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1.
A series of NiO-ZrO2 catalysts were prepared by coprecipitation from the mixed aqueous solution of nickel chloride-zirconium oxychloride, and
were modified with acids, H2SO4, H3PO4 and H3BO3. It was found that the NiO-ZrO2 catalyst containing 25 mole percent of nickel oxide and evacuated at 400‡C for 1.5 hr showed maximum catalylic activities
for 1-butene isomerization and ethylene dimerizalion. The catalytic activities for both isonierization and dimerizalion were
correlated with the acid strengths of the catalysts. The isonierization activity of 1-butene ran parallel with the dimerization
activity of ethylene, although the isomerization look place on relatively weak acid sites as compared with the dimerization. 相似文献
2.
Low-temperature combustion of various organic compounds on Pt/SO
4
–2
/ZrO2 and Pd/SO
4
–2
/ZrO2 was studied. For these organic compounds, especially saturated hydrocarbons, the combustion activities of Pt/SO
4
–2
/ZrO2 are higher than those of Pt/ Al2O3. Pt/SO
4
–2
/ZrO2 combustion catalysts can be used in a wide range of space velocity and oxygen content. The catalytic activity is enhanced with an increase of Pt loading from 0.1 to 1.0 wt%. The superacidity of the support material is responsible for the improvement in activity rather than an increase in catalyst surface area or metal dispersion. Pd/SO
4
–2
/ZrO2 are less active than Pt/SO
4
–2
/ZrO2. 相似文献
3.
以共沉淀-浸渍法制备了SO42-/TiO2/Al2O3型固体酸催化剂,醋酸与正丁醇酯化反应作为探针反应,考察SO42-/TiO2/Al2O3型固体酸催化剂的催化性能,采用响应面法对制备催化剂过程中的陈化温度、硫酸浸渍液浓度和焙烧温度因素进行优化,通过XRD和IR对制备的固体酸催化剂进行表征。结果表明,在陈化温度-4 ℃、硫酸浸渍液浓度1.48 moL·L-1和焙烧温度586 ℃条件下制得的催化剂催化性能最高,醋酸正丁酯酯化率可达98.1%,重复使用性良好。 相似文献
4.
以硝酸锆为主要原料,采用酸浸渍法制得SO4^2-/ZrO2-SiO2固体超强酸,对主要影响其催化活性的焙烧温度进行了考察,并将制得的SO4^2-/ZrO2-SiO2作催化剂,合成了丁酸异戊酯,确定了最佳工艺条件。实验表明制得的该催化剂具有较高的催化活性,用其催化合成丁酸异戊酯其收率达93%。 相似文献
5.
Xin Zhang Xiaogang Li Junsheng Wu Renchun Yang Zhihua Zhang 《Catalysis Letters》2009,132(1-2):253-258
V2O5/TiO2 catalyst with 3% (w/w) V loading has been prepared by sol–gel method. The characterization results of the catalyst structure and catalytic activity show that VO X state is strongly dependent on the calcination temperature. Little effect is found for phase structure of TiO2 support on catalytic activity. High catalytic activity in wide temperature range (240–420 °C) is observed for the catalysts calcinated at different temperatures at a space velocity of 50,000 h?1. Space velocity and alkali metal oxides strongly influence the catalytic activity of the catalyst which was calcinated at 450 °C, furthermore, the one has high tolerance to SO2 in our test conditions. 相似文献
6.
7.
With the integrative transformation of non α-tocopherols, glycerides, free fatty acids, and methyl alcohol in cottonseed oil deodorizing distillate as the target reaction, we prepared highly catalytic SO42?/ZrO2-MoO3 solid acid catalyst by precipitation–wet impregnation. The optimal conditions for catalyst preparation were then determined by varying sulfuric acid concentration, MoO3 loading factor, calcination temperature, and calcination time. The structure of SO42?/ZrO2-MoO3 solid acid catalyst was then examined by X-ray diffraction (XRD), Brunauer–Emmett–Teller measurements, scanning electron microscopy, and other methods. Results show that the MoO3 loading factor (percentage weight ratio of MoO3 to ZrO2), impregnation concentration of sulfuric acid, and calcination temperature were the most important factors that influenced catalytic activity. The optimal conditions for catalyst preparation were an MoO3 loading factor of 20%, a sulfuric acid impregnation concentration of 0.75 mol/L, a calcination temperature of 550 °C, and a calcination time of 6 h. The obtained catalyst exhibited the highest catalytic activity under these conditions. 相似文献
8.
Changes of the V2O5/Al3O3 catalyst aged for up to 10 years under real conditions of the selective catalytic reduction of NO
x
by ammonia (SCR) at the tail gases of the nitric acid plant were characterized by51V NMR spectroscopy, porosimetry, temperature programmed reduction (TPR) and catalytic activity measurements. The catalytic activity and the redox properties of the catalyst were found intact. Only small variations of the ratio of the octahedral and tetrahedral vanadia species were documented by51V NMR on aged catalyst. 相似文献
9.
In this work, a catalyst with FeVO4 nanorods supported on TiO2 was prepared and applied for NH3–SCR reaction. A significantly enhanced low temperature catalytic activity has been achieved in the presence of 10% H2O with the active window shifting by 15 °C to lower temperatures, compared to the classical catalyst with FeVO4 nanoparticles supported TiO2. For the catalyst containing FeVO4 nanorods, enhanced redox ability and enriched surface active oxygen species originated from its unique crystal structure and predominantly exposed reactive crystal facets (− 2 1 0) on the catalyst surface are responsible for its improved low temperature catalytic activity. 相似文献
10.
The mesoporous molecular sieve Zr-MCM-41 was synthesized under hydrothermal conditions. Zr-MCM-41 material was impregnated using sulfuric acid to prepare SO
42-/Zr-MCM-41. The obtained materials were characterized by XRD, FT-1R, N2 adsorption/desorption and NH3-TPD analysis technique. The results indicated that SO
42-/Zr-MCM-41 was of better mesoporous structure, long range ordering and crystallites, and that SO
42-existed in the skeleton of Zr-MCM-41 and enhanced its acidity. SO42-/Zr-MCM-41 were firstly used as catalyst in the esterification of terpineol. The catalytic results were compared with those obtained by using sulfuric acid (33%), HY, HZSM-5 and SO42-/ZrO2 as catalysts. It was showed that SO42-/Zr-MCM-41 were not only of better catalytic activity and selectivity, but also of better regenerable performance. The effects of synthesis methods of catalysts and Si/Zr mole ratio on catalytic properties were also studied. In addition, AlCl3 was supported on the synthesized mesoporous molecular sieves to get composite catalysts that were firstly used to catalyze the polymerization of -pinene. It was showed that the catalytic result of the composite catalyst was better than that AlCl3 alone.*To whom correspondence should be addressed. E-mail: yushitao@elong.com 相似文献
11.
The K2CO3/MoS2 catalyst for higher alcohols synthesis with synthesis gas as feedstock was prepared. The catalyst was characterized by TPR, in-situ XPS, XRD and SEM. Effects of pretreatment with H2, CO or synthesis gas on activity and selectivity of the catalyst were investigated. Results showed that there was a remarkable induction period about 180 h at the initial reaction stage for the un-treated catalyst. The catalytic performances for alcohols synthesis changed notably during the induction period. The induction period was confirmed to be resulted primarily from the sulfur losing and K element dispersion on the surface of ADM catalysts. Pretreatment of the catalyst could remarkably shorten the time of induction period as well as promote the catalytic activity. Furthermore, the higher alcohols (C2 + OH) content in the liquid products were enhanced after the catalyst pretreated by CO or synthesis gas which could be ascribed to the increasing of Mo4+ content on the surface of the catalyst. 相似文献
12.
《Journal of Industrial and Engineering Chemistry》2014,20(4):1577-1580
CeO2–CuO catalyst prepared by citric acid method was investigated for selective catalytic reduction of NO with NH3. The activity of the CeO2 catalyst was enhanced about 8–27% in the temperature range of 125–225 °C at a space velocity of 28,000 h−1 by the addition of Cu. It was found that the state of Cu species had great impact on the SCR performance of CeO2–CuO catalyst. Cu2+ can enhance the low temperature activity of SCR reaction, while CuO would promote NH3 oxidation before SCR reaction at high temperature, which would cause the decrease of its high temperature SCR activity. 相似文献
13.
用浸渍法制备了以Al2O3为载体、Ni为活性组分的Ni/Al2O3二氧化碳甲烷化催化剂,在等温固定床反应器中研究了在Ni/Al2O3催化剂作用下,高纯氯化氢中微量CO2甲烷化反应效果,并考察了温度、压力、氯化氢体积空速以及H2/CO2摩尔比对CO2转化率的影响,同时研究了催化剂活性、稳定性及其再生性能。结果表明,在温度为250℃、压力为4.0 MPa、氯化氢空速为100 h-1、H2/CO2摩尔比为500:1条件下,CO2甲烷化反应效果最好,其转化率可达到90%左右,对于高纯氯化氢中微量CO2的脱除起到很好的效果;催化剂在温度高于300℃时,反应不久后会迅速失活;催化剂再生性能只能部分恢复到新鲜水平。 相似文献
14.
R. Yu F.-S. Xiao D. Wang Y. Liu G. Pang S. Feng S. Qiu R. Xu S. Ma 《Catalysis Letters》1997,49(1-2):49-52
A novel type of complex oxide HxV2Zr2O9.H 2O with V4+ and V5+ mixed valence has been hydrothermally synthesized in a V2O5-ZrO2-H2O system at 240°C for 5 days in presence of NaF. The catalytic data over these complex oxides show that these complex oxides
are catalytically very active in phenol hydroxylation by 30% aqueous hydrogen peroxide, and their catalytic activity is dependent
on crystal size of the catalysts. The phenol conversion over the catalyst with crystal size of 7 μm is twice that over the
catalyst with crystal size of 35 μm. The V5+ species are suggested to be the catalytic active sites. Some other factors which influence the catalytic activity were also
investigated.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
The ammoximation of different ketones and aldehydes to their corresponding oximes catalyzed by K6[PW9V3O40]·4H2O was carried out with hydrogen peroxide and ammonia in isopropanol at room temperature. High yields of oximes were obtained in this catalytic system. This catalytic system was proved to be heterogeneous by the ammoximation activity of removal of catalyst and the elemental analysis of the filtrate after reaction. A possible procedure for the ammoximation catalyzed by K6[PW9V3O40]·4H2O with H2O2 and NH3·H2O was proposed. The fresh and used catalysts were characterized by IR and 31P MAS NMR, which revealed the good stability of the catalyst. 相似文献
16.
12-Tungstophosphoric acid supported on montmorillonite K10 (PWA/mont-K10) catalysed Pechmann condensation reaction was reported.
The catalyst was characterized by XRD, FTIR, UV–Vis DRS, surface area and pore size analysis, TGA and acidity by DRIFTS using
pyridine. The morphology of the catalyst was studied by SEM. The activity of mont-K10, mont-KSF,
\textSO 4 2 - \mathord