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91.
Studies on the effects of iron and nickel incorporation into the hydrothermal synthesis of ANA zeolite were carried out. The presented work reveals that pure Fe‐Al analcime is synthesized by using starting composition with a higher iron(III) content than reported in previous publications. Furthermore, the iron(III) and nickel(II) contents play important roles in the framework of the synthesized zeolite. XRD, FT‐IR spectroscopy, diffuse reflectance UV/Vis spectroscopy, nitrogen adsorption and SEM were used to characterize the synthesized zeolites. These investigations showed that loading of iron and nickel ions in ANA zeolite changes the pore size and morphology of analcime zeolite.  相似文献   
92.
Calixarenes, as nano-baskets, are considered an important group of macrocycles as the third famous host molecules after cyclodextrins and crown ethers have been subject to extensive researches in construction of many extractants, transporters, stationary phases, electrode ionophores and optical and electrochemical sensors over the past four decades. Because of the recent rapid growth in the publications of calixarene applications, this review paper has focused on different analytical applications of calixarenes in the main fields of separation, electroanalysis, spectroscopy and chemometrics. The objectives and the results of about 300 references mainly were published in recent 6 years with emphasis on the analytical applications were reviewed.  相似文献   
93.
Silicon-29 NMR spectra were obtained for more than 20 aqueous alkaline silicate solutions containing methanol. A signal assigned to CH3OSi(OH)3 or one of its deprotonated congeners was studied in detail for the first time for the solution conditions involved. Its appearance was monitored as a function of the solution compositions. The pseudo-equilibrium constant for its formation is of the order of 0.65. Copyright © 2001 John Wiley & Sons, Ltd.  相似文献   
94.
95.
Pentafluorophenylammonium triflate(PFPAT) was found to be a highly efficient catalyst for the preparation of 2,4,6- triarylpyridines from the reaction of acetophenone derivatives,aromatic aldehydes and ammonium acetate.Present methodology offers several advantages,such as short reaction time,high yields,simple procedure with an easy work-up and the absence of any volatile and hazardous organic solvent.In addition,this catalytic system can act as an active,inexpensive,metal-free,recoverable and recyclable catalyst.  相似文献   
96.
In the current study,the hybrid effect of a corona discharge and γ-alumina supported Ni catalysts in CO2 reforming of methane is investigated.The study includes both purely catalytic operation in the temperature range of 923-1023K,and hybrid catalytic-plasma operation of DC corona discharge reactor at room temperature and ambient pressure.The effect of feed flow rate,discharge power and Ni/γ-Al2O3 catalysts are studied.When CH4/CO2 ratio in the feed is 1/2,the syngas of low H2/CO ratio at about 0.56 is obtained,which is a potential feedstock for synthesis of liquid hydrocarbons.Although Ni catalyst is only active above 573K,presence of Ni catalysts in the cold corona plasma reactor(T≤523K) shows promising increase in the conversions of methane and carbon dioxide.When Ni catalysts are used in the plasma reaction,H2/CO ratios in the products are slightly modified,selectivity to CO increases whereas fewer by-products such as hydrocarbons and oxygenates are formed.  相似文献   
97.
Aluminium‐27 nuclear magnetic resonance spectroscopy (27Al NMR) does not yield fully resolved spectra for end‐group aluminates attached to different silicate species. For example, the chemical shifts of all q1 (end‐group aluminates) lying in the range δ ≈ 72.2–77 ppm are observed on average at δ ≈ 74.6 ppm in an NMR spectrum. With the aim of better characterisation of different q1 linked units, we first made some attempts to resolve the signals that might arise from different q1 linkages through the application of suitable experimental methods and then followed up this work by applying some calculation methods. Some of the observed differences and evidence have not been previously detected experimentally, but were clearly apparent from our calculations (Table 1) as well as in our experimental data. Therefore, in such a situation, theoretical calculations of NMR chemical shifts can be very helpful and can provide some missing information.  相似文献   
98.
Solubility data of CO2 in aqueous N-methyldiethanolamine (MDEA) solutions of concentration (2.52, 3.36, and 4.28) kmol/m3 were obtained at temperatures (313, 323, and 343) K and partial pressures ranging from about (30 to 5000) kPa. A thermodynamic model based on extended Debye–Hückel theory was applied to predict and correlate of CO2 solubility in various aqueous amine solutions. The effect of piperazine (PZ) concentration on CO2 loading in MDEA solutions was determined at PZ concentration (0.36, 0.86, and 1.36) kmol/m3. Using experimental data in various temperatures the interaction parameters of activity coefficient model for these systems were determined. The results show the model consistency with experimental and literature data and PZ is beneficial to the CO2 loading. The comparison of results of this study with previous data work shows the wide range of CO2 loading considered in this work and the better agreement of model with experimental data. The average absolute relative deviation percent (δAAD) for all data points were 8.11%.  相似文献   
99.
A series of new 1,2/1,3-bis[o-(N-methylidenamino-5-aryl-3-thiol-4H-1,2,4-triazole-4-yl)phenoxy]alkane derivatives 3a-d and bis[o-(N-methylidenamino-2-thiol-1,3,4-thiadiazole-5-yl)phenoxy]alkanes 6a-c were prepared by condensation of 4-amino-5-(aroyl)-4H-1,2,4-triazole-3-thiols 2a-b or 2-amino-5-mercapto-1,3,4-thiadiazole with bis-aldehydes 1a-c. Further reaction of compounds 3a-d and 6a-c with dibromoalkanes afforded the new macrocycles 5a-f and 8a-d. The cyclization does not require high dilution techniques and provides the expected azathia macrocycles in good yields, ranging from 55% to 68%.  相似文献   
100.
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