Preparation and Performance of Al_2TiO_5-TiO_2-SiO_2 Honeycomb Ceramics by Doping Rare Earth

A preferable honeycomb ceramics of Al2TiO5-TiO2-SiO2 doped by CeO2 and Er2O3 with high performance was prepared by means of extrusion molding and the effects of CeO2 and Er2O3 on the mechanical strength, thermal stability, and sintering temperature of ATS ceramics were mainly investigated. The experimental results and the microscopic analysis by scanning electron microscope, X-ray powder diffxaction, and TG-DSC showed that adding CeO2 and Er2O3 into ATS could prohibit the growth of their crystal grains and make their size uniform, which finally decrease its sintering temperature, and also enhance its mechanical performance as well as thermal stability. After the reforming, ATS doped by 0.5% CeO2 ＋0.5% Er2O3 was sintered at 1250 ℃, its bending strength reached to 177A MPa and thermal expansion coefficient was 3.8 ~ 10^-6/℃ at 25 - 1000℃, which provided a promising basis of making monolithic honeycomb catalyst of deNOx.

Preparation and properties of SiC honeycomb ceramics by pressureless sintering technology

SiC honeycomb ceramics with parallel channels and macroporous walls were prepared by combining extrusion molding with pressureless sintering technology in the presence of starch.The extrusion molding constructed honeycomb structure with parallel channels,while the starch formed spherical macropores on the channel walls.The density and bending strength of SiC honeycomb ceramics decreased with the increase of starch content,while the phase compositions did not vary with the starch content.The control in starch addition could adjust the pore structures on the channel walls of SiC honeycomb ceramics.

Continuous near-complete photocatalytic degradation of toluene by V/N-doped TiO_(2)loade d on honeycomb ceramics under UV irradiation

Photocatalytic degradation of volatile organic compounds(VOCs)is a significant applying aspect of pho-tocatalysis.Both the modulation of photocatalysts and the rational dispersion of them on supports are key for solar-driven VOC degradation.Conventional batch-type photoreactors have low efficiency while continuous-flow photoreactors suffer from the problem of incomplete removal of VOCs.Herein,aiming for continuous and complete degradation of toluene gas as the target contaminant,continuous-flow pho-tocatalytic degradation reactors were made by adhering the vanadium and nitrogen codoped TiO_(2)on honeycomb ceramics(V/N-TiO_(2)@HC)by a simple sol-gel method.In such a reactor,the rich ordered pores in the HC accelerate mass transport of toluene,and the introduction of V/N dopants narrows the bandgap and widens the light absorption range of TiO_(2),together resulting in continuous and nearly-complete pho-tocatalytic degradation of toluene.The unique and stable structure of HC allows the photocatalysts to be reused.The degradation rate of toluene gas can reach 97.8%,and after 24 rounds of photocatalytic degra-dation,there is still a degradation rate of 96.7%.The impacts of loading times and gaseous flow rate on the photocatalytic performance of V/N-TiO_(2)@HC are studied in detail.Our study provides a practical so-lution for the continuous and complete photocatalytic degradation of VOCs and opens a new application field for HC.

Degradation of benzophenone in aqueous solution by Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation

Comparative studies of ozonation alone, ceramic honeycomb-catalyzed and Mn-Fe-K modified ceramic honeycomb catalyzed ozonation processes have been undertaken with benzophenone as the model organic pollutant. The experimental results showed that the presence of Mn-Fe-K modified ceramic honeycombs significantly increased the removal rate of benzophenone and TOC compared with that achieved by ozonation alone or ceramic honeycomb-catalyzed ozonation. The electron paramagnetic resonance （EPR） experiments verified that higher benzophenone removal rate was attribute to more hydroxyl radicals generated in the Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation. Under the conditions of this experiment, the degradation rate of all the three ozonation processes are increasing with the amount of catalyst, temperature and value of pH increased in the solution. We also investigated the effects of different process of ozone addition, the optimum conditions for preparing catalyst and influence of the Mn-Fe-K modified ceramic honeycomb after multiple-repeated use.

Structured NiFe catalysts derived from in-situ grown layered double hydroxides on ceramic monolith for CO_(2) methanation

Monolithic catalysts for CO_(2) methanation have become an active research area for the industrial development of Power-to-Gas technology.In this study,we developed a facile and reproducible synthesis strategy for the preparation of structured NiFe catalysts on washcoated cordierite monoliths for CO_(2) methanation.The NiFe catalysts were derived from in-situ grown layered double hydroxides(LDHs)via urea hydrolysis.The influence of different washcoat materials,i.e.,alumina and silica colloidal suspensions on the formation of LDHs layer was investigated,together with the impact of total metal concentration.NiFe LDHs were precipitated on the exterior surface of cordierite washcoated with alumina,while it was found to deposit further inside the channel wall of monolith washcoated with silica due to different intrinsic properties of the colloidal solutions.On the other hand,the thickness of in-situ grown LDHs layers and the catalyst loading could be increased by high metal concentration.The best monolithic catalyst(COR-AluCC-0.5M)was robust,having a thin and well-adhered catalytic layer on the cordierite substrate.As a result,high methane yield was obtained from CO_(2) methanation at high flow rate on this structured NiFe catalysts.The monolithic catalysts appeared as promising structured catalysts for the development of industrial methanation reactor.

Catalytic decomposition of ethyl acetate over La-modified Cu-Mn oxide supported on honeycomb ceramic

The La-modified Cu-Mn spinel oxide was successfully coated onto honeycomb ceramic by a washcoating method for complete catalytic decomposition of ethyl acetate.The La-modified Cu-Mn oxides were characterized by X-ray diffraction,X-ray fluorescence,H_(2)-temperature programmed reduction,Brunauer-Emmett-Teller method,field-emission scanning electron microscopy and high-resolution transmission electron microscopy.The effects of different precipitants and rare earth doping on the structure and catalytic performance of the catalysts were investigated.The results show that the CuMn_(2)O_(4) spinel with(NH_(4))_(2)CO_(3) as a precipitant can form a larger specific surface area and a suitable pore size,which is beneficial to the absorption of ethyl acetate.Although the rare earth doping does not significantly change the crystal phase structure of the catalyst,it improves its reducibility and lowers the temperature of the catalytic decomposition.With respect to the catalytic decomposition of ethyl acetate,the rare earth-modified Cu-Mn oxide supported on honeycomb ceramic shows excellent catalytic performance with 100% conversion under the conditions of 239℃,space velocity of 12500 h^(-1) and 1000 ppm.And the ethyl acetate removal rate is still 100% after 1440 min of continuous reaction.

Electrically Conductive Honeycomb Monolith of Nanolaminated Ti_3AlC_2:Preparation and Characterization

Nanolaminated Ti3AlC2honeycomb monolith with parallel and uniform holes has been prepared through a facile extrusion route by using Ti3AlC2powder as the main raw material.The fabricated honeycomb monolith has high compressive strength of 133 ± 11 and 59 ± 9 MPa,along and perpendicular to the extrusion direction,respectively.It also has good electrical conductivity,and excellent match of thermal expansion coefficient with the washcoat material of γ-AI2O3.These combined properties endow the honeycomb monolith a promising candidate as catalysis substrate for cleaning vehicle exhaust.

Experimental study on oxidative decomposition of nitrobenzene in aqueous solution by honeycomb ceramic-catalyzed ozonation

The ozonation of nitrobenzene in aqueous solu-tion was carried out in a semi-batch reactor to investigate the degradation efficiency,the effect factors,and the reaction mechanism,where honeycomb ceramic was used as a cata-lyst.The presence of honeycomb ceramic could improve the degradation rate of nitrobenzene by 15.46%compared to the results of ozonation alone.Under the conditions of this exper-iment,the degradation rate of honeycomb ceramic-catalyzed ozonation increased by 12.94%with the increase of the amount of catalyst from 1 to 5 blocks.The degradation rates all increased greatly with the increase of temperature and pH of the solution in the processes of honeycomb ceramic-catalyzed ozonation and ozonation alone.But,when the pH of the solution increased to 9.50,the advantage of the honey-comb ceramic-catalyzed ozonation process would be lost.The experimental findings indicated that in the processes of ozonation alone and honeycomb ceramic-catalyzed ozona-tion,nitrobenzene was primarily oxidized by•OH free radical in aqueous solution.The adsorption of nitrobenzene was too limited to have an important influence on the degradation rate of nitrobenzene.With the same total dosage of applied ozone,the multiple step addition of ozone showed much higher removal efficiency than that obtained by one step in the two processes.

Catalytic ozonation of reactive red X-3B in aqueous solution under low pressure： decolorization and OH. generation

Catalytic ozonation of Reactive Red X-3B in aqueous solution had been carried out in an ozone oxidation reactor where Mn-Fe-ceramic honeycomb was used as the catalysts. The presence of Mn-Fe-ceramic honeycomb catalyst could obviously improve the deco- loration efficiency of Reactive Red X-3B and the utilization efficiency of ozone compared to the results from non-catalytic ozonation. Adsorption of Reactive Red X-3B had no obviously influence on the degradation efficiency. Addition of tert-butanol significantly decreased the degradation efficiency, indicating that the degradation of Reactive Red X-3B followed the mechanism of hydroxyl radical （OH.） oxidation. The operating variables such as reaction pressure and ozone supply had a positive influence on the degradation efficiency, mainly attributing to facilitate the ozone decomposition and OH. formation.