共查询到20条相似文献,搜索用时 15 毫秒
1.
Wan Azelee Wan Abu Bakar Rusmidah Ali Abdul Aziz Abdul Kadir Salmiah Jamal Mat Rosid Nurul Shafeeqa Mohammad 《燃料化学学报》2012,40(7):822-830
A series of alumina supported cobalt oxide based catalysts doped with noble metals such as ruthenium and platinum were prepared by wet impregnation method.The variables studied were difference ratio and calcination temperatures.Pt/Co(10∶90)/Al2O3 catalyst calcined at 700 ℃ was found to be the best catalyst which able to convert 70.10% of CO2 into methane with 47% of CH4 formation at maximum temperature studied of 400 ℃.X-ray diffraction analysis showed that this catalyst possessed the active site Co3O4 in face-centered cubic and PtO2 in the orthorhombic phase with Al2O3 existed in the cubic phase.According to the FESEM micrographs,both fresh and spent Pt/Co(10∶90)/Al2O3 catalysts displayed small particle size with undefined shape.Nitrogen Adsorption analysis showed that 5.50% reduction of the total surface area for the spent Pt/Co(10∶90)/Al2O3 catalyst.Meanwhile,Energy Dispersive X-ray analysis(EDX) indicated that Co and Pt were reduced by 0.74% and 0.14% respectively on the spent Pt/Co(10∶90)/Al2O3catalyst.Characterization using FT-IR and TGA-DTA analysis revealed the existence of residual nitrate and hydroxyl compounds on the Pt/Co(10∶90)/Al2O3 catalyst. 相似文献
2.
Trichloroethylene has been found to act as a rate enhancing co-factor in the liquid phase, tantalum (V) halide catalyzed, fluorine-for-chlorine exchange reaction of 1,2-dichloro-1,1-difluoroethane (R-132b) to 2-chloro-1,1,1-trifluorethane (R-133a). Several trifluoromethyl substituted benzenes have also been found to be rate-enhancing solvents. 相似文献
3.
The dehydrogenation of isobutane (IB) to produce isobutene coupled with reverse water gas shift in the presence of carbon dioxide was investigated over the catalyst Cr2O3 supported on active carbon (Cr2O3/AC). The results illustrated that isobutane conversion and isobutene yield can be enhanced through the reaction coupling in the presence of carbon dioxide. Moreover, carbon dioxide can partially eliminate carbonaceous deposition on the catalyst and keep the active phase (Cr2O3), which are then helpful to alleviate the catalyst deactivation. 相似文献
4.
Koji Shiba Hirofumi Hinode Masataka Wakihara 《Reaction Kinetics and Catalysis Letters》1998,64(2):281-288
Selective reduction of nitric oxide (NO) by ethene in the presence of excess oxygen was investigated using a silver supported
on TiO2 (Ag/TiO2) catalyst. Ag/TiO2 showed high catalytic activity for the reduction of NO to N2 and N2O. The activity for the reduction of NO to N2 and N2O was enhanced with an increase up to 3 wt.% Ag loading level. On increasing the concentration of ethene, the catalytic activity
for the reduction of NO to N2 and N2O was enhanced. The reduction of NO over Ag/TiO2 catalyst never proceeds without coexistent oxygen. 相似文献
5.
6.
合成了Cu/Al原子比分别为2.0、3.1、4.1的CuAl类水滑石样品,焙烧得到CuAl复合氧化物。在Cu/Al原子比为3.1的CuAl氧化物表面浸渍碱金属盐溶液,制备改性CuAl复合氧化物,用AES、XRD、FT-IR、BET、H2-TPR、XPS等技术对催化剂进行了结构表征,考察了CuAl复合氧化物组成、碱金属助剂类型和K的前驱物对改性催化剂在有氧气氛中催化分解N2O活性的影响。结果表明,Na、K、Cs改性CuAl复合氧化物均提高了催化剂活性,但K助剂的增强效应最显著;钾的不同前驱物改性CuAl复合氧化物的催化活性有显著差异,加入碳酸钾、草酸钾提高了催化剂的活性,而加入醋酸钾、硝酸钾反而降低了催化剂活性。优化出的K改性CuAl复合氧化物催化剂在含氧含水气氛的N2O分解反应中表现出了较高的活性。 相似文献
7.
采用浸渍法制备了一系列用于甲烷选择催化还原(CH4-SCR)氮氧化物的Co/MOR催化剂。采用XRD、BET、TG-MS、H2-TPR、NH3-TPD和NO-TPD等手段对催化剂进行表征,并对其在甲烷选择催化还原氮氧化物反应中的活性进行评价。结果表明,钴物种以Co3O4尖晶石形态存在于Co/MOR催化剂中;与MOR载体相比,引入钴物种后,催化剂的酸性、氧化还原能力和对NO的吸脱附能力均发生了变化。在甲烷选择催化还原氮氧化物反应中,Co/MOR的催化活性与其氧化还原性能和对NO的吸脱附性能直接相关;其中,Co负载量为10%的Co(10)/MOR催化剂的CH4-SCR脱硝活性最好,在330℃下NO的转化率达54.2%。 相似文献
8.
Alberto M. Becerra María E Iriarte Adolfo E. Castro Luna 《Reaction Kinetics and Catalysis Letters》2003,79(1):119-125
The kinetics of the CO2-reforming of methane over a stable Ni/γ-Al2O3 catalyst has been studied in the range of 773-873 K, at normal pressure and various CO2/CH4 molar ratios. An Eley-Rideal type model gives good agreement with the experimental observations and the kinetic parameters
are statistically significant.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
9.
采用卧式程序控温电加热陶瓷管反应器,在N2和模拟烟气气氛中、300~1 100℃下,研究了SO2对甲烷在金属铁及其氧化物表面还原NO反应的影响。采用XRD等手段对反应前后铁催化剂样品的组成变化进行了表征,分析了SO2在甲烷-铁脱硝反应中的作用机理。结果表明,甲烷在金属铁及氧化铁表面能够高效率地还原NO,NO还原效率不受烟气中SO2的影响。在SO2体积分数为0.01%~0.04%的N2气氛中,温度高于700℃时,金属铁上NO还原率和SO2脱除率可同时达到100%。在SO2体积分数为0.01%~0.04%的模拟烟气中,当温度高于850℃时,NO还原效率达到90%以上;温度为950℃时,NO还原效率达到98%,SO2对NO还原效率的影响可忽略。当反应温度为1 000℃时,在含0.02%SO2的模拟烟气中,甲烷的体积分数为1.13%时,持续100 h金属铁表面上的NO还原效率都能保持95%以上。 相似文献
10.
Takashi Kamegawa Masaya Matsuoka Masakazu Anpo 《Research on Chemical Intermediates》2008,34(4):427-434
A highly dispersed Cr6+-oxide species on silica (Cr/SiO2) was found to act as an efficient photocatalyst for the selective oxidation of CO into CO2 with O2 in the presence of H2 under visible (λ>420 nm) or solar light irradiation at 293 K. UV-Vis, photoluminescence and FT-IR investigations revealed
that the selective reactivity of the photoexcited tetrahedral Cr6+-oxide species ([Cr5+−O−]*) with CO, as well as the high reactivity of the photoreduced Cr6+-oxide species (Cr4+-oxide species) with O2 both play significant roles in this reaction. 相似文献
11.
以正己烷作为裂解原料烃类代表,Pt-Sn/Al2O3催化剂作为氢选择性燃烧催化剂,对直接内加热方式提供热量促使裂解原料达到可裂解温度的可行性进行了研究。结果表明,温度相同时,Pt-Sn/Al2O3 催化剂存在时氢燃烧的选择性明显高于无催化剂存在时的非催化氢燃烧过程,Pt-Sn/Al2O3 催化剂是优良的氢选择性燃烧催化剂。该催化剂在催化氢选择性燃烧过程中,存在一个临界温度点650℃。当物流入口温度低于650℃时,氢燃烧选择性达90%以上;高于650℃时,由于非催化氢燃烧所占总燃烧反应比例加大,造成氢燃烧选择性有所降低。同时,在一定温度下,要获得高的氢燃烧选择性及氧气转化率,须综合考虑氢烃比和氢氧比的影响。 相似文献
12.
Guang-jian Wang Yong-ning Qin Zhi Ma Xiao-zhou Qi Tong Ding 《Reaction Kinetics and Catalysis Letters》2006,89(2):229-236
Summary The reduction mechanism of SO2 by CO using LaCoO3 and doped copper as catalysts was investigated. The activity, selectivity of sulfur and the COS amount under various reaction
conditions were tested. The results showed that the Cu doped catalysts were better than the undoped catalyst and 10% copper-doping
gave the optimum catalyst. 相似文献
13.
采用共沉淀法制备了系列Au/αFe2O3 MOxM=Zr、Al、Mg、Ca、Ba)催化剂,通过N2物理吸附、XRD、H2-TPR和CO2-TPD-MS等手段对催化剂的物化性质进行表征,考察了富氢下低温水煤气变换(WGS)反应中助剂对Au/αFe2O3催化剂性能的影响。结果表明,助剂ZrO2能有效提高Au/α Fe2O3催化剂在富氢气氛下低温WGS反应活性和稳定性,反应温度150℃时CO转化率可达88.45%,且催化剂具有较高的稳定性。研究发现,添加ZrO2助剂能抑制载体晶粒的生长,降低载体晶粒度,提高催化剂的比表面积,改善催化剂的还原性能和表面酸碱度,从而提高催化剂的催化活性和稳定性。 相似文献
14.
采用浸渍法制备了多壁碳纳米管(MWCNT)负载的Cu2O和CuI催化剂,并运用粉末X射线衍射、红外光谱、扫描电镜-能量散射谱、透射电镜和NH3程序升温脱附等技术对催化剂进行了表征。结果表明,催化剂中沉积的Cu2O和CuI分别以立方相和γ相存在于MWCNT上,且表现出由弱到强的拉电子(Lewis酸)性能。将催化剂用于催化芳醛与2-氨基吡啶氧化酰胺化反应合成N-(吡啶-2-基)苯酰胺类化合物,产物选择性为100%,收率为50%–95%。 CuI/MWCNT催化剂上产物分离收率性能好于Cu2O/MWCNT,但后者的循环使用性能更好。与共价的CuI相比,离子化的Cu2O与极性的酸活化的MWCNT间具有更适宜的相互作用,这种不同的相互作用可显著影响2-氨基吡啶的氨基对芳醛羰基的亲核进攻速率。 相似文献
15.
Junhua Li Jiming Hao Lixin Fu Tianle Zhu Zhiming Liu Xiangyu Cui 《Reaction Kinetics and Catalysis Letters》2003,80(1):75-80
The activities of metal oxide CuO, SnO2, CoO, Ag2O, ZnO or noble metal Pt, Pd, Rh-doped In2O3/Al2O3 catalysts for selective catalytic reduction of NO by propene were investigated. The temperature windows for NO reduction
over noble metal-doped In2O3/Al2O3 catalysts were shifted and broaden slightly compared with single component catalyst alone.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
Suppressed formation of CO2 and H2O in the oxidative coupling of methane over La2O3/MgO catalyst by surface modification
下载免费PDF全文
![点击此处可从《天然气化学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Oxidative coupling of methane (OCM) is a promising way to convert methane into C_2 hydrocarbons. However, CO_2 and H_2O are by-products of the reaction. To utilize the higher activity of lanthanum oxide and save its usage, MgO supported La_2O_3 catalyst was prepared. Surface modification of the catalyst with nitric acid was made to suppress the formation of the by-products. Experimental results indicated that the addition of nitric acid increased the surface oxygen species with binding energy of ca. 531.7 eV and at the same time reduced the pore volume of the catalyst. These effects of nitric acid finally led to the increase of C_2 selectivity and the decrease of the by-products formation. Hydrogen selectivity was found about 14%- 18% over the catalysts adopted in this work. 相似文献
17.
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
18.
以Ag/Al2O3为催化剂,采用原位漫反射傅里叶变换红外光谱法研究了SO2对C3H6选择性还原NOx反应的影响. 结果表明, SO2在催化剂表面转化为硫酸盐,并且随着硫酸盐累积量的增加,其主要红外特征吸收峰由低波数向高波数漂移. 高浓度表面硫酸盐的存在不仅抑制了催化剂表面硝酸盐的生成,而且抑制了硝酸盐与表面烯醇式物种(RCH=CH-O-)或乙酸盐物种进一步反应,生成活泼的反应中间体异氰酸酯(-NCO), 这是导致Ag/Al2O3催化剂上C3H6选择性还原NOx活性降低的主要原因. 相似文献
19.
Ramyah Radman Abdullah A. Al-Kahtani Wafa K. Mekhamer A. Yacine Badjah Hadj Ahmed 《Green Chemistry Letters and Reviews》2020,13(4):1-10
ABSTRACT Vicinal diols are important building blocks for chemicals and pharmaceuticals. Currently, they are produced from olefins using solvents and harmful oxidants unfavorable from an environmental and economic point of view. This work lies on the synthesis of 1,2 cyclohexane diol from cyclohexene by a green route. To achieve it, a series of Cobalt Keggin heteropolyanion salt (Co1.5PW12O40) loaded on activated carbon with different contents was prepared, characterized and tested for the synthesis of diol. The effect of various parameters such as reaction temperature, reaction time and CO2 pressure on the reaction was studied. The effect of reaction temperature in the range 60-80 °C showed that high temperatures favor diol formation while low temperatures favor cyclohexanone and a segmented concave Arrhenius graph was observed. The results of this work showed that oxidation by H2O2 in the presence of CO2 is an efficient oxidant system for the production of 1.2 cyclohexane diol over carbon activated carbon supported Co1.5PW12O40. Thanks to CO2 as a soft oxidizing agent, a conversion of 96.9% and a selectivity in 1, 2 cyclohexane diol of 64.2% was obtained. This simple, safe and environmentally method could be an alternative green route for vicinal diols production from alkenes. 相似文献
20.
M. Hassanein S. Gerges M. Abdo S. El-Khalafy 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):22-26
The catalytic activity and stability of anionic cobalt(II) porphyrin complexes: 5,10,15,20-tetrakis(2,6-dichloro-3-sulfonatophenyl)porphyrinatocobalt(II), 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5disulfonatophenyl)porphyrinatocobalt(II) and the cationic cobalt(II) porphyrin: 5,10,15,20-tetrakis[4-(diethylmethylammonio)phenyl]porphyrinatocobalt(II) tertraiodide have been investigated in the oxidation of 2-mercaptoethanol by dioxygen. All complexes were efficient catalysts for the auto-oxidation of 2-mercaptoethanol. The cationic cobalt(II) porphyrin has been found to be the most reactive catalyst. The rate of auto-oxidation of 2-mercaptoethanol catalysed by 5,10,15,20-tetrakis(2,4,6-trimethyl-3,5disulfonatophenyl)porphyrinatocobalt(II) has been found to increase with increasing the pH from 7 to 9 then decreased at higher pH. The rate constants of auto-oxidation reaction showed linear dependence on catalyst concentration and saturation kinetics in both 2-mercaptoethanol concentrations and dioxygen pressure. Anionic cobalt(II) porphyrin complexes showed higher stability than the cationic catalyst in repeat oxidation reactions. Immobilizing the anionic catalysts on ion exchange resin and supporting the cationic catalyst on clay mineral montmorillonite improved their stabilities towards oxidation. 相似文献