不同晶体结构MnO2纳米催化剂低温NH3-SCR性能研究

为了探究催化剂的结构和催化活性的关系,采用水热法制备了四种不同晶体结构的MnO₂纳米催化剂（α-MnO₂、β-MnO₂、γ-MnO₂和δ-MnO₂）,并考察了其低温NH₃-SCR活性。结果表明,不同晶体结构催化剂的活性不同,依次为γ-MnO₂ > α-MnO₂ > β-MnO₂ > δ-MnO₂,γ-MnO₂表现出最高的催化活性,NO_x转化率在150-260℃超过90%。随后,通过X射线衍射（XRD）、扫描电子显微镜（SEM）、N₂吸附-脱附、热重（TG）、红外光谱（FT-IR）、程序升温还原（H₂-TPR）及吡啶吸附红外光谱（Py-FTIR）等表征手段对催化剂的结构和性质进行分析。结果表明,α-MnO₂和β-MnO₂为纳米棒,γ-MnO₂和δ-MnO₂为纳米针,催化剂的比表面积并不是影响低温NH₃-SCR活性的主导因素。γ-MnO₂具有适宜的孔道结构、较强的氧化还原能力、丰富的化学氧含量和Lewis酸酸性位点,是其具有最高低温NH₃-SCR活性的原因。     

TiO2-modified nano-egg-shell Pd catalyst for selective hydrogenation of acetylene

Pd-based egg-shell nano-catalysts were prepared using porous hollow silica nanoparticles(PHSNs)as support,and the as-prepared catalysts were modified with TiO2 to promote their selectivity for hydrogenation of acetylene.Pd nanoparticles were loaded evenly on PHSNs and TiO2 was loaded on the active Pd particles.The effects of reduction time and temperature and the amount of TiO2 added on catalytic performances were investigated by using a fixed-bed micro-reactor.It was found that the catalysts showed better performance when reduced at 300 C than at 500 C,and if reduced for 1h than 3h.When the amount of Ti added was 6 times that of Pd,the catalyst showed the highest ethylene selectivity.     

纳米Ni催化剂在超稠油水热裂解降黏中的应用研究

采用甲基环己烷水正辛醇AEO9形成的微乳液体系制备纳米金属Ni催化剂，并利用该催化剂催化辽河超稠油的水热裂解反应。研究结果表明， 280℃时纳米金属Ni能够促进超稠油的水热裂解反应。与原超稠油相比，反应后样品的硫质量分数由0.45%降到0.23%，胶质、沥青质质量分数分别降低了15.83%、15.33%；GC-MS分析结果表明，甲基环己烷在改质过程中能够脱氢生成甲苯；C、H元素分析结果表明，反应后样品中胶质、沥青质的H/C原子比增加，说明从甲基环己烷上脱下的氢能够转移到超稠油中。表面活性剂AEO9、水和油，在改质结束后的降温过程中，形成了稳定的油包水型乳液，起到乳化降黏作用；而添加的甲基环己烷、正辛醇均能起到稀释降黏作用；在上述降黏作用的协同影响下，反应后样品50℃时的黏度由原来的139800mPa·s降至2400mPa·s，由此表明，纳米Ni催化剂对辽河超稠油水热裂解降黏的催化效果显著。     

Preparation,characterization and catalytic activity of a nano-Co(II)-catalyst as a high efficient heterogeneous catalyst for the selective oxidation of ethylbenzene,cyclohexene, and benzyl alcohol

This paper reports the preparation of a nano-Co(II)-catalyst (NCC) by anchoring of Co ions on immobilized bipyridylketone over the nano-sized SiO₂/Al₂O₃ mixed oxides. The nano-Co(II)-catalyst has been characterized by elemental analysis, BET, FT-IR, DR UV–vis and SEM. The catalytic activity of the catalyst towards the oxidation of ethylbenzene, cyclohexene, and benzylalcohol to different chemically and pharmaceutically important products were evaluated with tert-butyl hydroperoxide (TBHP) in the absence of solvent. Under optimized conditions, the nano-catalyst proved highly selective towards the acetophenone, 2-cyclohexene-1-one and benzaldehyde as reaction products, with excellent conversion rates.     

CeO2/TiO2异质结纳米花的制备及光催化性能研究

异质结催化剂以其优异的光电性能、光催化性能及在降解有机污染物上的实用性,吸引了广大研究者的注意.采用水热法,制备了CeO2/TiO2异质结纳米花,利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、和紫外-可见光吸收(UV-vis)等分析手段对制备的样品形貌和结构进行表征,并以甲基橙为目标污染物,考察了样品的光催化性能,并且对光催化降解的机理进行了分析.我们发现,这种异质结构将其紫外-可见光吸收边由紫外光区域拓宽到可见光区域,从而提高光响应范围.研究表明CeO2/TiO2异质结纳米花表现了优异的催化活性,在60 min内降解了98;的甲基橙,这主要是源于其特殊的异质结构,能增强光催化活性.     

Catalysis of SO42--ZrO2/TiO2 nanometer solid superacid

Superacid catalyst SO42--ZrO2/TiO2 was applied in esterification of Acetic Acid and Butanol. The particle size of ZrO2 in the catalyst was about 12.5 nm. In catalyst preparation conditions, the effect factor order on catalytic activity is H2SO4 concentration ＞ calcination temperature ＞ ZrO2 supported content. The optimum preparation condition is as follows: ZrO2 content 3.5g/g; calcination temperature 600℃, and H2SO4 concentration 0.5mol/L. The catalytic activity is 96.5 vol%.SO42-/MxOy solid superacid is a kind of green catalyst, whose application perspective is bright. In this paper, SO42--ZrO2/TiO2 solid superacid was prepared with nanometer compound carrying method. The acidic strength of catalysts was measured with the following Hammett indicators, 2,4-dinitrofluorobenzene (H0=-14.52) and p-nitrochlorobenzene (H0=-12.70). Catalytic activity was evaluated with esterification reaction of Acetic Acid and Butanol. Reaction temperature was at 105℃, and reaction time was only 1h. The conversion rate of Acetic Acid was analyzed by a gas chromatograph (GC-14C SHIMADZU in Japan)The experimental results showed that H2SO4 concentration had more influences on catalytic activity than other two factors, calcination temperature and ZrO2 supported content. Since sulfur absorbed on the surface of metal oxides is necessary to the acidity of SO42-/MxOy solid superacid,H2SO4 concentration in impregnation solution is needed enough high. But, it can't be too much high,otherwise, Zirconium sulfate formed on the catalyst surface will be harmful influences on catalytic activity. In researched cover, 0.5mol/L H2SO4 concentration is the most suitable, and the catalyst prepared with this concentration has very strong acidity.The optimum preparation condition is as follows: ZrO2 content 3.5g/g; calcination temperature 600℃, and H2SO4 concentration 0.5mol/L. In the catalyst prepared with above conditions, the acidic strength (H0) of the catalyst is smaller than ＜-14.52, and catalytic activity is 96.5 vol%. When it was re-used in esterification reaction, catalytic activity decreased gradually with re-used times increasing(seen in Table 1). But after catalyst is used repeatedly up to five times, catalytic activity (84.3 vol %)is still higher than that of H2SO4 catalyst.The X-ray diffraction patterns showed that ZrO2 supported in TiO2 belonged tetragonal zirconia phases. Through the calculation of Scherrer formula, the particle size of ZrO2 in the catalyst is about 12.5 nm. After SO42- promoted nanometer ZrO2/TiO2 compound carrier, the diffraction peaks of tetragonal zircoma become broader and the strength weaker. It shows that adding SO4 ions restrains the crystallization of ZrO2, diminishes the size of particles. This might be why SO42--ZrO2/TiO2 has high catalytic activity and stability in acidic catalysis reaction.     

The influence of mixed nano-Al2O3+CuO catalysts that are initial radiation in air environment on the surface impact in the oxidation processes

ABSTRACT

In this paper, the oxidation/conversion process of carbon monoxide (CO) has been examined under various temperatures on the surface of three types of catalysts (TAl₂O₃, TAl₂O₃+CuO and RTAl₂O₃+CuO). The catalyst samples have been exposed to γ-rays in various absorption doses which allow us to analyze anion center distribution. The example research shows that the size and element density of anion nanocenters depends on the radiation dose. The high fraction of atomic oxygen emerged on the surface of mixed nano-Al₂O₃ and Al₂O₃-CuO shows a continuing increase depending on absorption dose, while the initial radiation creates additional anion (O–) centers. Consequently, a contraction of the energy required to activate the centers derives faster conversion.     

CaO@SiO_2纳米固体碱的制备、表征及其大豆油酯交换反应催化性能

采用溶胶-凝胶法合成Ca O@Si O_2固体碱催化剂,以聚苯乙烯有机聚合物为硬模板剂和以P123为软模板剂对Ca O的微观形貌进行调控。并将其应用于大豆油与甲醇的酯交换制备生物柴油的反应体系中。通过对Ca O@Si O_2纳米固体碱催化剂进行X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电镜(TEM)、CO_2-TPD及N_2的吸附-脱附(BET)表征发现,不仅制备得到了形貌归整的纳米固体颗粒,而且得到了Ca O包裹在Si O_2表面的核壳结构。进一步考察了不同的硅钙质量比、反应温度、催化剂的用量以及油醇物质的量比对生物柴油收率的影响,生物柴油的收率最高可以达到95.6%。     

KCC-1 aminopropyl-functionalized supported on iron oxide magnetic nanoparticles as a novel magnetic nanocatalyst for the green and efficient synthesis of sulfonamide derivatives

A new magnetic nanocatalyst (Fe₃O₄@KCC-1-npr-NH₂) was synthesized directly through the reaction of Fe₃O₄@KCC-1 with (3-aminopropyl) triethoxysilane (APTES) using a hydrothermal protocol. Prepared nanocomposite was used as a magnetically reusable nanocatalyst for an efficient synthesis of a broad range of sulfonamide derivatives in water as a green solvent at room temperature and the products are collected by filtration with excellent yields (85–97%). The nanocatalyst could be remarkably recovered and reused after ten times without any significant decrease in activity. This mild and simple synthesis method offers some advantages including short reaction time, high yield and simple work-up procedure.     

Iron oxide magnetic nanoparticles supported on amino propyl-functionalized KCC-1 as robust recyclable catalyst for one pot and green synthesis of tetrahydrodipyrazolopyridines and cytotoxicity evaluation

In this study, paramagnetic dendritic fibrous nano-silica functionalized by aminopropyltriethoxysilan (Fe₃O₄@KCC-1-nPr-NH₂) was synthesized using a novel hydrothermal protocol and used as a highly efficient, recyclable and heterogeneous nanocatalyst for the synthesis of a wide range of tetrahydrodipyrazolopyridines derivatives ( 5a-5 m ). The influence of different reaction parameters, such as the effects of solvent, temperature, time and concentration of catalyst for the synthesis of tetrahydrodipyrazolopyridine (2a) were studied. This catalyst could be reused for ten consecutive recycles without any considerable loss in its catalytic activity. This novel synthesis method offers some advantages including short reaction time, high yield and simple work-up procedure. Finally, the newly synthesized tetrahydrodipyrazolopyridines derivatives ( 5a-5f ) were characterized by ¹H and ¹³C NMR, IR and CHN.