Co改性Mo/MCM-22催化剂上甲烷无氧芳构化及积炭研究

 研究了Co的添加对Mo／MCM－22催化剂甲烷无氧芳构化反应性能的影响．发现用共浸渍法制备的Co／Mo摩尔比为0．2的催化剂具有较高的活性,而先浸渍Mo后浸渍Co的催化剂具有较好的稳定性．XRD实验表明,Co及Mo的氧化物均高度分散在分子筛表面,其担载降低了分子筛的衍射强度．不同接触时间下催化剂的反应结果表明,接触时间长,积炭选择性随接触时间增加而迅速增加;接触时间短,积炭选择性随接触时间增加而减少．积炭催化剂的TG研究表明,催化剂上的积炭主要有两种形式．低温积炭随反应时间增加而迅速增多,高温积炭的变化则较为缓慢．低温积炭可能是导致催化剂活化和失活的主要原因．高温积炭可能是一种大分子量的碳氢物种,位于MCM－22分子筛的“超笼”中,表明MCM－22有较大的容积炭能力．     

光沉积法合成纳米金属Pd负载的MCM-TiO2及其光催化性质研究

用光沉积方法由PdCl₄^2-和Ti修饰的MCM-41合成了纳米钯团簇Pd/MCM-TiO₂,用XPS,N₂吸脱附等温线,UV-Vis和Raman光谱对其结构进行了表征.将该团簇用于苯酚的光降解和Cr(Ⅵ)还原为Cr(Ⅲ)的反应中,表现出较高的光催化活性.     

大比表面积炭质吸附剂的表面及孔隙发展

以石油焦为原料研究了采用KOH活化法制备大比表面积炭质吸附剂时表面及孔隙的发展。实验发现虽然KOH加入量 ,水乙醇溶液中乙醇含量和提高热处理终温以及延长热处理时间都使比表面积增大 ,但是水乙醇加入总量的增加则导致比表面积下降。KOH加入量以 60～ 75%为宜 ,此时其利用率在 40 0m2 g以上。孔隙分布研究表明水乙醇加入总量 ,乙醇含量和热处理温度的提高都使 1～ 2nm微孔孔容及其在 1～ 2 0nm微孔孔容中所占比率增加。实验发现大比表面积炭质吸附剂的比表面积与碘值之间存在一定相关性。由于碘值不存在N2 吸附BET比表面积的过高估计现象 ,因而这给用碘值来更合理评价大比表面积炭质吸附剂的相对吸附能力提供了可能。     

石油焦渣油浆燃烧特性的试验研究

石油焦渣油浆是为电站燃油锅炉开发的一种新型代用燃料,本文对南京金陵石化所提供的渣油和石油焦所制成石油焦渣油浆的燃烧特性进行了试验研究。结果表明,浓度为４０％的石油焦渣油浆可以成功地进行制备、加热、输送和燃烧,并具有较高的燃烧效率;石油焦渣油浆的浓度、油焦浆的加热温度、负荷和氧量对其燃烧效率有很大影响。     

Bipolar switching properties of amorphous TiO2 thin film grown on TiN/Si substrate

Pt/TiO₂/TiN device with the amorphous TiO₂ film grown at room temperature under an oxygen partial pressure of 1.0 mTorr showed reliable bipolar switching behavior. During the electroforming process, a large number of oxygen vacancies formed in the TiO₂ film and accumulated at the Pt/TiO₂ interface. The barrier height of the Schottky contact of the Pt/TiO₂ interface was reduced owing to the presence of these oxygen vacancies, resulting in the low-resistance state (LRS). Moreover, oxygen ions diffused into the TiN electrode during the electroforming and set processes. On the other hand, the oxygen ions in the TiN electrode diffused out and reacted with oxygen vacancies in the TiO₂ film during the reset process, and the device changed from the LRS to the high-resistance state (HRS). Conduction in the LRS and HRS can be attributed to Ohmic conduction and the trap controlled space charged limited mechanism, respectively.     

锰改性活性焦脱除合成气中单质汞的影响因素

采用等体积浸渍法制备了Mn改性活性焦吸附剂(Mn-AC),研究了模拟合成气(0.04%H2S、20%CO、30%H2、N2为平衡气体)下Mn-AC对单质汞的吸附特性,并利用BET、XPS、XRD等手段对吸附剂进行表征,分析了还原性气体对吸附剂脱汞性能的影响。结果表明,在模拟合成气气氛下,Mn-AC具有优异的汞脱除能力,200℃下2 h内平均汞脱除率达到84.3%。合成气中,H2S提供了具有脱汞能力的活性硫吸附位(Sad),显著地提高了Mn-AC的高温脱汞能力;H2消耗了吸附剂表面的活性氧,不利于活性硫的生成,CO消耗了生成的活性硫吸附位,两者对汞脱除均有抑制作用。高温下由于活性硫和汞的反应减弱,同时H2的抑制作用加强,吸附剂对单质汞的脱除能力下降。     

Coking-resistant Ni-ZrO2/Al2O3 catalyst for CO methanation

Highly coke-resisting Zr O2-decorated Ni/Al2O3 catalysts for CO methanation were prepared by a two-step process. The support was first loaded with Ni O by impregnating method and then modified with Zr O2 by deposition-precipitation method(IM-DP). Nitrogen adsorptiondesorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, H2 temperatureprogrammed reduction and desorption, NH3temperature-programmed desorption, and zeta potential analysis were employed to characterize the samples. The results revealed that, compared with the catalysts with the same composition prepared by co-impregnation(CI) and sequential impregnation(SI) methods, the Ni/Al2O3 catalyst prepared by IM-DP showed much enhanced catalytic performance for syngas methanation under the condition of atmospheric pressure and a high weight hourly space velocity of 120000 m L g-1 h-1. In a 80 h life time test under the condition of 300–600°C and 3.0 MPa, this catalyst showed high stability and resistance to coking, and the amount of deposited carbon was only 0.4 wt%. On the contrary, the deposited carbon over the catalyst without Zr O2 reached 1.5 wt% after a 60 h life time test. The improved catalytic performance was attributed to the selective deposition of Zr O2 nanoparticles on the surface of Ni O rather than Al2O3, which could be well controlled via changing the electrostatic interaction in the DP procedure. This unique structure could enhance the dissociation of CO2 and generate surface oxygen intermediates, thus preventing carbon deposition on the Ni particles in syngas methanation.     

Effect of Ni loadings on the activity and coke formation of MgO-modified Ni/Al_2O_3 nanocatalyst in dry reforming of methane

MgO-modified Ni/Al2O3 catalysts with different Ni loadings were prepared and employed in dry reforming of methane （DRM）. The effect of Ni loadings on the activity and coke formation of Ni/MgO-A1203 catalysts were investigated. The synthesized catalysts were characterized by XRD, N2 adsorption-desorption, SEM, TPO and TPR techniques. The obtained results showed that increasing nickel loading decreased the BET surface area and increased the catalytic activity and amount of deposited carbon. In addition, the effect of gas hourly space velocity （GHSV） and feed ratio were studied.     

Dehydrogenative activity of catalysts with low palladium content

Catalysts containing as little as 0.5 mass. % Pd are highly active in the dehydrogenation of cyclohexane when Sibunite® or active alumina (for gas dehumidification) are used as catalyst supports. Dehydrogenative activity of the Pd/Al₂O₃ catalyst is further increased upon surface sulfidation and addition of 0.25–0.5 mass. % Re.Translated fromIzvestiya Akademii Nauk. Seriya Khmicheskaya, No. 2, pp. 422–423, February, 1993.     

气相沉积法制备聚酰亚胺薄膜不同单体配比的表征及其性能影响

聚酰亚胺微球作为惯性约束聚变的重要候选靶丸之一,其力学性能和热学性能的提高对于实现聚变点火有重要意义.本文以均苯四甲酸二酐和二氨基二苯醚为原料,采用气相沉积法制备了不同单体配比的聚酰胺酸薄膜,研究了制备聚酰胺酸薄膜过程中不同单体蒸发温度对薄膜组成的影响,并对聚酰胺酸薄膜进行热环化处理.采用红外光谱仪分析了聚酰胺酸薄膜和聚酰亚胺薄膜的组成,结果表明:随着二酐蒸发温度的增加,聚酰胺酸薄膜中过量二酐单体的红外吸收振动特征峰(1780 cm~(-1),1850 cm~(-1)强度增加,单体配比由二胺过量到二酐二胺配比均衡再到二酐过量.热环化处理的过程中,薄膜中过量单体会再次蒸发,其红外图谱显示最终产物只有聚酰亚胺,但单体配比接近样品聚酰亚胺红外特征振动峰(1380 cm~(-1))强度更大.X射线衍射图谱显示配比接近的样品具有更高的晶化程度,说明过量单体的存在抑制了聚酰胺酸分子链的生长,造成分子量降低.采用纳米压痕仪和热重分析仪分别测量了聚酰亚胺薄膜的弹性模量和硬度以及失重曲线,结果表明分子量的降低会造成聚酰亚胺薄膜的弹性模量和硬度的降低,同时热稳定性也变差.扫描电子显微镜图像显示聚酰亚胺薄膜呈层状结构,单体配比接近的样品表面状况更好,这一点与聚酰亚胺分子的生长规律相符合.