红外光谱法研究烯烃对Ce（Ⅳ）Y分子筛脱硫效果的影响

选取1-辛烯、1,5-己二烯、环己烯等作为模拟汽油中的烯烃模型化合物,采用FT-IR方法得到饱和吸附不同模拟油之后的Ce（Ⅳ）Y分子筛的红外光谱图,根据红外光谱信息研究烯烃对Ce（Ⅳ）Y分子筛选择性吸附脱硫性能的影响。研究发现,Ce（Ⅳ）Y分子筛阳离子和烯烃的双键发生了σ-π络合,从而跟与Ce（Ⅳ）Y存在SM作用的噻吩形成了竞争吸附。在含烯烃的模拟油中,由于烯烃和分子筛发生相互作用,占据了吸附剂的活性位,导致Ce（Ⅳ）Y分子筛的脱硫性能显著降低。     

影响CeY分子筛吸附脱硫性能因素的研究

通过液相离子交换法对NaY分子筛进行改性制得CeY分子筛，采用静态法考察了改性CeY分子筛中铈离子的负载量、焙烧温度、铈的价态、吸附水和分子筛骨架的结构对CeY分子筛吸附脱硫性能的影响。采用XRD和ICP分别对不同CeY分子筛的骨架结构及阳离子负载量进行了分析。结果表明，二次交换后,离子交换度达到88.9%，分子筛已达到交换平衡；最佳焙烧温度为500 ℃，温度过高会破坏分子筛的骨架结构；Ce(Ⅳ)Y的脱硫性能明显好于Ce(Ⅲ)Y；分子筛上的吸附水对硫化物的吸附能力也有较大的影响。     

Structural features of binary microporous zeolite composite Y-Beta and its hydrocracking performance

Y-Beta zeolite composites denoted as HS-FBZ (High-Silica-Faujasite-Beta-Zeolite) were synthesized hydrothermally using high silica Y as precursor and characterized by XRD, N₂ adsorption, SEM, HRTEM, NH₃-TPD and FT-IR spectra of pyridine. The results reveal that the different ratios of Y and Beta zeolites in the composites induced the change of surface areas, pore diameters and acid properties of HS-FBZ, and the extended Beta layers on the zeolite Y surface were observed. The composite exhibited an excellent hydrocracking activity for heavy oil. Compared with the corresponding physical mixture of Y and Beta zeolites, the zeolite composite as a hydrocracking catalyst for vacuum gas oil increased the heavy naphtha yield by 5.61 wt% and the jet fuel yield by 11.52 wt%.     

Deep desulfurization by selective adsorption on a heteroatoms zeolite prepared by secondary synthesis

Gallium atoms have been introduced into the framework of Y zeolite by treating the zeolite with an aqueous solution of ammonium hexafluoro gallate. Desulfurization of various model fuels containing about 500 μg/g sulfur were studied over the synthesized Y zeolite ([Ga]AlY) with a liquid hourly space velocity of 7.2 h^− 1 at ambient conditions. The sulfur adsorption capacity was 7.0, 14.5, and 17.4 mg(S)/g adsorbent for thiophene, 4,6-dimethyldibenzothiophene (4,6-DMDBT), and tetrahydrothiophene (THT), respectively. The charges on S atom in thiophene, 4,6-DMDBT and THT, calculated by using density functional theory (DFT), are − 0.159, − 0.214 and − 0.298, respectively, implying that the S–M bond between the adsorption sites and thiophene is much weaker than that between the adsorption sites and THT or 4,6-DMDBT.     

Y型分子筛微波法改性及其选择性吸附脱硫性能

通过微波法进行液态离子交换对NaY分子筛进行改性，采用静态实验对不同吸附剂的脱硫性能进行了考察，筛选出Ce(Ⅳ)-Y吸附性能最好。采用固定床技术对Ce(Ⅳ)-Y的吸附脱硫能力进行了研究，同时运用程序升温脱附法（TPD）和频率响应方法（FR）对吸附脱硫机理进行了进一步探讨。采用微波法进行离子交换改性后的Ce(Ⅳ)-Y分子筛的离子交换度与传统水热法比较有明显提高，吸附容量较NaY有显著提高。     

Screening of Inorganic Adsorbents for Selective Adsorption of Thiophene from Model Gasoline

Hydrodesulfurization-treated (HDS-treated) gasoline with low sulfur content is an important source of primary fuel for fuel cells, although it contains sulfur compounds, thiophene (TP), benzothiophene (BTP), and thiophene alkylated derivatives, known as a poison for the reformer catalysts and the electrode catalysts of fuel cells. Adsorptive removal of TP from model organic liquid of HDS-treated gasoline was screened on different kinds of inorganic adsorbents: hydrous metal oxides, mixed metal oxides, aluminosilicates, acidic salts of multivalent metal, hetero polyacidic salt, and metal salts of iron hexacyanate. All the adsorbents showed very low TP uptake, less than 5% of the total TP amount when metal ions were not loaded on the adsorbent. On the other hand, some metal ion (Ag, Cu, and Ce) loaded adsorbents had good TP adsorptive properties. On simple metal oxides, Ag ion was better for the formation of adsorption center than Ce or Ni ions. In zeolite group, Ce-loaded Y-zeolite showed the largest TP uptake (99% of the total TP amount). Hydrous cerium oxide and the Ce-loaded adsorbents prepared from K₄[Fe(CN)₆], Silicagel, TiO₂, and ZrO₂ did not show TP selectivity. The effect of coexisting toluene on TP adsorption was studied from the TP solutions with and without toluene.     

Effects of oxygenates and moisture on adsorptive desulfurization of liquid fuels with Cu(I)Y zeolite

Oxygenates (i.e., ethanol and MTBE as required additives in gasoline) and moisture were found to have strong inhibiting effects on desulfurization by adsorption with zeolite. The effects of each individual molecule were studied quantitatively by using a model fuel (500 ppmw thiophene in 80% n-octane + 20% benzene). Cu(I)Y was used as the π-complexation sorbent. Ab initio molecular orbital calculations showed that the adsorption bond energies with Cu(I)Y were: 21.4 kcal/mol for thiophene; 31.0 kcal/mol for MTBE and 41.6 kcal/mol for ethanol. Separation or selectivity factors can be estimated from heats of adsorption, and the inhibiting effects were predicted to follow the order of the relative heats of adsorption: water > ethanol > MTBE > thiophene. The inhibiting effects were measured by the decreases in the desulfurization capacities of Cu(I)Y in the presence of each additive in the model fuel. The results were in agreement with the theoretical prediction. In addition, the desulfurization capacity was strongly dependent on the liquid hourly space velocity because of the diffusion limitation of thiophene in the zeolite crystals.     

AgCo13X改性分子筛的制备与吸附脱硫性能

采用液相离子交换法制备了以金属离子Co2+和Ag+共同改性的AgCo13X分子筛吸附剂,并用XRD、NH3-TPD、BET和TG等技术对其结构进行表征。在模拟柴油中考察了吸附剂对二苯并噻吩(DBT)的脱硫性能。结果表明:AgCo13X分子筛的脱硫性能优于单一离子改性的Co13X和Ag13X分子筛;而Co13X和Ag13X分子筛的脱硫性能又明显高于未改性的13X分子筛。当Ag+离子交换浓度为0.1 mol/L时制备的Co2+和Ag+共同改性的AgCo13X分子筛具有最好的脱硫性能,其脱硫率为99.91%。剂油比为0.02 g/mL,当吸附时间为1 h即可达到吸附平衡;吸附剂具有良好的稳定性和再生性,再生后的脱硫率达到98.21%。     

Rhodium supported on thermally enhanced zeolite as catalysts for fuel reformation of jet fuels

Autothermal reformation of military jet fuel (1096 ppmw sulfur) was investigated with rhodium supported on thermally stabilized Y zeolite catalysts. The zeolite catalysts were thermally stabilized by ion exchanging with nitrate solutions of rare-earth metals (La, Ce, Sm, Gd, Dy and Er). Surface area analyses indicated that the exchanged zeolite could maintain its porous structure as high as 950 °C instead of 800 °C for a commercial NaY zeolite. The structure of the exchanged zeolite was characterized by X-ray diffraction (XRD). Rh-SmNaY zeolite reforming catalysts were prepared by incipient wetness and organometallic synthesis. The JP8 reforming experiments were performed in a short contact time adiabatic reactor with a monolithic catalyst with the addition of air and steam at a temperature below 920 °C. The effects of steam and fuel-to-air ratio (C/O ratio) were studied. Hydrogen and carbon monoxide were produced as the main products. Durability tests were performed with Rh/SmNaY-zeolite catalysts. This work shows that zeolite based catalysts can convert transportation fuels such as high sulfur jet fuel (over 1000 ppmw S) to syngas for solid oxide fuel cell applications.     

Evaluation of sorbents for thiophene removal from liquid hydrocarbons

Thiophene is a commonly occurring sulfur compound in liquid hydrocarbon streams produced in a petroleum refinery. The concentration of thiophene often needs to be reduced to very low levels for most applications. Selective adsorption of thiophene is investigated in n-heptane, 1-octene and xylenes and their mixtures. A variety of adsorbents were tested for their selectivity and adsorption capacity. Improvements in adsorption capacity were attempted based on analysis of the adsorption mechanism. Adsorption capacity of NaX zeolite was found to be highest among tested adsorbents. However, competitive adsorption from xylenes reduced adsorption capacity for thiophene from mixtures containing large concentration of xylenes. Langmuir model is applied to describe observed competitive adsorption. Selective adsorption of organic sulfur compound could be used as a polishing step in a purification scheme which allows sulfur removal from hydrocarbons at low temperature and without the use of expensive hydrogen.     

超声法制备Ce^4＋/13X分子筛的吸附脱硫性能

采用在离子交换过程中引入超声的方法制备了Ce4 /13X分子筛,考察了超声法对分子筛的制备及脱硫性能的影响,并考察了静态吸附条件对Ce4 /13X在低硫模型汽油(硫含量为23 mg/kg)中的脱硫性能影响。结果表明,超声法可显著缩短分子筛离子交换平衡的时间,提高离子交换度,且能有效地提高活性组分Ce在分子筛表面的含量,脱硫实验结果也显示吸附容量有明显的提高。常温常压,吸附时间为2.5 h,剂油质量比为0.0072的条件下,Ce4 /13X对噻吩的脱硫效果最好,吸附量为0.07653mmol/g,脱硫率可达到76.5%。Freundlich等温式能很好地关联噻吩在Ce4 /13X上的吸附平衡数据。450℃空气气氛中焙烧4 h的方法,可较好地再生Ce4 /13X。     

Adsorption of pharmaceuticals from aqueous solutions on synthetic zeolites

The objectives of this study were to measure the sorption capacity of a dilute solution of drugs in water on hydrophobic zeolites and to quantify aspects of their adsorption mechanisms for potential use in wastewater remediation. The removal of three drugs, erythromycin (ERY), carbamazepine (CBZ) and levofloxacin (FLX) from water using three organophilic zeolites (Y, mordenite (MOR), ZSM-5) was investigated. Adsorption isotherms show that these three drugs are adsorbed in remarkable amounts by Y. These data were confirmed by thermogravimetric analysis. The presence of these drugs inside the Y cage was revealed by unit cell parameter variations and structural deformations obtained by X-ray structure analyses carried out using the Rietveld method on zeolite after adsorption. Our results indicate that the adsorption properties of zeolitic materials do not only depend on micropore size and that zeolite shape selectivity also depends on structural features which are difficult to determine “a priori”. In order to test the ability of organophilic zeolites in removing drugs from wastewater, the adsorption of ERY, FLX and CBZ on zeolite Y from water samples collected at the outlet of a wastewater treatment plant located in Northern Italy was determined. These drugs were almost completely adsorbed by Y zeolite, confirming that this material is suitable for removing drugs from wastewater.     

稀土改性载铜Y分子筛吸附汽油中的噻吩

采用液相离子交换法制备了Cu+-Y分子筛和稀土改性Cu+-Y分子筛,以正己烷为溶剂,噻吩和苯分别作为硫化物和芳烃的代表形成模拟汽油体系,考察了它们的脱硫效果。结果表明,稀土增强了Cu+-Y分子筛对噻吩的吸附质量比。对只含噻吩的1号模拟汽油,稀土改性Cu+-Y分子筛对噻吩的穿透吸附质量比Cu+-Y分子筛增加了9.5%,稀土增强了Cu+-Y分子筛对噻吩的选择性;对含苯的2号模拟汽油,稀土改性Cu+-Y分子筛比Cu+-Y分子筛吸附噻吩的质量比增加了5.6%。稀土改性Cu+-Y分子筛脱硫剂易于再生,再生后仍有很好的吸附能力,可重复使用。     

燃料油中硫化物的选择性吸附研究进展

综述了不同吸附剂脱硫和选择性吸附两方面的机理及研究进展。在燃料油选择性吸附脱硫研究的吸附剂中,使用最多的是金属阳离子改性的Y型分子筛,以Cu、Ni和Ce改性的Y型分子筛最为成熟。其吸附脱硫机理主要包括π-络合吸附和金属S—M键作用。燃料油（以汽油和柴油为主）组成复杂,含大量烯烃、芳烃、烷烃及少量的氮化物、氧化物、水及胶质,影响吸附剂的吸附脱硫效果,而烯烃和芳烃严重影响吸附剂的选择性吸附脱硫性能。各种吸附剂对富含烯烃或芳烃的燃料油中的硫化物选择性和硫容量不同,但都不高。研究吸附剂与燃料中的硫化物的选择性吸附机理,对研发具有高选择性和高吸附容量的吸附剂起推动作用。     

改性介质的调变对NaY沸石后处理及其催化裂化性能的影响

Y型沸石作为FCC催化剂的主要活性组分,其酸性能和孔结构的改性效果直接决定了催化剂的性能优劣。选取酸性能为调变对象,分别采用两种不同的改性介质（CeY焙烧气氛和铵离子交换pH）对NaY沸石进行后改性处理。将所得的改性Y沸石进行了红外（IR）、X光电子能谱（XPS）和低温氮气物理吸附等表征分析。最后,使用真实油品VGO在固定流化床反应评价装置ACE上对改性样品的催化性能进行了评价。研究发现,选取Ce离子作为改性介质时,可通过改变后处理过程中的焙烧气氛来调变沸石不同酸类型的分布（Brønsted/Lewis acid,B/L）,实现对应的USY沸石的催化性能的调控;选取铵离子作为改性介质时,适当地调节第1次铵离子交换pH的苛刻程度,能够在调变超稳Y沸石B酸量的同时提高Y型沸石的介孔体积。     

Adsorption of thiophene and toluene on NaY zeolites exchanged with Ag(I), Ni(II) and Zn(II)

The present study evaluates the adsorption capacity of thiophene and toluene and their competitive behaviour on zeolite NaY exchanged with transition metals (5 wt% Ni, Zn and Ag). The headspace chromatography technique was used to obtain monocomponent apparent adsorption isotherms of thiophene and toluene with NaY, NiY, ZnY and AgY using isooctane as an inert solvent at 30 and 60 °C. Selectivity between toluene and thiophene at saturation capacities were also measured at 30 °C. The adsorption capacity for thiophene increased for the studied adsorbents as follows: NaY < ZnY < NiY < AgY at 30 °C and NaY < NiY < ZnY < AgY at 60 °C. Toluene is less adsorbed, but within the same order of magnitude as thiophene and following the same sorbent order. All adsorbents were moderately selectivity for toluene. Nevertheless, the sulfur content was successfully reduced in the presence of aromatics and olefins in immersion tests with a model fuel mixture. These results show the importance of inserting transitions metals in the zeolitic structure to enhance the adsorption of both aromatic and sulfur containing compounds in organic liquid mixtures, which shows promise to meet environmental standards in transportation fuels.     

CuY分子筛的制备及吸附脱硫性能研究

采用液相离子交换制备了Cu（II）Y,在高温N2氛条件下使其自动还原为cu（I）Y。在不同条件下对Cu（I）Y进行了静态吸附脱硫测试,考察了在室温下,不同温度、时间、液固质量比对CuY分子筛吸附脱硫性能的影响,样品中的硫含量通过微库仑综合分析仪进行测定。同时系统比较了Cu（I）Y和Cu（II）Y吸附脱硫性能。结果表明,温度为70℃,吸附时间为6h,液固质量比为60：1的条件下,Cu（I）Y对噻吩（T）溶液的脱硫效果最好,且Cu（I）Y分子筛的脱硫效果要明显好于Cu（II）Y分子筛。     

Adsorptive separation of meta-xylene from C8 aromatics

Industrial adsorptive separation process for liquids is most successful when the involved species have very close boiling points, making distillation expensive or are thermally sensitive at convenient distillation temperatures. The adsorption process was studied for separating meta-xylene from a feed mixture containing all C₈ aromatics on binder-free X and Y zeolites in the liquid phase. Zeolitic adsorbents with different SiO₂/Al₂O₃ were synthesized by the hydrothermal method and ion-exchanged with alkaline metal cations like lithium, sodium and potassium. The adsorption process was carried out in a breakthrough system at temperature of 110–160 °C and pressure of 6–8 atm. The influence of adsorbent moisture content on the separation process was studied. The optimization of adsorption process was also investigated by the changing operation conditions. The isotherms for each isomer of C₈ aromatics and the desorbent possess the adsorption characteristics of Langmuir type. The selectivity factor of meta-xylene and the saturation adsorption capacities of adsorbates were determined. It was observed that the selectivity of meta-xylene increased by sodium ion-exchanging of cationic sites in Y zeolite and the selectivity factor of meta-xylene/para-xylene, meta-xylene/ortho-xylene and meta-xylene/ethylbenzene in the optimum conditions was determined to be 2.62, 2.83 and 5.93, respectively.     

Deep desulfurization of gasoline using ion-exchange zeolites: Cu(I)- and Ag(I)-beta

Solid adsorbents Cu(I) and Ag(I) metal exchanged beta zeolites were prepared by solid-state ion-exchange (SSIE) method. Crystallographic structure of the prepared adsorbents has been characterized by XRD analysis. The texture of the prepared adsorbents was investigated using N₂ sorption. Pyridine IR measurements have been carried out to investigate the nature of the acid sites of the adsorbents. The deep-desulfurization performance of such adsorbents has been evaluated through fixed-bed adsorption technique with model gasoline containing thiophene and benzothiophene at ambient temperature and pressure. The obtained results revealed that the breakthrough capacities of Cu(I)- and Ag(I)-beta zeolite with the optimized Cu⁺ or Ag⁺ content are 0.239 mmol S/g and 0.237 mmol S/g, respectively. The remaining sulfur in the desulfurized gasoline is less than 1 ppmw. Their desulfurization capacity for actual FCC gasoline blend is reduced about 30% due to the competitive adsorption from olefins and aromatics. However, The capacity regeneration of Cu(I)- and Ag(I)-beta zeolite sorbents was carried out for 9 times. It is more than 95% recovery of desulfurization after the first regeneration, and it keeps little reduction after subsequent 8 times of regeneration. Such studies included the effect factors on desulfurization performance, such as metal exchange content, SiO₂/Al₂O₃ ratio, acidity, and other texture properties of the zeolite etc.     

Heterogeneous Catalytic Transformation of Citronellal to Menthol in a Single Step on Ir-Beta Zeolite Catalysts

The synthesis of menthol from citronellal was studied on bifunctional Ir/Beta zeolite catalysts, prepared via impregnation of Beta zeolite with different concentrations of Ir. The results show that Beta zeolites, impregnated with Ir, catalyze the one-pot full conversion of citronellal to menthol by consecutive acid-catalyzed cyclization and Ir-catalyzed hydrogenation. The best results (95% selectivity for the menthol isomers, of which 75% is the desired (±)-menthol) were recorded on 3% Ir/Beta zeolite catalyst. In contrast with earlier studies, 0.05 g Ir/Beta catalyst per mL of substrate leads to complete and selective substrate transformation. The textural properties, acidity and hydrogenation function were studied by liquid N₂ adsorption–desorption, FT-IR, XPS and hydrogen chemisorption techniques. To clarify the mechanism of the cyclization of citronellal, tests were also performed using zeolites with different acidity and loaded with other metals (Pt, Pd, Rh, Ru).