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Instruments / Technical Area	Publication Details	Published
I11-High Resolution Powder Diffraction	Molecular understanding of the catalytic consequence of ketene intermediates under confinement Wei Chen , Guangchao Li , Xianfeng Yi , Sarah J. Day , Karolina A. Tarach , Zhiqiang Liu , Shang-Bin Liu , Shik Chi Edman Tsang , Kinga Góra-Marek , Anmin Zheng Journal Of The American Chemical Society DOI: 10.1021/jacs.1c08036 Open Access Show Abstract ▼ Abstract: Neutral ketene is a crucial intermediate during zeolite carbonylation reactions. In this work, the roles of ketene and its derivates (viz., acylium ion and surface acetyl) associated with direct C–C bond coupling during the carbonylation reaction have been theoretically investigated under realistic reaction conditions and further validated by synchrotron radiation X-ray diffraction (SR-XRD) and Fourier transformed infrared (FT-IR) studies. It has been demonstrated that the zeolite confinement effect has significant influence on the formation, stability, and further transformation of ketene. Thus, the evolution and the role of reactive and inhibitive intermediates depend strongly on the framework structure and pore architecture of the zeolite catalysts. Inside side pockets of mordenite (MOR), rapid protonation of ketene occurs to form a metastable acylium ion exclusively, which is favorable toward methyl acetate (MA) and acetic acid (AcOH) formation. By contrast, in 12MR channels of MOR, a relatively longer lifetime was observed for ketene, which tends to accelerate deactivation of zeolite due to coke formation by the dimerization of ketene and further dissociation to diene and alkyne. Thus, we resolve, for the first time, a long-standing debate regarding the genuine role of ketene in zeolite catalysis. It is a paradigm to demonstrate the confinement effect on the formation, fate, and catalytic consequence of the active intermediates in zeolite catalysis.	Sep 2021
I11-High Resolution Powder Diffraction	Cooperative catalytically active sites for methanol activation by single metal ion-doped H-ZSM-5 Wei-Che Lin , Simson Wu , Guangchao Li , Ping-Luen Ho , Yichen Ye , Pu Zhao , Sarah Day , Chiu Tang , Wei Chen , Anmin Zheng , Benedict T. W. Lo , Shik Chi Edman Tsang Chemical Science 3 DOI: 10.1039/D0SC04058D Diamond Proposal Number(s): [16358] Open Access Show Abstract ▼ Abstract: Catalytic conversion of methanol to aromatics and hydrocarbons is regarded as a key alternative technology to oil processing. Although the inclusion of foreign metal species in H-ZSM-5 containing Brønsted acid site (BAS) is commonly found to enhance product yields, the nature of catalytically active sites and the rationalization for catalytic performance still remain obscure. Herein, by acquiring comparable structural parameters by both X-ray and neutron powder diffractions over a number of metal-modified ZSM-5 zeolites, it is demonstrated for the first time that active pairs of metal site-BAS within molecular distance is created when single and isolated transition metal cation is ion-exchanged with the zeolites. According to our DFT model, this could lead to the initial heterolytic cleavage of small molecules such as water and methanol by the pair with subsequent reactions to form products at high selectivity as that observed experimentally. It may account for their active and selective catalytic routes of small molecule activations.	Oct 2020
B18-Core EXAFS	An efficient base-metal NiMn/TiO2 catalyst for CO2 methanation Wilbert L. Vrijburg , Emanuele Moioli , Wei Chen , Min Zhang , Bas Terlingen , Bart Zijlstra , Ivo A. W. Filot , Andreas Zuttel , Evgeny A. Pidko , Emiel J.m. Hensen Acs Catalysis DOI: 10.1021/acscatal.9b01968 Diamond Proposal Number(s): [16250] Open Access Show Abstract ▼ Abstract: Energy storage solutions are a vital component of the global transition towards renewable energy sources. The Power-to-Gas (PtG) concept, which stores surplus renewable energy in the form of methane, has therefore become increasingly relevant in recent years. At present, supported Ni nanoparticles are preferred as industrial catalysts for CO2 methanation due to their low cost and high methane selectivity. However, commercial Ni catalysts are not active enough in CO2 methanation to reach the high CO2 conversion (>99 %) required by the specifications for injection in the natural gas grid. Herein we demonstrate the promise of promotion of Ni by Mn, another low-cost base metal, for obtaining very active CO2 methanation catalysts, with results comparable to more expensive precious metal-based catalysts. The origin of this improved performance is revealed by a combined approach of nanoscale characterization, mechanistic study, and density functional theory calculations. Nanoscale characterization with STEM-EDX and X-ray absorption spectroscopy shows that NiMn catalysts consist of metallic Ni particles decorated by oxidic Mn2+ species. A mechanistic study combining IR spectroscopy of surface adsorbates, transient kinetic analysis with isotopically labelled CO2, density functional theory calculations and microkinetics simulations ascertain that the MnO clusters enhance CO2 adsorption and facilitate CO2 activation. A macroscale perspective was achieved by simulating the Ni and NiMn catalytic activity in a Sabatier reactor, which revealed that NiMn catalysts have the potential to meet the demanding PtG catalyst performance requirements, and can largely replace the need for expensive and scarce noble metal catalysts.	Jul 2019

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