CO2 Hydrogenation Over Ni-Based Zeolites: Effect of Catalysts Preparation and Pre-reduction Conditions on Methanation Performance

Abstract

In this work, CO 2 methanation reaction was studied on Ni-based zeolite catalysts, which were prepared by incipient wetness impregnation of USY zeolite with 5 wt% Ni. The effects of the drying method after impregnation, the calcination temperature and the pre-reduction temperature on the catalysts performances were evaluated. The catalysts were characterized by N 2 adsorption, hydrogen temperature programmed reduction, diffuse reflectance UV-Vis spectroscopy (DRS UV-Vis), transmission electron microscopy and X-ray diffraction. Drying under microwaves irradiation induced remarkable changes on the type, location and reducibility of Ni species at the same time that leaded to effects in the structural and textural properties of the support and in the average nickel particle size. As a result, changes in the catalytic performances were observed. The calcination temperature changed the location and reducibility of the Ni species being concluded that calcining at 300°C leads to higher conversions and selectivities. At high reduction temperatures the amount of reduced Ni species (active sites) was greater, but the impact of sintering processes was also stronger. For catalysts with 5 % Ni, the reduction at 550°C was observed as the most favourable. However for 14 % Ni sample no remarkable effects were observed by reducing at higher temperatures. Thus, it was proved that CO 2 conversion and CH 4 selectivity can be maximised through the proper choice of both preparation and pre-reduction conditions.

Micro- and mesoporous supports for CO2 methanation catalysts: A comparison between SBA-15, MCM-41 and USY zeolite

“…So far, few works have been published dealing with the use of micro and mesoporous materials as supports for Ni-based CO2 and CO methanation catalysts [6][7][8][9][10][11][12][13][14][15][16][17] , the mainly used being USY zeolite, SBA-15 and MCM-41. Ni-based USY zeolite catalysts showed interesting performances towards methanation being reported the effect of Ni content, Ce addition, the preparation method conditions and some highlights concerning the reaction mechanism 6,[17][18][19] . In addition, SBA-15 and MCM-41 mesoporous materials were used due to their large pore sizes and interesting textural properties for the dispersion of metal species and the prevention of sintering processes.…”

Ni‐Ce/Zeolites for CO2 Hydrogenation to CH4: Effect of the Metal Incorporation Order

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a] InÞsG raÅa, [b] JosØ M. Lopes, [a] andC arlosH enriques* [a] Introduction CO 2 methanation, as af orm of alleviating CO 2 emissions, has been the focus of much attention in the last few years, with thermal, photocatalytic,e lectrochemical, or even plasma assisted processes being used. [44][45][46][47][48][49] Amongt he different supports used, zeolitesh ave been revealed to be interesting materials, as their properties (e.g.,S i/ Al ratio, compensating cation) can be easily modified to meet the requirements of the reaction.Ni-basedu ltrastable Yz eolites (USY) have been appliedt o the CO 2 methanation reaction, with very promising results. [44][45][46][47][48][49] Amongt he different supports used, zeolitesh ave been revealed to be interesting materials, as their properties (e.g.,S i/ Al ratio, compensating cation) can be easily modified to meet the requirements of the reaction.

Ni-basedu ltrastable Yz eolites (USY) have been appliedt o the CO 2 methanation reaction, with very promising results.

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Microwave, Ultrasound, and Mechanochemistry: Unconventional Tools that Are Used to Obtain “Smart” Catalysts for CO2 Hydrogenation

“…MW can be used during catalyst preparation in different manners: for instance, the effect of MW drying vs. conventional drying in the preparation of Ni-exchanged zeolites for CO2 methanation (2) has been recently studied [48]. The catalysts were prepared by incipient wetness impregnation of USY (Ultra Stabilized Y) zeolite with 5 wt % Ni.…”

“…Unfortunately, the positive effects brought about by MW-assisted drying, like better Ni dispersion, were counterbalanced by the loss in zeolite crystallinity and, as a result, no appreciable improvement in the catalytic activity was obtained in terms of both CO 2 conversion and selectivity to CH 4 . This was likely due to the fact that the support was a zeolite, for which the crystallinity of porous cavities is a crucial aspect [48].…”