Recent Advances in the Development of Highly Conductive Structured Supports for the Intensification of Non-adiabatic Gas-Solid Catalytic Processes: The Methane Steam Reforming Case Study

Abstract

Structured catalysts are strong candidates for the intensification of non-adiabatic gas-solid catalytic processes thanks to their superior heat and mass transfer properties combined with low pressure drops. In the past two decades, different types of substrates have been proposed, including honeycomb monoliths, open-cell foams and, more recently, periodic open cellular structures produced by additive manufacturing methods. Among others, thermally conductive metallic cellular substrates have been extensively tested in heat-transfer limited exo- or endo-thermic processes in tubular reactors, demonstrating significant potential for process intensification. The catalytic activation of these geometries is critical: on one hand, these structures can be washcoated with a thin layer of catalytic active phase, but the resulting catalyst inventory is limited. More recently, an alternative approach has been proposed, which relies on packing the cavities of the metallic matrix with catalyst pellets. In this paper, an up-to-date overview of the aforementioned topics will be provided. After a brief introduction concerning the concept of structured catalysts based on highly conductive supports, specific attention will be devoted to the most recent advances in their manufacturing and in their catalytic activation. Finally, the application to the methane steam reforming process will be presented as a relevant case study of process intensification. The results from a comparison of three different reactor layouts (i.e. conventional packed bed, washcoated copper foams and packed copper foams) will highlight the benefits for the overall reformer performance resulting from the adoption of highly conductive structured internals.

Plasma-Deposited CoO–(Carbon Matrix) Thin-Film Nanocatalysts: The Impact of Nanoscale p-n Heterojunctions on Activity in CO2 Methanation

“…This was already noticed in our previous studies [6]. In turn, plasma treatment of the ad-CoO film (PT-CoO fresh) causes a sharp increase in the sp 3 carbon content, which, apart from the previously mentioned preferential etching, is the result of the action of argon plasma on the carbon matrix [23]. After the catalytic process, these films reveal a huge increase in the carbon content (C/Co), including sp 2 carbon (sp 2 /sp 3 ratio increases), which, however, should not be associated with changes in the chemical structure of the film surface, but with the formation of the carbon deposit.…”

“…Similarly to the ad-CoO spent film (Table 1), after treatment with the reaction mixture of CO 2 and H 2 at 400 • C, an increase in the C(sp 3 ) content compared to C(sp 2 ) was observed in the ad-CM film, but also in the TT-CM film (Figure 5 and Table 2), which is not the case in the spent TT-CoO film (Table 1). 3 ) ratio for the as-deposited and thermal-treated (fresh and spent) carbon matrix films.…”

“…Among different forms of catalysts, those applied as coatings of structured packings such as meshes, open-cell foams, and honeycomb monoliths deserve special attention due to their versatility and potential for improving process efficiency when applied in heterogeneous reactors [1,2]. Catalytic structured packings can be successfully employed in various processes, such as automotive gas treatment, the combustion of volatile organic compounds, CO 2 methanation, methane/methanol steam reforming, and many others [3]. Compared to the conventional packed beds of particle catalysts, structured catalysts offer lower pressure drop, better mass and heat transfer, and vast possibilities for tailoring their design to specific applications, providing great potential for process intensification in demanding applications, such as CO 2 valorization [4].…”

Joule-Heated Catalytic Reactors toward Decarbonization and Process Intensification: A Review

“…This requires electrified reactors with high flexibility, which, i.e., can be operated in dynamic conditions with very fast changes of the input energy supply and a good thermal response along the catalytic bed and, besides, storage strategies for the feedstocks. In this regard, process intensification could represent a very promising way to address such challenges, as small systems offer high flexibility and low operative costs during startup and shutdown. − It should be considered however that not only the reactor but also all the up- and downstream operations (e.g., separations) would need to be redesigned. Also the high level of heat integration/recovery makes running a process for just a few hours difficult.…”

Influence of Catalytic Supports on Methane Steam Reforming: A Short Review

“…Hence, depending on the intended application, a catalytic support can attain different morphology and chemical composition. Different research is still on going towards improving the specific properties of these support materials [23,24]. The importance of the support in the steam-reforming process cannot be overstated.…”