Molecular Simulation of Adsorption of Quinoline Homologues on FAU Zeolite

The Grand Canonical Monte Carlo(GCMC) simulation method was used to investigate the adsorption properties of quinoline homologues(quinoline, 2-methyl quinoline, and 2,4-dimethyl quinoline) on the FAU zeolite. The adsorption heat, adsorption isotherms, and adsorption sites of them were obtained. At the temperature ranging from 673.15 to 873.15 K, the Henry constant of quinoline homologues calculated on the FAU zeolite was applied to simulate their adsorption heat. And its value was more in accordance with the related data reported in the literature. The results showed that their isosteric heat decreased in the following order: 2,4-dimethyl quinoline(118.63 kJ/mol) > 2-methyl quinoline(110.45 kJ/mol) > quinoline(98 kJ/mol), and complied with the order of their adsorbate basicity. The competitive adsorption of three components of quinoline homologues on the FAU zeolite was calculated numerically at a temperature of 773.15 K and a pressure range of 0.1—100 MPa under the Universal force field. Their adsorption capacity decreased in the following order: quinoline > 2-methyl quinoline > 2,4-dimethyl quinoline. The smaller the molecule size of the adsorbate, the greater the saturated adsorption capacity would be. It was found that the quinoline homologues could be adsorbed in the main channels of 12- membered-ring framework of the zeolite. Simultaneously, the influence of silica/alumina ratio on the adsorption property of quinoline homologues in FAU zeolite was studied. The smaller the silica/alumina ratio, the greater the isosteric heat and adsorption capacity would be.

Mechanism transformation of cyclohexene-thiophene competitive adsorption in FAU zeolite

Competition of hydrocarbon compounds with sulfides in gasoline has caused a not very high selectivity of sulfides in adsorption desulfurization so far,resulting in a reduction of catalyst lifetime as well as more sulfur oxide emissions.Tostudy the whole competitive process changing with the increase of the loading,the dynamic competition adsorption mechanism of cyclohexene and thiophene in siliceous faujasite(FAU)zeolite was analyzed by the Monte Carlo simulation.The results showed that with the increase of the loading,thiophene and cyclohexene had different performances before and after the inflection point of 40 molecule/UC.The adsorbates were distributed ideally at optimal sites during the stage that occurred before the inflection point,which is called the“optimal-displacement adsorption”stage.When approaching the inflection point,the competition became apparent and the displacement appeared accordingly,some thiophene molecules at S sites(refers to the sites inside the supercages)were displaced by cyclohexene.After the inflection point,the concentration of adsorbates at W sites(refers to the 12-membered ring connecting the supercages)was significantly reduced,whereas the adsorbates at S sites got more concentrated.The stage some cyclohexene molecules displaced by thiophene and inserted into the center of the supercage can be named as the“insertion-displacement adsorption”stage,and both the adsorption behavior and the competitive relationship became localized when the adsorption amount became saturated.This shift in the competitive adsorption mechanism was due to the sharp increase of interaction energy between the adsorbates.Besides,the increase in temperature and ratio of Si/Al will allow the adsorbates,especially thiophene molecules to occupy more adsorption sites,and it is beneficial to improve the desulfurization selectivity.

The Microwave Direct Heating of Zeolite FAU in an Open System

Zeolite FAU was heated directly by microwave irradiation at 2450 MHz in an open system without special loading materials. It was discovered that zeolite X was heated to 1473 K about 90 seconds at power output of 400 W. HY type zeolite was also heated to 1373 K although it needed relative long time (about 11 minutes). Influences of exchangeable cations and adsorbed substances on zeolites ability to absorb microwaves were also discussed.

Eco-friendly synthesis of high silica zeolite Y with choline as green and innocent structure-directing agent

Zeolite synthesis in contemporary chemical industries is predominantly conducted using organic structure‐directing agents(OSDAs),which are chronically hazardous to humans and the environment.It is a growing trend to develop an eco‐friendly and nuisanceless OSDA for zeolite synthesis.Herein,choline is employed as a non‐toxic and green OSDA to synthesize high silica Y zeolite with SiO2/Al2O3 ratios of 6.5–6.8.The prepared Y zeolite samples exhibited outstanding(hydro)thermal stability at ultrahigh temperature owing to the higher SiO2/Al2O3 ratio.The XRF,SEM,29Si‐NMR and 13Na+results suggested that choline plays a structure‐directing role in the synthesis of Y zeolite,while the feed molar fraction of Na+is a crucial determinant for the framework SiO2/Al2O3 ratio and the crystal morphology.

Forming and Gathering of SnO2 Nanoparticles on External Surface of High Silica TON, MFI and FAU Type Zeolites

Tin dioxide （SnO2） nano-particles were prepared on high silica TON, MFI and FAU type zeolites by impregnation of SnC12 solution and subsequent calcination at 873 K. XRD and SAED were used to characterize the crystalline phase, and TEM was used to characterize the morphology, the particle size and the agglomerative state of the formed nano-materials. The nano-particles, which possess 8 nm, 10-80 nm and 6 nm in size, were found to form on the outer surface of TON, MFI and FAU zeolites, respectively. SnO2 microcapsules and SnOz netlike nanostructure were obtained by decomposition of SnO2-TON and SnO2-MFI in 40% hydrofluoric acid at room temperature. Compared with the nano-particles formed on NaY zeolite, the special morphology and the agglomerative state of SnO2 nanostructures on TON and MFI type zeolites with one and two dimension channel system indicate that the heterogeneous framework, surface structure and property perform important function for forming and growing SnO2 nanostructure on the outer surface of the zeolites.

Novel method for the preparation of Cs-containing FAU（Y） catalysts for aniline methylation

Cs-containing FAU（Y）-type zeolite catalysts were prepared by conventional and novel ion exchange procedures followed by incipient wetness impregnation with CsOH. The novel ion exchange procedure involved hydrothermal treatment of NaY zeolite in aqueous solution of CsCl at 140-200 ℃ for 6-24 h. The samples were characterized by low-temperature nitrogen adsorption, X-ray fluorescence analysis, X-ray powder diffraction, scanning electron microscopy, 23Na, 27Al and 133Cs magic angle spinning nuclear magnetic resonance, CO2 and NH3-Temperature programmed desorption. The results show that hydrothermal treatment at 200 ℃ allows to obtain higher degrees of ion-exchange （up to 83%） with respect to conventional method giving maximum 66%- 69%. Catalytic properties of Cs-containing FAU（Y） were studied in aniline methylation. The yield of Nomethylani- line is shown to correlate with catalyst＇s basicity. The best catalyst performance was achieved over the catalyst with the highest ion-exchange degree impregnated with CsOH. The selectivity to N-methylaniline over this catalyst reached 96.4%.