Fabrication of a Ceramic Foam Catalyst Using Polymer Foam Scrap via the Replica Technique for Dry Reforming

Abstract

Megapores with spherical-like cells connected through windows and high porosities make up catalyst supports in the form of ceramic foams. These characteristics provide significant benefits for catalytic processes that are limited by mass or heat transport. This study focuses on the manufacture of ceramic foam using a polymeric sponge replica process and polymer foams as a template for catalyst supports, which are industrial waste from the packaging sector. To make ceramic foam catalysts, they were dipped in a catalyst solution, followed by a breakdown stage and a sintering process. Experiments focused on determinants that affect the desired characteristics of ceramic foams, such as the types of polymer foams that affect foam morphology, the rheology of catalyst solution that affects catalyst dispersion, and the polymer decomposition rate that affects catalytic performance during dry reforming of the methane process. The cell architectures of polyurethane and polyvinyl alcohol foams are attractive for catalyst support preparation because they have 98−99% porosity and typical cell sizes of 200 and 50 μm, respectively. The polyurethane performance was superior to the performance of polyvinyl alcohol in terms of higher porosity and better catalytic-solution absorption offering high catalyst active areas. The catalyst prepared from concentrated 10 wt % Ni/Al 2 O 3 −MgO (10NAM) slurry had the highest surface area (59.18 m 2 /g) and the highest metal oxide dispersion (5.65%). These results are relevant to the flow behavior of catalyst slurry which plays a key role in coating the catalyst gel on the polymer template. The thermal decomposition rate used to remove the polymer template from the catalyst structure is proportional to the ceramic foam structure (catalyst support structure). The slow decomposition rate bent and fractured foam-cell struts more than the faster rate. On the other hand, achieving good catalyst dispersion on catalyst supports necessitated a high sintering rate. When sintering was adjusted at a high sintering rate, the metal− particle dispersion was relatively high, around 7.44%, and the surface area of ceramic foam catalysts was 64.61 m 2 /g. Finally, the catalytic behavior toward hydrogen production through the dry reforming of methane using a fixed-bed reactor was evaluated under certain operating conditions.

Structure of Industrial Sacrificial Fragile Cementitious Foams

“…Foaming mechanisms may be essential to address the experimental outcomes. The foaming processes of cementitious composites and other foamed materials are intimately related to the slurries’ viscosity that can be affected by the particle size, morphology, and other characteristics of the materials. ,− In our work, different particle size distributions and particle morphology were observed for the fillers (Figures –), which would cause different viscosities of the cementitious slurries with the same mix proportions. At the beginning stage of foaming, H 2 O 2 decomposed into water and oxygen, and bubbles would homogeneously nucleate in the slurries (Figure a,f).…”

“…Such pore–skeleton structural mechanisms were also employed to tune the macroproperties of composites in different application scenarios. 33 , 34 …”

“…The lower pore anisotropy (Figure d) and skeleton tortuosity of SFCF-1 (Figure c) may account for the higher strength (Figure d). Such pore–skeleton structural mechanisms were also employed to tune the macroproperties of composites in different application scenarios. , …”

“…Such pore−skeleton structural mechanisms were also employed to tune the macroproperties of composites in different application scenarios. 33,34 Discussion on Foaming Mechanisms. In this work, all of the SFCFs possessed completely the same manufacturing processes; however, a largely different collapse strength and pore−skeleton structure was reported (Figures 7, 9 −11).…”