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1.
The activation of propene in selective catalytic reduction (SCR) of NO on 4% Ag/Al2O3 has been studied by in situ infrared (IR) spectroscopy. Distinctive propene activation products were detected in the SCR of NO, depending on the nature of surface oxygen and nitrogen oxide species on Ag/Al2O3. C3H6 was oxidized to acetate species in an O2 + C3H6 atmosphere on Ag/Al2O3 above 573 K. The addition of NO to the C3H6 + O2 feed gas suppressed the formation of acetate species but increased the proportion of acrylate species. Acrylate species were further confirmed to be formed preferentially from C3H6 oxidation without the O2 atmosphere on Ag/Al2O3 or nitrate-adsorbed Ag/Al2O3. On the other hand, adsorption of NO led to the formation of nitrito species on Ag/Al2O3, but the nitrito was barely oxidized to nitrate species unless there was an O2 atmosphere at 473–673 K. Thus, the oxidation of propene to acetate species, or the formation of nitrate from nitrito, is attributed to two competitive electrophilic reactions. The formation of nitrate from nitrito species decreased electrophilic oxygen species that oxidized propene to acetate. Nevertheless, the first dehydrogenation of propene to form acrylate species on nitrate-adsorbed Ag/Al2O3 is a nucleophilic reaction, as it is on Ag/Al2O3. Furthermore, there was no decrease in reaction activity for formation of acrylate species on nitrate-adsorbed Ag/Al2O3 compared to Ag/Al2O3. This led to the total reaction occurring easily through the propene nucleophilic oxidation branch because the presence of the adsorbed nitrogen oxides changed selectively the formation rates of the surface reductants. IR spectra data further demonstrate that acrylate and acetate species, as the surface reductants, reacted with nitrate to generate isocyanate intermediates in the SCR of NO. The effect of structures of different reductants on NO reduction is discussed. 相似文献
2.
Fe-Ag/AlO催化丙烯还原NO的实验研究 《燃料化学学报》2017,45(11):1365-1375
以蜂窝状陶瓷为载体,采用溶胶凝胶法和浸渍法制备了不同Fe/Ag负载量的Fe-Ag/Al_2O_3催化剂。以C_3H_6为还原剂,在模拟烟气条件下和200-700℃范围内,程序控温的陶瓷管流动反应器上进行了催化还原NO的性能评估。结果表明,7.2Fe/1.9Ag/20Al_2O_3/CM在500和550℃时催化C_3H_6还原NO的脱硝效率分别超过90%和达到100%。铁离子能有效地提高Ag/20Al_2O_3/CM催化剂抵抗烟气中的SO_2和H_2O的能力。结果表明,当烟气中含有体积分数为0.02%的SO2和8%的H_2O时,在500℃时7.2Fe/1.9Ag/20Al_2O_3/CM催化C_3H_6还原NO的脱硝效率不受影响,在6 h的连续实验中保持90%的脱硝效率而没有下降。而未经铁离子修饰的2Ag/20Al_2O_3/CM的催化活性则受烟气中的SO2和H_2O影响很大,0.02%的SO2和8%的H_2O分别使2Ag/20Al_2O_3/CM在500℃时催化C_3H_6还原NO的脱硝效率迅速从70%分别下降至46%和25%。XRD和SEM表征结果表明,经铁离子修饰后的7.2Fe/1.9Ag/20Al_2O_3/CM催化剂中,形成了AgFeO_2以及Fe~(3+),催化剂表面变得疏松多孔,形成以Fe_3O_4为主的针状和片状晶体。H_2-TPR结果表明,7.2Fe/1.9Ag/20Al_2O_3/CM比Ag/20Al_2O_3/CM在更宽的温度范围内具有更好的还原特性。吡啶吸附红外光谱(Py-FTIR)实验结果显示,Fe增加了催化剂表面的Lewis酸性位。 相似文献
3.
Yihua Zhang Run Liu Yumei Teng Erti Fang Zhengyu Huang Xiankang Zeng 《Reaction Kinetics and Catalysis Letters》1996,58(1):91-96
A new type of catalyst from supporting C60 on MoO3 and Al2O3 has been prepared. The effect of different order of impregnation and calcination atmosphere on catalyst are investigated by the solution test in toluene, UV-VIS spectroscopy and temperature programmed reduction (TPR). The results show that when the catalyst was prepared by supporting MoO3 on C60/Al2O3 and calcined in N2, there is a stronger interaction between C60, MoO3 and Al2O3, but when supporting C60 on MoO3/Al2O3, the interaction is relatively weak. We consider that in the former method a new complex, Mo–C60–O–Al, is formed. 相似文献
4.
Satoshi Sumiya Mika Saito Masataka Furuyama Nobutsune Takezawa Kiyohide Yoshida 《Reaction Kinetics and Catalysis Letters》1998,64(2):239-246
The Ag/Al2O3 catalyst supported on cordierite honeycomb (Ag/Al2O3/ cordierite) is highly active forthe reduction of lean NOx by ethanol. Addition of H2O enhances the NOx reduction to CO2 and N2, and suppresses the formation of by-products such as CO, CH3CHO and C2H4. 相似文献
5.
Masahide Shimokawabe Atsushi Ohi Nobutsune Takezawa 《Reaction Kinetics and Catalysis Letters》1994,52(2):393-397
Over metal oxides (SiO2, ZrO2, Al2O3, MgO, La2O3, and CaO) with-H values of metal oxide formation higher than 700 kJ/mol, C3H6 reacts with NO2 in preference to O2. 相似文献
6.
The nature of the surface species on Pt/Al2O3 for the SCR of NO by C3H6 under excess oxygen has been investigated. An experiment consisting of three steps shows that there are at least three types
of surface species occurring on the catalyst surface. However, a reactivity test and an investigation of surface species after
adding a second metal (Fe, Sn, Co, Cr or W) to Pt/Al2O3 indicate that only (ClHmOn)HT species play an important role in NO reduction at a low operating temperature.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
7.
The preparation of pure K3Al(C2O4)3·mH2O (2<m<3) is described. Dependent on the mode of preparation, the following were found to be contaminants of the desired product: K2C2O4·1H2O; KHC2O4; KHC2O4·H2C2O4·2H2O; H2C2O4·2H2O; different forms of aluminium oxide hydrate; K4Al2(OH)2(C2O4)4· (2+x)H2O (0.7<x<1.7) and K2Al2(H2O)2(C2O4)4· 4H2O. 相似文献
8.
New adsorbents containing cuprous chloride dispersed on pillared interlayered clays (PILC) have been prepared and studied for olefin-paraffin separations. High surface-area PILC's were synthesized with different metal oxide (Al2O3, Fe2O3, TiO2 and ZrO2) as the intercalating pillars. Cuprous chloride was dispersed in a submonolayer form on these PILC's. Pure-component isotherms were measured for C2H4, C2H6, C3H6 and C3H8 at 25°C and 60°C. All sorbents exhibited high C2H4/C2H6 and C3H6/C3H8 ratios with significantly high amounts of olefins adsorbed. The best sorbent was CuCl/TiO2-PILC which showed a C2H4/C2H6 ratio of 5.3 and C3H6/C3H8=2.9 at 25°C. In all cases, olefins adsorbed by -complexation with Cu(I) ion, reflected by heats of adsorption in the range 10.7–13.7 kcal/mol, as compared to 4.8–6.9 kcal/mol for the physical adsorption of the paraffins. The -complexation was fully reversible, limited only by the rates of pore diffusion. Diffusion of C2's was rapid while for C3's the diffusion reached 60% completion in approximately 6 min. Comparing these results with those of CuCl/-Al2O3, the olefin/paraffin adsorption ratios were not as high as those of the later. However, the olefin isotherms on the PILC-supported CuCl displayed the desirable feature of having a steeper portion above the knee of the isotherm (the knee occurred at below 0.1 atm). This was a useful feature for separation because it yielded a larger working capacity. The steeper isotherm was attributed to a higher degree of energy heterogeneity as the PILC contained both surfaces of pillars and clay layers as opposed to only -Al2O3. 相似文献
9.
Qing-Yuan Bi Li-Qiong Xing Qiang Zhou Meng-Fei Luo 《Journal of fluorine chemistry》2009,130(6):528-533
A series of La-doped Al2O3 catalysts were prepared and tested for the vapor phase hydrofluorination of C2H2 to vinyl fluoride (CH2CHF, VF). It was found that the La-doped catalyst gave a stable catalytic performance and a higher selectivity to the desired VF and a lower selectivity to coke deposition compared with the pure Al2O3 catalyst. The enhancement in VF selectivity on the La-doped catalyst was due to the elimination of acidic sites on the Al2O3 surface by the addition of La2O3, evidenced by NH3-TPD results, which could also explain the declined selectivity to coke deposition on the catalyst. Raman result indicated there were two different vibration forms of CH distortion and CC expansion for the coke deposition. 相似文献
10.
11.
Insung Nam Jeong Gil Seo Sunhwan Hwang In Kyu Song 《Research on Chemical Intermediates》2010,36(6-7):685-692
Production of middle distillate (C10–C20) from synthesis gas (CO + H2) through hydrocracking of wax (>C21+) was carried out in a dual-bed reactor. Fischer–Tropsch catalyst (Co/TiO2) was used in the first-bed reactor to produce wax from synthesis gas, and a mesoporous Pd–alumina composite catalyst (Pd–Al2O3) was used in the second-bed reactor to produce middle distillate through hydrocracking of wax. Both Fischer–Tropsch synthesis function of Co/TiO2 catalyst and hydrocracking function of Pd–Al2O3 catalyst were deactivated during 100 h-hybrid Fischer–Tropsch synthesis reaction. It was revealed that deactivation behaviors of Co/TiO2 and Pd–Al2O3 catalysts were governed by different factors. Wax accumulation and Co sintering were responsible for deactivation of Co/TiO2 catalyst in the Fischer–Tropsch synthesis reaction. Loss of Pd dispersion and Pd surface area of Pd–Al2O3 catalyst was responsible for its decreased catalytic performance in the production of middle distillate through hydrocracking of wax. 相似文献
12.
V. L. Klimov G. A. Bergman O. K. Karlina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2006,80(11):1816-1818
It was shown that the published data on the thermodynamic properties of aluminum monooxycarbide Al2OC (ed) are not consistent with the phase diagram of the Al2O3-Al4C3 system. A thermodynamic modeling of the equilibrium state of the Al2O3-Al4C3 system made it possible to obtain new estimates of the standard entropy and enthalpy of formation of aluminum monooxycarbide: S°(298.15 K, cd. Al2OC) = 45.3 J/(K mol) and Δf H°(298.15 K, cd, Al2OC) = ?625.6 kJ/mol. 相似文献
13.
Sunee Srihiranpullop Piyasan Praserthdam Tharathon Mongkhonsi 《Reaction Kinetics and Catalysis Letters》2001,72(1):125-131
The cooperative effect on catalyst deactivation of Pt-based catalysts for dehydrogenation reaction was investigated using the combination of Pt-based/SiO2 and Al2O3. The presence of the effect was confirmed by reaction test, CO adsorption, H2-TPD and TPO. Considering conversion, active site, H2 uptake and the nature and amount of coke, interestingly, the physical mixture of Pt-based catalyst supported on SiO2 with 100-120 mesh and Al2O3 60-80 mesh was similar to Pt-based Al2O3. The concept of combination of two catalytic functions, acidity and metallic species, will certainly provide the possibility of better catalyst design. 相似文献
14.
15.
以ZnAl-NO3-LDHs为前体,采用离子交换法将2-苯基苯并咪唑-5-磺酸(PBSA)插入到ZnAl-NO3-LDHs层间,借助XRD、FTIR、TG-DTA和UV-Vis等手段对样品进行表征。结果表明,PBSA阴离子可以完全取代前体层间的NO3-离子,组装得到晶体结构良好的ZnAl-PBSA-LDHs。对其结构进行研究发现,ZnAl-PBSA-LDHs中存在主体与客体以及客体与客体之间的相互作用,具有超分子结构特征。ZnAl-PBSA-LDHs在350 nm以下的紫外吸收能力较PBSA客体和ZnAl-NO3-LDHs前体显著增强,热稳定性也有所提高。将ZnAl-PBSA-LDHs以1.0%的质量比加入到聚丙烯(PP)中制备成ZnAl-PBSA-LDHs/PP薄膜,显著提高了PP的耐紫外光老化性能。 相似文献
16.
A. V. Chistyakov P. A. Zharova M. V. Tsodikov S. A. Nikolaev I. N. Krotova D. I. Ezzhelenko 《Kinetics and Catalysis》2016,57(6):803-811
The direct conversion of ethanol into the linear primary alcohols C n H2n+1OH (n = 4, 6, and 8) in the presence of the original mono- and bimetallic catalysts Au/Al2O3, Ni/Al2O3, and Au–Ni/Al2O3 was studied. It was established that the rate and selectivity of the reaction performed under the conditions of a supercritical state of ethanol sharply increased in the presence of Au–Ni/Al2O3. The yield of target products on the bimetallic catalyst was higher by a factor of 2–3 than that reached on the monometallic analogs. Differences in the catalytic behaviors of the Au, Ni, and Au–Ni systems were discussed with consideration for their structure peculiarities and reaction mechanisms. 相似文献
17.
L. M. Yun S. A. Makhmudov Kh. M. Shakhidoyatov Ch. Sh. Kadyrov S. S. Kasymova 《Chemistry of Natural Compounds》1980,16(5):495-498
The condensation of 2-amino-3-methylquinazolin-4-one and its 6-nitro derivative with dialkyl-, arylalkyl-, and heterylformamides
has given the corresponding formamidines of the quinazolinone series. The details of the compounds synthesized are as follows
X, R, R′, yield (%), mp (°C, ethanol), Rf (chloroform-methanol (20:1) Al2O3): empirical formula: H, CH3, CH3, 77, 238–240, 0.49, C12H14ON4; H, C2H5, C2H5, 65, 208–210, 0.96, C14H18ON4; H, CH3, C6H5, 84, 162–164, 0.54, C17H16ON4; H, (CH2)2O(CH2)2, 60, 196–197, 0.43, C14H16O2N4; H, (CH2)5, 6.6, 196–198, 0.4, C15H18·ON4; NO2, CH3, CH3, 64. 194–196, 0.83, C12H13O3N5; NO2, C2H5, C2H5, 37, 142–144, 0.8, C14H17O3N5; NO2; CH3, C6H5, 38, 298, 0.88, C17H15O3N5; NO2, (CH2)2O(CH2)2, 60, 148–150, 0.7, C14H15O4N5.
Institute of the Chemistry of Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh
Soedinenii, No. 5, pp. 680–684, September–October, 1980. 相似文献
18.
Serge Ello Laurence Pirault-Roy Attila Wootsch Zoltán Paál 《Reaction Kinetics and Catalysis Letters》2008,94(2):301-310
Platinum-germanium catalysts supported on a non-acidic Al2O3 have been prepared by adding Ge in amounts corresponding nominally to 1/8 (PtGe1/8/Al2O3); 1/2 (PtGe1/2/Al2O3); 1 (PtGe1/Al2O3) and 2 (PtGe2/Al2O3) monolayers by controlled surface reaction of Ge(n-C4H9)4 to Pt/Al2O3. These catalysts were characterized by electron microscopy (TEM), FTIR of CO adsorption and H2 chemisorption. The ring opening of ethylcyclopentane (ECP) was studied as a test reaction between 543 and 633 K. PtGe1/8/Al2O3 catalyst produced the most ring opening products (ROP) in the whole temperature range. A good agreement with statistical
values of ROP was observed at low temperature, but at higher temperature, the opening became selective, producing mostly heptane.
Bimetallic catalysts PtGe1/Al2O3 and PtGe2/Al2O3 led to a nonselective hydrogenolysis, similar to the monometallic platinum catalyst Pt/Al2O3. The catalysts PtGe1/Al2O3 and PtGe2/Al2O3 produced ROP with the lowest selectivity; instead, much aromatics and fragments were formed, in increasing amounts above
600 K. 相似文献
19.
The effect of H2S on the activity and selectivity of catalysts (Ru/Al2O3, Pd/Al2O3 and Ru and Pd promoted molydena-alumina) was different (on differnt catalysts and different conversions of cyclohexene). Ru-containing catalysts showed higher sulfur sensitivities than the Pd-containing ones. The sequence of catalysts by their H2S uptake related to mass of catalyst was PdMo/Al2O3RuMo/Al2O3Mo/Al2O3>Pd/Al2O3Ru/Al2O3. 相似文献
20.
Effect of LaFeO3 Decoration and Ozone Treatment on Thermal Stability of Au/Al2O3 for CO Oxidation 总被引:1,自引:1,他引:0
The 1.1%Au/LaFeOx/Al2O3 catalysts were prepared by the iso-volume impregnation method and activated with H2 or O3. The catalytic performance for CO oxidation at room temperature was investigated by accelerated deactivation tests in 1.0% CO reactant stream at 550 °C. The introduction of La and Fe enhanced the thermal stability of Au/Al2O3 with a decrease in initial activity, probably due to the formation of LaFeO3 perovskite on the Al2O3 surface. The 1.1%Au/2%LaFeO3/Al2O3 catalyst activated by H2 can transform 65% CO into CO2 at room temperature after pretreatment in 1.0% CO reactant stream at 550 °C for 2 h, whereas 1.1%Au/Al2O3 activated by H2 totally loses its activity. O3 activation can always make 1.1%Au/LaFeO3/Al2O3 more active than that of H2 activation during the pretreatment process in 1.0% CO. After pretreatment for 10 h, 1.1%Au/2%LaFeO3/Al2O3 activated by O3 still shows 40% conversion of 1.0% CO at room temperature, whereas those activated by H2 become inactive completely. The better thermal stability of the catalysts activated by O3 may be due to that O3 activation leads to the formation of partially oxidized state of Au in Au/FLA-O3, which may reinforce the interaction between the metal and support. 相似文献