The Role of Active Sites Location in Partial Oxidation of Methane to Syngas for MCM-41 Supported Ni Nanoparticles

Abstract

The supporting modes of active metal over mesoporous materials play an important role in catalytic performance. The location of Ni nanoparticles inside or outside the mesoporous channel of MCM-41 has a significant influence on the reactivity in partial oxidation of methane to syngas reaction. The characterization data using different techniques (Transmission Electron Microscope (TEM), X-Ray Diffraction (XRD), N2 adsorption-desorption, H2 Temperature-Programmed Reduction (H2-TPR), and Inductively Coupled Plasma (ICP)) indicated that nickel was located outside the mesoporous channels for the impregnation method (Ni/MCM-41), while nickel was encapsulated within MCM-41 via the one-step hydrothermal crystallization method (Ni-MCM-41). The nickel atoms were mainly dispersed predominantly inside the skeleton of zeolite. When the load amount of Ni increased, both of Ni species inside the skeleton or pore channel of zeolite increased, and the ordered structure of MCM-41 was destroyed gradually. Contributed by the strong interaction with MCM-41, the Ni particles of Ni-MCM-41 were highly dispersed with smaller particle size compared with supported Ni/MCM-41 catalyst. The Ni-MCM-41 displayed higher catalytic performance than Ni/MCM-41, especially 10% Ni-MCM-41 due to high dispersity of Ni. The confinement effect of MCM-41 zeolite also afforded high resistance of sintering and coking for 10% Ni-MCM-41 catalyst. Especially, 10% Ni-MCM-41 catalyst showed outstanding catalytic stability.

Mesoporous Sn-In-MCM-41 Catalysts for the Selective Sugar Conversion to Methyl Lactate and Comparative Life Cycle Assessment with the Biochemical Process

“…At a temperature of 320–360 °C, the reduction of the most exposed extraframework metal oxides takes place. 59 In the three cases, the H 2 consumption is very low and only a soft shoulder can be observed. This is consistent with the fact that most of the metal is in the MCM-41 structure; however, there is a little amount of metal in the particle surface that could contribute to the higher amount of metal determined by XPS (see Table 2 ).…”

“…The three corresponding curves depict the existence of three reduction temperatures. At a temperature of 320–360 °C, the reduction of the most exposed extraframework metal oxides takes place . In the three cases, the H 2 consumption is very low and only a soft shoulder can be observed.…”

“…The peak at 520−550 °C corresponds to metal atoms near the surface of the framework, while the peak at 640−690 °C corresponds to metal atoms deeper inside the MCM-41 walls, with stronger interactions that are more challenging to be reduced. 42,59 It can be seen that the reduction peaks of Sn-In-MCM-41 are located at intermediate temperatures between those of Sn-MCM-41 and In-MCM-41, due to the presence of both metals in the structure.…”

Efficient Rice-Husk-Derived Silica Nanocatalysts for Organic Dye Removal from Water

“…The present study revealed that the Ni catalyst proved to be more efficient than the Fe catalyst. Up to now, Ni-MCM-41 has not been applied as a catalyst for rhodamine oxidation, being used for methane partial oxidation [61] or for carbon and oxygenate reduction in the copyrolysis process of polypropylene and cellulose [62]. Additionally, Ni-MCM-41 was applied as adsorbent for dye removal [52].…”

Zeolite confinement-catalyzed cleavage of C–O/C–C bonds in biomass

“…113 In recent years, metals encapsulated in mesoporous zeolite have also been developed, showing high catalytic stability because of the combination of the ability to reduce coke formation and metal sintering provided by the mesoporous and encapsulation effects, respectively. 179,180 In the unique encapsulation structure of metal@zeolite – the metal is encapsulated in the zeolite, so that larger external harmful substances are inevitably restricted by the pore size of the zeolite when approaching the metal sites, thus preventing poisoning of the metal sites – is described in the next section, as this aspect is somewhat related to the pores of the zeolite.…”