Symposium CI
Porous Ceramics for Environmental Protection, Energy-related Technologies and Advanced Industrial Cycles

Session CI-1 - Novel Synthesis and Processing

CI-1:IL01  Colloidal Processing of CeO2 Pellets with Hierarchical Porosity as Spent Fuel Matrix Analogue
S. FERNANDEZ, J. COBOS, Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain; R. MORENO, Instituto de Cerámica y Vidrio, Consejo Superior de Investigaciones Científicas, Madrid, Spain

Nuclear fuel is subjected to high levels of radiation during operation, leading to substantial modifications of the fresh fuel microstructure. Thus, the evolution of the microstructure and mechanical properties of spent fuel prior to and during disposal must be studied. Since handling of the spent fuel has to be done under hazardous conditions an alternative method is by using analogue with the same microstructure as UO2 spent fuel. Irradiated fuel has a radial microstructure with graded porosity from the center to the RIM of the pellet. The objective of this work is to produce CeO2 pellets with a similar microstructure to that of irradiated fuel pellets. A simple way to reproduce the porosity gradient of the final radial structure of the spent fuel is proposed consisting on the production of a central disc by axial pressing and an outer ring produced by slip casting. In order to obtain the adequate control of the microstructure the colloidal and rheological properties of aqueous suspensions were optimised for the preparation of the outer ring by slip casting around the green inner disc obtained by pressing, which acts as a permeable mold. Sintering conditions were adjusted to reach the desired final densities and phase and microstructural characterisation was then performed.


CI-1:IL02  Novel Processing of Open Celled Glass and Glass-ceramic Foams
E. BERNARDO, A. RINCON ROMERO, P. RABELO MONICH, H. ELSAYED, Università degli Studi di Padova, Dipartimento di Ingegneria Industriale, Padova, Italy

A new technique for the production of highly porous glass-based foams has been developed, according to the combination of alkali activation and gel casting. The alkali activation of soda-lime waste glass powders allows for the obtainment of well-dispersed concentrated suspensions, undergoing gelification by treatment at low temperature (75 °C), with formation of calcium silicate hydrated compounds. An extensive direct foaming may be achieved by mechanical stirring of partially gelified suspensions, comprising also a surfactant. The final microstructure (total amount of porosity, cell size) can be directly correlated with the degree of gelification and firing conditions. In fact, depending on the temperature, the porosity could be mostly closed or open: sintering at temperatures well below the crystallization temperature allows some viscous flow, with formation of thin membranes between adjacent cells; on the contrary, sintering at the crystallization temperature determines the ‘freezing’ of the open-celled structure from mechanical foaming. The process can be extended to several types of CaO-rich glasses, including bioactive glasses, glasses from the melting of inorganic waste and even mixtures of soda-lime glass and slags.


CI-1:IL03  Fabrication of Porous Si3N4/SiC Ceramics via Rapid Nitridation Processing and ZrO2 as Catalyst
YUPING ZENG, Shanghai institute of Ceramics, CAS, Shanghai, China

Porous Si3N4/SiC ceramics were prepared using Si and SiC as raw materials, Y2O3 as sintering additive and ZrO2 as catalyst. The effect of Y2O3 or ZrO2 on the nitridation rate of the specimens was investigated as a function of temperature, nitridation time. Porous Si3N4/SiC ceramics with ZrO2 addition nitrided at 1400℃for 3h showed high nitridation degree and good mechanical properties. The experimental results revealed that ZrO2 was transformed to ZrN during nitridation and the promoted nitridation of Si was attributed to the interconversion between ZrO2 and ZrN. The nitridation time on the mechanical properties of samples with ZrO2 as catalyst was further investigated. After nitriding at 1400℃ for 3, 6 or 12h, Porous Si3N4/SiC ceramics with a high porosity over 58%, a high flexural strength over 88.9MPa and a linear shrinkage lower than 0.6% were obtained, and the catalytic mechanism of ZrO2 was also discussed.


CI-1:IL04  Additive Manufacturing of Porous Ceramics using Inorganic Polymers
P. COLOMBO, University of Padova, Dept. Industrial Engineering, Padova, Italy

This talk will discuss the fabrication of porous structures starting from pure preceramic polymers (e.g. silicone resins) or silicone resins plus reactive fillers to produce advanced silicate ceramic phases, including bioceramics and Ceramic Matrix Composites, suitable for different potential applications. Different types of additive 3D manufacturing techniques were employed, including: a) direct printing using a fused deposition printer; b) direct printing using a paste extrusion printer (Direct Ink writing); c) indirect printing using a powder bed-based printer (in collaboration with researchers from BAM, Berlin, Germany); d) indirect printing using a stereolithographic printer; e) indirect printing with sub-micron resolution using 2 Photon Polymerization fabrication. This talk will also report on DIW of geopolymer inks; geopolymer pastes with optimized pseudo-plastic with yield stress behavior were developed and used for the fabrication of highly porous 3D lattices for filtration applications. Indirect powder-based additive manufacturing of geopolymers was carried out in collaboration with a company (Desamanera, Italy), and a binder mixture of suitable reactivity and rheology was sprayed on a bed of marble powder, resulting in large scale parts (that can be up to 6x6x6 m3).


CI-1:L06  Solidification Templating of Porous Polysilazane-derived Ceramics
T. KONEGGER, R. OBMANN, TU Wien, Institute of Chemical Technologies and Analytics, Vienna, Austria

In the recent past, the preparation of porous ceramics through the polymer precursor route has emerged as a viable alternative to conventional powder-based approaches. For many prospective applications, aligned or directed pores are required. Solidification templating, also known as freeze-casting, is a straightforward method to generate highly ordered, directional pore structures. However, in contrast to conventional freeze-casting involving the freezing of aqueous suspensions of particles, solidification templating of liquid polymer precursors, in particular compounds undergoing hydrolytic decomposition, is highly challenging, requiring completely new processing techniques. Here, we present a novel approach to prepare porous polysilazane-derived ceramics by combining non-aqueous solidification templating with a low-temperature photopolymerization process. Through this technique, we are able to extend the freeze-casting technique to water-sensitive liquid precursor compounds such as polysilazanes. A systematic correlation between solidification and polymerization parameters allows for the generation of polymer-derived non-oxide ceramic structures with highly variable pore geometries.


CI-1:IL08  Uniformly Porous Ceramics with 3-D Network Structure (UPC-3D) Prepared by Pyrolytic Reactive Sintering
YOSHIKAZU SUZUKI, Faculty of Pure and Applied Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan

When raw materials contain gasifiable components in their crystal structure, such as carbonate, oxalate, and hydroxide, these components can act as “intrinsic pore-forming agents” during sintering. In combination with the reactive sintering process, well-controlled pore structures can be obtained. This method is called the pyrolytic reactive sintering process. In 2000, using natural dolomite CaMg(CO3)2 as a starting material, the author et al. developed uniformly porous CaZrO3/MgO composite with a 3D network structure. This method has expanded to various porous ceramics, such as pseudobrookite with rod-like grains in 2010, beta alumina with plate-like grains in 2017, spinel, and so on. In this lecture, we introduce the detail of processing and some potential applications of UPC-3D, e.g., water purification filters.


CI-1:IL09  Reticulated Porous Ceramics – Cellular Stuctures for a Multitude of Functionalization Strategies
M. SCHEFFLER, S. RANNABAUER, Inst. of Material and Joining Technology, University of Magdeburg, Germany; U. BETKE, A. LIEB, F. SCHEFFLER, Inst. of Industrial Chemistry, University of Magdeburg, Germany

Even if the first patent dealing with reticulated porous ceramics (RPCs) was granted more than 50 years ago, there is still an immense interest in this type of cellular materials. This is, on the one hand side, due to the broad variety of materials – ceramics, metals, glasses – processable into RPC structures. On the other hand side, there is still room for micro-/macrostructural modifications of the strut materials, i.e. by filling the hollow inner part or by coating the outer part. Both strategies may be used to provide additional functionality to RPCs such as electric conductivity, catalytic activity, filtration activity or to provide better mechanical properties. In the first part of this paper processing of RPCs is discussed with a focus on the materials variety and processing conditions. The second part deals with novel modification und functionalization strategies of the RPCstruts: i) fluid phase infiltration of the hollow strut cavities, ii) fluid phase infiltration of the sintered-strut porosity and iii) surface properties modification of the outer struts. The third part will address novel applications such as heat pumps or heat storage materials, or rystallization-coating with microporous materials, e. g. for catalysis, or by tailoring the surface chemical properties.


CI-1:L10  Porous Glass-ceramics from Alkali Activation and Sinter-crystallization of Waste Glass Mixtures
P. RABELO MONICH¹, A. RINCON ROMERO¹, D. HÖLLEN², E. BERNARDO¹, ¹Dipartimento di Ingegneria Industriale, Università degli Studi di Padova, Padova, Italy; ²Chair of Waste Processing Technology and Waste Management, Montanuniversität Leoben, Leoben, Austria

Alkali-activated aqueous slurries of fine glass powders, mostly deriving from the plasma processing of municipal solid waste (‘Plasmastone’), were found to undergo progressive hardening, at low temperature (75 °C), owing to the formation of C-S-H (calcium silicate hydrate) gels. Before complete setting, slurries could be easily foamed by vigorous mechanical stirring, with the help of a surfactant; finally, the resulting open-celled structure could be ‘freezed’ by a subsequent sintering treatment, with crystallization of Ca-Fe silicates. The densification of the struts upon firing was enhanced by mixing Plasmastone with recycled glasses, up to 40 wt%, and operating on the firing temperature (from 800 to 1000 °C). A total porosity exceeding 75 vol%, comprising both well-interconnected macro-pores and micro-pores on cell walls, was accompanied by good compressive strength, well above 1 MPa. The stabilization of pollutants generally increased with increasing firing temperature and glass content, with some exceptions; no practical leaching was observed from samples deriving from Plasmastone combined with 30 wt% borosilicate glass from the recycling of pharmaceutical vials.


CI-1:L12  Glass Ceramic Foams from Vitrified Wastes Produced by Inorganic Gel Casting and Sinter-crystallization
A. RINCON, E. BERNARDO, Department of Industrial Engineering, University of Padova, Padova, Italy; M. SALVO, Department of Applied Science and Technology, DISAT, Politecnico di Torino, Torino, Italy  

Vitrification is one of the most efficient technique applied to hazardous wastes to produce homogeneous glasses, with high chemical durability and to incorporate possible pollutants into the amorphous structure of glass. Costs and energy consumption are the main drawbacks that could be well compensated by the conversion of waste glasses into new, usable and high added value glass-based materials. An innovative technique has been developed to produce cellular glass–ceramics from vitrified waste. In particular, we referred to vitrified bottom ashes of municipal solid waste incinerators and asbestos-containing waste. The method is based on the combination of alkali activation and inorganic gel casting. The initial vitrified waste materials first undergo to partial dissolution in weakly alkaline aqueous solutions; the subsequent progressive gelification, due to condensation reactions, is exploited to entrap air at low temperature, by intensive mechanical stirring with the help of a surfactant. The so obtained green cellular structure is later stabilized by sintering treatments at 800, 900 and 1000°C. Highly porous glass-ceramics feature porosities from 70 to 82%, with compressive strength values, from 2 to 6.4 MPa. In addition, leaching test confirm the stabilization of pollutants.


CI-1:IL13  From Micro to Ultra-Macro Porosity in Alkali Bonded Ceramics (Geopolymers)
E. PAPA, A. NATALI MURRI, E. LANDI, V. MEDRI, CNR-ISTEC, Faenza, Italy

Alkali bonded ceramics are synthetic and amorphous alkali aluminosilicates, also known as geopolymers, with properties varying among those of ceramics, cements, zeolites or refractories. Aluminosilicate powders are chemically consolidated in alkali aqueous solutions under mild thermal treatment (<100°C). At the atomic scale, SiO4 and AlO4 tetrahedra form Si–O–Al–O rings and chains, producing a 3-D network able to endow the material with several properties. The microstructure is intrinsically mesoporous being composed of nano-particulates separated by pores, whose size can be tailored changing the Si/Al/H2O ratios, the alkali cation or the synthesis conditions. Hierarchical pore systems can be constructed combining this mesoporosity with an induced macro- and ultra-macroporosity. Indeed, direct and indirect foaming techniques can be used to vary the pores morphology, orientation and dimensional range, depending on the final uses and applications of the material. Ice-templating can be used to obtain geopolymers with unidirectional lamellar pores, while blowing agents can generate materials with isotropic rounded pores. Fillers, as zeolite or expanded vermiculite, can add porosity respectively in the micro or ultra-macro range, and further functionalize the geopolymer.


CI-1:L14  Processing and Application of Porous TiC-Carbon Nanocomposites for Radioactive Ion Beam Production at CERN-ISOLDE
J.P. RAMOS, T. STORA, CERN, Geneva, Switzerland; A.M.R. SENOS, C.M. FERNANDES, CICECO, Aveiro, Portugal; P. BOWEN, EPFL, Switzerland

We have developed a novel TiC-carbon nanocomposite that displays high porosity, high specific surface area, extended stability under high temperatures and intense and highly pulsed proton beam conditions. These characteristics are beneficial for the constant production of 37K radioactive beams at the CERN-ISOLDE facility. Commercial nanometric TiC was mixed with three different carbon allotropes (graphite, carbon black and multi walled nanotubes) to stabilize the TiC nanostructure and maintain porosity at temperatures >1500 C. Using attrition milling the degree of agglomeration of the TiC powder was reduced with the Dv50 decreasing from 1.7 µm to 370 nm. The three different types of TiC and carbon suspensions were mixed, dried, pressed and sintered in high vacuum at 1500, 1650 and 1800 C. The nanostructured composites had porosities varying from about 5% to 60%, depending on the amount of carbon and the sintering temperature. They were characterised by MIP, NAD, SEM and XRD. The most stable composites, TiC-carbon black, showed grain sizes of 76 nm even after heat treatment at 1800°C. The processing route was scaled up and targets of 50 g were produced and results on the first successful use of TiC-carbon target (prototype) operated at CERN-ISOLDE will be presented.


CI-1:L15  High Content SiO2 Porous Glass Ceramics for High Temperature Applications and their Properties
L. ORTMANN, F.P. LUDWIG, U. HEIZE, QSIL GmbH Quarzglasschmelze Ilmenau, Langewiesen, Germany; H. RICHTER, IKTS Hermsdorf, Germany

For many years the QSIL GmbH produces fused silica glasses with the help of the plasma melting process. Besides, are produced before all Billets (hollow cylinder) with diameters to 550 mm, wall strengths to 150 mm and lengths up to 2500 mm with a very energy-efficient process. The silica glasses are often used as reactor pipes in thermal processes to 1100°C in different industrial branches. Because the deformation permanence of the fused silica is limited in the continuous operation to 1100°C. It was tried to develop a material with similar thermal, mechanical and chemical qualities and however, a clearly higher deformation permanence and is suitable for the application at temperatures greater than 1300°C. In support of the technology of the form stabilisation of fused silica, a glass ceramics were developed which show a SiO2 content ≥ 94% and guarantee after the crystallisation process a thermal form permanence of the material up to temperatures of 1500°C and surprice showed a very good permeability for gasses and liquids with low viscosities. The production process will be describe from the plasma melting process about forming process to the crystallisation process. In the following the thermo-mechanical properties of the porous glass ceramic are described and the limitation in the application of the material are discussed Besides it is tried to indicate a connection between certain qualities of the glass ceramics and the material composition as well as the crystallisation terms.


CI-1:IL17  Controlling the Pore Structure of Porous Ceramics Fabricated by the Gel-casting Method
YUNZI XIN, DAISUKE ASAI, JEONGSOO HONG, TAKASHI SHIRAI, Advanced Ceramics Research Center, Nagoya Institute of Technology, Nagoya, Aichi, Japan

Porous ceramics exhibiting high permittivity, large surface area, light weight and good thermal insulating properties have attracted much attention in many potential applications such as filters, catalyst carriers, sensors, bioceramics and construction materials. Gel-casting is one of the simplest approaches for preparing porous ceramics by combining the foaming of slurry of ceramic powder and organic monomers followed by in-situ polymerization. The fabricated porous ceramics show relatively high intensity and gel-casting method is also applicable for complicated shaped porous ceramics. Hydroxyapatite (HAp), Ca10(PO4)6(OH)2, has been intensely utilized as absorbent, bioceramics for artificial bone and tooth, as well as ion exchange material. HAp also attracted much attention as non-precious metal containing catalyst for oxidative decomposition of organic volatile compounds (VOCs) due to its thermal-excited superoxide radial site on surface. In this work, a HAp porous filter is developed by gel-casting. The control of pore structure will be introduced in detail and the catalyst performance of HAp porous filter for VOCs decomposition will also be demonstrated.


CI-1:L18  Tailoring the Microstructure of TiO2 Photoactive Electrodes by using Cellulose Nanofibers and by Polyelectrolyte Multilayer Absorption
Z. GONZALEZ GRANADOS¹, J. YUS¹, A.J. SANCHEZ-HERENCIA¹, A. RODRÍGUEZ², J. DEWALQUE³, L. MANCERIU³, C. HENRIST³, B. FERRARI¹, ¹Institute of Ceramics and Glass, CSIC, Tailoring through Colloidal Processing Group 5, Madrid, Spain; ²Chemical Engineering Department, University of Cordoba, Campus de Rabanales, Cordoba, Spain; ³University of Liege, Group of Research in Energy and Environment from Materials (GREENMAT), Liege, Belgium University

The TiO2 coatings with porous microstructures and high specific surface are highly on demand for application involving photoactivity phenomena such as solar cells or photocatalytic degradation. Many attempts to improve the photoresponse of the TiO2 electrodes are based on strategies to induce better reactant–catalyst contact through the design of complex structures with large surface-to-volume ratio. The TiO2 structuring and photoactivity can be controlled by tuning the physical properties (particle size, crystalline phase, preferred orientation) but also by shape forming of the TiO2 material host (e.g. soft or hard templating). This work promotes the development of novel strategies to tune the microstructure of TiO2 films which have been processed by a simple and easy up-scalable industrial method such as the dip-coating of colloidal suspensions of TiO2 modified particles. For this, two routes have been exploited: (1) the polyelectrolyte multilayer absorption (Layer by Layer - LbL methodology) and (2) the use of nanofibrillated cellulose (bioresources from agricultural wastes) as hard template. Finally, the microstructural differences (detected by SEM) have been discussed in terms of photovoltaic efficiency, dye loading (by UV-Visible Spectroscopy) and charge transfer(by EIS).


CI-1:IL20  Advanced Nanoporous Carbon Based Materials: Challenges and Opportunities
A. VINU, Global Innovation Chair Professor and Director, Global Innovative Center for Advanced Nanomaterials, Faculty of Natural Built Environment and Engineering, The University of Newcastle, Callaghan, Newcastle, NSW, Australia

Highly ordered nanoporous materials have been receiving a lot of attention in the recent years owing to their excellent textural properties including very high surface area, large pore volume and uniform pore size distribution. These properties make them attractive for various applications including energy storage and conversion, catalysis, sensing, and drug delivery. However, the performance of these materials in these applications is mainly dictated by their structure, morphology, functional elements both in the wall structure and the pore channels of these materials. In this talk, I will present the methods to fabricate a series of nanoporous carbon based materials including pristine carbon, functionalized carbons, carbon nitrides, boron carbon nitrides, conducting polymers, fullerenes and biomolecules with ordered nanoporous structure, controlled morphology and tunable pores. In addition, I will talk about different ways to control the structure, morphology and the functional elements in the wall structure and the pore diameter of these fascinating nanostructures. At the end of the talk, the structure-property relationship and its impact on the final performance of the above materials on sensing, and energy storage and conversion will be presented.

 
Session CI-2 -  Absorption, Capillary Phenomena and Thermophysical Behaviour

CI-2:IL02  Thermophysical Behaviour of Porous Ceramics in Atmospheres with Controlled Humidity. Relevance to Drying of Green Bodies
B. NAIT-ALI, S. OUMMADI, A. ALZINA, C. DANGLADE, M. ZOUAOUI, D.S. SMITH, University of Limoges, Limoges, France

Thermophysical properties of ceramics are important in applications or fabrication processes where heat transfer management is required. In real service conditions with humidity, porous ceramics take up water. Modification of the thermal properties (specific heat and thermal conductivity) has to be taken into account for better understanding and/or modelling of the material behavior. Variation in the specific heat with water content can be described by the rule of mixtures, but thermal conductivity variations require more attention. As a model case, experimental data on thermal conductivity variations with water content for porous zirconia ceramics are compared with analytical predictions taking into account the volume fraction of each phase and the water location in the material. A more complex situation is encountered in the drying of ceramic green bodies with strong variations in the water content. We present how the thermal conductivity evolves at different stages in the process and what kind of information related to water location can be deduced. These data will be discussed with microstructure observations during drying, using an environmental SEM. The influence of the thermal conductivity on the drying rate will also be revealed by comparing alumina and kaolin pastes.


CI-2:IL03  Hierarchically Porous Metal Hydroxides Through an Assembly of Crystalline Nanobuilding Blocks
YASUAKI TOKUDOME, M. TAKAHASHI, Department of Materials Science, Graduate School of Engineering, Osaka Prefecture University, Sakai, Japan

Green processes attract increasing attention because of their urgent need that is caused by environmental concerns. Metal hydroxides are known as a family of promising green materials due to the feasibility of their aqueous synthesis under moderate/ambient conditions, and moreover, inherent functionalities that are available in aqueous media free from poisoning. Especially, layered hydroxide 2D crystals composed of low-valence metal cations exhibit additional highlighted properties, such as reversible intercalation/deintercalation and anisotropic ion transfer. In this presentation, soft chemical approaches allowing the nanostructuration of metal hydroxides are demonstrated. Starting from metal salts and acids dissolved in an aqueous solvent, the nanocrystallization of metal hydroxides was induced by an epoxide-mediated alkalization reaction. Highly-supersaturated reaction solutions, i.e., concentrated reaction mixtures were employed for the induction of the nanocrystallization. The nanocrystals were then used as nanobuilding blocks (NBBs) for the controllable formation of 3D architectures through two different schemes. Special attension will be focused on adsorption capability onto these porous materials for environmental/bio applications.


CI-2:IL04  Low Temperature Processing of Silicon Carbide Membranes for Wastewater Treatment
YOUNG-WOOK KIM, HEE-JONG YEOM, HUI-YING SHENG, Functional Ceramics Laboratory, Department of Materials Science and Engineering, University of Seoul, Seoul, South Korea

Porous SiC membrane supports were fabricated from SiC and a bonding agent (glass frit or Si) at temperatures ranging from 850oC to 1400oC in air by a simple pressing and heat-treatment process. During heat-treatment, the glass frit and Si transformed to a viscous glass phase and SiO2, respectively, which acted as a bonding material between SiC particles and as a protecting layer for severe oxidation of SiC particles. The specific flow rate of the SiC membrane supports increased with increasing SiC particle size in the initial composition. This result indicates that the specific flow rate, in the porosity range of 35-50%, is primarily dependent on the pore size rather than the porosity. Crack-free γ-Al2O3-coated glass-bonded SiC membranes and all SiC membranes were successfully prepared using a simple heat-treatment and dip-coating process at a temperature as low as 850ºC in air. The SiC membranes with a support prepared from 10 μm SiC powder showed an exceptionally high oil rejection rate (99.9%) at a transmembrane pressure of 101 kPa. The typical flexural strength, steady state flux, and oil rejection rate of the alumina-coated SiC membrane were ~80 MPa, 1.78 x 10-5 m3m-2s-1, and 99.9%, respectively


Session CI-3 - Structure and Functional, Mechanical and Thermal Properties of Porous Ceramics; Structure/Transport/Functional Properties Relationships

CI-3:IL01  Mechanical Properties of Porous Ceramics
S. MEILLE, Université de Lyon, INSA de Lyon, MATEIS UMR CNRS 5510, Villeurbanne, France

Highly porous ceramics (typically above 40 vol%) show a high potential for multifunctional applications. The presence of an interconnected porous network allows the transport through the material: liquids or gases for filtration, cells access and vascularisation for biomaterials. It can also improve insulation properties and acoustic absorption for construction materials. The mechanical properties are however strongly affected by porosity and must be carefully characterized. This presentation will focus on the influence of microstructural parameters (volume fraction and morphology of the porosity) on different mechanical parameters (fracture strength in tension and uniaxial compression, instrumented indentation) for porous ceramics. The determination of specific constitutive laws for such materials will be discussed, possibly taking into account the compaction at high compression pressures.


CI-3:IL02  Oxidation-bonded SiC Membrane for Water Treatment
IN-HYUCK SONG, S.Z.A. BUKHARI, J.H. HA, J.M. LEE, Korea Institute of Materials Science (KIMS), Changwon, Gyeongnam, South Korea

Porous SiC is a proven viable material for microfiltration membranes, but its application has been limited by high fabrication cost. In this study, the oxidation bonding technique was used for the first time to fabricate SiC microfiltration membrane. The study was divided into two parts: optimization of the slurry used to dip coat the SiC particles over a porous SiC ceramic support and controlling the oxidation behaviour of SiC with respect to temperature. The oxidation behaviour during different thermal treatments was related to pore morphology and ultimately to membrane permeance. By coating the clay-bonded SiC support with oxidation-bonded SiC and sintering the coating at 1100 °C for 1 h, we prepared a defect-free microfiltration membrane with pure-water membrane permeance of >210 l m−2 h−1 bar−1, an average pore size of 93 nm, and a narrow pore-size distribution.


CI-3:IL03  Material Design for High Temperature Application
F. RAETHER, G. SEIFERT, Fraunhofer Center for High Temperature Materials and Design (HTL), Bayreuth, Germany

Various types of pores are introduced in high temperature ceramics to improve material properties, e.g. thermal shock resistance and insulation performance. On the other hand pores deteriorate mechanical properties like strength and creep resistance. Considering pores there is a conflict of objectives which require a careful design of pore fraction, pore size and pore shape in the respective ceramic microstructure. Systematic tools are presented for an integrated computational materials engineering (ICME) of porous high temperature ceramics. ICME comprises simulation of processing, microstructure, material properties and performance. In addition, experimental data on high temperature material properties of porous ceramics are obtained using novel thermooptical measuring devices. Some applications of these systematic methods are presented with new porous ceramics developed for high temperature use, e.g. kiln furniture and thermal insulation.


CI-3:IL04  Hydrogen-selective Si-based Inorganic-organic Hybrid Membranes for Solar Hydrogen Production via Photoelectrochemical Water-splitting
YUJI IWAMOTO, Nagoya Institute of Technology, Nagoya, Japan

Recently, increasing attention has been directed to a novel hydrogen production system using photoelectrochemical water-splitting cells. This system essentially requires hydrogen separation from co-produced oxygen, and membrane separation is one of the candidate processes. Since the hydrogen separation process is operated in the presence of water at low temperatures (below 373 K), there are several technical issues for the membranes such as swelling and blockage of hydrogen-permeable meso/micropore channels by water condensation. In this paper, our recent study on the polymer-derived Si-C-(O)-H inorganic-organic hybrid membranes will be presented. The water vapor adsorption-desorption isotherm analysis at room temperature revealed that the hybrids showed excellent hydrophobicity compared to sol-gel derived silica and gamma alumina which have been frequently used for ceramic membranes. The hybrid membrane samples showed good hydrogen-selectivity under dry condition at 298 to 353 K as well as under various water partial pressures up to RH=100% at 323 K, and these results will be shown and discussed from a viewpoint to develop novel hydrogen separation membranes for solar hydrogen production systems.


CI-3:L05  Aerogel Based Composites for Applications in Energy Technologies
G. REICHENAUER, C. SCHERDEL, ZAE Bayern, Wuerzburg, Germany

Aerogels are materials with tailorable porosity and pore size in the nano range. Its extraordinary physical properties are i.a. low thermal conductivity, high specific surface area for adsorption of gases and ions as well as low sound velocity and high acoustical damping. However, aerogels are brittle materials making them difficult to process and handle. In between, hybrid aerogels and composite aerogel materials have been developed. Their main advantages lie in the largely improved processing properties allowing for upscaling and introduction of additional functionalities by an extra phase. Examples are e.g. high mechanical stability at still low thermal conductivity, microscopic integration of battery functionalities in an electrostatic energy storage device (Pseudocaps) or targeted anisotropies (e.g. for thermal management). We give several examples for aerogel based composites developed recently, such as fiber reinforced porous carbons for high temperature thermal insulation, carbon based electrodes for electrical storage applications, silica foam composites for ambient temperature insulation and organic aerogels for acoustic impedance matching. We provide information on advantages in processing and compare the properties of the composites with the pure aerogels.


CI-3:L07  Impact of Illite Clay and Sintering Conditions on Development of Porous Cordierite Ceramics
M. RUNDANS, G. SEDMALE, L. GRASE, Riga Technical University, Institute of Silicate Materials, Riga, Latvia; K. Baltakys, Kaunas University of Technology, Faculty of Chemical Technology, Department of Silicate Technology, Kaunas, Lithuania

Cordierite ceramics can be described as materials having high temperature stability due to low coefficient of thermal expansion, combined with good mechanical strength and chemical stability. Such materials are widely used as substrate material for catalytic processes and supports for high temperature applications. In this work porous cordierite ceramic samples have been prepared by using two kinds of clays in starting compositions that differ by their content of illite and carbonate minerals. The changes of porosity, bulk density, modulus of elasticity, coefficient of thermal expansion and compressive strength have been investigated under gradual changes in maximum sintering temperature from 1200°C to 1350°C. The obtained porous ceramics samples can be characterized by macroscopic pore structure with apparent porosity approximately 60-70 vol%. Crystalline phase is composed from cordierite and magnesium spinel as trailing phase. Compressive strength test results show that the overall trend is related to mineral composition of used illite clay and to the sintering temperature. When higher carbonate mineral clay is used, the compressive strength of material is generally higher (30-35 MPa). A similar trend has also been found for modulus of elasticity and CTE measurements as well.


Session CI-4 -  Advances in the Characterization of the Porous Structures

CI-4:IL01  2D and 3D Imaging Characterization Techniques for Porous Ceramics
G. BRUNO, BAM, Bundesanstalt für Materialforschung und –prüfung, Berlin, Germany

The combination of microstructural data with other experimental techniques and with modeling is paramount, if we want to extract the maximum amount of information on porous material properties. In particular, quantitative image analysis, statistical approaches, direct discretization of tomographic reconstructions represent concrete possibilities to extend the power of the tomographic 3D representation to insights into the material and component performance. I will show a few examples of possible use of X-ray tomographic data for quantitative assessment of porosity in ceramics. Moreover, I will show how not-so-novel 2D characterization techniques, based X-ray refraction, can allow a great deal of insights in the damage evolution in microcracked (and porous) ceramics. I will show how X-ray refraction can detect objects (e.g. microcracks) below its own spatial resolution. Finally, I will discuss the link between the microstructural findings and the mechanical properties of porous microcracked ceramics.


CI-4:IL02  Characterization of Porous Ceramics via µCT
T. FEY, Chair of Glass and Ceramics, University Erlangen-Nürnberg, Erlangen, Germany

Cellular materials offer a wide spectrum of applications such as catalyst support structures, lightweight materials, energy adsorption, energy storage materials and filters. For filtration purpose an open-cell structure is needed. Beside light microscopy approaches in the past on several cross cut sections nowadays the use of x-ray microcomputer tomography (µCT) gives a full 3D-Model of the microstructure at given scanning resolution. Different porous ceramic foams and periodic cellular structures and composites are analysed by µCT-measurements providing 3D-volume data for microstructural evaluation. Starting from reconstructed 2D-slices structural parameter as cell size and strut thickness as well as surface and porosity can be calculated. Especially pore connectivity, pore network structure with their branch nodes and tortuosity are calculated from the pore volume data after thresholding. Due to the fact that experimental permeability measurements are limited in pressure and temperature range as well as type of gas or liquid (e.g. molten metal), simulation of permeability is in particular focus of interest. Based on micro computertomography (µCT) data the pore network is extracted for permeability simulations and tortuosity calculations. Darcian (linear) and Forchheimer (non-linear) permeability can be calculated from the simulated pressure drop in a defined volume of a cellular ceramic foam. A certain pore path within this volume for e.g. minimum pressure drop can be expressed by calculation of tortuosity.


CI-4:L04  Environmental Remediation of Silicon Oxycarbide (SiCO) Porous Materials
S. AGUIRRE-MEDEL, P. KROLL, Chemistry and Biochemistry Department, University of Texas, Arlington, TX, USA

We report synthesis of template-free porous silicon oxycarbide (SiCO) materials, their microstructural characterization and performance in environmental applications. One of processes consists of reacting siloxane precursors containing Si-H bonds with cross-linkers bearing vinyl groups using a platinum catalyst. The reaction in diluted solutions (80-95 vol%) converts the siloxanes into aerogels after supercritical drying in CO2. The other synthesis method involves hydrolysis and condensation reactions to obtain a cross-linked gel which is slowly dried at 45 °C to obtain a porous material. Porous SiCO materials are transformed via thermal treatment in controlled atmospheres into SiCO ceramics. The mesoporous SiCO ceramics show adsorption behavior towards organic dyes. We use UV-Vis spectroscopy to monitor the disappearance of the characteristic absorbance peak of the dyes. We characterize the porous SiCO materials’ specific surface area, nanoparticle size, pore size distribution, average pore size and total porosity. We are also interested in the investigation of the mechanism of the adsorption process. Specifically, we investigate the adsorption process dependence on microstructural and chemical properties of the material.


CI-4:L05  Spatially Resolved NMR Study of Regular and Irregular Ceramic Catalysts by Thermally Polarized Gas
M. MIRDRIKVAND, W. DREHER, DFG Research Training Group MIMENIMA (Micro-, meso- and macroporous nonmetallic Materials), In-vivo-MR Group, Department of Chemistry, University of Bremen, Bremen, Germany

The most important parameter influencing mass transport in ceramic foam catalysts is pore window size. It is promising to use Nuclear Magnetic Resonance (NMR) techniques as powerful geometrical characterization methods to investigate the effect of pore window size on propagator function of gases in catalytic gas phase systems. These techniques provide information for designing new tailored structures, which offer higher mass transport efficiency. In our study, commercial ceramic structures were experimentally investigated via an optimized localized Pulsed Field Gradient Stimulated Echo (PFG-STE) method to demonstrate the powerful advantages of using NMR for non-invasively characterizing opaque systems. The measurements show the local variations of the gas displacement function and diffusion coefficients in an arbitrary volume element and spatial direction. The results can be used for determining effective diffusivity and comparing the results with the average dispersion of gases predicted by numerical simulations of heterogeneous systems. The optimized method was applied on a 7T MRI system using a broad range of diffusion observation times (5-70 ms). The study allows a local comparative investigation of the gas propagator, diffusion coefficient and tortuosity for the structures.

 
Session CI-5 - Modeling and Simulation of Porous Structure and Properties

CI-5:IL01  Modelling of the Thermal Properties of Porous Ceramics: From Green to Fired Bodies
D.S. SMITH, B. NAIT-ALI, S. OUMMADI, F. PUECH, D. NOUGUIER, A. ALZINA, Institute of Research for Ceramics (CNRS UMR 7315), University of Limoges, Limoges, France

The presence of a pore phase in a polycrystalline ceramic has strong effects on the thermal properties and in particular by reducing the thermal conductivity. A toolbox of analytical relations, corresponding to the 2 phase mixture approach, will be presented and compared to experimental data for thermal conductivity of oxide ceramics containing pore volume fractions from 5 to 95%. In a first series of examples, important factors for the design of porous thermal insulation will be illustrated. The second part of the talk concerns the thermophysical properties of ceramic green bodies which typically contain 45-50% of porosity. Relevant to processing, changes in thermal conductivity of the green body with thermal treatment can be related to the sintering mechanisms. In addition to densification affecting the pore volume fraction, which can be handled by the approach described in the first part, attention will be paid to the role of neck formation which controls the particle – particle contact area in the porous body. A simplified approach to describe the thermal resistance of these contacts is developed. Finally, decrease in thermal response time of an alumina green body during firing, determining transient temperature distribution within the body, is discussed.


CI-5:IL02  Modelling of Porous Ceramics Produced by Additive Manufacturing
A. ORTONA, SUPSI, Manno, Switzerland

Porous ceramics are employed in several industrial application because of their unique properties resulting from the combination of a solid ceramic phase (e.g. Al2O3, ZrO2, SiC) and a gaseous or liquid phase (e.g. air, molten metal). Indeed they are vastly applied. Some examples are: molten metal filtration, catalytic supports and heat exchangers. To comply with the end users requirements a component must then be designed and its behavior simulated in relevant working conditions. In the case of foams, their morphology is approximated to a lattice of polyhedral cells in order to reproduce a numerical domain to which apply equations reproducing the phenomena under study. With the recent advent of additive manufacturing (AM) the design approach of this porous bodies has dramatically changed, opening up new unlimited possibilities. If once the engineering effort was devoted to simulate the behavior of an approximated object, it is now possible to optimize, through simulation, the optimal porous structure, not necessarily a lattice, specifically to its function and finally to produce it. This work presents this new approach providing some example of components produced by AM.


Session CI-6 - Progress in Applications of Porous Ceramics

CI-6:IL01  Additively-manufactured Reactors for the Intensification of H2 Production by Steam Methane Reforming: Fabrication, Functionalization and Recycling Issues
F. ROSSIGNOL, T. CHARTIER, B. TROUILHET, IRCER, UMR CNRS 7315, Limoges cedex, France; B. CROISSANT, R. FAURE, P. DEL GALLO, AIR LIQUIDE, CRPS, Jouy en Josas, France

Functionalized millistructured reactors-exchangers are promising solutions for the intensification of heterogeneous catalytic processes such as production of H2 by steam methane reforming (SMR). Off-site compact devices with volume production adapted to local consumption is today a general trend, for which additive manufacturing (AM) contributes to achieve enhanced performance and flexibility. Indeed the design complexity accessible through AM allows reducing heat and mass transfer limitations compared to conventional fixed bed reactors. Here we will discuss recent results about those complex additively-manufactured SMR reactors focusing on fabrication, functionalization and recycling issues, while paving the way to an industrial deployment in a short term.


CI-6:L02  Development of Small Scale Ceramic Microbial Fuel Cells for Clean Energy Extraction from Urine
I. GAJDA, X.A. WALTER, T. OBATA, J. GREENMAN, I. IEROPOULOS, Bristol BioEnergy Centre, BRL, T-Bloc, University of the West of England, Bristol, UK

During the last 20 years great interest in Microbial Fuel Cells (MFCs) has intensified due to the extraction of clean electricity from waste streams such as urine. The technology is based on ceramic built MFCs in which the terracotta chassis is also the membrane between the anode and the cathode half-cells. The microbial engine (anode) bio-transforms the organic matter in urine to generate direct electric current, whilst the cathode reduces oxygen allowing the extraction of water and nutrients from the waste stream. By improving the reactor configuration, size, electrode/volume ratio and further multiplication of units into stacks, the technology is able to produce usable power levels to operate indoor lighting, robots or charge devices such as mobile phones. Physical and chemical stability of ceramic based MFCs is allowing to also extract valuable compounds from urine in the cathode chamber in the form of catholyte adding value to the sustainable treatment of waste. This work is aiming to look into the improved levels of electric current with the use of non-platinum cathode catalyst as well as the physicochemical nature of the extracted catholyte as a metric of current induced treatment.


CI-6:L03  Transesterification of Soybean Oil using Geopolymers as Heterogeneous Catalysts
R.F. BOTTI¹, M.D.M. INNOCENTINI², P. PASTORE³, L.R. SAN GREGORIO², P. COLOMBO¹, ¹Department of Industrial Engineering, University of Padova, Padova, Italy; ²Course of Chemical Engineering, University of Ribeirão Preto, Ribeirão Preto-SP, Brazil; ³Department of Chemical Sciences, University of Padova, Padova, Italy

Diesel fuel plays an essential role in a country's economy but many problems are caused when fossil fuels are used. Biodiesel is a good substitute for diesel thanks to its similar properties. This work investigated biodiesel production by transesterification of soybean oil with methanol using geopolymers as heterogeneous catalysts. Geopolymers were prepared by mixing metakaolin with an alkaline solution. Three types of catalysts were prepared in powder form: Na-, K- and Na+K-based geopolymers. The influence of geopolymer heat treatment was also evaluated. The reaction condition tested was: methanol:oil ratio 7.5:1; catalyst amount 3%(w/w) of oil; temperature 70°C; time 2h. The reaction yield was calculated by GC while XRD, TGA-DTA and BET analysis were employed to obtain information about geopolymer. Atomic absorption spectrometry analysis was done to quantify the Na and K leached into the biodiesel. The results showed the geopolymers work as catalysts. The conversion is higher when the Na+K-based geopolymer is used (~95%), possibly due to the higher SSA. Moreover, the yield of reactions seems to be dependent on the geopolymer heat treatment. It should be noted that the biodiesel still contains some Na or K impurities, so a further optimization of material and process is required.


CI-6:L04  Ultrasmall Mesoporous Silica: A Better Catalysis Support
JIASHENG WANG, W. WU, W.H. WANG, M. BAO, School of Petroleum and Chemical Engineering, Dalian University of Technology, Panjin, China

Mesoporous silica materials as excellent supports have been widely applied due to their high specific surface area and tunable channel. It is well known that decreasing the particle size of porous support to shorten the channel length could reduce the mass transfer resistance and improve the catalytic activity. Ultrasmall mesoporous silica nanoparticles (UMSN, < 25 nm),have more advantages over the conventional mesoporous silica nanoparticles (MSN) as support because the decrease of their particle size shortens the access path and increases the specific area. In addition, the mesopores of UMSN make the internal active sites accessible to some big molecules, like DBT, which are difficult to enter microporous channels due to size limitation. Thus we chose to prepare UMSN as support to improve the efficiency of mass transfer. In this work, we synthesized subnano-MoO3 supported on UMSN (ca. 14 nm) with “raisin-bun structure” by reverse microemulsion. The subnano-MoO3/UMSN exhibited better catalytic activity compared to subnano-MoO3/ultrasmall microporous silica.


CI-6:IL05  Polymer-derived Mesoporous Ceramics as Catalysis Supports and Co-catalysts for Hydrogen Generation
A. LALE¹, U.B. DEMIRCI², S. BERNARD¹, ¹Institut de Recherche sur les céramiques (IRCER) UMR 7315 CNRS-Centre Européen de la Céramique, Limoges Cedex, France; ²Institut Européen des Membranes - IEM UMR 5635, Université de Montpellier, Montpellier Cedex, France

There is a trend toward more flexibility and an increased interest in "smart” and ”adaptive” materials with the objective to meet most industrial specifications. Nitrides and carbonitrides can be considered as such strategic materials. They attract increasing interest due to their properties targeted for future materials and technologies especially because they bear intrinsic multifunctionality through the synthesis of multi-element compounds. Inherent difficulties to the traditional techniques for manufacturing such multi-element materials can be overcome by the development of synthetic paths where chemistry of materials and ceramic science are combined rationally to process multi-scale complex solid state architectures. The Polymer-Derived Ceramics (PDCs) route offers new preparation opportunities in ceramic sciences. The molecular origin of preceramic polymers and the possibility to shape then pyrolyze them into advanced materials play a major role in the preparation of ceramics endowed with properties that reach far beyond those of existing materials. This presentation will be particularly focused on the polymer synthesis/processing/pyrolysis to design micro-/mesoporous nanocomposites as catalyst supports or co-catalysts for hydrolysis of liquid hydrogen carriers.


CI-6:IL06  High Performance Porous Ceramics for Energy Related Applications
J. GURAUSKIS^{1, 2}, V. GIL^{1, 3}, ¹Fundación Agencia Aragonesa para la Investigación y Desarrollo (ARAID), Zaragoza, Spain; ²AENEAM Advanced Membrane Technologies S.L., Zaragoza, Spain; ³Fundación Nuevas Tecnologías del Hidrógeno en Aragón, Parque Tecnológico Walqa, Huesca, Spain

The ability to manufacture ceramic materials with efficient porosity and sufficient mechanical robustness is important for a broad range of applications, e.g.: catalyst supports, filters, fuel cells, electrolysis electrodes, membrane reactors, CO2 capture and flue gas purification. The use of sacrificial pore formers, one of the most commonly used methods to generate porous ceramic structures, delivers random and inefficient porosity. Therefore, alternative processing routes capable of delivering effective porosity are highly demand. Two approaches will be discussed: use of non-combustible pore formers for developing effective random porous structures and use of ice as templating for manufacturing hierarchical porous structures. Non-combustible pore former route is based on porosity formation after final sintering step via reduction or mild leaching and results in a highly interconnected porosity. Ice templating route is based on porosity creation through generation and sublimation of ice crystals. The talk will be illustrated with some practical examples, where the challenges related to fabrication of desired microstructure via these two approaches will be presented. Their performance for efficient mass transport in energy related applications will be also discussed.


CI-6:L07  Design Approach for Porous Ceramics in Concentrated Solar Power Application
J. ADLER, A. FÜSSEL, W. BECKERT, Fraunhofer IKTS, Dresden, Germany; F. ZAVERSKY, L. ALDAZ, M. SÁNCHEZ, National Renewable Energy Center (CENER), Solar Thermal Energy Department, Spain; A.L. AVILA-MARIN, M. ISABEL ROLDAN, J. FERNANDEZ-RECHE, CIEMAT-Plataforma Solar de Almeria, Spain

The application of porous ceramic as solar absorber element in receivers of concentrated solar power (CSP) plants is connected to high, partially contradicting requirements on the material and its design. Open-celled ceramic foams offer a unique scope of adjustable properties and are thus of particular interest. To enhance the efficiency and durability of the receiver elements, it is essential to identify an optimal compromise between very thin struts for the highest radiative efficiency at low pressure drop and high mechanical and oxidation stability as well as high thermal conductivity at once. Focused on high temperature stable pressure less sintered Silicon Carbide, an advanced design approach will be presented. This includes modifications of the material itself and its intrinsic structural parameters characterizing the foam, such as cell size, strut shape and the herewith connected porosity. To optimize the shape of the receiver element, different designs have been tested by CFD simulation and in a solar furnace, indicating the strong interconnection between structural and functional properties.
The presented investigations and results are part of the currently running project CAPTure (Competitive SolAr Power Towers), funded by the European Union.


CI-6:L08  Enzyme-modified Porous Ceramic Capillaries for Continuous Flow Hydrolysis of Proteins
M.M. HOOG ANTINK¹, T. SEWCZYK², S. KROLL³, S. BEUTEL², M. MAAS¹, K. REZWAN¹, ¹Advanced Ceramics, University Bremen, Bremen, Germany; ²Institute for Technical Chemistry, Leibniz University Hannover, Hannover, Germany; ³Institute for Bioplastics and Biocomposites, Hochschule Hannover, Hannover, Germany

Up to now, the industrial enzymatic hydrolysis of proteins for the preparation of peptides is mostly performed in batch processes. In this regard, enzyme reactors in a continuous flow set-up can be used to improve inherent fluctuations in the protein hydrolysate composition. Due to their incompressibility and susceptibility to chemical surface modification, ceramic membranes are ideal substrates in immobilized enzyme reactors. In this study, the influence of surface functionalization of porous ceramic capillaries on enzyme immobilization and on their applicability in continuous flow hydrolysis of proteins is investigated. Successful chemical functionalization of the ceramic with both amino and carboxy groups was achieved by silanization and confirmed by photometric assay and surface charge analysis. Enzymes could be immobilized by both non-covalent and covalent adsorption on different types of modified porous ceramics with the highest observed loading on carboxy functionalized capillaries. An enhanced stability of covalently bonded enzymes against wash-out was shown under continuous flow. Enzyme activity measurements and HPLC analysis of the protein hydrolysates showed an effect of surface functionalization on the enzymes’ performance and thereby on the resulting hydrolysates.


CI-6:IL09  Particle-stabilized Foams: From Satellite Housings to High Performance Insulators and Fire Protection Materials
U.T. GONZENBACH, P.N. STURZENEGGER, de Cavis Ltd., Duebendorf, Switzerland

More than a hundred years ago, Ramsden and Pickering discovered the ability of fine particles to stabilize oil-water interfaces. However, it was only recently that these principles were applied to the formation of liquid ceramic foams. Such foams are technically important soft matter and crucial as intermediates for the production of porous ceramics. However, their thermodynamically unstable nature is a critical issue that can be drastically improved using colloidal particles as foam stabilizers. In-situ hydrophobization of colloidal particles is a powerful method to deliberately tailor wettability of particles of all kind via adsorption of short-chain amphiphilic molecules in order to enable the formation of stable wet foams. This presentation takes you on a journey from the early discovery of emulsion stabilization with fine particles to the long road to commercialization of particle-stabilized ceramic foams. It gives an overview of our activities in this emerging field and describes our method in detail, focusing on parameters controlling foam formation and processing of wet foams into porous ceramics, also giving insights into the commercialization and application of this highly interesting material class.


CI-6:IL10  Porous Geopolymers for Indoor Humidity Control
I. LANCELLOTTI¹, J. KIVENTERA², M. ILLIKAINEN², C. LEONELLI¹, ¹Department of Engineering “Enzo Ferrari”, University of Modena and Reggio Emilia, Modena, Italy; ²University of Oulu, Fiber and Particle Engineering, University of Oulu, Oulu, Finland

Excessive relative humidity indoors air causes mould problems resulting in health risks and effects on lighting and acoustical quality occur together with problems in the storage of goods and durability of buildings. In this study, new cement like pastes suitable to prepare sustainable building materials and mortars, were developed. Metakaolin based geopolymers containing cellulose fibers were formulated using commercial alkaline solutions. Different amount of cellulosic fibers were added to metakaolin using a cellulosic gel containing 2wt% of cellulosic sheets. The samples characterization shows that the presence of cellulose in the matrix leads to porous microstructure with a total porosity higher than 50%. Porosity is almost completely open, therefore the capability of water absorption-desorption was evaluated to study the application of these materials for the humidity control in indoor environment for sustainable buildings. The results show that cellulose geopolymers have higher humidity control than the reference metakaolin sample , indeed after a strong dehydration the water absorption is not too fast, avoiding significant changes in humidity. The results obtained have been compared to commercial ceramic materials showing similar indoor humidity control efficiency.


CI-6:L11  Emission Studies of Hydrogen Combustion for Cooking and Heating on Catalytic Coated Ceramic Foams
U.F. VOGT, T. BUETLER, B. FUMEY, EMPA, Duebendorf, Switzerland

Catalytic combustion of hydrogen has the potential to play an important role in the conversion of stored hydrogen from renewable energy sources to heat for cooking, space heating and domestic hot water supply in residential and service sector buildings. The objective of this study is the analysis of emission in the flue gas, especially for NOx, from a catalytic hydrogen combustion process. The tested burner assembly consists of two highly porous silicon carbide foam plates, coated with alumina wash coat for a high surface area and platinum as catalyst. Hydrogen is supplied from below, the assembly and air is forced between two catalytic plates. The tests are carried out with 5, 10 and 15 Nl/min hydrogen and synthetic air as oxidant with lambda of 1.5, 2 and 3. Flue gas analysis is performed inline, with the analyser nozzles placed above the burner assembly in a tunnel.  Test runs are started at a burner surface temperature below 150°C and a total test duration of 6 min. No CO₂ and very low NOx values of 0.004 to 0.12 mg/kWh are measured. This is by a factor of 10³ lower than the new EU regulation of 56 mg/kWh and shows that at a very clean and intrinsically safe combustion of hydrogen is possible for domestic application such as cooking and heating. The tested burner is integrated into an autarky living unit as cooking stove.