Structural Aspects of Ternary Phase Ni/MoWS 2 Catalyst: An Aberration Corrected HRTEM Study
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Structural Aspects of Ternary Phase Ni/MoWS2 Catalyst: An Aberration Corrected HRTEM Study M. Ramos1,2, B. Torres1, Daniel Bahena3, M. José-Yacamán3, Lorena Alvarez-Contreras4 and R.R. Chianelli1 1) Materials Research and Technology Institute, University of Texas at El Paso, 500W University Ave, El Paso, TX. 79968, U.S. 2) Departmento de Física y Matemáticas, Universidad Autónoma de Ciudad Juárez, Avenida del Charro #450 N Ciudad Juarez, Chihuahua, MX. 32310 3) Department of Physics, University of Texas at San Antonio, One UTSA Circle, 78249 U.S. 4) Centro de Investigación en Materiales Avanzados S.C., Laboratorio Nacional de Nanotecnología. Chihuahua Miguel de Cervantes 120, Complejo Industrial Chihuahua, Chihuahua, C. P. 31109 México Abstract In the past 20 years, one of the best catalytic materials for hydrodesulphurization reactions of crude oil has been the transition sulfides, MoS2, known also as the “workhorse” of the refinery industry. It has been proven by this and other research groups that the MoS2 laminar structure can increase its catalytic activity when promoted with cobalt or nickel. The location of active sites seem to be at rim and edge sites on that particular laminar structure, as demonstrated using Mössbauer spectroscopy and x-ray techniques. However, due to maximum capability of this promoted systems, Co(Ni)/MoS2 to remove heterogeneous atoms (S, N, O) - a search for new catalytic materials has currently been an ongoing activity in the HDS community. Here, we will present the new family of ternary phase catalyst with special emphasis on their structural aspects, as revealed by aberration corrected (Cs) high-resolution transmission electron microscopy techniques, in an attempt to describe the nature of active sites on this porous nano-rod like catalytic materials. Key Words: MoS2, HRTEM, Catalytic, HDS Corresponding author: [email protected], [email protected] 1. Introduction The usage of characterization techniques, such as high-resolution transmission electron microscope (HRTEM), has been a method of high success [1]. By using HREM technique, it was possible to understand the honeycomb-like structure in MoS2 laminar structure [2]. Found experimentally by doing a combination of HRTEM measurements and computer assisted simulations, the slabs were held together by weak Van der Waals bonding at a distance of 0.62nm [3] in agreement with crystallographic information [4]. Later, another study indicated that honeycomb structures are created due to a formation of Moiré pattern in the basal (001) plane of MoS2, leading to a creation of metallic states on the edge of laminar structure [5, 6]. One of principal applications for this laminar MoS2 material is to be used as catalytic material. Edges of laminar MoS2 structure are able to attract heterogeneous atoms of Sulfur, Nitrogen,
Oxygen as contained in crude oil [7], and that catalytic activity can be enhanced by introducing Cobalt or Nickel at the edge of laminar structures (1010)-plane. This effect is known as “promoting systems” [8]. HRTEM techni
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