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1.
2.
Dong Zhang 《Korean Journal of Chemical Engineering》2008,25(5):1205-1207
Ceria-zirconia solid particles have been recognized as a key material of the automotive exhaust catalysts since they can release
and uptake oxygen owing to the rapid reversible oxidation states of cerium between Ce3+ and Ce4+. Several methods have recently been described to prepare the CeO2-ZrO2 solid particles used in the catalysts. In this paper, a new coprecipitation method is used to prepare the CeO2-ZrO2 solid particles. The Ce-Zr alcogel is dried and calcined in flowing N2 not in flowing air under atmospheric pressure. The results show that the ceria-zirconia sample calcined at 650 °C has high
surface area over 90 m2g−1, which drops to 40 m2g−1 following treatment at 900°C. 相似文献
3.
4.
《Diamond and Related Materials》2007,16(2):229-235
In this work, we reported a new plasma catalyst preparation method for carbon nanotube (CNT) formation. With this new method, argon glow discharge plasma was operated at room temperature and applied for the reduction of Pd/HZSM-5, instead of catalyst reduction thermally using hydrogen at elevated temperature. Such plasma reduced catalyst shows a high dispersion of metal particles. The multi-walled CNTs produced with this plasma reduced Pd/HZSM-5 exhibit structural graphene sheets in conical hollow shape, a typical structure observed in CNTs from catalytic methane decomposition. Some fiber fish bone type structures can be also observed. Compared to the hydrogen reduction (thermally), the reduction using argon plasma is feasible and effective for the preparation of catalyst for the CNTs formation. The glow discharge plasma catalyst reduction is very promising for the further development of green catalyst reduction technologies. 相似文献
5.
《Signal Processing: Image Communication》2005,20(4):295-314
This paper presents an efficient face segmentation algorithm based on binary partition tree. Skin-like regions are first obtained by integrating the results of pixel classification and watershed segmentation. Facial features are extracted by the techniques of valley detection and entropic thresholding, and are used to refine the skin-like regions. In order to segment the facial regions from the skin-like regions, a novel region merging algorithm is proposed by considering the impact of the common border ratio between adjacent regions, and the binary partition tree is used to represent the whole region merging process. Then the facial likeness of each node in the binary partition tree is evaluated using a set of fuzzy membership functions devised for a number of facial primitives of geometrical, elliptical and facial features. Finally, an efficient algorithm of node selecting in the binary partition tree is proposed for the final face segmentation, which can exactly segment the faces without any underlying assumption. The performance of the proposed face segmentation algorithm is demonstrated by experimental results carried out on a variety of images in different scenarios. 相似文献
6.
Solubility of dimethyl-2,6-naphthalene dicarboxylate in acetic acid, N,N-dimethylfonnamide, N,N-dimethyl acetamide, dimethyl sulphoxide, and N-methyl-2-ketopyrrolidine were determined using a dynamic method. The measured systems were correlated by UNIFAC group contribution method. A new main group (aromatic ester, ACCOO) was defined to express the activity coefficients of the aromatic ester. New interaction parameters of the ACCOO group were expressed as the first-order function of temperature and were determined from the experimental data. The calculated results for the new interaction parameters were satisfactory. The measured systems were also correlated with the Wilson and 2-h models, and the results were compared with those of the UNIFAC model. 相似文献
7.
Ming-yan Liu Wen Leng Ai-hong Qiang 《Chemical Engineering and Processing: Process Intensification》2008,47(12):2066-2075
In this work, the instantaneous data of inner wall temperatures obtained at given axial positions but for different heated tubes or at various axial positions but at the same heated tube in a tube-bank fluidized bed evaporator with a vapor–liquid–solid external natural circulation flow were analyzed by employing linear and nonlinear time series analysis methods, including correlation dimension and Kolmogorov entropy analyses besides time domain, power spectrum and autocorrelation analyses. It is found that nonlinear characteristics of the wall temperature time series vary with spatial position in the evaporator at given operation conditions, and thus the multi-phase flow boiling behavior. However, the signals obtained at given axial position but different heated tubes in the evaporator exhibit more similar nonlinear evolution behavior, and those measured in the same heated tube but at different axial heights in the evaporator undergo more distinct nonlinear dynamic behavior. Multi-scale phenomena in different spatial positions are also found and discussed. These transient aspects of inner wall temperatures are closely related to the average holdup of solid particles and motion of vapor bubbles in vapor–liquid–solid flow. These results can provide some valuable information on the system modeling and controlling from the point of view of nonlinearity. 相似文献
8.
Zhihong Xu Tao Jiang Hao Zhang Yujun Zhao Xinbin Ma Shengping Wang 《Frontiers of Chemical Science and Engineering》2021,15(3):698
Novel MgO-doped CaO sorbent pellets were prepared by gel-casting and wet impregnation. The effect of Na+ and MgO on the structure and CO2 adsorption performance of CaO sorbent pellets was elucidated. MgO-doped CaO sorbent pellets with the diameter range of 0.5-1.5 mm exhibited an excellent capacity for CO2 adsorption and adsorption rate due to the homogeneous dispersion of MgO in the sorbent pellets and its effects on the physical structure of sorbents. The results show that MgO can effectively inhibit the sintering of CaO and retain the adsorption capacity of sorbents during multiple adsorption-desorption cycles. The presence of mesopores and macropores resulted in appreciable change of volume from CaO (16.7 cm3∙mol−1) to CaCO3 (36.9 cm3∙mol−1) over repeated operation cycles. Ca2Mg1 sorbent pellets exhibited favorable CO2 capture capacity (9.49 mmol∙g−1), average adsorption rate (0.32 mmol∙g−1∙min−1) and conversion rate of CaO (74.83%) after 30 cycles. 相似文献
9.
探索催化剂的制备条件,包括搅拌温度、干燥温度、煅烧温度及煅烧时间对二甲苯氧化效果的影响,结果表明煅烧温度对氧化效果的影响最为明显。在其它制备条件(搅拌温度为60 ℃、干燥温度为60 ℃和煅烧时间为3 h)不变的前提下,通过改变煅烧温度(温度分别350、450和550 ℃),比较3种二甲苯氧化难易以及不同煅烧温度下氧化同一构型二甲苯的差异。整体而言,煅烧温度为350 ℃的催化剂性能最佳。邻、间和对3种二甲苯完全氧化的温度相差约15 ℃,其中,邻二甲苯最难氧化,完全氧化需260 ℃,间二甲苯次之,对二甲苯最易氧化。与此同时,利用XRD、XPS、N2吸附-脱附和H2-TPR等表征手段来分析煅烧温度造成3种不同构型二甲苯氧化程度差异性的原因。 相似文献
10.
Junyang Xu Yanjun Jiang Liya Zhou Li Ma Zhihong Huang Jiafu Shi Jing Gao Ying He 《中国化学工程学报》2021,38(10):237-246
Immobilization is an effective method to promote the application of enzyme industry for improving the stability and realizing recovery of enzyme.To some extent,the performance of immobilized enzyme depends on the choice of carrier material.Therefore,the development of new carrier materials has been one of the key issues concerned by enzyme immobilization researchers.In this work,a novel organic-inorganic hybrid material,nickel-carnosine complex (NiCar),was synthesized for the first time by solvothermal method.The obtained NiCar exhibits spherical morphology,hierarchical porosity and abun-dant unsaturated coordination nickel ions,which provide excellent anchoring sites for the immobiliza-tion of proteins.His-tagged organophosphate-degrading enzyme (OpdA) and ω-transaminase (ω-TA)were used as model enzymes to evaluate the performance of NiCar as a carrier.By a simple adsorption process,the enzyme molecules can be fixed on the particles of NiCar,and the stability and reusability are significantly improved.The analysis of protein adsorption on NiCar verified that the affinity adsorp-tion between the imidazole functional group on the protein and the unsaturated coordination nickel ions on NiCar was the main force in the immobilization process,which provided an idea way for the develop-ment of new enzyme immobilization carriers. 相似文献