A Short Review on Ni Based Catalysts and Related Engineering Issues for Methane Steam Reforming

Abstract

Hydrogen is an important raw material in chemical industries, and the steam reforming of light hydrocarbons (such as methane) is the most used process for its production. In this process, the use of a catalyst is mandatory and, if compared to precious metal-based catalysts, Ni-based catalysts assure an acceptable high activity and a lower cost. The aim of a distributed hydrogen production, for example, through an on-site type hydrogen station, is only reachable if a novel reforming system is developed, with some unique properties that are not present in the large-scale reforming system. These properties include, among the others, (i) daily startup and shutdown (DSS) operation ability, (ii) rapid response to load fluctuation, (iii) compactness of device, and (iv) excellent thermal exchange. In this sense, the catalyst has an important role. There is vast amount of information in the literature regarding the performance of catalysts in methane steam reforming. In this short review, an overview on the most recent advances in Ni based catalysts for methane steam reforming is given, also regarding the use of innovative structured catalysts.

Thermodynamic assessment of the stability of bulk and nanoparticulate cobalt and nickel during dry and steam reforming of methane

“…SRM is a well-stablished technology for the production of hydrogen-rich synthesis gas covering approximately 80-85% of the global H 2 production. [1][2][3][4] An upcoming alternative of great potential in regard to sustainability and valorisation of less abundant methane sources is dry reforming of methane (DRM, eqn (2)). Here, steam is replaced by CO 2 as the oxidative molecule for methane.…”

“…Incorporation of this greenhouse gas into the value chain of chemical sites makes DRM ecologically attractive as it further provides great potential to mitigate environmental challenges associated with GHG emissions. [4][5][6][7][8][9] In addition, the absence of steam decreases the energy requirements of DRM regarding heat-up of the reactants, which results in approximately 20% lower operating costs and a lower carbon footprint in comparison to SRM. 6,8 CH 4(g) + H 2 O (g) / 3H 2(g) + CO (g)…”

“…by increasing the steam-to-carbon ratio (S/C) in the inlet stream. 13,27,28 S/C ratios exceeding the stoichiometry of the reforming reaction (eqn (1)) render SRM a combination of methane reforming and water-gas shi (WGS) reaction (eqn (5)), 4 which also results in a typically desired increased H 2 /CO ratio in the product gas. The suppression of excessive coking and increased H 2 content in the produced synthesis gas are also the reason for co-feeding steam and CO 2 in the rst commercialisation attempts of DRM in industry, which renders the processes a combination of DRM and SRM.…”

Catalysts for Methane Steam Reforming Reaction: Evaluation of CeO2 Addition to Alumina-Based Washcoat Slurry Formulation

“…The idea of hydrogen as the next-generation energy carrier has widely spread in the last years, mainly because of the growing concerns related to environmental pollution, in particular greenhouse gasses emissions, which are strictly connected to fossil fuel combustion for power generation and automotive applications [1,2]. Methane steam reforming (MSR) is, to date, the most consolidated technology in hydrogen production [3,4]. The process is based on both the homonymous and the water gas shift (WGS) reactions, reported in Equations (1) and (2), which are a highly endothermic and a slightly exothermic equilibrium reaction, respectively.…”

“…The flattening of the thermal profile allows the decrease in the temperature gradient. In particular, this means that the desired temperature at the center of the catalytic bed can be reached with lower external temperatures [3]. Moreover, a monolith structured catalyst allows one to avoid some undesired effects, such as channeling or blocking, which are typical issues in powder-and/or pellet-fixed beds [15].…”