共查询到20条相似文献,搜索用时 575 毫秒
1.
在对βMo2N0.78催化剂加氢脱硫催化性能进行考察的基础上,对反应使用后催化剂的组成、结构变化、以及反应后催化剂再处理对活性的影响等几方面进行了研究。结果表明,在噻吩加氢脱硫条件下,βMo2N0.78 催化剂的氮含量下降,表层被硫化,而且钝化过程中产生的氮氧化物被消耗,但体相结构没有发生变化,表现了较强的抗硫化性能;脱硫反应前后催化剂的氢还原处理不能改善催化剂的活性,但预硫化催化剂在反应起始的活性与钝化催化剂在反应稳定时活性相近,加氢脱硫反应后催化剂的再次氮化处理,可以较大程度的恢复催化剂的初始活性。 相似文献
2.
A novel, crown-quat phase transfer catalyst has been synthesized and its catalytic activity examined in solid-liquid and liquid-liquid phase transfer systems. 相似文献
3.
An efficient heterogeneous Pd catalytic system has been developed, based on immobilization of Pd nanoparticles (PNPs) on a silica-bonded N-propylpiperazine (SBNPP) substrate. The SBNPP substrate effectively stabilizes the PNPs and improves their stability against aggregation. The catalytic activity of this catalyst was investigated in the cyanation of aryl halides with K4[Fe(CN)6 ] as the cyanide source. The catalyst could be recycled several times without appreciable loss of catalytic activity. 相似文献
4.
I.C. Neves G. Botelho P. Rebelo M.F.R. Pereira P. Pescarmona 《Polymer Degradation and Stability》2007,92(8):1513-1519
The catalytic degradation of high density polyethylene (HDPE) was investigated using AlTUD-1 as catalyst, a recently discovered mesoporous aluminosilicate. The catalytic activity of AlTUD-1 was evaluated by TGA measurements, using a polymer/catalyst ratio of 9:1. AlTUD-1 has a Brønsted acidic behaviour, three-dimensional (3D) connectivities and a pore diameters between 2 and 50 nm. Compared to HY zeolite, the large pore size of AlTUD-1 enhances a selective catalytic degradation of the polymer and prevents rapid deactivation. Moreover, the apparent activation energy of polymer cracking is much lower than with HY zeolite. For these reasons, AlTUD-1 is a potentially interesting catalyst for the catalytic cracking of plastic waste into liquid fuels. 相似文献
5.
采用等体积浸渍法制备了一系列不同Co/Mo原子比的碳纳米管(CNT)负载Co Mo催化剂。将该系列催化剂用于孤岛减压渣油加氢裂化反应,评价其催化效果,并在相同反应条件下与 γAl2O3负载Co-Mo催化剂的催化性能进行比较。结果表明,Co-Mo/CNT催化剂的催化效果略低于Co-Mo/γAl2O3催化剂。Co/Mo原子比对Co-Mo/CNT催化剂的催化效果有较大的影响。与相同载体的催化剂相比,当Co/Mo原子比为0.50时,Co-Mo/CNT催化剂具有最佳的催化效果,而Co-Mo/γAl2O3催化剂在Co/Mo原子比为0.35时具有最佳的催化效果。 相似文献
6.
Cu-SSZ-39, an active and hydrothermally stable catalyst for the selective catalytic reduction of NOx
M Moliner C Franch E Palomares M Grill A Corma 《Chemical communications (Cambridge, England)》2012,48(66):8264-8266
A Cu-exchanged SSZ-39 zeolite has been synthesized and tested for the selective catalytic reduction (SCR) of NOx. This material shows an excellent catalytic activity, and most importantly, an extraordinary hydrothermal stability. 相似文献
7.
采用丙烯气相进料,在预混段中先与双氧水的甲醇溶液混合后进入固定床反应器,考察了进料液中pH值、丙二醇单甲醚、乙硫醇以及铁锈等对丙烯环氧化连续反应中TS-1分子筛催化剂性能的影响。结果表明,进料液体pH值对催化剂的催化性能有影响,适宜的进料液体pH值在7左右;副产物丙二醇单甲醚含量的增加不会对催化剂性能产生影响;乙硫醇量的增加使环氧丙烷选择性下降,但不会引起催化剂的失活;而进料液体中铁锈的引入会导致催化剂中部分孔堵塞,使催化剂部分失活。当进料液中的pH值用0.1mol/L的氨水调节为7左右,在反应温度55℃,反应压力0.7MPa,TS-1催化剂具有较好的稳定性,经130h的连续试验考察,双氧水的转化率和环氧丙烷的选择性约为90%。 相似文献
8.
Parent AR Blakemore JD Brudvig GW Crabtree RH 《Chemical communications (Cambridge, England)》2011,47(42):11745-11747
The catalytic water-oxidation activity of Wilkinson's iridium acetate trimer (1) has been characterized electrochemically and by using chemical oxidants. We show that 1 can function as an operationally homogeneous water-oxidation catalyst when driven with sodium periodate as a primary oxidant, but rapidly decomposes using Ce(IV) as a primary oxidant. 相似文献
9.
[structure: see text] Poly(ethylene glycol)-supported TEMPO (PEG-TEMPO) has been prepared, and its catalytic activity in the chemoselective oxidation of alcohols with stoichiometric amounts of organic or inorganic oxidants has been investigated. The new metal-free catalyst exhibits high activity and is easily removed from the reaction mixture by filtration. Recycling experiments showed that PEG-TEMPO can be reused up to six times with no loss of catalytic activity. 相似文献
10.
Samahe Sadjadi Majid M. Heravi Mansoureh Daraie 《Research on Chemical Intermediates》2017,43(2):843-857
The nanoporous framework of a cyclodextrin nanosponge was used as catalyst for accelerating the one-pot, three-component reaction of dimedone, aldehyde, and phenols for synthesis of xanthene derivatives. Moreover, the nanocavities of cyclodextrin nanosponges were exploited for immobilization of heteropolyacids through the wet impregnation method. This catalyst exhibited superior catalytic performance compared to the bare cyclodextrin nanosponge. Despite the good catalytic activity, the leaching of the catalytic species did not allow efficient recovery and reusability. To circumvent this problem, the cyclodextrin nanosponge was amine-functionalized prior to heteropolyacid immobilization. The results proved that the amine functionalities had an effective role in preserving the catalytic species and improving the reusability through decreasing the leaching time. This catalyst was used for synthesis of a variety of xanthenes in aqueous media. The catalytic amount of catalyst afforded the desired product in excellent yields and with a relatively short reaction time. The results suggested cyclodextrin nanosponge-based catalysts as potential candidates for promoting chemical reactions. 相似文献
11.
Kim SW Son SU Lee SS Hyeon T Chung YK 《Chemical communications (Cambridge, England)》2001,(21):2212-2213
A new Pauson-Khand catalyst based on colloidal cobalt nanoparticles has been developed; the catalyst is highly effective for many intra- and inter-molecular Pauson-Khand reactions and can be recycled and reused many times without losing catalytic activity. 相似文献
12.
Ferrous methanesulfonate catalysing the conversion of aromatic,heteroaromatic,unsaturated,and aliphatic aldehydes to 1,1- diacetates at room temperature under solvent-free condition has been developed.The catalytic activity of seventeen metal methanesulfonates was compared under the same condition,ferrous methanesufonate proved to be the best.It can be easily recovered and reused for several times without distinct deterioration in catalytic activity.During the competitive protection between a ketone and ... 相似文献
13.
The catalytic activity of the manganese oxide was investigated for the oxidative functionalization of alkylaromatics to benzylic ketones using tert-butyl hydroperoxide (TBHP) as an oxidant. Manganese oxides of different types were tested for this reaction. Of all the oxides, the nano amorphous manganese dioxide exhibited significant catalytic activity and selectivity for the reaction. The nano amorphous MnO2/TBHP catalytic system could also be reused for six consecutive cycles with no considerable loss in catalytic activity. 相似文献
14.
Eriksson KL Chow WW Puglia C Bäckvall JE Göthelid E Oscarsson S 《Langmuir : the ACS journal of surfaces and colloids》2010,26(21):16349-16354
With the aim of extending the usefulness of an existing biomimetic catalytic system, cobalt porphyrin catalytic units with thiol linkers were heterogenized via chemical grafting to silicon wafers and utilized for the catalytic oxidation of hydroquinone to p-benzoquinone. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the morphology and composition of the heterogeneous catalyst. The results of the catalytic oxidation of hydroquinone obtained with porphyrins grafted on silicon were compared with those obtained earlier with the same catalyst in homogeneous phase and immobilized on gold. It was found that the catalysis could run over 400 h, without showing any sign of deactivation. The measured catalytic activity is at least 10 times higher than that measured under homogeneous conditions, but also 10 times lower than that observed with the catalytic unit immobilized on gold. The reasons of this discrepancy are discussed in term of substrate influence and overlayer organization. The silicon-immobilized catalyst has potential as an advanced functional material with applications in oxidative heterogeneous catalysis of organic reactions, as it combines long-term relatively high activity with low cost. 相似文献
15.
Stamp LM Mang SA Holmes AB Knights KA de Miguel YR McConvey IF 《Chemical communications (Cambridge, England)》2001,(23):2502-2503
A new polymer-supported chromium porphyrin has been prepared and fully characterised; its catalytic activity and recyclability were investigated for the ring-opening copolymerisation of 1,2-cyclohexene oxide (CHO) and carbon dioxide (CO2). 相似文献
16.
A new copper complex (2) has exhibited highly efficient catalytic activity of luminol chemiluminescence in water in the presence of ascorbic acid and dissolved O2 under conditions that conventional catalysts such as Cu(OAc)2, hemin or cyclen-Cu(II) did not show significant activity. 相似文献
17.
18.
Shi JY Wang CA Li ZJ Wang Q Zhang Y Wang W 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(22):6206-6213
We report a new method for the synthesis of hollow-structured phenylene-bridged periodic mesoporous organosilica (PMO) spheres with a uniform particle size of 100-200 nm using α-Fe(2)O(3) as a hard template. Based on this method, the hollow-structured phenylene PMO could be easily functionalized with MacMillan catalyst (H-PhPMO-Mac) by a co-condensation process and a "click chemistry" post-modification. The synthesized H-PhPMO-Mac catalyst has been found to exhibit high catalytic activity (98% yield, 81% enantiomeric excess (ee) for endo and 81% ee for exo) in asymmetric Diels-Alder reactions with water as solvent. The catalyst could be reused for at least seven runs without a significant loss of catalytic activity. Our results have also indicated that hollow-structured PMO spheres exhibit higher catalytic efficiency than solid (non-hollow) PMO spheres, and that catalysts prepared by the co-condensation process and "click chemistry" post-modification exhibit higher catalytic efficiency than those prepared by a grafting method. 相似文献
19.
Imidazolium-based polymer supported gadolinium triflate as a heterogeneous recyclable Lewis acid catalyst for Michael additions 总被引:1,自引:0,他引:1
A heterogeneous Lewis acid catalytic system has been developed by incorporating gadolinium triflate on to poly[styrene-co-(1-((4-vinylphenyl)methyl)-3-methylimidazolium) tetrafluoroborate] (1-Gd(OTf)3), and the catalytic activity of this system has been examined for Michael additions of amines and thiols to α,β-unsaturated esters and acrylonitrile. The reactions proceed in moderate to excellent yields in the presence of catalytic system 1-Gd(OTf)3. The catalytic system could be efficiently recycled and reused. 相似文献
20.
We describe the application of two stochastic optimization algorithms to heterogeneous catalyst design. In particular, we discuss the optimal design of a two-component catalyst for the diffusion limited A + B --> 0 and A + B2 --> 0 reactions in which each of the reactants are adsorbed specifically on one of the two distinct catalytic sites. The geometric arrangement of the catalytic sites that maximizes the catalyst activity is determined by the use of a genetic algorithm and a simulated annealing algorithm. In the case of the A + B --> 0 reaction, it is found that the catalyst surface with the optimal active site distribution, that of a checkerboard, is approximately 25% more active than a random site distribution. A similar increase in catalytic activity is obtained for the A + B2 --> 0 reaction. While both the genetic and simulated annealing algorithms obtain identical optimal solutions for a given reaction, the simulated annealing algorithm is shown to be more efficient. 相似文献