新兴精细化工讲座 第二章 合成沸石

一、从天然沸石到人工合成沸石沸石是一种结晶性硅铝酸盐,其一般组成可用Mx/n·[（AlO2）x·（SiO2）y]·wH2O来表示。人们不仅在天然矿物中发现了很多种沸石晶体,而且用人工方法不断地合成了各种新型沸石品种。最近,高硅沸石。

Preparation and antimicrobial ability of natural porous antibacterial materials

The liquid ion exchange method, solid salt melt method and dry-wet circulation method were used to prepare natural porous antimicrobial materials with natural minerals, such as zeolite, spilite, palygorskite and montmorillonite, respectively. Atomic absorption spectrum and X-ray diffraction analysis were carried out to investigate the effects of Ag^＋ , Cu^2＋ and Zn^2＋ on antimicrobial abilities of natural porous minerals, and the effect of preparation method on ion exchange capacity of antimicrobial material, respectively. The results show that for the ion exchange capacity, clay mineral is higher than fibrous mineral, i.e. both zeolite and montmorillonite are higher; the antimicrobial ability of material with Ag^＋ is the bests the exchange capacities of materials with Cu^2＋ or Zn^2＋ are all higher, but the antimicrobial ability of Cu^2＋ is better than that of Zn^2＋ .

Removal of Uranium（Ⅵ） by Fixed Bed Ion-exchange Column Using Natural Zeolite Coated with Manganese Oxide

The adsorption of uranium(Ⅵ)on the manganese oxide coated zeolite(MOCZ)from aqueous solution was investigated in a fixed-bed column.The experiments were conducted to investigate the effects of bed height,flow rate,particle size,initial concentration of uranium(Ⅵ),initial pH,presence of salt and competitive ions.The U-uptake by MOCZ increased with initial uranium(Ⅵ)concentration and bed height,but decreased as the flow rate and particle size increased.In the presence of salt and competitive ions,the breakthrough time was shorter.The adsorption capacity reached a maximum at pH of 6.3.The Thomas model was applied to the experimental data to determine the characteristic parameters of the column for process design using linear regression.The breakthrough curves calculated from the model were in good agreement with the experimental data.The BDST model was used to study the influence of bed height on the adsorption of uranium(Ⅵ).Desorption of uranium(Ⅵ)in the MOCZ column was investigated.The column could be used for at least four adsorption-desorption cycles using 0.1mol.L-1 NaHCO3 solution as the elution.After desorption and regeneration with deionized water,MOCZ could be reused to adsorb uranium(Ⅵ)at a comparable capacity.Compared to raw zeolite,MOCZ showed better capacity for uranium(Ⅵ)removal.

Study on Desulfurization of Naphtha by Modified Y Zeolite

NH4Y zeolite was prepared through ion-exchange of NaY zeolite with an ammonium salt. Then LaY zeolite was obtained through a secondary ion-exchange of NHaY zeolite with a rare earth salt solution followed by calcination of the zeolite product. Dynamic adsorptive desulfurization of naphtha was conducted in the presence of the modified LaY zeolite, and the sulfur content of the treated naphtha samples was analyzed by microcoulometry. The test results showed that under dynamic conditions the LaY zeolite prepared through secondary ion-exchange of NH4Y zeolite, which was prepared using 1.0 mol/L ammonium salt, with the rare earth salt exhibited a better desulfurization efficiency. Furthermore, the LaY zeolite achieved a best desulfurization effect at an adsorption temperature of 45 ℃ and an adsorbent/oil ratio of 1：2.

CH_4 oxidation to oxygenates with N_2O over iron-containing Y zeolites:Effect of preparation

Developing effective iron-incorporated zeolites and determining their active centers for the direct oxidation of CH_4 to oxygenates have remained challenging topics so far.In this paper,we successfully prepare the highly-dispersed iron supported Y zeolites by a facile solid-state ion-exchange method with ferrocene,which was conducted under water-free conditions followed by a series of calcination.Moreover,extra-framework dinuclear Fe^(2+)complexes are identified as so-called activeα-iron sites on zeolites.ICP-OES,N_2 adsorption–desorption test,X-ray diffraction,solid-state^(27)Al NMR,N_2O titration,TEM,EPR and^(57)Fe M?ssbauer spectra were carried out to characterize properties of sample structure,acid sites,as well as the supported iron species.Characterization results indicate that high-temperature treatments have no effect on the typical structure feature of zeolites.Compared with catalysts synthesized by conventional impregnation,the samples prepared by the facile approach possess abundant dinuclear Fe^(2+)complexes but no Fe_2O_3 bulks and show weak acidity.These lead to a higher oxygenate selectivity in CH_4 oxidation to oxygenates.Remarkably,the oxygenate(HCHO and CH_3OH)selectivity of 6.5% at 375°C can be eventually obtained.

AMMONIUM TREATMENT OFNATURAL CLINOPTILOLITE AND ITS CHARACTER OF ION-EXCHANGE

Ammonium can change the type of natural clinoptilolite from Jinyun ofZhejiang Province of China. The character of exchange and selectivity of ammonium type clinoptilolite to the alkali and alkaline - earth metal were investigated, the heatresistance and nitric acid - resistance of natural clinoptilolitewere discussed. All types of clinoptilolite were researched by means of X - ray,IR spectroscopy, DTA analyses. The ion exchange was experimented by columnoperation, indicating that the valid amount of exchange capacity of NH+4 typeclinoptilolite is more than 25mg/g.

Investigation of the Ion-Exchange Behavior of Zeolite Y in the Presence of Resin

Ion-exchange process of zeolite Y using ammonium-type resin as an exchange reagent was successfully carried out. The effect of temperature, space velocity and ion concentration on the breakthrough curves was carefully investigated. At the first exchange section, the maximum proportion of qualified zeolites(QR) was obtained at a temperature of 70 ℃, a weight hourly space velocity of 0.61 h-1, and an ion concentration of 197 mg/L. The minimum length of mass-transfer zone(MTZ) of the resin bed was achieved at a temperature of 70 ℃, a space velocity of 0.61 h-1, and an ion concentration of 423 mg/L. At the second exchange section, the length of MTZ of the resin bed was significantly increased, and the exchange of Na+ ions contained in zeolite Y was more difficult than that achieved at the first exchange section. In both the first and the second exchange sections, the zeolite Y subjected to ion exchange with the resin maintained the similar physical and chemical properties as compared to those exchanged by the conventional approaches, but the zeolite Y, which was obtained after ion exchange, contained a significantly lower content of Na2 O.

Esterification of Free Fatty Acids in Waste Cooking Oil by Heterogeneous Catalysts

Waste cooking oil(WCO) is becoming the most promising alternative feedstock to produce biodiesel due to its low cost in China. In this study, NKC-9 ion-exchange resin and H-beta zeolite were selected as heterogeneous catalysts in the WCO esterification process and their esterification characteristics were compared by orthogonal experiments. NKC-9 resin showed higher activity and achieved a higher final conversion compared with H-beta zeolite under the same reaction conditions. Reusability experiments showed that NKC-9 resin still exhibited high activity after 5 runs. The effects of the mole ratio of alcohol to oil, reaction time, reaction temperature and the catalyst dose were investigated by multifactor orthogonal analysis. The influence of the free fatty acid(FFA) content was also investigated, and the result showed that the esterification rate could be as high as 98.4% when the FFA content was 6.3wt%.

Development of Low Carbon Aquaculture System by Using Zeolite

Ammonia volatilization is a major process of N （nitrogen） loss that affects the environment. The best way of capturing volatilized ammonia-N could be using zeolite as a good ion exchange medium before it gets either volatilized or nitrified. Thus, captured ammonia-N could be used as a source of inorganic nitrogen in ponds to promote algal production without adding additional organic carbon and BOD （biochemical oxygen demand）. The zeolite used for the study was a commercially available zeolite, （CLINZEX） which was a fine powder （CEC （cation exchange capacity） 3.9-4 meq/g）. The experiment was conducted to assess the difference between manure loaded system and zeolite loaded system in terms of water quality, TAN （total ammoniacal nitrogen） release and algal productivity. The difference between the BOD values recorded in both the controls and treatments utilizing chicken manure as source of manure-N remained mostly above 10 ppm. Similarly, the difference between mean COD （chemical oxygen demand） values of control and treatment tanks always remained above 7 ppm. All the experimental tanks loaded with zeolite samples from chicken manure showed range of variation in TAN values （0.018-0.08 mg/1）. The range of values of chlorophyll a （1,029-5,150 mg/m~） recorded in the treatment tanks was higher than the values （54.6-1347 mg/m3） of chlorophyll a in the control tanks. F-test analysis done using highest mean values of BOD, COD, TAN and chlorophyll a showed a highly significant （P 〈 0.01） variation between the treatment and control tanks and at the same time no significant variation was found between time intervals.