High-silica faujasite zeolite-tailored metal encapsulation for the low-temperature production of pentanoic biofuels

Zeolite-encapsulated metal nanoclusters are at the heart of bifunctional catalysts,which hold great potential for petrochemical conversion and the emerging sustainable biorefineries.Nevertheless,efficient encapsulation of metal nanoclusters into a high-silica zeolite Y in particular with good structural integrity still remains a significant challenge.Herein,we have constructed Ru nanoclusters(~1 nm)encapsulated inside a high-silica zeolite Y(SY)with a SiO_(2)/Al_(2)O_(3) ratio(SAR)of 10 via a cooperative strategy for direct zeolite synthesis and a consecutive impregnation for metal encapsulation.Compared with the benchmark Ru/H-USY and other analogues,the as-prepared Ru/H-SY markedly boosts the yields of pentanoic biofuels and stability in the direct hydrodeoxygenation of biomass-derived levulinate even at a mild temperature of 180℃,which are attributed to the notable stabilization of transition states by the enhanced acid accessibility and properly sized constraints of zeolite cavities owing to the good structural integrity.

Y Zeolites Modified by Organosilane for Toluene Adsorption under High Humidity Condition

Y zeolites have moderate microporous pore size, large specific surface area, and good hydrothermal stability, which were widely used in industrial adsorption of volatile organic compounds (VOCs), but the performance of Y zeolites in adsorption of VOCs under high humidity conditions is terrible. In this paper, Y zeolites with different silica-alumina ratios were hydrophobically modified by organosilane and characterized by XRD, FTIR, SEM, BET, NMR. In the experiments of static and dynamic adsorption of VOCs by modified Y zeolites, it can be concluded that the static water adsorption capacity of Y zeolites with silica-aluminum ratio of 5 and 40 after silica modification decreased by 62 wt% and 53 wt%, under the conditions of high humidity, GHSV = 15,000 h-1, T = 35°C and initial concentration of toluene C0 = 5000 mg·m-3. The saturation adsorption capacity of toluene was increased from 0.06 g·g-1, 0.09 g·g-1 to 0.15 g·g-1, 0.21 g·g-1, the adsorption selectivity of Y zeolites for water was reduced and that for toluene was increased after Vapor phase silanization overlay modification. The present modification method might carry out targeted modification of zeolites surface, provide research ideas and guidance under high humidity conditions.

NiW/介孔Y型分子筛催化剂上菲加氢裂化过程研究

为了实现对煤焦油中副产物多环芳烃菲的有效利用,采用等体积浸渍法制备了介孔Y型分子筛负载金属Ni、W催化剂,利用XRD、H2-TPR、BET、SEM-EDS对制备的催化剂进行表征分析,并在固定床反应器中考察催化剂上菲加氢裂化性能,探讨了反应过程中空速、气液比、温度、压力对催化剂积碳率、菲的转化率、液体收率及产物分布的影响.研究表明,增加空速和气液比会降低催化剂的积碳率,过高的反应温度会导致催化剂快速地积碳失活.通过定时采样对裂解产物分析得到菲在催化剂上的裂解率变化情况,同时也能反映出催化剂的稳定性.对反应过程条件优化得到的最优条件为:空速6 h^(-1),气液比750,温度400℃,压力6.5 MPa.此时,菲的裂解率可以稳定在99%以上,同时催化剂保持较高的稳定性,在4 h内未出现活性降低.

Ag^(+)、Zn^(2+)、Cr^(3+)改性Y型分子筛吸附脱除喹啉的模拟计算研究

首先考察了吸附时间对三种改性Y型分子筛AgY、ZnY、CrY吸附脱除模拟燃料中喹啉的影响,结果发现三种分子筛对喹啉的吸附容量和去除率大小顺序均为:AgY>CrY>ZnY.运用Materials Studio软件,采用巨正则蒙特卡洛(GCMC)和密度泛函理论(DFT)对改性Y型分子筛吸附喹啉机理进行了模拟计算研究,得出以下结论:模拟计算AgY、ZnY、CrY的比表面积和孔体积与其低温N2吸附-脱附表征结果基本一致,并且发现改性Y型分子筛的吸附脱氮能力与比表面积和孔体积关系不大;以Fukui函数为基础,采用Mulliken和Hirshfeld两种布局数分析方法模拟计算了三种改性Y型分子筛的相对亲电性并分析Lewis酸强弱,其Lewis酸大小顺序为:AgY>CrY>ZnY;对三种改性分子筛进行了前线轨道分析,其化学吸附活性大小为AgYCrY>ZnY,模拟计算所得各种结果与实验结果顺序完全一致.

NiMo/Al_2O_3 catalyst containing nano-sized zeolite Y for deep hydrodesulfurization and hydrodenitrogenation of diesel

Two mixed-matrix NiMo/Al2O3 catalysts containing nano-and micro-sized zeolite Y have been prepared to explore the size effect of zeolite Y particle on the hydrodesulfurization（HDS）and hydrodenitrogenation（HDN）activities of fluid catalytic cracking（FCC）diesel.They were characterized by SEM,BET,XRD,H2-TPR,NH3-TPD and HRTEM.The results show that the catalyst containing nano-sized zeolite Y possesses larger average pore diameter,higher pore volume,weaker and lesser acid sites,more easily reducible metal phases,shorter MoS2 slabs and more slab layers than the catalyst containing micro-sized zeolite Y.The catalysts were also evaluated with a high-pressure fixed-bed reactor using real FCC diesel as feed.The results display that the catalyst containing nano-sized zeolite Y bears higher HDS and HDN activities and exhibits higher relative rate constant for the removal of total sulfur or nitrogen than the one containing micro-sized zeolite.

Isomerization of linear C5–C7 over Pt loaded on protonated fibrous silica@Y zeolite（Pt/HSi@Y）

A novel fibrous silica Y zeolite (HSi@Y) loaded with Pt has been studied based on its ability to produce protonic acid sites originating from molecular hydrogen. The Pt/HSi@Y was prepared using seed assisted crystallization followed by protonation and Pt-loading. The product formed had a spherical morphology with bicontinuous lamellar with a diameter in the range of 500-700 nm. The catalytic activity of the Pt/HSi@Y has been assessed based on light linear alkane (C5-C7) isomerization in a micro-catalytic pulse reactor at 423-623 K. A pyridine IR study confirmed that the introduction of fibrous silica on Y zeolite increased the Lewis acid sites corresponding with the formation of extra-framework Al which led to the generation of more protonic acid sites. A hydrogen adsorbed IR study showed that the protonic acid sites which act as active sites in the isomerization were formed via dissociative-adsorption of molecular hydrogen releasing electrons to the nearby Lewis acid sites. Thus, it is suggested that the presence of Pt and HSi@Y with a high number of Lewis acid as well as weak Bronsted acid sites improved the activity and stability in C5, C6 and C7 isomerization via hydrogen spill-over mechanism.

小晶粒NiY分子筛的合成及其加氢裂化反应性能

通过在小晶粒Y分子筛合成的过程中原位引入Ni源合成了一系列不同Ni掺入量的小晶粒Y-xNi分子筛,将活性金属Ni预浸渍到Y分子筛的骨架中。将Y-xNi分子筛和ASA混合物作为载体并采用等体积浸渍法负载Ni和W,制备了系列Cat-xNi加氢裂化催化剂,以正十六烷为反应物,探究其加氢裂化催化反应性能。采用扫描电子显微镜(SEM)、X射线衍射(XRD)、N2吸附-脱附、氨气程序升温脱附(NH3-TPD)、氢气程序升温还原(H2-TPR)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等表征手段分析了Ni的掺入对Y分子筛及Cat-xNi催化剂理化性质的影响。结果表明,Ni主要取代Al引入Y分子筛骨架;在Y分子筛中适量掺入Ni会提高Y分子筛的相对结晶度以及Bronsted酸和Lewis酸位点的数量,但过量的Ni掺入不利于Y分子筛的结晶。Ni的掺入削弱了金属与载体间的相互作用,提高了活性金属的硫化度及NiWS活性相的堆积数及分散度,调节了催化剂上金属中心与酸中心的匹配。催化性能评价结果显示,由于Ni改性能同时增加Br?nsted酸中心与NiWS活性中心数量,增强金属中心与酸中心之间的协同作用,因而在提高正十六烷加氢裂化活性的同时可避免其过度裂化,获得较高的中间馏分产物(C8-C12)选择性及收率。在360℃反应条件下,与Cat-0Ni催化剂相比,Cat-0.2Ni催化剂具有较高的n-C16转化率和C8-C12产物收率(达65.4%)。综上可知,采用原位合成法将活性金属Ni预浸渍在Y分子筛上可以有效调节裂化活性中心与加氢活性中心之间的平衡,从而提高其催化活性和中间馏分产物的收率。

Preparation, Characterization and Catalytic Behavior of 12-Molybdophosphoric Acid Encapsulated in the Supercage of Cs^＋-exchanged Y Zeolite

In order to solve the serious leaching problem of supported heteropoly acid catalysts in polar reaction media, 12-molybdophosphoric acid encapsulated in the supercage of Cs^＋-exchanged Y zeolite was prepared by the ＂ship in the bottle＂ synthesis. The influence of ion-exchange conditions and the synthesis parameters on the encaosulation of PMo12 were investigated. The obtained solid sample was characterized by X-ray diffraction （XRD）, 31p magic angle spin nuclear magnetic resonance （MAS NMR） and Fourier Transform Infrared Spectroscopy （FT-IR）, and its catalytic activity in the esterification of acetic acid and n-butanol was tested. The ion-exchange time, concentration of aqueous Cs^＋ solution, pH value, and amount of Mo added in the synthesis mixture were revealed to influence the encapsulation very remarkably. Under the optimal conditions, 12-molybdophosphoric acid could be successfully encapsulated in the supercage of CsY zeolite, and the samples showed considerable catalytic activity and excellent reusability in the esterification reaction.

Effective adsorptive denitrogenation from model fuels over yttrium ion-exchanged Y zeolite

The adsorption removal of indole and quinoline in octane with and without toluene over zeolites NaY and Yttrium Ion-exchanged Y(YY)using batch adsorption experiments was studied at 25℃and 0.1 MPa.YY was prepared by treating NaY with Y(NO3)3 solution twice via liquid ion-exchange method.NaY and YY were both characterized by XRD,SEM,N2 adsorption,XRF,NH3-TPD,and pyridine-FTIR techniques.Adsorption isotherms of indole,quinoline and toluene in octane were conducted at 25.0℃to explain the influence of toluene on nitrogen removal over NaY and YY.The partial destruct of the crystalline structure of NaY was observed after the introduction of yttrium ion,which led to an evident decline in BET surface area and pore volume of YY.Strong Br?nsted acidity and medium Lewis acidity were introduced by yttrium ion-exchange.Though the specific surface area and pore volume of YY were much lower than those of NaY,YY exhibited equivalent adsorption capacities for indole and quinoline as NaY in model fuels without toluene.In the presence of 20 vol%toluene,however,YY exhibited much higher adsorption capacities for indole and quinoline than NaY,especially in the case of quinoline.The improved toluene-tolerant of YY was ascribed to the strong acid–base interaction between YY and quinoline and the decreased adsorption strength between YY and toluene.

Synthesis of mesoporous high‐silica zeolite Y and their catalytic cracking performance

Mesoporous high‐silica zeolite Y with advantages of improved accessibility of acid sites and mass transport properties is highly desired catalytic materials for oil refinery,fine chemistry and emerg‐ing biorefinery.Here,we report the direct synthesis of mesoporous high‐silica zeolite Y(named MSY,SiO_(2)/Al2O_(3)≥9.8)and their excellent catalytic cracking performance.The obtained MSY mate‐rials are mesoporous single crystals with octahedral morphology,abundant mesoporosity and ex‐cellent(hydro)thermal stability.Both the acid concentration and acid strength of H‐form MSY are obviously higher than those of commercial ultra‐stable Y(USY),which should be attributed to the uniform Al distribution of MSY zeolite.The H‐MSY displays an obviously reduced deactivation rate and improved catalytic activity in the cracking reaction of bulky 1,3,5‐triisopropylbenzene(TIPB),as compared with its mesoporogen‐free counterpart and USY.In addition,H‐MSY was investigated as catalyst for the cracking of industrial heavy oil.The MSY‐based catalyst(after aging at 800 oC in 100%steam for 17 h)exhibits superior conversion(7.64%increase)and gasoline yield(16.37%increase)than industrial fluid catalytic cracking(FCC)catalyst under the investigated conditions.

Kinetics study and analysis of zeolite Y destruction

A series of zeolites,including USY zeolites without sodium,Na-USY at different Na contents,La-USY with different rare earth（RE） contents and La-Na-USY with RE and Na were prepared by an ion exchange method.They were investigated to understand the activation barriers for the destruction of Y zeolite structure under hydrothermal treatment and the effect of V using the solid-state kinetic model.The results showed that the pathways for Y zeolite destruction were dealumination,desiliconization and the disappearance of La-O bonds.Zeolites were destroyed by steam through acid hydrolysis,which was accelerated by V.In addition,Na and V exerted a synergistic effect on the framework destruction,and the formation of NaOH was the rate-determining step.The presence of RE elements decreased hydrolysis and stabilized the structure of the zeolites.The interaction between V and RE destroyed zeolite structure by eliminating the stabilizing La-O[RE-OH-RE]^（5＋）bridges in the sodalite cages.

Y分子筛结构特性与催化性能的固体核磁共振研究进展

作为一类在石油炼制与化工领域应用极其广泛的工业催化剂,Y分子筛的活性中心结构及酸性特征(酸类型、酸强度、酸浓度、酸分布和空间邻近性等)与其催化性能(反应活性、选择性和稳定性等)密切相关。准确描述活性中心结构、酸性特征及催化反应微观机理是建立其结构特性与催化性能之间内在关联的必要前提,也是实现Y分子筛催化效能进一步提升的关键所在。主要综述了近年来固体核磁共振(NMR)技术在Y分子筛局域精细结构的表征、酸性特征的定性与定量分析及催化反应机理等方面的研究进展,并对其发展方向进行了展望。

Effect of metal content on the activity and product selectivity of n-decane hydroisomerization over Ni-Pd/HY zeolite

Metal-loaded zeolite catalysts were synthesized and examined in the hydroisomerization of n-decane.Specifically,zeolite Y was impregnated with 0.1 wt%Pd and varying amounts of Ni（0.1-0.5 wt%].The crystallinity of the metal-loaded catalysts was characterized by X-ray diffraction,and the average metal particle size was determined by transmission electron microscopy.The states of Pd and Ni were identified by X-ray photoelectron spectroscopy.Ammonia temperature-programmed desorption analysis revealed the occurrence of ion-exchange of some of the catalyst acid sites with Ni-（2＋）.The reducibility of the HY zeolite-supported Pd,Ni,and Pd-Ni catalysts was studied by temperature-programmed reduction.The hydroisomerization of n-decane over the prepared catalyst was conducted at 200-450℃ under 1 atm.Ni addition of up to 0.3 wt%over 0.1 wt%Pd/HY enhanced the n-decane conversion and isomerization product selectivity.The improved selectivity of the mono- and dibranched isomers suggested the occurrence of a protonated cyclopropane intermediate mechanism.However,further Ni addition above 0.3 wt%considerably reduced the activity and isomerization selectivity.The bimetallic catalysts were more selective toward the formation of dibranched isomers,i.e.,those containing a higher octane number.

Structural Changes of Y Zeolites with Different Initial SiO_2/Al_2O_3 Ratios during Hydrothermal Treatment

The effects of the initial framework SiO2/Al2O3 ratio and temperature on the structural changes of NaY zeolites during hydrothermal treatments are studied. Two samples with different framework SiO2/Al2O3 ratios are subjected to hydrothermal treatment at four different temperatures. For zeolite with a lower initial SiO2/Al2O3 ratio of 4.2, mesopores are easily formed because more framework aluminum is detached. Moreover, two kinds of mesopores are produced at a higher temperature due to the interconnection of vacancies and smaller mesopores. For zeolite with a higher initial SiO2/Al2O3 ratio of 6.0, there are less mesopores formed as compared with the lower initial SiO2/Al2O3 ratio sample, but there are some macropores formed. This may be attributed to the isolation of vacancies and the different distributions of aluminum in the crystal lattice of the zeolite. The experiment data show that NaY with the SiO2/Al2O3 ratio of 6.0 retains a high relative crystallinity during the hydrothermal treatment. This proves that a high framework SiO2/Al2O3 ratio benefits the stability of zeolite.

镧负载方式对Y分子筛抗钒性能的影响

分别采用不同方式在Y分子筛上负载相同量的稀土元素镧(La),制备得到了Y2、Y3、Y4分子筛样品,系统考察了La引入方式对Y分子筛理化性质和微反活性的影响。结果表明:在采用浸渍法负载La得到的Y2分子筛中,La以离子态存在,且在焙烧过程中La离子更易于迁移到分子筛内部结构中,并更多进入分子筛的α笼;在采用沉淀法负载La得到的Y3和Y4分子筛中,La以非离子态存在,且在焙烧过程中La物种较少向分子筛内部迁移,更多存在于分子筛表面上;与Y2分子筛相比,采用La与草酸先沉淀后负载到分子筛上的方式制备的Y3分子筛具有更好的水热稳定性和微反活性,说明赋存在分子筛表面上的La可以更好地改善分子筛的抗钒性能。

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.

H-Y-zeolites induced heterocyclization:Highly efficient synthesis of substituted-quinazolin-4(3H) ones under microwave irradiation

A highly efficient synthesis of 2-amino-N-substituted-benzamides was performed by the condensation ofisatoic anhydride with several amines in solvent-free conditions under microwave irradiation. H-Y-zeolites induced heterocyclization of these products with ortho-esters under similar conditions afforded the relevant substituted-quinazolin-4（3H）ones in high yields.

Adsorption Thermodynamics and Diffusion Kinetics of PX over Na Y Zeolite Synthesized by In-Situ Crystallization from Kaolin Microsphere

Para-xylene was chosen as the probe molecule to study adsorption thermodynamics and diffusion kinetics on NaY zeolite and composite structured NaY zeolite synthesized by in-situ crystallization from kaolin microsphere(designated as Na Y/kaolin composites) separately, using a high precision intelligent gravimetric analyzer(IGA). The adsorption isotherms showed normal Langmuir type-Ⅰ behaviors. The increased adsorption heat with an increasing p-xylene coverage supported a mechanism of phase transition, diffusion and re-arrangement of p-xylene molecules during the adsorption process. The rearrangement seemed to be most pronounced at an adsorption loading of 2.13 and 2.29 mmol/g for Na Y zeolite and Na Y/kaolin composites respectively. Compared with Na Y zeolite, a 2—3 times higher in the diffusion coefficient of p-xylene was observed on Na Y/kaolin composites when the pressure was more than 50 Pa. Temperature-programmed desorption(TPD) of p-xylene on two samples from room temperature to 450 ℃ at a special loading has also been investigated by IGA. Results showed only single desorption peak appeared for Na Y zeolite, indicating that adsorption can only occur in the super-cage structure. Comparably, there were two different peaks for in-situ synthesized Na Y zeolite, corresponding to the two thermo desorption processes in both super-cage structure and the channels provided by kaolin, respectively.Key words:

煤气化渣制备单一相Y分子筛研究

煤气化渣是煤化工固体废弃物,含有大量的硅元素和铝元素,可以作为原料合成高附加值的Y分子筛材料,实现资源利用。以宁夏宁东煤气化渣为原料,采用酸碱预处理和导向剂诱导水热合成法,通过优化工艺条件,成功获得了具有八面体形貌、单一相的Y分子筛。详细考察了酸碱预处理条件、硅铝比、水硅比、晶化温度、晶化时间、导向剂含量等因素对合成样品晶相的影响,并采用XRD、XRF、SEM、FT-IR等技术对煤气化渣合成Y分子筛样品的性质进行了分析。通过优化工艺条件,水硅比降低到了20,晶化时间缩短到了24 h,合成的Y分子筛产品具有较好的结晶度和高的比表面积,比表面积达到538 m^(2)/g,总孔体积达到0.350 cm^(3)/g。

Different Influences of Lanthanum and Cerium on Stability of Y Zeolite and Their DFT Calculations

In this paper,the different influences of lanthanum (La) and cerium (Ce) species on the stability of Y zeolite were studied by X-ray diffractometry (XRD),X-ray photoelectron spectroscopy (XPS),and multinuclear (27Al,29Si) solidstate nuclear magnetic resonance spectroscopy (NMR).It was found that the stability of Y zeolite could be enhanced by the introduction of La or Ce species;however,the former effect was more remarkable than the latter.These results were also confirmed theoretically by density functional calculations.There was a strong interaction between the rare earth (La or Ce) species and Y zeolite clusters,which restrained the formation of extra-framework aluminum and enhanced evidently the stability of Y zeolite.Furthermore,the interaction between La species and Y zeolite was stronger than that of Ce species with Y zeolite.