Planar, Polysilazane‐Derived Porous Ceramic Supports for Membrane and Catalysis Applications

Abstract

Porous, silicon carbonitride-based ceramic support structures for potential membrane and catalysis applications were generated from a preceramic polysilazane precursor in combination with spherical, ultrahigh-molecular weight polyethylene microparticles through a sacrificial filler approach. A screening evaluation was used for the determination of the impact of both porogen content and porogen size on pore structure, strength, and permeability characteristics of planar specimens. By optimizing both the composition as well as cross-linking parameters, maximum characteristic biaxial flexural strengths of 65 MPa and porosities of 42% were achieved. The evolution of an interconnected, open-pore network during thermal porogen removal and conversion of the preceramic polymer led to air permeabilities in the order of 10−14 m2. The materials were further exposed to long-term heat treatments to demonstrate the stability of properties after 100 h at 800°C in oxidizing, inert, and reducing environments. The determined performance, in combination with the versatile preparation method, illustrates the feasibility of this processing approach for the generation of porous ceramic support structures for applications at elevated temperatures in a variety of fields, including membrane and catalysis science.

Tubular ceramic structures from polymer precursors with controlled porosity, strength, and permeability characteristics

“…18), 19) However, for an anticipated use of these materials on a larger scale, up to the industrial application, planar geometries are less suitable due to a decreased functional surface. Generally, a tubular setup of supports with an increased surfaceto-volume ratio is preferred.…”

Determination of Mechanical Properties of Composite Supports Used in Catalytic Membranes for Hydrogen Production and Separation

“…There are several types of researches in literature dealing with the mechanical properties of alumina‐based ceramic supports used in membranes and catalytic applications . However, results attained exhibited discrepancies resulted from the fabrication method, type of binder employed and sintering processes in a wide range …”

“…[5][6] There are several types of researches in literature dealing with the mechanical properties of alumina-based ceramic supports used in membranes and catalytic applications. [7][8][9][10][11] However, results attained exhibited discrepancies resulted from the fabrication method, type of binder employed and sintering processes in a wide range. [7][8][9][10][11] A binder must be used to bring and bind the alumina particles together for obtaining sufficient mechanical properties in supports.Amount of binder used is effective in providing acceptable mechanical strength.…”

Open‐Porous Silicon Nitride‐Based Ceramics in Tubular Geometry Obtained by Slip‐Casting and Gelcasting

“…[3,4] Separation processes employing porous ceramic materials, such as micro-and ultrafiltration or gas separation, have gained increasing attention in various industrial sectors, reaching from chemical and biochemical processing to energy-and environment-related fields, with the particular benefit of improved operability in harsh thermal and chemical environments compared to conventional polymer-based materials. [5] A wide variety of methods and approaches has been reported on the generation of porous Si 3 N 4 and related ceramics, including direct foaming, [6] the addition of pore-forming agents, [7][8][9] combustion synthesis, [10] freeze-casting, [11] or phase separation. [12] Another straightforward approach is partial sintering, where the sintering process is halted before full densification, thus retaining an open-porous pore network between partially connected Si 3 N 4 particles in the final material.…”