger , T. Ramirez-Reina , Zhong Li , Fanhui Meng","doi":"10.1016/j.mcat.2024.114567","DOIUrl":"10.1016/j.mcat.2024.114567","url":null,"abstract":"<div><div>The production of light olefins from the hydrogenation of CO<sub>2</sub> is an efficient way to utilize CO<sub>2</sub>, where the surface oxygen vacancy in metal oxide plays an important role in CO<sub>2</sub> adsorption and activation. Here, the Ga-Zr metal oxides were prepared by hydrolysis of urea at different temperatures and combined with SAPO-34 to prepare the bifunctional catalyst for CO<sub>2</sub> hydrogenation to light olefins. The surface oxygen vacancy content of Ga-Zr oxide increases with increasing urea hydrolysis temperature, and a high CO<sub>2</sub> conversion of 26.4% and C<sub>2</sub><sup>=</sup>–C<sub>4</sub><sup>=</sup> hydrocarbon selectivity of 87.2% were obtained by a well-matched amount of desorbed CO<sub>2</sub> and H<sub>2</sub>. Using the CO<sub>2</sub> and H<sub>2</sub>/HCOOH/CH<sub>3</sub>OH as probe molecules, the <em>in-situ</em> DRIFT spectra reveal that the CO<sub>2</sub> could be activated on surface oxygen vacancy and converted to CO<sub>3</sub>* and HCO<sub>3</sub>* species, which were further hydrogenated to HCOO* and CH<sub>3</sub>O* species. While the by-product CO mainly originates from the decomposition of HCOO* and the presence of SAPO-34 converts CH<sub>3</sub>O* to C<sub>2</sub><sup>=</sup>–C<sub>4</sub><sup>=</sup>. The current study illustrates that boosting the surface oxygen vacancy in defected surfaces of metal oxide and providing a matching H<sub>2</sub> dissociation ability is the key to improve the performance of CO<sub>2</sub> hydrogenation to light olefins.</div></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114567"},"PeriodicalIF":3.9,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Quan Zhang, Zikang Li, Lingxiang Peng, Cuiru Wang, Zhiqiang Yao
{"title":"A high-throughput screening of catalyst for efficient nitrogen fixation: Transition metal single-atom anchored on an emerging synthesized biphenyl network","authors":"Quan Zhang, Zikang Li, Lingxiang Peng, Cuiru Wang, Zhiqiang Yao","doi":"10.1016/j.mcat.2024.114564","DOIUrl":"10.1016/j.mcat.2024.114564","url":null,"abstract":"<div><p>Synthesizing efficient and selective green ideal catalysts has been an increasingly critical, yet unsolved, issue for the ammonia synthesis industry, hindering the growing global demand for environmental protection and energy efficiency. Electrocatalytic nitrogen reduction reaction (eNRR) is a promising technology for low-energy ammonia synthesis. However, designing efficient electrocatalysts for NRR remains challenging. The emergence of graphene-like substrates offers exciting prospects for addressing this challenge and facilitating single-atom catalysts in eNRR. Here, we report the innovative selection of a recently synthesized two-dimensional biphenyl network (2D BPN) compound as a substrate. Its excellent conductivity and porosity enable stable transition metal atoms (TMs) support for constructing eNRR electrocatalysts. we evaluated the feasibility of 23 TMs anchored on BPN for eNRR by high-throughput first-principles calculations. Through a systematic five-step strategy, we identified several single-atom catalysts (SACs) with potential for eNRR, including Mo@BPN, V@BPN, W@BPN, and Re@BPN. Among them, Mo@BPN exhibited the best balance in the adsorption of key reaction intermediates (e.g., N<sub>2</sub>H and NH<sub>3</sub>) and demonstrated a low limiting potential (-0.37 V). In addition, the underlying mechanism of NRR activity was elucidated by analyzing the extrinsic patterns revealed through the screened catalysts. A triangular volcano diagram, incorporating the initial protonation step, adsorption free energy, and final protonation step, revealed the NRR activity trend. Overall, this study provides a solid theoretical foundation and valuable guidance for future experimental exploration of efficient electrocatalysts for ammonia synthesis on BPN. Crucial insights into the theoretical design of efficient electrocatalysts are also offered.</p></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114564"},"PeriodicalIF":3.9,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270429","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kaixuan Ke , Ling Guo , Zhipeng Qi , Dou Dou , Han Ma , Xianying Fang , Linguo Zhao
{"title":"Molecular cloning, expression, and biochemical characterization of carotenoid cleavage dioxygenase 1 (LbCCD1) from Lycium barbarum","authors":"Kaixuan Ke , Ling Guo , Zhipeng Qi , Dou Dou , Han Ma , Xianying Fang , Linguo Zhao","doi":"10.1016/j.mcat.2024.114561","DOIUrl":"10.1016/j.mcat.2024.114561","url":null,"abstract":"<div><div>Carotenoid cleavage dioxygenases (CCDs) play a pivotal role in the biosynthesis of volatile apocarotenoids, which have significant industrial applications due to their aromatic and bioactive properties. This study focuses on the molecular cloning and biochemical characterization of the LbCCD1 from <em>Lycium barbarum</em>. The LbCCD1 gene was successfully cloned and heterologously expressed in <em>Escherichia coli</em> and several carotenoids were using as substrates for investigate its specificity by in vitro and in vivo experiment. The LbCCD1 protein was able to cleave a variety of carotenoids including β-carotene, zeaxanthin, astaxanthin, and β-apo-8′-carotenal, at the 9, 10 (9′, 10′) double bond to produce β-ionone, 3‑hydroxy-4-oxo-β-ionone, and 3‑hydroxy-β-ionone, respectively in vitro. LbCCD1 could also cleave zeaxanthin and β-carotene at the 9, 10 (9′, 10′) double bond to produce β-ionone, respectively, in E. coli accumulating carotenoids. Interestingly, LbCCD1 did not exhibit cleavage activity on lycopene either in vivo or in vitro unlike other CCD1 family enzymes.</div><div>In the previous experiment, it was confirmed that LbCCD1 exhibits cleavage activity towards β-apo-8′-carotenal in vitro, so we used β-apo-8′-carotenal as the substrate for characterizing the enzymatic properties. The expression of LbCCD1 was optimized at such conditions (temperature 24 °C, IPTG 0.1 mM, induction time 24 h). The biochemical characterization of LbCCD1 revealed the optimal activities were at pH 9 and 55 °C. The addition of 10 % ethanol could increase enzyme activity to above 15 %. However, the concentration of Fe<sup>2+</sup> has a minimal effect on enzyme activity. The V<sub>max</sub> for β-apo-8′-carotenal was 8.6 U/mg, while the K<sub>m</sub> was 0.27 mM. To preliminarily verify the potential of LbCCD1 as a biological component for β-ionone production. By introducing LbCCD1 into the β-carotene-high-producing chassis cell and optimizing the conditions (temperature 30 °C, IPTG 0.01 mM, Fe<sup>2+</sup> concentration 0.05 mM), the β-ionone yield reached 21.45 mg/L. This study focused on one of the CCDs derived from woody plants, which have been relatively underexplored. It lays the groundwork for expanding the CCD enzyme library, identifying suitable CCDs, and investigating the structure-function relationship of CCDs. Furthermore, it sets the stage for engineering novel CCD genes and developing advanced applications of CCDs as biocatalysts and platforms for synthetic biology. These advancements will enable the efficient production of volatile aroma compounds from carotenoids.</div></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114561"},"PeriodicalIF":3.9,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311839","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pengfei Liu , Xiaoying Feng , Mingqian Wang , Wanfei Hu , Xing Gao , Yanyan Xing , Qiang Wang , Junying Zhang
{"title":"Theoretical study on borophene as metal-free catalyst for selective conversion of NO","authors":"Pengfei Liu , Xiaoying Feng , Mingqian Wang , Wanfei Hu , Xing Gao , Yanyan Xing , Qiang Wang , Junying Zhang","doi":"10.1016/j.mcat.2024.114556","DOIUrl":"10.1016/j.mcat.2024.114556","url":null,"abstract":"<div><div>The electrocatalytic reduction of NO (NORR) and selective catalytic reduction of NO by CO (CO-SCR) are the two most attractive approaches for selective conversion of NO. Herein, a bifunctional metal-free catalyst 2-Pmmn borophene is reported that is effective for both NORR and CO-SCR. NO can form NH<sub>3</sub> and N<sub>2</sub> through NORR and CO-SCR respectively. The results show that NO chemically adsorbed on the surface of borophene through the N<img>O terminal can be electrocatalytically reduced to NH<sub>3</sub>. The optimal reaction path for NO to generate NH<sub>3</sub> is through the protonation process of *NHO instead of *NOH. The rate-determining step is the hydrogenation of *NH<sub>2</sub>O to *NH<sub>2</sub>OH, and the free energy increases by 0.41 eV. At the same time, NO can also react with CO on the surface of borophene to form N<sub>2</sub> and CO<sub>2</sub>. First, NO can form chemically adsorbed ONNO intermediate through N<img>N coupling, then ONNO can be denitrified to form N<sub>2</sub> and residual oxygen, and finally residual oxygen and CO can generate CO<sub>2</sub> through the LH mechanism. The rate-determining step of the reaction is the N<img>N coupling process of NO, and activation energy barrier is 1.27 eV. The present work provides theoretical insights for the effective conversion of NO.</div></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114556"},"PeriodicalIF":3.9,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142311838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Catalytic oxidation of butylated hydroxytoluene using thermally treated cobalt-copper layered double hydroxides: Synthesis, structural evolution, and mechanistic insights","authors":"JiYu Wang, Naiwang Liu, Li Shi, Xuan Meng","doi":"10.1016/j.mcat.2024.114484","DOIUrl":"10.1016/j.mcat.2024.114484","url":null,"abstract":"<div><p>This study investigates the application of cobalt-copper layered double hydroxides (LDHs) in the oxidation of butylated hydroxytoluene (BHT) and explores their catalytic behavior during thermal treatment. LDHs were synthesized via coprecipitation, and various ratios of Co-Cu hydrotalcite were subjected to thermal treatment. Structural analysis revealed that thermal treatment transforms the LDHs into mixed metal oxides. Among the synthesized catalysts, Co1Cu3-LDHs exhibited superior catalytic activity in the oxidation of BHT. Techniques such as XRD, FT-IR, TGA, N<sub>2</sub> adsorption-desorption, SEM, and XPS were employed to investigate the structural changes and surface properties of the LDHs. The Co1Cu3-LDH catalyst, treated at 250 °C, exhibited outstanding catalytic performance, attributed to the synergistic effects between Co and Cu. Upon optimizing the reaction conditions, the conversion of BHT reached 99 %, with a selectivity of 77 % towards 3,5-di‑tert‑butyl‑4-hydroxybenzaldehyde (BHT-CHO). The oxidation mechanism involves the oxidation of the π-electron system on the benzene ring and deep oxidation of the phenolic hydroxyl methyl group, with two potential reaction pathways proposed.</p></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114484"},"PeriodicalIF":3.9,"publicationDate":"2024-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Phenoxazinone synthase-like activity: Schiff base bound model complexes","authors":"Poulami Koley , Bidyut Ghosh , Jyotipriyo Bhattacharyya , Alokesh Hazari","doi":"10.1016/j.mcat.2024.114523","DOIUrl":"10.1016/j.mcat.2024.114523","url":null,"abstract":"<div><p>In order to get a better life, industrial revolution prevails worldwide since past few centuries but the rapid growth of industrialization in our planet invites different type of severe pollutions and hence environmental damage, which has now impacted on the survival of mankind. Although, the survival of mankind demands physical resourses but these are limited in quantity. In this problematic situation, biomimetics can be a solution. Biomimetics is the study which deals with nature and natural phenomenon to investigate the fundamental mechanisms, and afterwards to apply the concepts in the field of science, technology, and vastly in medical. In this present study, we look into one of the biomimetic enzymes, phenoxazinone synthase. Phenoxazinone synthase is an important class of enzyme that catalyzes the oxidation of <em>o</em>-aminophenol to aminophenoxazinone with the activation of molecular dioxygen. Bioinorganic chemists are largely influenced by the nature's design on phenoxazinone synthase and hence they are excited to synthesize this mimics model enzyme to understand the mechanistic pathways properly, so that they can explored its potential applications in the field of bioelectronics, material science, optoelectronics, and biomedical. In the literature, a significant number of Schiff base bound model complexes (about 126) for phenoxazinone synthase-like activity have been synthesized and catalytically characterized by different research groups. A variety of Schiff base ligands (about 68) are employed to prepare such model complexes with different nuclearities in presence of one or more 3<em>d</em> metals like V, Mn, Fe, Co, Ni, Cu and Zn in order to modulate the catalytic activity and to get a better structure property relationship on phenoxazinone synthase activity. This article aims to explore the recent advances, challenges, and opportunities in bioenzymatic catalysis, highlighting its promise to revolutionize the way we create value added compounds and materials.</p></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114523"},"PeriodicalIF":3.9,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Haotian Guo , Xinhuan Lu , Wang Zhang , Meiling Zhang , Lin Zhao , Dan Zhou , Qinghua Xia
{"title":"Highly efficient oxidation of various thioethers with molecular oxygen catalyzed by bimetallic SnMo-MOF","authors":"Haotian Guo , Xinhuan Lu , Wang Zhang , Meiling Zhang , Lin Zhao , Dan Zhou , Qinghua Xia","doi":"10.1016/j.mcat.2024.114555","DOIUrl":"10.1016/j.mcat.2024.114555","url":null,"abstract":"<div><p>Bimetallic or polymetallic materials often exhibit different catalytic activities due to the interaction between different metal centers compared with monometallic materials. Here, we designed and synthesized a new bimetallic catalyst SnMo-MOF with tin and molybdenum as metal centers by solvothermal synthesis, which could realize the oxidation of diphenyl sulfide (Ph<sub>2</sub>S) and difurfuryl sulfide (FFS) under mild conditions, and selectively generate sulfoxide and sulfone, respectively. The introduction of Sn enhanced the Lewis acidity of the catalyst surface and the electron transfer between Sn and Mo led to bimetallic synergistic catalysis, which made a great contribution to the high conversion and selectivity of sulfide oxidation. This is reflected in the complete conversion of Ph<sub>2</sub>S and FFS with 91.8% and 98.1% selectivity of diphenyl sulfoxide (Ph<sub>2</sub>SO) and difurfuryl sulfone (FFSO<sub>2</sub>), respectively. The composite material had good substrate adaptability for the catalytic oxidation of other phenyl sulfides and furfuryl sulfides, which opens interesting prospects for the development of new MOF materials as efficient heterogeneous catalysts for the oxidation of thioethers.</p></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114555"},"PeriodicalIF":3.9,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kunrou Zhang , Yongbin Guo , Ke Zhang , Zean Xie , Linlin Mei , Xintong Wang , Wenxi Wang , Yangyang Song , Guichang Wang , Zhen Zhao
{"title":"Insights into Cl effect for propylene epoxidation over Ag2O(111) surface: A periodic density functional theory study","authors":"Kunrou Zhang , Yongbin Guo , Ke Zhang , Zean Xie , Linlin Mei , Xintong Wang , Wenxi Wang , Yangyang Song , Guichang Wang , Zhen Zhao","doi":"10.1016/j.mcat.2024.114552","DOIUrl":"10.1016/j.mcat.2024.114552","url":null,"abstract":"<div><p>As an environmentally friendly way, propylene epoxidation forming propylene oxide (PO) catalyzed by Ag-based catalyst had received considerable attentions, which was important in the chemical industry. The experimental results exhibited that the products of propylene epoxidation catalyzed by Ag<sub>2</sub>O were PO and carbon dioxide. In this work, the spin-polarized density functional theory (DFT) calculations combined with a Hubbard U correction were performed to investigate propylene epoxidation on Ag<sub>2</sub>O(111) and Cl−Ag<sub>2</sub>O(111) surfaces, and reaction micro-mechanism of propylene epoxidation was discussed in detail. The micro-mechanism mainly included two pathways: the allylic hydrogen stripping (AHS) pathway and the intermediary propylene oxametallacycles (OMMP) pathway. In the AHS pathway, the allyl radical can be generated, which was considered as a precursor for acrolein formation, and completed combustion yielding CO<sub>2</sub>. In the OMMP pathway, PO, propanal and acetone can be created through the propylene oxametallacycle intermediates. Our calculated results indicated that the O<sub>suf</sub> site on the Ag<sub>2</sub>O(111) surface has a stronger basicity than the O<sub>suf</sub> site on the Cl−Ag<sub>2</sub>O(111) surface, the stronger basicity was beneficial for the AHS pathway, and carbon dioxide can be regarded as the main product for propylene epoxidation. It was also found that PO became the main product with the effect of Cl doping on the Ag<sub>2</sub>O(111) surface, and the electrostatic effect of Cl−Ag<sub>cus</sub> can improve the adsorption ability between the Ag<sub>cus</sub> site and the absorbate. Moreover, energetic span model analysis were carried out and found that the TOF or the orders of selectivity are: acrolein > acetone > propanal ≅ PO on clean surface, PO > acetone > acrolein > propanal on the Cl doped surface, and acrolein, as a precursor, was easily completely burned to CO<sub>2</sub>, the results confirmed that the selectivity of PO can be enhanced by the effect of subsurface Cl<sup>-</sup> doping. The present study aimed to help workers to find high selectivity and activity catalyst for propylene epoxidation.</p></div>","PeriodicalId":393,"journal":{"name":"Molecular Catalysis","volume":"569 ","pages":"Article 114552"},"PeriodicalIF":3.9,"publicationDate":"2024-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142270425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}