Cordierite Honeycomb Research Articles

Cordierite ceramic membrane preparation using gas solid reaction growth for nanoparticles filtration

Mullite whiskers have been successfully grown on the surface of cordierite honeycomb ceramics by the gas-phase growth method. The cilia-like structure can significantly improve the filtration precision. The acicular mullite whiskers grew on the cordierite present nanometer-sized (200–300 nm) diameters and micrometer-sized (1–2 μm) lengths. Owing to mullite whiskers growth on surface of pores, the morphology of pores is changed and the microstructure change will lead to filtration precision increasing. The composites with the largest ratio of length/diameter mullite whiskers possess the highest filtration precision, which can reach 122.42 nm, 255.00 nm and 458.67 nm in intercepting different particle size of nano-SiO2, respectively. Moreover, the bending strength of the cordierites were enhanced due to the generation of mullite whiskers, these generated whiskers intersected with each other forming many unfixed lap-jointing points. The porous ceramics membrane with the unique microstructure has great potential application in gas-solid separation field and liquid-solid separation field.

Low-Temperature Catalytic Oxidation of Volatile Organic Compounds (VOCs) using Transition Metal Mixed Oxide Catalysts

This paper discusses the modification of MnOx by doping various metals, such as Cu, supported on cordierite honeycomb ceramics, which were easily synthesized by using the impregnation method. The physicochemical properties were comprehensively featured via the BET, XRD, SEM-EDX and H2-TPR techniques. Activity results suggested that the introduction of doping metals significantly enhanced the catalytic performance of Cu1Mn2Ox compared to single metal oxides. Furthermore, in the catalytic oxidation of benzene and toluene, the monolithic Cu1Mn2Ox catalyst demonstrates the best catalytic performance. It was able to completely oxidize the two compounds at 275oC with a reaction velocity (WHSV) of about 18,000 mL/(g•hr) and pollutant concentrations of 7000 ppm and 12000 ppm, respectively. The formation of a Cu-Mn solid solution with spinel Cooper-Manganese structure was thought to be the cause of the excellent catalytic performance of monolithic Cu1Mn2Ox. This resulted in an increase in the amount of adsorbed oxygen species on the surface and a high lattice oxygen mobility. This can improve catalyst reducibility and oxygen species activity, as demonstrated by significantly higher dehydrogenation temperatures of Cu-Mn composite oxides through H2-TPR. Meanwhile, the monolithic Cu1Mn2Ox catalyst showed good stability in 16 hours of testing and cycle ability test and showed great potential in practical application.

Magnesium borate whiskers/La2-XCeXZr2O7 catalysts preparation on cordierite honeycomb ceramic surfaces for soot catalytic oxidation͏

Magnesium borate whiskers were used to prepare a hierarchical microstructure on cordierite ceramic substrate through the precipitation-molten salt method. The La2-XCeXZr2O7 catalyst was then loaded onto the magnesium borate whiskers to form the hierarchical microstructure. The Ce-doped catalysts exhibited a significant improvement in the catalytic activity of soot combustion compared to the La2Zr2O7 catalyst. The study employed various techniques to characterize the structural morphology and phase composition, including scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffraction (XRD). The growth of Magnesium borate whiskers (Mg2B2O5) with diameters of 100–200 nm and lengths of 2–5 μm were grown and tightly bonded to the cordierite ceramic substrate to mimic the structure of human respiratory system cilia. This could improve the filtration efficiency of soot in car exhaust. BET analysis showed that the specific surface area of cordierite increased from 0.684 m2/g to 1.363 m2/g after whisker growth. The study confirmed that the whiskers were firmly attached to the cordierite ceramic substrate, as demonstrated by the binding strength experiments. The addition of Ce metal has been found to significantly enhance soot combustion due to the presence of more active oxygen species and superior mobility of lattice oxygen species with more oxygen vacancies. The catalyst's intrinsic redox property was characterized using X-ray photoelectron spectroscopy (XPS) and H2 temperature-programmed reduction (H2-TPR). The semi-quantitative thermogravimetric analysis (TG-DTG) and the temperature-programmed oxidation (TPO) of catalysts showed that Z-La1.9Ce0·1Zr2O7 exhibited the highest catalytic activity for soot combustion, with an ignition temperature of 268 °C, a peak temperature of 418 °C, and a temperature of 90 % soot conversion of 464 °C. Furthermore, cyclic stability experiments demonstrate that the Z-La1.9Ce0·1Zr2O7 catalyst exhibits excellent structural stability and consistent catalytic performance. This distinctive microstructure holds great potential for applications in the field of DPF.

Quench-induced Cu-ZnO catalyst for hydrogen production from methanol steam reforming

Methanol steam reforming (MSR) is considered as a promising approach to provide hydrogen for proton-exchange membrane fuel cells. However, it is challenging to develop effective and durable Cu-based catalysts. Herein, Cu-ZnO catalysts are prepared by facile quenching of ZnO in copper nitrate solution followed by reduction to obtain the desired metal loading and induce the doping of surface metal heteroatoms for producing more vacancies. Catalysts enriched with oxygen vacancies can efficiently activate H2O and rapidly transform C-containing intermediates, resulting in higher methanol conversion and lower CO selectivity. As a result, the quenched optimal catalyst achieves 100 % methanol conversion and 0.05 % CO selectivity at 280 ℃, exhibiting the excellent catalytic performance in MSR reaction. In practical applications, structured catalysts are more attractive for large-scale catalytic reactions owing to the low pressure drop and high utilization efficiency. Therefore, ZnO-Cu3 catalyst is coated on cordierite honeycomb ceramics with 100 % methanol conversion and 0.04 % CO selectivity at 280 ℃. After 100 h of the reaction, the structured catalyst remains ∼ 92.3 % with CO selectivity varying from 0.02 to 0.06 %, demonstrating the good catalytic stability in the long-term experiment. In addition, the evolution of reactants and intermediates on the catalyst surface are briefly described by FTIR spectra. This study offers a novel and efficient approach to obtain highly active and durable catalysts with great potential for industrial-scale preparation and application.

K+ doping Ce-Sm oxide catalysts on cordierite honeycomb ceramic substrate for soot catalytic combustion

K+ doping Ce-Sm oxide catalysts on cordierite honeycomb ceramic substrate for soot catalytic combustion

A method to in-situ synthesize surface coating of SiC nanowhiskers on cordierite honeycombs by combining aluminothermic, silicothermic and carbothermic reduction reactions

A simple in-situ method was proposed to synthesize surface coating of SiC nanowhiskers on cordierite honeycombs by aluminothermic, silicothermic, and carbothermic reduction reactions. The surface coating of SiC nanowhiskers was synthesized by controlling the partial pressure of SiO gas on the surface of honeycombs, based on the pore-forming process using aluminium(Al) agent. Increasing the porosity of the honeycombs provided aisles to volatilize SiO gas, and the growth of SiC nanowhiskers changed from inside the honeycomb wall to on the honeycomb surface. SEM and TEM observations revealed that the relatively high porosity (≥45%) and sintering temperature (1250–1300 °C) were necessary for obtaining surface coating of SiC nanowhiskers, and the nanowhisker-coating having the smooth morphology and a thickness of ∼150 µm was obtained at 1250 °C. Compared with cordierite honeycombs without SiC nanowhiskers, SiC nanowhiskers inside the honeycomb walls could improve the compressive strength and thermal conductivity with increasing rates of 121% and 123%, respectively, and the surface coating of SiC nanowhiskers increased the specific surface area of the honeycombs by 241 times.

By-product reduction for the non-thermal plasma removal of toluene using an α-MnO2/Cordierite honeycomb monolithic catalyst in a honeycomb structure

The practical implementation of non-thermal plasma (NTP) combined with catalysts still faces challenges due to the by-products, such as O3 and nanoparticles. In this study, α-MnO2/Cordierite honeycomb monolithic (CHM) catalyst was used to reduce the by-products for NTP degradation of toluene. The by-products analysis shows that using the α-MnO2/CHM catalyst not only improves the degradation efficiency up to 98% and COX selectivity to 50%, but also simultaneously and greatly reduces the release of three types of hazardous by-products, organic components, ozone, and particles. The mechanisms of toluene degradation and by-product formation were investigated through online monitoring which can be summarized in two ways: direct degradation by energetic electrons and reactive radicals in the discharge region, and deep oxidation by active oxygen species on the catalyst surface. This investigation can improve our understanding of VOC degradation by combining monolithic catalysts with plasma, and accelerate the implementation of plasma-catalyzed technology in real-world.

Cordierite@MOFs with Easy Recovery in CO2 Cycloaddition.

The objective of this research is to create monolithic heterogeneous catalysts (cordierite@MOFs) through the application of metal-organic framework (MOF) materials onto honeycomb cordierite for CO2 cycloaddition. By employing monolithic catalysts instead of powdered catalysts, the recycling and reusability of catalysts during postreaction treatment can be significantly improved.

CuO–ZnO catalyst decorated on porous CeO2-based nanosheets in-situ grown on cordierite for methanol steam reforming

Development of efficient and durable structured catalysts for hydrogen production by methanol steam reforming (MSR) is becoming extremely appealing owing to their low pressure drop and large open area. In this work, porous CeO2-based nanosheet array is in-situ grown on the surface of cordierite honeycomb ceramic by a simple hydrothermal approach. The generated porous nanosheet structure not only surpasses the obstacle of low specific surface area of cordierite (increasing from 4.4 to 252.6 m2 g-1), but also the peak area ratio of oxygen vacancies on the support surface rises from 19.7% to 29.7%, which are favorable to promote the catalytic activity and reduce by-product CO selectivity of structured catalysts in MSRreaction. Importantly, the structured catalysts formed by decorating CuO–ZnO catalysts on CeO2-based nanosheets via sol-gel combustion method remain porous structure, offering an ideal space for reactant entry and mass transfer diffusion, which facilitates reaction triggering and product discharge. The optimal structured catalyst achieves 100% methanol conversion at 260 °C without CO and the methanol conversion remains at 94.7% after 100 h of the reaction, exhibiting the excellent catalytic activity and durability. Thus, the structured catalyst has potential for industrial-scale preparation and application, especially for on-site hydrogen production in vehicles.

Effect of starch pore formers with different particle sizes on cordierite porous ceramics

Particulate matter (PM) from vehicle exhaust can be effectively removed by cordierite particulate filters. The pore size and distribution of the cordierite particulate filter are very important to PM trapping efficiency. The main factors affecting the pore formation of porous cordierite ceramics are the grain size of the feedstock, the size of pore-forming agent particles, the sintering process, etc. Talc, kaolin, silicon oxide, alumina, and boehmite were used as the raw materials, and the effects of starch pore formers of different particle sizes on the CTE, XRD, microstructure, pore size distribution, and mechanical strength of honeycomb cordierite were investigated.

Application of metal-BDC-derived catalyst on cordierite honeycomb ceramic support in a microreactor for hydrogen production

Three metal-organic frameworks including Ce-BDC, In-BDC and In/Ce-BDC and corresponding derived CuO/ZnO/In2O3/CeO2 catalysts were prepared. The catalyst-loaded cordierite honeycomb ceramic supports were applied in a microreactor for hydrogen production via methanol steam reforming. The In/Ce-BDC-derived catalyst exhibited a methanol conversion rate of 100%, a hydrogen yield of 0.336 mol/h and an energy efficiency of 54% at 300 °C and an inlet methanol flow rate of 0.112 mol/h. Moreover, CO with content lower than 1.5% and catalytic stability of 30 h was recorded. The high specific surface area and superior redox property of the In/Ce-BDC-derived catalyst were characterized. The increased contents of oxygen vacancies and surface oxygen, in collaboration with the improved solid solubility of CuO and ZnO, were associated with the charge exchange induced by the strong interaction between In2O3 and CeO2, leading to the excellent catalytic performance of the In/Ce-BDC-derived catalyst.

Preparation and characterization of Na4Mn9O18 whiskers on channel surface of cordierite honeycomb ceramics for soot catalytic combustion

Na4Mn9O18 whiskers were prepared on the wall of cordierite honeycomb ceramics using the molten salt synthesis, and Na4Mn9O18 whiskers were grew on channel surface of cordierite honeycomb ceramics to form hierarchical microstructure for catalytic combustion of soot. Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used to characterize the structural morphology and phase compositions. Na4Mn9O18 whiskers with aspect ratio of 24.4 measured by statistics. It was found that the loading rate of the monolithic catalyst reaches 3.588% while the binding rate after sonication almost no change. Whiskers are tightly combined with the cordierite ceramic substrate by the binding strength experiments and EDS analysis. The oxygen temperature-programmed desorption (O2-TPD) measurements were performed to investigate the O2 adsorption property. The catalytic performance of the samples were examined by semi-quantitative thermal gravimetric analysis (TG-DTG) and temperature-programmed oxidation (TPO). The catalyst performance study demonstrates that Na4Mn9O18 whiskers decrease the soot combustion temperature apparently. Experiments show the characteristic temperature could be reduced by increasing the catalyst loading. The Na4Mn9O18 decreased the ignition temperature of soot particles oxidation, and the cycle stability experiment confirmed that the sample (0h-m-k) has good structural stability and stable catalytic performance. The coarseness of the interface increased because Na4Mn9O18 whiskers grew on the cordierite substrate, and the trapping ability improved. Na4Mn9O18 is an important type of catalyst which is rarely studied in catalytic oxidation of soot. This catalyst displays good activity and stability in the soot catalytic oxidation. This unique microstructure has potential application in the DPF field.

Hydrogen production via supercritical water gasification of glycerol enhanced by simple structured catalysts

The supercritical water gasification (ScWG) technology is a promising alternative for H2-rich gas production from renewable sources, such as residual glycerol from biodiesel manufacture. Combined with heterogeneous catalysts, the ScWG process can achieve improved selectivity towards the desired products and high conversion efficiency in short reaction times. In this work, the efficiency of a synthesized Ni-based catalyst supported in cordierite (CRD) honeycomb structure on the ScWG of glycerol was evaluated and compared with two commercial automotive catalysts. Initially, to determine the best experimental conditions, the ScWG experiments were conducted in the absence of catalysts at constant conditions pressure (25 Mpa) and volumetric flow rate (10 mL min−1). The temperature range of 400–700 °C and glycerol feed composition between 10 and 34 wt% were evaluated. The catalysts evaluated were characterized by SEM-EDS, XRD, N2 adsorption/desorption, XRF, WDS and TGA. The liquid and gaseous products were analyzed by TOC and gas chromatography, respectively. Results indicated that Ni/CRD catalyst showed the highest H2 yield (5.38 mol H2 per mol of glycerol fed) and long-term stability. Additionally, a comparison between the experimental results on the ScWG of glycerol and simulated thermodynamic equilibrium data was also reported. Thus, results demonstrated the great potential of the prepared catalyst to improve H2-rich gas production from glycerol gasification.

Fe-containing carbon-coated monoliths prepared by CVD in gaseous toluene abatement - parametric analysis of the Fenton process

The degradation of toluene (present in a gas stream) by the heterogeneous Fenton process was evaluated in a bubble column reactor. The process was catalyzed by macrostructured carbon-coated monoliths that were synthesized by chemical vapor deposition (CVD), which allowed carbon growth in honeycomb cordierite monoliths, while the iron (metal phase) was incorporated by adsorption. A detailed parametric study was carried out to evaluate the effect of the main variables and process operating conditions, namely channel density of the monolith, hydrogen peroxide concentration, pH and catalyst load; as process responses, the amount of toluene transferred - η, hydrogen peroxide consumption and dissolved organic carbon (DOC) concentration in the liquid phase were assessed. The maximum ratio between the toluene transferred per catalysts mass - η/W - (6.8 ×10−2 moltoluene gcat−1), with total oxidant consumption and higher intermediate compounds remaining in solution (DOC = 33 mgC dm−3), was reached when the process was performed with a monolith with a channel density of 230 cpsi, initial pH = 3.0, [catalyst] = 0.8 g dm−3, [H2O2] = 20 mmol dm−3. During all experiments, only a small amount of iron was leached from the catalyst to the liquid phase (ca. ≤1.0 wt%), proving its stability for such application; in fact, it was found that homogenous process contribution due to iron leaching towards the overall performance is ca. 10%.

Synthesis of Co,Ce Oxide Nanoparticles Using an Aerosol Method and Their Deposition on Different Structured Substrates for Catalytic Removal of Diesel Particulate Matter

The synthesis of Co and Ce oxide nanoparticles using precipitation of precursor salt solutions in the form of microdroplets generated with a nebulizer proved to be an efficient, fast and inexpensive method. Different morphologies of single oxides particles were obtained. Ceria nanoparticles were almost cube-shaped of 8 nm average size, forming 1.3–1.5 μm aggregates, whereas cobalt oxide appeared as rounded-edged particles of 37 nm average size, mainly forming nanorods 50–500 nm. Co3O4 and CeO2 nanoparticles were used to generate structured catalysts from both metallic (stainless steel wire mesh monoliths) and ceramic (cordierite honeycombs) substrates. Ceria Nyacol was used as a binder to favor the anchoring of catalytic particles thus enhancing the adhesion of the coating. The resulting structured catalysts were tested for the combustion of diesel soot with the aim of being used in the regeneration of particulate filters (DPFs). The performance of these structured catalysts was similar to or even better than that exhibited by the catalysts prepared using commercial nanoparticles. Among the catalysts tested, the structured systems using ceramic substrates were more efficient, showing lower values of the maximum combustion rate temperatures (TM = 410 °C).

Study on the Adsorption Properties of Oxalic Acid-Modified Cordierite Honeycomb Ceramics for Neutral Red Dyes.

Removal of organic dyes from water by monolithic adsorbents is considered as an efficient and no-secondary pollution method. Herein, for the first time cordierite honeycomb ceramics (COR) treated with oxalic acid (CORA) were synthesized. This CORA exhibits outstanding removal efficiency toward the azo neutral red dyes (NR) from water. After optimizing the reaction conditions, the highest adsorption capacity of 7.35 mg·g-1 and a removal rate of 98.89% could be achieved within 300 min. Furthermore, investigation of the adsorption kinetics indicated this adsorption process could be described as a pseudo-second-order kinetic model with k 2 and q e of 0.0114 g·mg-1·min-1 and 6.94 mg·g-1, respectively. According to the fitting calculation, the adsorption isotherm could also be described as the Freundlich isotherm model. The removal efficiency could be maintained above 50% after 4 cycles, negating the need for toxic organic solvent extraction, offering a method for bringing the technology one step closer to industrial application and giving CORA promising potential in practical water treatment.

Low-energy production of a monolithic catalyst with MnCu-synergetic enhancement for catalytic oxidation of volatile organic compounds

Producing a low-cost catalyst by a low-cost method is one of the hottest topics in the field of catalytic oxidization of volatile organic compounds (VOCs). In this work, a catalyst formula with a low-energy requirement was optimized in the powdered state, and verified in the monolithic state. An effective MnCu catalyst was synthesized at a temperature as low as 200 °C. Removals were all bigger than 88% for toluene, ethyl acetate, hexane, formaldehyde, and cyclohexanone at a low temperature of 240 °C. The MnCu catalyst was then loaded on a honeycomb cordierite, which was also effective for toluene removal at 240 °C. After characterizations, active phases were Mn3O4/CuMn2O4 in both the powdered and monolithic catalysts. The enhanced activity was attributed to balanced distributions of low-valence Mn and Cu, as well as abundant surface oxygen vacancies. The obtained catalyst is produced by low energy and effective at low temperature, which suggests a perspective application.

Ru-based monolithic catalysts for the catalytic oxidation of chlorinated volatile organic compounds.

A series of cordierite monolithic catalysts with Ru species supported on different available low-cost carriers were prepared and investigated for the elimination of CVOCs. The results suggest that the monolithic catalyst with Ru species supported on anatase TiO2 carrier with abundant acidic sites exhibited the desired catalytic activity for DCM oxidation with the T 90% value of 368 °C. In addition, a pseudo-boehmite sol used as binder was introduced into the preparation of the monolithic catalysts to further improve the adhesion between the powder catalysts and cordierite honeycomb carrier. The results suggest that although the T 50% and T 90% of the Ru/TiO2/PB/Cor shifted to higher temperature of 376 and 428 °C, the weight loss of the coating for the Ru/TiO2/PB/Cor catalyst was improved and decreased to 6.5 wt%. Also, the as-obtained Ru/TiO2/PB/Cor catalyst exhibited ideal catalytic properties for the abatement of ethyl acetate and ethanol, indicating that the catalyst can meet the demand for the treatment of actual multi-component industrial gas.

Hydrogen Production System through Dimethyl Ether Autothermal Reforming, Based on Model Predictive Control

In this study, a thermodynamic analysis of the low temperature autothermal reforming (ATR) of dimethyl ether (DME) for hydrogen production was conducted. The Pd/Zn/γ-Al2O3 catalyst coated on the honeycomb cordierite ceramic was applied to catalyze the reaction, and the optimum activity temperature of this catalyst was demonstrated experimentally and through simulations to be 400 °C. Furthermore, an optimal model predictive control (MPC) strategy was designed to control the hydrogen production rate and the catalyst temperature. Experimental and simulation results indicated that the controller was automated and continuously reliable in the hydrogen production system. By establishing the state-space equations of the autothermal reformer, it can precisely control the feed rates of DME, high-purity air and deionized water. Ultimately, the hydrogen production rate can be precisely controlled when the demand curve changed from 0.09 to 0.23 mol/min, while the catalyst temperature was maintained at 400 °C, with a temporary fluctuation of 4 °C during variations of the hydrogen production rate. Therefore, the tracking performance of the hydrogen production and the anti-disturbance were satisfactory.

Scalable design of zinc-bromine battery in 3-dimensional honeycomb lattice for superior low-cost battery

Most of the existing redox flow batteries adopt 1-dimensionally stacked cells in which electrodes, flow frames, gaskets, and membranes are repeatedly stacked in one direction. However, these stacked cells suffer from system complexity, high cost, and insufficient cell performance. Herein, we suggest an attractive cell configuration with a 3-dimensional ceramic framework by adopting an industrially available cordierite honeycomb structure. We successfully demonstrate a zinc bromine battery (ZBB) with this 3-dimensional framework. Because the porous ceramic structure shows multi-functional characteristics as membranes and electrolyte channels as well as the cell housing, it does not require expensive membranes or flow frames, thus significantly reducing the stack manufacturing cost by about 64.5%. Furthermore, it shows superior behavior in terms of cell performance such as rate characteristics (>97% coulombic and >63% energy efficiencies at 60 mA/cm2), practical energy density (52 Wh/L), and cyclability over 500 cycles, compared to previous studies on ZBBs. By connecting more channels in serial or parallel mode, flexible scale-up is feasibly demonstrated without any performance degradation.