This review will explore the influences of the active metal, support, promoter, preparation methods, calcination temperature, reducing environment, particle size and reactor choice on catalytic activity and carbon deposition for the dry reforming of methane Bimetallic (Ni−Pt, Ni−Rh, Ni−Ce, Ni−Mo, Ni−Co) and monometallic (Ni) catalysts are preferred for dry reforming compared to noble metals (Rh, Ru and Pt) due to their low-cost Investigation of support materials indicated that ceria−zirconia mixtures, ZrO2 with alkali metals (Mg2+, Ca2+, Y2+) addition, MgO, SBA-15, ZSM-5, CeO2, BaTiO3 and Ca08Sr02TiO3 showed improved catalytic activities and decreased carbon deposition The modifying effects of cerium (Ce), magnesium (Mg) and yttrium (Y) were significant for dry reforming of methane MgO, CeO2 and La2O3 promoters for metal catalysts supported on mesoporous materials had the highest catalyst stability among all the other promoters Preparation methods played an important role in the synthesis of smaller particle size and higher dispersion of active metals Calcination temperature and treatment duration imparted significant changes to the morphology of catalysts as evident by XRD, TPR and XPS Catalyst reduction in different environments (H2, He, H2/He, O2/He, H2−N2 and CH4/O2) indicated that probably the mixture of reducing agents will lead to enhanced catalytic activities Smaller particle size (

Dry reforming of methane: Influence of process parameters—A review

Whereas noble metal compounds have long been central in catalysis, Earth-abundant metal-based catalysts have in the same time remained undeveloped. Yet the efficacy of Earth-abundant metal catalysts was already shown at the very beginning of the 20th century with the Fe-catalyzed Haber–Bosch process of ammonia synthesis and later in the Fischer–Tropsch reaction. Nanoscience has revolutionized the world of catalysis since it was observed that very small Au nanoparticles (NPs) and other noble metal NPs are extraordinarily efficient. Therefore the development of Earth-abundant metals NPs is more recent, but it has appeared necessary due to their “greenness”. This review highlights catalysis by NPs of Earth-abundant transition metals that include Mn, Fe, Co, Ni, Cu, early transition metals (Ti, V, Cr, Zr, Nb and W) and their nanocomposites with emphasis on basic principles and literature reported during the last 5 years. A very large spectrum of catalytic reactions has been successfully disclosed, and catalysis has been examined for each metal starting with zero-valent metal NPs followed by oxides and other nanocomposites. The last section highlights the catalytic activities of bi- and trimetallic NPs. Indeed this later family is very promising and simultaneously benefits from increased stability, efficiency and selectivity, compared to monometallic NPs, due to synergistic substrate activation.

The recent development of efficient Earth-abundant transition-metal nanocatalysts

In recent years, CO2 reforming of methane (dry reforming of methane, DRM) has become an attractive research area because it converts two major greenhouse gasses into syngas (CO and H2 ), which can be directly used as fuel or feedstock for the chemical industry. Ni-based catalysts have been extensively used for DRM because of its low cost and good activity. A major concern with Ni-based catalysts in DRM is severe carbon deposition leading to catalyst deactivation, and a lot of effort has been put into the design and synthesis of stable Ni catalysts with high carbon resistance. One effective and practical strategy is to introduce a second metal to obtain bimetallic Ni-based catalysts. The synergistic effect between Ni and the second metal has been shown to increase the carbon resistance of the catalyst significantly. In this review, a detailed discussion on the development of bimetallic Ni-based catalysts for DRM including nickel alloyed with noble metals (Pt, Ru, Ir etc.) and transition metals (Co, Fe, Cu) is presented. Special emphasis has been provided on the underlying principles that lead to synergistic effects and enhance catalyst performance. Finally, an outlook is presented for the future development of Ni-based bimetallic catalysts.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/cphc.201700529

A Review on Bimetallic Nickel‐Based Catalysts for CO2 Reforming of Methane

Catalytic conversion of CO2 to produce fuels and chemicals is attractive in prospect because it provides an alternative to fossil feedstocks and the benefit of converting and cycling the greenhouse gas CO2 on a large scale. In today's technology, CO2 is converted into hydrocarbon fuels in Fischer-Tropsch synthesis via the water gas shift reaction, but processes for direct conversion of CO2 to fuels and chemicals such as methane, methanol, and C2+ hydrocarbons or syngas are still far from large-scale applications because of processing challenges that may be best addressed by the discovery of improved catalysts-those with enhanced activity, selectivity, and stability. Core-shell structured catalysts are a relatively new class of nanomaterials that allow a controlled integration of the functions of complementary materials with optimised compositions and morphologies. For CO2 conversion, core-shell catalysts can provide distinctive advantages by addressing challenges such as catalyst sintering and activity loss in CO2 reforming processes, insufficient product selectivity in thermocatalytic CO2 hydrogenation, and low efficiency and selectivity in photocatalytic and electrocatalytic CO2 hydrogenation. In the preceding decade, substantial progress has been made in the synthesis, characterization, and evaluation of core-shell catalysts for such potential applications. Nonetheless, challenges remain in the discovery of inexpensive, robust, regenerable catalysts in this class. This review provides an in-depth assessment of these materials for the thermocatalytic, photocatalytic, and electrocatalytic conversion of CO2 into synthesis gas and valuable hydrocarbons.

/pdf/core-shell-structured-catalysts-for-thermocatalytic-2men11johy.pdf

Core–shell structured catalysts for thermocatalytic, photocatalytic, and electrocatalytic conversion of CO2

This paper describes the design of a Ni/La2O3 catalyst using La2O2CO3 nanorod as a support precursor (denoted as Ni/La2O3-LOC) via a wet impregnation method for dry reforming of methane (DRM). The results showed that La2O3 derived from the La2O2CO3 precursor maintained its initial morphology upon thermal treatment and could highly disperse Ni particles on it. Additionally, the nanorod-shaped support could provide more medium-strength basic sites to facilitate CO2 adsorption and activation on its surface. Consequently, the Ni/La2O3-LOC catalyst reached 70% of CH4 conversion and 75% of CO2 conversion at 700 °C after 50 h DRM reaction with a H2/CO ratio of 0.87. The enhanced metal-support interaction restricted the sintering of nickel particles under harsh reaction conditions. Coke evolution on the catalysts was also investigated to understand coke formation mechanism and the role of La2O2CO3 in coke elimination. It has been found that nickel dispersion can affect distribution of coke and La2O2CO3 on the surface of catalyst, both of which have a close relation with catalytic performance.

Dry reforming of methane over Ni/La2O3 nanorod catalysts with stabilized Ni nanoparticles

The CO2 (dry) reforming of methane (DRM) reaction is an environmentally benign process to convert two major greenhouse gases into synthesis gas for chemical and fuel production. A great challenge for this process involves developing catalysts with high carbon resistance abilities. Herein we synthesize, for the first time, a yolk–satellite–shell structured Ni–yolk@Ni@SiO2 nanocomposite for the DRM reaction by varying the shell thickness of Ni@SiO2 core shell nanoparticles. The formation of Ni–yolk@Ni@SiO2 is proved to be shell thickness dependent. Compared with Ni@SiO2, Ni–yolk@Ni@SiO2 with 11.2 nm silica shell thickness shows stable and near equilibrium conversion for CH4 and CO2 for 90 h at 800 °C with negligible carbon deposition. The dual effects of formation of small satellite Ni particles due to strong Ni–SiO2 interactions and yolk shell structures contribute to its high activity and stability. These findings shed light on the design of other metal yolk silica shell nanocomposites to be utilized in r...

Yolk–Satellite–Shell Structured Ni–Yolk@Ni@SiO2 Nanocomposite: Superb Catalyst toward Methane CO2 Reforming Reaction

A highly dispersed and anti-coking Ni–La2O3/SiO2 catalyst for syngas production from dry carbon dioxide reforming of methane

Ultrasmall copper nanoparticles (1.6 nm) on silica catalysts were successfully prepared via an in situ self-assembled core–shell precursor route. XRD, SEM-EDS and chemisorption results showed that only fatty acids with carbon chain length > 2 carbon atoms could effectively promote the dispersion of copper on silica. XPS results showed that non-stoichiometric copper butyrate was formed when butyric acid was used as a capping agent, and this non-stoichiometric compound of copper butyrate self-assembles into a shell structure outside the core of copper nitrate species. The in situ self-assembled core–shell structure could effectively prevent the copper particles from agglomeration. The catalytic performances of as-prepared 10% Cu/SiO2 catalysts enhanced with fatty acids with carbon chain length > 2 carbon atoms exhibited good activities for water–gas shift reaction due to the high proportion of defect sites, highly dispersed Cu particles and/or isolated Cu atom sites.

Liuye Mo

Papers

Yolk–Satellite–Shell Structured Ni–Yolk@Ni@SiO2 Nanocomposite: Superb Catalyst toward Methane CO2 Reforming Reaction

A highly dispersed and anti-coking Ni–La2O3/SiO2 catalyst for syngas production from dry carbon dioxide reforming of methane

An in situ self-assembled core–shell precursor route to prepare ultrasmall copper nanoparticles on silica catalysts

Preparation of highly dispersed Cu/SiO2 doped with CeO2 and its application for high temperature water gas shift reaction

Highly dispersed supported metal catalysts prepared via in-situ self-assembled core-shell precursor route