Photopolymerization-based processing of porous polymer-derived ceramics for catalysis applications

Abstract

Heterogeneous catalysts are increasingly utilized under demanding conditions, requiring the use of high-performance ceramics as support materials. Achieving a high surface area, strong support-catalyst interactions, and well-tailored macroporous structures for efficient product flow is essential. To meet these requirements, vat photopolymerization, an additive manufacturing technique, was employed using preceramic polymers (PCP) to fabricate tailored polymer-derived ceramic (PDC) structures. PDCs offer the possibility of direct incorporation of catalytically active metal centers into the ceramic matrix and enable the adjustment of porosity on various length scales through chemical modification. Additionally, PDCs facilitate the production of SiC-based materials through vat photopolymerization.The influence of the initial polymer composition on the final ceramic material was evaluated. SiC particles were introduced as inert fillers to overcome limitations of part sizes due to their high shrinkage during pyrolysis and gain SiC-based materials. Additionally, active Mo-based fillers were introduced to produce silicide, carbide, and ternary molybdenum phases within the ceramic matrix, with potential catalytic activity. The metal modification of PSO was pursued with metal precursor systems. In-situ formation of metal nanoparticles within the SiOC matrix could be found. In catalytic test reactions the activity of the hybrid materials towards CO2 methanation were proven.To introduce controlled hierarchical porosity in the ceramic material, tailored photopolymerization-induced phase separation was employed within a PSO resin. The phase separating system was further modified by several metal precursors, containing Ni, Co, Mo, and La. The introduction of Ni and Co led to in-situ formation of metal nanoparticles, while Mo remained dispersed in the SiOC matrix. With the introduction of La, the formation of La rich domains within the amorphous ceramic could be found. The catalytic activity of Ni and Co could be proven towards CO2 methanation.