In situ synthesized Cu-ZSM-5/cordierite for reduction of NO

ZSM-5 zeolites were directly synthesized on the surface of honeycomb cordierite substrates by hydrothermal method and certified by XRD and SEM techniques; the adhesion of ZSM-5 coatings was evaluated by ultrasonic vibration. Cu-ZSM-5/cordierite monolithic catalyst was prepared by ion-exchange and impregnation method and applied for the selective catalytic reduction （SCR） of NO by NH3 using a simulated diesel exhaust. The results show that the cordierite surface is almost completely covered by ZSM-5 crystals and the crystallization time greatly impacts the loadings and adhesion of ZSM-5 coatings on substrate, the NOx removal rate over Cu-ZSM-5/cordierite is above 90% in a temperature range of 240-480℃. Moreover, Cu-ZSM-5/cordierite prepared by different methods shows a wide temperature window （240-540 ℃） with high NO removal activities.

One-step hydrothermal synthesis of Cu-SAPO-34/cordierite and its catalytic performance on NO_x removal from diesel vehicles

Cu-SAPO-34/cordierite catalysts were prepared via one-step hydrothermal synthesis method and their performances to remove NO x from the diesel vehicle exhaust were evaluated. The morphology, structure, Cu content and valence state were characterized by SEM, XRD, ICP and XPS, respectively. The experimental results show the active component Cu of the catalysts via in situ synthesis could significantly improve the selective catalytic reduction （SCR） activities of NOx and the optimal Cu content is in the range of 0.30%-0.40%（mass fraction）. No N 2 O is detected by gas chromatograph （GC） during the evaluation process, which implies that NOx is almost entirely converted to N2 over Cu-SAPO-34/cordierite catalyst. The conversion rate of NOx to N2 by NH3 over catalyst could almost be up to 100%in the temperature range of 300-670 ℃with a space velocity of 12000 h-1 and it is still more than 60% at 300-620 ℃ under 36000 h-1. The catalysts also show the good hydrothermal and chemical stability at the atmosphere with H 2 O.

丙烷在Ce-Fe/Al_2O_3/cordierite上选择性催化还原NO

利用凝胶溶胶法和浸渍法制备了Ce-Fe/Al_2O_3/cordierite催化剂,实验研究了其催化丙烷选择性还原NO的特性。结果表明,当铈的负载量从1%增加至5%时,Ce-Fe/Al_2O_3/cordierite的C_3H_8-SCR性能先增强后减弱,3.5Ce-Fe/Al_2O_3/cordierite具有最佳的脱硝性能,在有氧条件下,600℃时可实现96.5%的脱硝效率。Ce的加入能够提升Fe/Al_2O_3/cordierite催化剂的抗硫性能。烟气中通入0.02%的SO_2后,3.5Ce-Fe/Al_2O_3/cordierite催化丙烷还原NO的转化率始终维持在93%,而没有经过Ce修饰的Fe/Al_2O_3/cordierite的NO转化率从88%下降为80%左右。利用XRD、N_2吸附-脱附、SEM、H_2-TPR、吡啶吸附红外光谱等手段研究了催化剂的物理化学性质。结果表明,加入助剂铈能与Fe形成了固溶体,增加催化剂表面Lew is酸浓度和氧化还原能力,从而提高了催化丙烷还原NO的性能。过多的铈引入会减少Fe_2O_3结晶体的形成,不利于在C_3H_8-SCR反应中形成NO_2/NO_3^-物种,从而导致NO还原效率下降。

Co/Fe/Al_2O_3/cordierite催化C_3H_6选择性还原NO的实验研究

采用溶胶凝胶法和浸渍法制备了负载于蜂窝陶瓷上的Co/Fe/Al_2O_3/cordierite催化剂,在陶瓷管流动反应器上对其催化C_3H_6选择性还原NO的性能进行了测试。结果表明,该催化剂表现出最优脱硝性能,在模拟烟气条件下,当反应温度为550℃时可实现97%的脱硝效率。Co的引入可显著增强Fe/Al_2O_3/cordierite催化剂抗SO_2和H_2O的能力。在模拟烟气中同时引入0.02%SO_2和3%H_2O后,1.5Co/Fe/Al_2O_3/cordierite的脱硝性能受影响甚微,当反应温度高于500℃时1.5Co/Fe/Al_2O_3/cordierite催化C_3H_6还原NO的效率均可达到90%以上;相比之下,未经Co修饰的催化剂Fe/Al_2O_3/cordierite脱硝性能受到了严重的抑制,在整个反应温度区间(200-700℃)内,其催化C_3H_6还原NO的效率最高不足50%。XRD和SEM表征结果表明,经过适量的Co修饰后的1.5Co/Fe/Al_2O_3/cordierite表面变得更疏松,且形成了以钴铁和钴铝双金属氧化物为主要成分的球状晶粒。H_2-TPR结果表明,相比于Fe/Al_2O_3/cordierite,1.5Co/Fe/Al_2O_3/cordierite有更好的低温还原性能。PyFTIR结果表明,Co的引入可使催化剂表面的Lewis酸明显增加,且生成了Brnsted酸。N2吸附-脱附表征结果表明,Co可增大催化剂的比表面积。

Experimental and Kinetic Study of Selective Catalytic Reduction of NO with NH_3 over CuO/Al_2O_3/Cordierite Catalyst

The CuO/γ-Al2O3/cordierite catalyst, after being sulfated by sulfur dioxide (SO2) at 673 K, exhibits high activities for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH3) at 573-723 K. The intrinsic kinetics of SCR of NO with NH3 over CuO/γ-Al2O3/cordierite catalyst has been measured in a fixed-bed reactor in the absence of internal and external diffusions. The experimental results show that the reaction rate can be quantified by a first-order expression with activation energy Eá of 94.01 kJ·mol-1 and the corresponding p re-exponential factor A′ of 3.39×108 cm3·g-1·s-1 when NH3 is excessive. However, when NH3 is not enough, an E ley-Rideal kinetic model based on experimental data is derived with Ea of 105.79 kJ·mol-1, the corresponding A of 2 .94×109 cm3·g-1·s-1, heat of adsorption-Hads of 87.90 kJ·mol-1 and the corresponding Aads of 9.24 cm3·mol-1. The intrinsic kinetic model obtained was incorporated in a 3D mathematical model of monolithic reactor, and the agreement of the prediction with experimental data indicates that the present kinetic model is adequate for the reac-tor design and engineering scale-up.

Preparation of Cordierite Ceramic Using Mixtures of Ce^(4+)-Modified Amorphous Powder and Oxide Powders

The cordierite ceramic with a high strength and a low thermal expansion coefficient was prepared by using mixtures of Ce4 +-modified cordierite amorphous powder and oxide powders of MgO, Al2O3 and SiO2 as starting materials. The transformation procedure of the powders was analyzed by XRD method and the surface morphology of ceramics was examined by SEM method. The flexural strength was measured in a mechanical property testing machine using the Three-Point-Bending sample. Experimental results show that the ceramic added with 10%(mass fraction) of Ce4+-modified amorphous powder is composed ofα-cordierite and small amount of CeO2 particles, and has a porosity of 15% (volume fraction) and a flexural strength of 32.6 MPa when sintered at 1350℃for 3 h. It is suggested that this low-cost process is suitable for preparing the components such as supports of vehicle exhaust converters and diesel particulate trappers.

In-situ Synthesis of ZSM-5 with Different Si/AlRatios on Honeycomb-shaped Cordierite and their Behavior on NO Decomposition

Zeolites ZSM-5 with different Si/Al ratios were in-situ synthesized on the surface ofhoneycomb-shaped cordierite support for the first time. Characterizations of XRD and SEM wereperformed and it has been proved that the zeolite ZSM-5 was grown on the surface of the cordieritehomogeneously. NO decomposition on the Cu exchanged ZSM-5/cordierite monolith catalysts wasalso studied. It was found that the monolith catalysts have a fine initial activity at 673K and GHSVof 10,000h-1. Such method should be a good way to make auto exhaust converter with monolithcatalyst for NOx removal.

Influence of TiO_2 Mineralizer on the Crystalline Structure of Cordierite Synthesized from Aluminum Slag

By adding small amount of TiO2, aluminum slag could be used to synthesize cor- dierite. α-Al2O3, TiO2 and dehydrated talc could generate solid solution to accelerate the solid-state reaction to form cordierite. The experimental results show that the content of cordierite increases with the increase of TiO2 added. 3.0% of TiO2 is determined to be the best amount, because all crystalline substances are converted into cordierite at this content. Philips X’pert plus software analysis shows that when the content of TiO2 is from 0 to 1.0%, cordierite has the same hexagonal structure as the single crystal and the lattice parameters change slightly; when the content of TiO2 is from 1.0 to 2.0%, the cordierite still keeps hexagonal structure but the lattice parameters change greatly; when the content of TiO2 is from 2.0 to 3.5%, the cordierite is converted from hexagonal into rhombic and the lattice parameters change accordingly.

Preparation and Characterization of Carbon Nanotubes-Coated Cordierite for Catalyst Supports

The carbon nanotubes-coated cordierite （CNTs-cordierite） was fabricated by pyrolysis of ethine on cordierite with iron catalyst, which was penetrated into the cordierite substrate by vacuum impregnation. The cordierite substrate, carbon naontubes, and CNTs-cordierite were characterized by SEM, TEM/HREM, BET, and TGA. The results show that the carbon nanotubes were distributed uniformly on the surface of cordierite. A significant increase in BET surface area and pore volume was observed, and a suitable pore-size distribution was obtained. On the CNTs-cordierite, carbon nanotubes penetrated into the cordierite substrate, which led to a remarkable stability of the CNTs against ultrasound maltreatment. Growth time is an important factor for thermostability and texture of the sample. The mass increased but the purity decreased with the growth time, which caused the exothermic peak shift to low temperature, and the corresponding full width half maximum （FWHM） of the peak in DTG increased.

Studies on the Structure and Properties of Cordierite Synthesized by Talc-Magnesite

Homogeneous cordierite has been synthesized at low cost by talc-magnesite and coal gangue as the main raw materials. The mechanism of synthesizing cordierite under such a composing system of raw materials, and the effect of temperature on the crystal cell parameters and microstructure and thermal expansion coefficient of cordierite crystal have been studied via testing methods of XRD, SEM, etc. The result shows that the homogeneous cordierite can be synthesized by the systematic composing materials of ＂talc-magnesite-coal gangue-talc＂ with heat pre-servation at 1350 ℃ for 1 h; as the keeping time is prolonged, Al^3＋ and Mg^2＋ in cordierite crystal are replaced by a few impurity ions such as Fe^3＋, Fe^2＋, etc., and the crystal cell parameters of cordierite present an increase trend; as the high-temperature heat preservation is prolonged, the content of glassy phase in the sample is increased, its density is improved, and its thermal expansion coefficient presents an increase trend.

Synthesis of Refractory Cordierite from Calcined Bauxite, Talcum and Quartz

A cordierite was synthesized from calcined bauxite, talcum, and quartz. The properties and microstructure of the cordierite sintered samples were characterized by Archimedes＇ method, thermal dilatometry, X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and so on. The experimental results showed that calcined bauxite could broaden the range of synthesizing temperature from 1300 ℃ to 1420 ℃ and get pure cordierite. The bulk density and linear thermal expansion coefficient of the sample synthesized at 1420 ℃ for 2 h were 1.97 g·cm^-3 and 2.1×10^-6 ℃^-1, respectively. The XRD analysis showed that the major crystalline phase was a-cordierite with almost no glassy matters, the SEM images illustrated a small vent hole and the size were 5 -100 μm, the well-grown hexagonal and granular cordierite grains had the sizes distributed among 0.1-8 ;xm, and providing high mechanical strength and lower linear thermal expansion coefficient.

Influence of Fe_2O_3 Impurity on the Crystalline Structure of Cordierite Synthesized from Waste Aluminum Slag

The influence of Fe2O3 impurity on the crystalline structure of cordierite synthesized from waste aluminum slag is discussed. XRD and SEM techniques were employed to characterize the crystalline structure and microstructure of each specimen. Philips X’pert plus software was used to determine the lattice parameters of each specimen. The results show that the Fe2O3 content of 0.8～1.6wt% is beneficial to the formation of cordierite, with the cordierite amount reaching 90wt%. So 0.8～1.6wt% is considered as the allowable Fe2O3 content in the specimens and 0.8wt% is determined to be the best after overall analysis. Plus software analysis shows that the cordierite in each specimen has the same symmetrical hexagonal structure as the single crystal, and the lattice parameters as well as the lattice dimensions change slightly.

Effects of Chemical Treatments on Thermal Expansion Properties of Cordierite Ceramics

Cordierite honeycomb ceramics was treated with 1.5 M HNO3 , followed with 1.5 M NaOH at 93 ℃. The combination of acid treatment with alkali treatment significantly diminished the rebounding of coefficient of thermal expansion （CTE） caused by heat treatment, a phenomenon observed in samples treated solely with acid. Inductively coupled plasma （ICP） analysis results reveal that the alkali treatment preferentially dissolved ＂free＂ SiO2 left in the acid-treated samples, which is considered to be a key factor responsible for the CTE rebounding.

Influence of Impurity Na_2O on Crystalline Structure of Cordierite Synthesized from Aluminum Sludge

By adding small amount of TiO2, aluminum slag could be used to synthesize cor- dierite. α-Al2O3, TiO2 and dehydrated talc could generate solid solution to accelerate the solid-state reaction to form cordierite. The experimental results show that the content of cordierite increases with the increase of TiO2 added. 3.0% of TiO2 is determined to be the best amount, because all crystalline substances are converted into cordierite at this content. Philips X’pert plus software analysis shows that when the content of TiO2 is from 0 to 1.0%, cordierite has the same hexagonal structure as the single crystal and the lattice parameters change slightly; when the content of TiO2 is from 1.0 to 2.0%, the cordierite still keeps hexagonal structure but the lattice parameters change greatly; when the content of TiO2 is from 2.0 to 3.5%, the cordierite is converted from hexagonal into rhombic and the lattice parameters change accordingly.

Preparation,Structure Characterization and Hydrodesulfurization Performance of B-Ni_2P/SBA-15/Cordierite Monolithic Catalysts

A series of B-Ni2P/SBA-15/cord monolithic catalysts were prepared by coating the slurry of the B-Ni2P/SBA-15 precursors on a pretreated cordierite support, and followed by temperature-programmed reduction in a H2 flow. The samples were characterized by X-ray diffraction （XRD） and N2 adsorption-desorption technique. The catalytic activities for the hydrodesulfurization （HDS） of dibenzothiophene （DBT） were evaluated. The results showed that Ni2P phase was present in all B-Ni2P/SBA-1 5/cord monolithic catalysts. The specific surface areas （SBET） of the B-Ni2P/SBA-15/cord monolithic catalysts was first increased to 167 m2· g-1, and then decreased to 155 m2· g-1 with the increase of boron contents. The catalytic activity also showed the similar trend with the increase of boron contents. The 1.75% （by mass） B-Ni2P/SBA-15/cord monolithic catalysts exhibited the highest DBT conversion of 98.4% at 380 ℃. The cordierite-based monolithic catalysts showed better low temperature sensitivity for HDS of DBT in comparison with the particle catalysts. Moreover, two HDS routes, direct desulfurization （DDS） and hydrogenation （HYD）, proceeded independently over B-Ni2P/SBA-15/cord monolithic catalysts and the main pathway was DDS.

Synthesis of Cordierite by Decomposition of Metal Nitrates on the Surface of Carbon Black Powder

Cordierite precursor was obtained through a process, which involved the decomposition of metal nitrates on the surface of ultrafine carbon black powder between 100-300℃ and the gasification of the carbon black at higher temperature in air. The average size of the particles, which were heat-treated at 700℃ for 10h, is about 1020nm, and the specific surface area is about 129m 2/g. The experimental results show that the ultrafine particles of cordierite precursor can be produced by this process. The precursor powder was calcined at different temperatures. X-ray diffraction examination indicates that β-quartz is crystallized from the amorphous matrix around 850℃ firstly and then MgO-Al 2O 3 spinel and α-cordierite appears. Above 1000℃, MgO-Al 2O 3 spinel and cristobalite disappear gradually and form an intermediate phase (sapphirine). At around 1300℃, the main phase is α-cordierite, and no other phase is detected.

Combinatorial Optimization of Ba/Fe-cordierite Solid Solution （Ba0.05Fe0.1Mg）2Al4Si5O18 for High Infrared Radiance Materials

A combinatorial chemistry method was employed to screen the Ba2＋ and Fe3＋ incorporated into cordierite structure （Ba0.05Fe0.1Mg）2A14Si5018 for exploring of high infrared radiance materials. A series of square-type sample array that consists of 7×7 compositions was syn- thesized by ink-jetting nitrate solutions into micro-reactor wells in a ceramic plate and then heat-treated at high temperatures. X-ray diffraction and infrared thermograph were used to analyze the effects of Ba2＋/Fe3＋ incorporating on the lattice distortion of cordierite and resultant changes in infrared radiance properties. Based on the results of X-ray phase analy- sis and radiance measurement of the scale-up prepared samples, the optimal Ba2＋ and Fe3＋ co-adding amount was determined to be 5%Ba2＋ plus 10%Fe3＋. Moreover, the infrared emissivity of the optimal composition at 100 ℃ was found to be higher than 0.8 in a wide wavelength range of 5-24μm. The research work demonstrates a promising application of Ba2＋/Fe3＋ cordierite solid solution as a kind of infrared heating materials for energy saving.

Research on application of different particle sizes of cordierite on castable refractory

Effect of different particle sizes of cordierite on properties of castable refractory by different heat treatment temperatures were investigated respectively with mullite and bauxite as raw materials, calcium aluminate cement as binders. After 24 h curing in mould and another 24 h curing at 110 ℃ after demoulding, the specimens were heat treated at 1 000 ℃, 1 300℃ and 1 500℃ for 3 h, respectively. The bulk density （ BD）, permanent linear change （ PLC）, modulus of rupture（MOR） and clod crushing strength（CCS）, thermal expansion coefficient and thermal shock resistance were examined. The results show that there is no obvious effect on adjusting permanent linear change and bulk density of castables by adding different particle sizes of cordierite at low temperature and intermediate temperature. Modulus of rupture of castable increase with the decreasing of the particle sizes of cordierite after heat treated by 1 000 ℃ and 1 300℃. In this experiment, thermal shock resistance of the castable with cordierite whose particle size is 0 - 1 mm is the best.

Enhanced photo-catalytic activity of the composite of TiO_2 and conjugated derivative of polyvinyl alcohol immobilized on cordierite under visible light irradiation

A novel visible light active photo-catalyst named CHC/C-PVA/TiO2, the composite of titanium dioxide（TiO2）with conjugated derivative of polyvinyl alcohol（C-PVA） loaded on a cordierite honeycomb ceramic（CHC）substrate, was fabricated by combining the synthesis of TiO2 sol, preparation of C-PVA via thermally treating polyvinyl alcohol, and immobilization of TiO2 sol and C-PVA on CHC. By detecting the change of UV–vis absorption spectra of the model organic pollutant（methyl orange（MO）） in the presence of the composite under visible light irradiation, the photo-catalytic activity was evaluated and the results show that the CHC/C-PVA/TiO2 composite has an enhanced photo-catalytic activity when compared to the CHC/TiO2 composite. Besides, the CHC/C-PVA/TiO2 shows a good photo-catalytic stability after the fourth cycles. The structure analyses by scanning electron microscope（SEM） and energy dispersive X-ray spectroscopy（EDS） show the coexistence of C-PVA and TiO2 on the CHC and the cracks on the surface of CHC/C-PVA/TiO2. Result of ultraviolet-visible diffuse reflection spectroscopy（UV–vis DRS） reveals that the CHC/C-PVA/TiO2 can absorb both ultraviolet and visible light while result of X-ray photoelectron spectroscopy（XPS） indicates the existence of C, O and Ti elements in the CHC/C-PVA/TiO2. The typical structures as well as the optical characteristics of the CHC/C-PVA/TiO2 are responsible for the enhancement in the photo-catalytic activity.

Cordierite Ceramics Prepared from Poor Quality Kaolin for Electric Heater Supports: Sintering Process, Phase Transformation, Microstructure Evolution and Properties

To efficiently utilize the kaolin, an economical way of preparing cordierite ceramic with high performance for electric heater supports was put forward. In this study, sintering process, phase transformation, microstructure evolutions were systematically studied by heating microscope, X-ray diffraction, scanning electronic microscope and thermal analysis. Properties（physical properties, electrical properties and coefficient of thermal expansion（CTE）） were tested for comprehensive performance evaluation. The results showed that the utilization of poor quality kaolin broadened the firing range of cordierite ceramic which was from 1 200 to 1 380 ℃. Microstructure becomes loose with increasing of the pore size, which had significant influence on bending strength and electrical properties. High content of K2 O in poor quality kaolin was the reason for liquid phase generation in sintering process, which further leads to microstructural changes. The cordierite ceramic sintered at 1 320 ℃ had the properties as follows： CTE of 1.98×10^（-6） ℃^（-1）（500 ℃）, bending strength of 90 MPa, apparent porosity of 15.1%, dielectric constant of 7.5（100 Hz）, and volume resistivity of 1.05×109 Ω·cm（100 Hz）. The comprehensive properties are very suitable for use as electric heater supports.