Ultrastable Y Zeolite Research Articles

Spontaneous Dispersion of Gold Nanoparticles Loaded on USY Zeolites as Analyzed by XAFS, XRD, and TEM

Abstract Structural changes in the gold particles of Au-loaded ultrastable Y (USY) zeolite were analyzed by X-ray absorption fine structure, X-ray diffraction, and transmission electron microscopy. Au particles undergo spontaneous dispersion on the USY support under H2 atmosphere at a temperature of 773 K to give Au particles with an average diameter of 1.8 nm and narrow size distribution.

Hydrocracking of AATO on Ni/USY and Ni-Co/ USY Zeolite Catalysts

A series of Ni and Ni-Co were maintained on a mixed support of USY (ultrastable Y) zeolite and active aluminum oxide. The catalysts were characterized by means of element analysis, BET and XRD. The characterization results suggested that the active metal components were introduced without changing the microstructure. Then catalytic hydrocracking activity was studied using AATO (distillate of coal tar) in a tubular reactor. AATO conversion was 39.40% and 41.37% using the 10%Ni/USY catalyst and 10%Ni-6%Co/USY catalyst, the hightest total selectivity of benzene and xylol was 67.1% in 10%Ni-10%Co/USY catalyst than others under the reaction conditions studied [T=480°C, P=4.5MPa, LHSV=3.0h-1].

Selective Ring Opening of Methylcyclopentane and Methylcyclohexane Over Iridium Bifunctional Catalysts Supported on Surface Modified γ-Al2O3, SiO2 and Ultra Stable Y Zeolites

Selective ring opening of methylcyclopentane (MCP) and methylcyclohexane (MCH) over a series of Iridium catalysts supported on γ-alumina, silica and ultra-stable Y (USY) zeolites was investigated. The acid density of the supports was modified by co impregnation of potassium in small quantities and its effect on conversion, yield and selectivity was evaluated. USY zeolites showed 26.9–38.1 and 27.5–33.7% of conversion with ring opening selectivities between 56.4–63.8 and 94.3–97.7% for MCP and MCH, respectively. Whereas on silica, the conversions were 10.7–16.6 and 10.4–14.0% with 96.9–99.0 and 93.3–99.1% selectivity. Interestingly, potassium acted as a promoter in case of USY zeolites while suppressed of activity of Ir supported on γ-alumina and silica. The reaction conditions such as temperature, pressure, contact time and the feed/catalyst ratio were optimized. The evaluation of catalysts’ activity and selectivity towards ring opening of MCP and MCH is of great importance in understanding which catalyst modification could be effective in treatment of gasoline/diesel feed stocks for improving octane/cetane rating and fuel quality. Selective ring opening of methylcyclopentane and methylcyclohexane over a series of Iridium catalysts supported on surface modified by co impregnation of potassium of γ-alumina, silica and USY zeolites was investigated and its effect on conversion, yield and selectivity was evaluated.

Enhancement in the Catalytic Activity of Pd/USY in the Heck Reaction Induced by H2 Bubbling

Pd was loaded on ultra stable Y (USY) zeolites prepared by steaming NH4-Y zeolite under different conditions. Heck reactions were carried out over the prepared Pd/USY. We found that H2 bubbling was effective in improving not only the catalytic activity of Pd/USY, but also that of other supported Pd catalysts and Pd(OAc)2. Moreover, the catalytic activity of Pd/USY could be optimized by choosing appropriate steaming conditions for the preparation of the USY zeolites; Pd loaded on USY prepared at 873 K with 100% H2O gave the highest activity (TOF = 61,000 h−1), which was higher than that of Pd loaded on other kinds of supports. The prepared Pd/USY catalysts were applicable to the Heck reactions using various kinds of substrates including bromo- and chloro-substituted aromatic and heteroaromatic compounds. Characterization of the acid properties of the USY zeolites revealed that the strong acid site (OHstrong) generated as a result of steaming had a profound effect on the catalytic activity of Pd.

ChemInform Abstract: Transformation of m-Xylene Over Al-Pillared Clays and Ultrastable Zeolite Y.

The reaction of m-xylene has been carried out at 623 K over Al-pillared beidellite and montmorillonite, and over ultrastable zeolite Y (USY) as a reference catalyst. These microporous acidic solids exhibit similar open porosities and, therefore, the activity toward disporportionation and/or isomerization is not primarily ruled by geometrical limitations but merely reflects the relative amount and strength of the acid sites, strong Broensted acid sites being required for disproportionation and weaker ones for isomerization. In terms of overall conversion and disproportionation selectivity, USY is more active than the pillared clays. This is due to a higher content of strong acid sites and to the greater micropore volume of USY. Al-pillared beidellite is more active than Al-pillared montmorillonite, which is interpreted in terms of framework substitution differences between the two clays. The OH/Al molar ratio of the starting pillaring solution does not confer to the pillared materials any significant effect on their catalytic performances. Deactivation is observed for all the catalysts, and there is some evidence that the stronger sites would deactivate first. 40 refs., 3 tabs., 2 tabs.

PREPARATION AND CHARACTERIZATION THE NON-SULFIDED METAL CATALYST: Ni/USY and NiMo/USY

The two-new catalysts had been prepared by using the impregnation method according to Nugrahaningtyas [6] and Li [4]. One catalyst is of Nickel (Ni), supported on Ultra Stable Zeolite Y (USY), whereas the other one is NiMo supported on same supporting agent. These new catalysts are expected to be more effective when applied on the hydrotreatment reaction in standpoint of its capabilities on removing the unwanted-heteroatom. Characterization those two types of catalysts then carried out by using the criteria of acidity, porosity and, metal content. The result shows that these non-sulfide catalysts have several good characters that supporting their usefulness in hydrotreatment-catalytic reaction. In addition, catalyst NiMo/USY - 1 performs many ideal criteria as the best functional catalyst. Keywords: Non-sulfided Catalyst, hydro-treating, preparation, characterization

Upgrading of light cycle oil via coupled hydrogenation and ring-opening over NiW/Al 2O 3-USY catalysts

A series of ultrastable Y (USY) zeolite samples with different acidities and pore sizes are prepared via hydrothermal and acid treatments. NiW sulfide catalysts are maintained on a mixed support of USY zeolite and Al 2O 3. The catalytic coupled hydrogenation and ring-opening performance are studied on a continuous fixed-bed reactor using tetralin as the model compound. All catalysts show high tetralin conversions under the reaction conditions studied [ T = 613 K, P = 4.0 MPa, LHSV = 2.0 h −1, H 2/oil (v/v) = 500]. Product yields and selectivity are mainly determined by the zeolite property (i.e., acidity). A medium to strong zeolite acidity is the key factor in the ring-opening selectivity of tetralin. A maximum high cetane ring-opening product yield of 39.1 wt% is obtained at a C 10 yield of 98.2 wt% for a USY zeolite with medium acidity. Using an fluid catalytic cracking light cycle oil feedstock, the activity of the catalyst is higher than that of commercial catalysts, giving a 14-unit cetane number increase at a diesel yield of 97.6 wt%. Because the first step of the ring-opening reaction is hydrogenation, the catalyst must have high hydrogenation activity. The WS 2 slabs have a high average layer number of 2.7 on the catalyst using the support presented here.

Shape-selective diisopropylation of naphthalene in H-Mordenite: Myth or reality?

Selective diisopropylation of naphthalene to 2,6-diisopropylnaphthalene is a challenging goal in sustainable catalysis. Ultrastable Y and H-Mordenite zeolites are the best catalysts reported in the literature with respect to 2,6-diisopropylnaphthalene selectivity. It is generally accepted that in the case of H-Mordenite, shape-selectivity is responsible for the observed 2,6-diisopropylnaphthalene selectivity, while on Ultrastable Y-zeolite, the observed selectivity reflects the internal thermodynamic equilibrium of positional isomers. Revisiting both the experimental and the computational work in this field now leads to the conclusion that shape-selectivity of whatever kind can be ruled out in the case of H-Mordenite. H-Mordenite catalysts produce usually a kinetically controlled mixture of diisopropylnaphthalene isomers which can shift to the direction of a thermodynamical distribution at high reaction temperatures or over more active catalysts.

Ni-Mo-Titania-Alumina Catalysts with USY Zeolite for Low Pressure Hydrodesulfurization and Hydrocracking

Titania-alumina based catalysts were prepared and tested for hydrodesulfurization (HDS) and hydrocracking activity in the temperature range 300°C to 350°C in a fixed-bed reaction system using 4,6-dimethyldibenzothiophene (4,6-DMDBT) dissolved in n-hexadecane. Characterization results show that the metal-loaded titania-alumina possesses a high pore radius and pore volume but low surface area. The physical mixing with USY zeolite increased its surface area. The surface area was further increased upon mixing with nanoporous alumina. The total ammonia based acidity of the titania-alumina was lower than that of the ultra stable Y (USY) zeolite, but Ni-Mo loading was found to increase the acidity. The acidity of titania-alumina was further increased by mixing with nanoporous alumina and USY zeolite. All catalysts exhibited good HDS and hydrocracking activity for 4,6-DMDBT and n-hexadecane. The catalyst showing the highest HDS activity using 4,6-DMDBT was further tested and was found to have reasonable activity for both low- and high-sulfur vacuum gas oil feeds. This study demonstrated low-pressure HDS activity of the catalysts.

Photoluminescence study of terbium-exchanged ultrastable Y zeolites: Number of species, photoluminescence decays, and decay-associated spectra

Terbium-exchanged ultrastable Y (USY) zeolites were investigated by using time-resolved photoluminescence spectroscopy techniques and methods. To determine the distribution of terbium species in USY zeolites together with their photoluminescence properties, several analysis methods for the time-resolved luminescence spectra were used such as the area normalization of time-resolved photoluminescence spectra, singular value decomposition, global nonlinear least squares, and the maximum entropy. Except for a questionable long lifetime, small contribution of a terbium species with lifetime of 1.9–2.1 ms, all the experimental and analysis results converged to a two terbium species distribution with lifetimes varying between 410–440 and 1000–1100 μs. The effects of the silylation of terbium-exchanged USY zeolites with phenyl-, vinyl-, and hexadecyltrimethoxysilanes on the lanthanide’s photoluminescence properties were also described.

Transition-metal-free microporous and mesoporous catalysts for the epoxidation of cyclooctene with hydrogen peroxide

Transition-metal-free microporous and mesoporous materials were studied as heterogeneous epoxidation catalysts. MCM-41-type materials and zeolites with various porous structures and aluminium or gallium content but devoid of any transition metal were prepared and tested in the epoxidation of cyclooctene with aqueous hydrogen peroxide. The most promising catalytic results were obtained with Al-MCM-41, Ga-MCM-41, and ultra-stable zeolite Y (USY) with a low Si/Al ratio. All of these catalysts have acid sites of moderate strength. With Ga-MCM-41, 95% conversion of cyclooctene with 96% selectivity toward the epoxide was reached after 24 h of reaction. The catalyst could be recycled with no loss of catalytic properties.

Sustainable Solid Catalyst Alkylation of Commercial Olefins by Regeneration with Supercritical Isobutane

Supercritical isobutane regeneration of an ultrastable Y-zeolite (USY) alkylation catalyst was examined in a continuous, automated reaction/regeneration system. Two feeds were studied: a synthetic...

Identification and Measurements of Strong Brønsted Acid Site in Ultrastable Y (USY) Zeolite

By using the IRMS-TPD method in which IR (infrared) and MS (mass spectroscopy) worked together, acid sites of USY (ultrastable Y) zeolite were studied. A new band of OH playing a role of Brønsted acid was clearly detected on Na2H2-ethylenediaminetetraacetic acid (EDTA)-treated USY at 3595 cm(-1) during an elevation in temperature after the adsorption of ammonia. MS-measured TPD (temperature-programmed desorption) of NH3 and IR-measured TPD of the NH4+ cation coincided well to show that this zeolite consisted of the Brønsted acid sites. The MS-TPD profile at higher temperatures corresponded to the IR-TPD of the 3595-cm(-1) band, and therefore, this OH was identified as a strong acid site. From comparison between IR-TPD of OH and MS-TPD, numbers of three kinds of Brønsted OH (i.e., those in super and sodalite cages of a Y zeolite structure) and created strong Brønsted acid site were quantified. On the other hand, strength of the Brønsted acid site DeltaH was determined individually by a simulation method, where the corrected IR-TPD of OH was simulated based on the proposed equation. Thus, a new strong Brønsted acid site was identified in the EDTA-treated USY, and the amount and strength was measured quantitatively.

EXAFS study on the sulfidation behavior of Pd, Pt and Pd–Pt catalysts supported on amorphous silica and high-silica USY zeolite

The sulfur tolerance of monometallic Pd, Pt and bimetallic Pd–Pt catalysts supported on slightly acidic ultra-stable Y (USY) zeolite (SiO 2/Al 2O 3 = 390) and on non-acidic silica, having mesopores with a pore diameter of 3 or 10 nm, were investigated using the CO adsorption method and the extended X-ray adsorption fine structure (EXAFS) method. Well-dispersed noble metal particles supported on USY zeolite and silica with an average pore diameter of 3 nm showed high surface sulfur tolerance and high catalytic hydrogenation activity, although bulk phase sulfidation simultaneously occurred. The synergistic effects of sulfur tolerance were significant in the bimetallic Pd–Pt particles supported on USY zeolite and silica with an average pore diameter of 3 nm. On the other hand, on silica with an average pore diameter of 10 nm, the surface sulfur tolerance of low dispersed noble metals was the lowest, although its bulk phase sulfur tolerance was the highest. The Pd K-edge and Pt L III-edge EXAFS spectra indicated a strong interaction between the well-dispersed noble metal particles and the supports of the USY zeolite and silica with an average pore diameter of 3 nm. This distorted structure may increase the sulfur tolerance of noble metals, though some surface and bulk phase sulfidation simultaneously occurred.

Detection of active sites for paraffin cracking on USY zeolite by 27Al MQMAS NMR operated at high magnetic field 16 T

27Al MAS (magic angle spinning) and 3Q (triple quantum) MAS NMR (nuclear magnetic resonance) at a very high magnetic field (16 T, 700 MHz for 1H) enabled us to detect all the Al species on a series of modified Y zeolites. In a USY (ultra stable Y) zeolite after steaming, extra-framework Al species with various environments were detected, while only framework Al (IV) was observed in the parent NaY zeolite. 3QMAS NMR clearly identified the tetra-coordinated extra-framework Al with a large structural anisotropy (IV b), in addition to the penta-(V) and hexa-coordinated (VI) species. Na 2H 2-EDTA (ethylenediaminetetraacetic acid) treatment of the USY was found to convert the V and VI species into the IV b species. Increase in the Brønsted acid strength and the catalytic activity for octane cracking has been found on the Na 2H 2-EDTA-treated USY. Therefore, it is speculated that the IV b species is the origin of enhanced Brønsted acidity (and thereby the high cracking activity) of the USY zeolite.

The effect of supercritical isobutane regeneration on the nature of hydrocarbons deposited on a USY zeolite catalyst utilized for isobutane/butene alkylation

The chemical nature of hydrocarbons remaining on an ultrastable Y-zeolite (USY) utilized for liquid phase isobutane/butene alkylation reaction at 333 K and 1.1 × 10 7 Pa before and after supercritical isobutane regeneration (SFR) at 453 K and 1.1 × 10 7 Pa are presented. Catalyst samples were deactivated to different levels by running the alkylation reaction for different times on stream (TOS) and regenerated under flowing supercritical isobutane for 60 min. Nitrogen physisorption, temperature-programmed oxidation (TPO), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and ultraviolet-visible (UV–vis) spectroscopy measurements suggested that the SFR process was effective in recovering catalyst surface area and micropore volume and that most coke precursors were removed from samples regenerated after short TOS, when the level of activity for trimethylpentanes (TMP) production was high. Samples that were allowed to react for longer TOS contained unsaturated hydrocarbons that, instead of being extracted by the supercritical fluid, dehydrogenated during the SFR process to produce more condensed species.

Deactivation Studies During Catalytic Cracking of C8Aliphatic Hydrocarbons over Ultrastable Y-Zeolite. Conversion and Product Yield Profiles with Time Onstream

The deactivation of an ultrastable Y-zeolite during cracking of n-octane, isooctane and 1-octene was studied in a fixed-bed reactor. The relative reactivities of the three reactants in increasing order were n-octane < isooctane < 1-octene. At high residence times, complete conversion was achieved followed by a relatively slow decline that, in fact, presented a falsified deactivation picture. On the other hand, a surprising olefin yield increase with time onstream was observed, i.e., isobutene during isooctane cracking and octene isomers in the case of 1-octene. The isobutene yield increase was assigned to preferential deactivation of strong acid sites that allowed primary products to desorb into the gas phase, increasing their apparent yield rather than undergo secondary reactions. Similarly, 1-octene isomers showed a yield increase with time onstream due to stronger deactivation of cracking reactions than isomerization.

Effect of vanadium on USY zeolite destruction in the presence of sodium ions and steam—studies by solid-state NMR

The effect of deposited vanadium on the thermal destruction of ultra stable Y (USY) zeolite in the presence of sodium ions and steam was investigated by solid-state NMR. When USY zeolite containing few sodium ions was heated in a dry atmosphere, SiOH groups, which corresponded to defect sites, and strong adsorption sites were formed by the dealumination. The former mainly caused an increase in the mean void volume per supercage and the latter originated from cationic extra framework Al in the supercages. Furthermore, in the dry atmosphere, the sodium ions inhibited the dealumination; the effect of the deposited vanadium on the structural change was not large. After the heat treatment in 100% steam, in case of USY zeolite containing few sodium ions, the crystallinity and the supercage structure hardly changed although the dealumination occurred remarkably. This process did not depend on the deposited vanadium. Data suggested that the heat treatment in 100% steam causes the framework stabilization. In case of USY zeolite containing a number of sodium ions, the synergistic effect between a few deposited vanadium ions and the sodium ions on the framework destruction in 100% steam was tremendous. We propose that the deposited vanadium functions as vanadic acid and catalyzes the conversion of the sodium ions into NaOH. Thus, an increase in the NaOH content promotes the ‘dissolution’ of the zeolite crystal, i.e. the framework destruction. In addition, when the sample containing both a few vanadium ions and a number of sodium ions was heated in 100% steam, the supercage was plugged partially. We believe that the blockage compounds in the supercage are sodium vanadates.

Study of Interactions between Ion-Exchanged Chromium and Impregnated Vanadium in USY Zeolite Material

The steam treatment effect on the structure stability and acidity of ultrastable Y (USY) and Cr(III)-exchanged USY zeolites is investigated in the presence and absence of impregnated vanadium at 1000 up to 4000 ppm concentrations. Under steam-treatment conditions and in the presence of vanadium, the obtained results give evidence of the complete structure breakdown of an USY zeolite sample, which is nearly proportional to the percent dealumination; however, the structure breakdown of a Cr(III)-exchanged USY zeolite sample is limited even though the percent dealumination is still high. In addition, it is proved that the impregnated vanadium attacks selectively the strong acid sites, i.e., removes isolated framework Al atoms; however, although this action comes to completeness, the zeolite structure of the Cr(III)-exchanged USY sample is strong enough to keep its crystallinity at a high percentage. Finally, the acidity measurements give evidence that the Cr(III)-exchanged USY zeolite possesses medium streng...

Isopropylation of Xylenes Catalyzed by Ultrastable Zeolite Y (USY) and Some Other Solid Acid Catalysts

The isopropylation of all three xylene isomers was carried out over ultrastable zeolite Y (USY) catalyst to give corresponding dimethyl (1-methylethyl) benzenes, or in other words dimethyl cumenes (DMCs), using isopropanol as alkylating agent. The effect of reaction temperature, space velocity, substrate-to-alkylating-agent molar ratio, and time-on-stream on conversion of xylene isomers and selectivity to dimethyl cumene was studied. Isopropylation of xylenes over USY gives quite high (80 to 95%) DMC selectivity among the dimethyl cumenes, along with a 70–90% yield of DMCs in total products with respect to limiting reagents, i.e., isopropylating agents at relatively low reaction temperatures (423±10 K) and at quite high xylene conversions (85–97% of theoretical maximum value). The solid acid catalysts zeolites H–Y, H-beta, H–mordenite, as well as silica–alumina and sulfated zirconia, were included for comparative studies in the isopropylation of m-xylene.