Y-zeolite Catalysts Research Articles

Pyrolytic Depolymerization Mechanisms for Post-Consumer Plastic Wastes

Fast pyrolysis of five post-consumer plastic waste materials was studied using pyrolysis coupled with gas chromatography/mass spectrometry (Py-GC/MS) technique. Prescription medicine bottles, landfill liners, and one type of industrial plastic waste represented polyolefin-based polymers, whereas packaging material represented polystyrene, and other industrial plastic waste represented polyurethane. The noncatalytic and catalytic degradation mechanisms of all five post-consumer plastic wastes were elucidated. The noncatalytic pyrolysis experiments were conducted at a temperature of 600 °C for a residence time of 5 min. For catalytic pyrolysis, a spent FCC catalyst was utilized for polystyrene, a sulfated zirconia-based catalyst was utilized for polyurethane, and a Y-zeolite catalyst was used for polyolefinic plastic waste. The results suggested that the thermal reaction has higher monomeric and oligomeric selectivity than the catalytic reaction. Results from the catalytic runs showed that the addition of catalysts greatly influences product compositions and has a significant effect on the selectivity of a specific compound. One of the plastic wastes, landfill liner, was selected for a batch scale pyrolysis at 420–440 °C using Y-zeolite as a catalyst to demonstrate the product properties and potential use of the liquid product formed. The complete product distribution of plastic crude oil was performed followed by distillation to produce aviation range fuel. The fuel properties of aviation range fuel were examined, and results suggested that the fuel fraction can be easily blended with commercially available fuels for direct applications.

Thermocatalytic pyrolysis of Sesbania bispinosa biomass over Y-zeolite catalyst towards clean fuel and valuable chemicals

The thermocatalytic pyrolysis of Sesbania bispinosa (SB) biomass was performed in a cylindrical-shaped pyrolyzer to produce renewable fuel and chemicals. The important process parameters, such as temperature, heating rate, and N2 flow rate, were optimized using the response surface methodology (RSM). Pyrolysis of the SB biomass was also performed at different catalyst to biomass ratios (C/B) (1:3, 1:6, 1:9, and 1:12). The pyrolysis findings indicated that normal pyrolysis produced a greater yield of bio-oil (42.53 wt %) than catalytic pyrolysis (40.71 wt %) that obtained at 1:9 C/B ratio. The use of catalyst reduced the yield of bio-oil; however, fuel characteristics get enhanced. FTIR analysis of normal and catalytic bio-oil verified the existence of different functional groups, whereas GCMS result at optimized pyrolysis condition confirmed increased hydrocarbons in the catalytic bio-oil. Further, the characterization result of the biochar revealed its potential for use in a variety of industrial and agricultural applications.

Modulating accessibility, acidity and hydrogenation functions on mesoporous NiO1-x/Y-zeolite for vanillin hydrodeoxygenation

A 10 wt % NiO on mesoporous Y-zeolite catalyst was studied for vanillin hydrodeoxygenation. Vanillin, having aldehyde, ether and hydroxyl groups is a representative moiety of lignin. Characterization results indicated that alkali-treated zeolites featured mesoporous craters and, after NiO impregnation, yielded a bifunctional acid-hydrogenation catalyst. Mesoporous Y-zeolite allows a greater accessibility of vanillin to Brønsted acid sites (BAS) giving one order of magnitude higher activity in comparison with pristine Y-zeolite, besides of eliminating methoxy group on the former, but not on the later. Nonetheless, alkali-treatment of Y-zeolite should be done with low alkali concentration to have a balance between craterization and zeolite's crystalline structure. Y-zeolite having both micro- and mesoporous are a more effective choice than untreated Y-zeolite. Methoxy groups can be eliminated through protonation on BAS without aromatic ring hydrogenation, providing aromatic phenolic compounds at low hydrogen consumption.

Effect of synthesis and activation methods on the character of CoMo/ultrastable Y-zeolite catalysts

Abstract The properties of three types of CoMo/USY catalysts with different synthesized methods have been studied. The sequential and co-impregnation methods followed by activation using calcination and reduction process have been conducted. The properties of the catalysts were examined using Fourier-transform-infrared (FTIR) spectroscopy, X-ray diffraction (XRD) with refinement, and surface area analyzer (SAA). The FTIR spectrum study revealed the enhanced intensity of its Bronsted acid site, and the XRD diffractogram pattern verified the composition of pure metals, oxides, and alloys in the catalyst. The SAA demonstrated the mesoporous features of the catalyst. Scanning electron microscopy showed an irregular particle morphology. Additional analysis using the transmission electron microscopy indicated that the metal has successfully impregnated without damaging the USY structure.

Renewable Aromatics from Tree-Borne Oils over Zeolite Catalysts Promoted by Transition Metals.

Despite the ever-growing demand for benzene-toluene-xylene (BTX), the alternative route of production from tree-borne oils is rarely investigated and poorly understood. Here, we have synthesized a Zn-loaded Y-zeolite catalyst for the continuous production of bio-BTX from tree-borne oils (nonedible seed oil), e.g., neem oil. Our approach involves low-temperature selective cracking-dehydrogenation-aromatization of neem oil over metal-supported catalysts to xylene-rich aromatics. The physicochemical properties of the prepared catalyst were characterized using powder XRD, N2 physisorption, TEM, NH3-TPD, XPS, Py-FTIR, solid-NMR, and TG analyses. Mesoporous Y-zeolites with a pore diameter of 7.4 Å showed better selectivity toward aromatics and were found to be the most effective catalyst for the aromatization process, especially for BTX. The aromatic yield was found to increase with the addition of Zn, and the highest conversion of 90-94% with an ∼75% BTX yield was achieved with the ZnY catalyst. During aromatization, a sizable number of short alkanes and olefins were also obtained on acidic Y-zeolites. The off-gas composition shows the presence of ∼45% C2-C4 olefins with 8.9% H2. The incorporation of Zn species can promote the dehydrogenation activity, and the subsequent aromatization required a suitable pore network. The optimized ZnY catalyst inspires the formation of toluene and xylenes, inhibiting the formation of benzene and gaseous alkanes.

Bi-Functional Pd/Y-Zeolite Reforming Nanocatalyst Engineered Employing Polyvinylpyrrolidone and 2-(3,4-epoxycyclohexyl)Ethyltrimethoxysilane

This article reports novel engineering route of bi-functional Pd/Y-zeolite reforming nanocatalyst. Palladium nanostructures, synthesized adopting 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane as the reducing species and polyvinylpyrrolidone as the capping moiety, have been impregnated on Y-zeolite catalyst support for the purpose of imparting enhanced catalytic efficiency. Various characterization techniques have been performed such as UV/Visible spectroscopy, TEM, EDAX, SEM and BET method.

Comparison of Isobutane/n-Butenes Alkylation over Y-Zeolite Catalyst in CSTR, Fixed Bed and Circulating Flow Reactors

Isobutane/olefin alkylation is an important route to obtain high-quality gasoline. There is an apparent interest to apply zeolite based catalysts for this process to eliminate large scale usage of liquid catalysts such as H2SO4 and HF. Solid catalysts require a specific reactor system design involving frequent catalyst regeneration and operation at low concentration of the olefin. The aim of this work was to compare different reactor types: CSTR, “once-through” fixed bed type and circulating flow reactors (CFR), which are typically considered as suitable options for industrial implementation. The experiments were done on decationated Y-zeolite catalyst. Different paraffin/olefin ratios, temperature and circulation rates were studied. Catalysts and process performance are discussed based on the catalyst lifetime and the alkylate octane number. Analysis of diffusion limitations in different reactor types and optimization of the circulation rate in CFR were done. It was found that isobutane alkylation in a circulating flow reactor shows approximately the same catalyst lifetime even at a high circulation rate not exhibiting any positive impact of back-mixing on this process. However, a circulating flow reactor has demonstrated a much better quality of alkylate with the research octane number higher by 4.9 points. Additional operational costs related to the reactor effluent recycle are fully covered by the alkylate quality improvement even at a high circulation ratio.

A study of coke formed by heavy oil volatilization/decomposition on Y-zeolite

Coke related catalyst deactivation is still attractive for many researchers as the complexity of carbon precursor. Y-zeolite is one of the most popular catalyst used in petrochemical industry, which is also progressively degrading by coking. In this piece of work, the effects of volatilization/decomposition temperature and sample-to-catalyst ratio on the coke formed from heavy oil volatilization/decomposition in the presence of Y-zeolite catalyst have been investigated. Temperature plays a significant role in determining the nature of the carbon formed, with higher temperatures favouring a higher graphitic-to-amorphous carbon ratio. Higher sample-to-catalyst ratios lead to higher amounts of coke, but does not affect the graphitic-to-amorphous carbon ratio as the same volatilization/decomposition temperature.

Non-catalytic and catalytic pyrolysis of Ulva prolifera macroalgae for production of quality bio-oil

Pyrolysis of Ulva prolifera macroalgae (UM), an aquatic biomass, was carried out in a fixed-bed reactor in the presence of three zeolites based catalysts (ZSM-5, Y-Zeolite and Mordenite) with the different catalyst to biomass ratio. A comparison between non-catalytic and catalytic behavior of ZSM-5, Y-Zeolite and Mordenite catalyst in the conversion of UM showed that is affected by properties of zeolites. Bio-oil yield was increased in the presence of Y-Zeolite while decreased with ZSM-5 and Mordenite catalyst. Maximum bio-oil yield for non-catalytic pyrolysis was (38.5 wt%) and with Y-Zeolite catalyst (41.3 wt%) was obtained at 400 °C respectively. All catalyst showed a higher gas yield. The higher gas yield might be attributed to that catalytic pyrolysis did the secondary cracking of pyrolytic volatiles and promoted the larger small molecules. The chemical components and functional groups present in the pyrolytic bio-oils are identified by GC–MS, FT-IR, 1H-NMR and elemental analysis techniques. Phenol observed very less percentage in the case of non-catalytic pyrolysis bio-oil (9.9%), whereas catalytic pyrolysis bio-oil showed a higher percentage (16.1%). The higher amount of oxygen present in raw biomass reduced significantly when used catalyst due to the oxygen reacts with carbon and produce (CO and CO2) and water.

Influence of catalyst bed temperature and properties of zeolite catalysts on pyrolysis-catalysis of a simulated mixed plastics sample for the production of upgraded fuels and chemicals

The pyrolysis-catalysis of a simulated mixture of plastics representing the plastic mixture found in municipal solid waste has been carried out to determine the influence of process conditions on the production of upgraded fuel oils and chemicals and gases. The catalysts used were spent zeolite from a fluid catalytic cracker (FCC), Y-zeolite and ZSM-5 zeolite. The addition of a catalyst to the process produced a marked increase in gas yield, with more gas (mainly C1–C4 hydrocarbons) being produced as the temperature of the catalyst was raised from 500 °C to 600 °C. The Si/Al ratio of the catalysts influenced the composition of other gases with the more basic catalysts producing more CO and the strongly acidic catalyst producing more H2. The yield of product oil decreased with the addition of the catalysts, but the oil was of significantly lower molecular weight range, containing a product slate of premium fuel range C5–C15 hydrocarbons. In addition, the content of aromatic compounds in the product oil was increased; for example, benzene and toluene accounted for more than 90% of the aromatic content of the oil from the strongly acidic Y-zeolite catalysts. A reaction scheme is proposed for the production of single-ring aromatic compounds via pyrolysis-catalysis of plastics.

Synthesis, Characterization and Catalytic Dehydration of Glycerol to Acrolein Over Phosphotungstic Acid Supported Y-Zeolite Catalysts

Vapour phase catalytic dehydration of glycerol to acrolein was studied over phosphotungstic acid (PTA) supported (with different loadings of PTA) on Y-zeolite catalysts. The active component PTA was varied between 10 and 40% w/w on the support Y-zeolite and was synthesized by the wet impregnation method. The physico-chemical characterization of the catalyst samples was investigated by X-ray diffraction (XRD), FT-IR, Raman and by the gas adsorption measurements. The XRD results showed that active component PTA is highly dispersed in an amorphous form at lower loadings of PTA and attained a crystalline state beyond 20 wt% of PTA. Both Raman and FT-IR spectra indicated that the Keggin ion structure of PTA was present in a highly dispersed state in the supported PTA/zeolite catalysts as compared to the bulk form of PTA. Temperature programmed desorption (TPD) of ammonia and FT-IR spectra of pyridine adsorption were used to determine the acidic properties of the PTA catalysts. The TPD of ammonia showed the presence of moderate acidity on the catalyst surface. The total acidity increased with raise in PTA loading up to 20 wt% and beyond this, it had decreased. The FT-IR results suggested the presence of Bronsted acidity. The Pore size increased with PTA loading until 20 wt%. Finally, the PTA/zeolite catalysts were tested for the gas phase dehydration of glycerol in a fixed-bed, micro-reactor in the temperature range between 250 and 300 °C. Among all the catalysts tested, PTA (20 wt%)/zeolite showed a total conversion of 100% glycerol and a selectivity of 79% for acrolein. These results are correlated with surface acidity, textural and structural properties of the PTA/zeolite catalysts. Glycerol dehydration products over Lewis and Bronsted acidic sites.

Preparation and application of metal loaded ZSM-5 and y-zeolite catalysts for thermo-catalytic pyrolysis of real end of life vehicle plastics waste

In this work synthetic zeolite catalysts were modified by metal loading and used for real end of life vehicle plastic waste pyrolysis. ZSM-5 and y-zeolite catalysts were loaded by Ce2+, Cu2+, Fe2+, Fe3+, H+, Mg2+, Ni2+, Sn2+ and Zn2+ and the catalytic effects of both parent and metal loaded catalysts were tested by thermogravimetric method. The catalysts morphology and other properties were followed by N2 adsorption/desorption isotherms, Fourier transformed infrared spectroscopy, Scanning Electron Microscopy and energy dispersive x-ray fluorescent spectroscopy. Significant difference in micropore, mesopore and macropore surface area, and average pore diameter was concluded. In general, the surface areas could be decreased by metal loading onto the catalyst surface. Parent y-zeolite had larger surface areas than that of parent ZSM-5 catalyst. Based on EDXRFS analysis, catalysts were loaded by 8–10% metals. Regarding grain size, in general y-zeolite based catalysts had smaller grains and the distribution was also narrower, than ZSM-5 based catalysts. The Si/Al ratio was 17.11–21.75 in case of ZSM-5 catalysts and 2.04–2.91 regarding y-zeolite catalyst. Based on first order kinetic approach, the reaction kinetic parameters were also calculated and evaluated. Waste end-of life vehicle (ELV) started to decompose at 426 °C (T5%) and finished at 525 °C (T95%). Catalysts can decrease the activation energies of decomposition. Same order of the activation energy decreasing of both ZSM-5 and y-zeolite based catalysts was found: Cu<Ce<Mg<Ni<Fe(III)<Fe(II)<Zn<Sn, however, y-zeolite based catalysts had advanced properties in activation energy decreasing than ZSM-5 based.

Thermo-catalytic two-step pyrolysis of real waste plastics from end of life vehicle

This work focuses to the thermo-catalytic pyrolysis of real plastic waste from End of Life Vehicle. Two-step batch reactor fitted with electric heating was used for pyrolysis. Zeolite catalysts (ZSM-5, β-zeolite and y-zeolite) was used in the first reactor at 425°C and 485°C, while the product yield and composition were further modified by the using of structured Ni/Mo–Al2O3 catalyst in the 2nd reactor at 380°C. No water/steam was feed into the 2nd reactor. Gas-chromatography, high-pressure liquid chromatography, size exclusion chromatography and Fourier transformed infrared spectroscopy were used for identification of pyrolysis products, while the catalyst morphology was investigated by scanning electron microscopy. Catalysts in the 1st reactor had a significant effect to the product yields and decreased the time required for pyrolysis. ZSM-5 and y-zeolite catalysts had high activity in carbon frame isomerization. β-zeolite catalyst could crack the polymer main chain with high efficiency; however, its deactivation was the fastest. Structured Ni/Mo-Al2O3 in the 2nd reactor affected the gas/pyrolysis oil ratio, increased the hydrogen yield in gases, monoaromatic yield in pyrolysis oil and owing to the coke formation, its surface was fully covered by coke depositions after the pyrolysis. The hydrocarbon compositions of pyrolysis oils were favourable for further separation and refinery application.

Aromatic fuel oils produced from the pyrolysis-catalysis of polyethylene plastic with metal-impregnated zeolite catalysts

Pyrolysis-catalysis of high density polyethylene (HPDE) was carried out in a fixed bed, two stage reactor for the production of upgraded aromatic pyrolysis oils. The catalysts investigated were Y-zeolite impregnated with transition metal promoters with 1 wt% and 5 wt% metal loading of Ni, Fe, Mo, Ga, Ru and Co to determine the influence on aromatic fuel composition. Pyrolysis of the HDPE took place at 600 °C in the first stage of the reactor system and the evolved pyrolysis gases were passed to the second stage catalytic reactor, which had been pre-heated to 600 °C. Loading of metals on the Y-zeolite catalyst led to a higher production of aromatic hydrocarbons in the product oil with greater concentration of single ring aromatic hydrocarbons produced. The single ring aromatic compounds consisted of mainly toluene, ethylbenzene and xylenes, while the 2-ring hydrocarbons were mainly naphthalene and their alkylated derivatives. There was a reduction in the production of multiple ring aromatic compounds such as, phenanthrene and pyrene. The addition of the promoter metals appeared to have only a small influence on aromatic oil content, but increased the hydrogen yield from the HDPE. However, there was significant carbon deposition on the catalysts in the range 14–22 wt% for the 1% metal-Y-zeolite catalysts and increased to 18–26 wt% for the 5 wt% metal-Y-zeolite catalysts.

The Predisposition of Iraqi Rice Husk to Remove Heavy Metals from Aqueous Solutions and Capitalized from Waste Residue

This study is deal with study the potential of Iraqi Rice Husk (IRH) on the removal of three heavy metals pollutant which were (Mg, Mn and Mo) ions from industrial wastewater using different design parameters by adsorption process. Results show that the removal efficiency were (93.95, 97.18 and 95.26) % for heavy metal (Mg, Mn and Mo) respectively from aquatic solution decreased with increasing of initial concentration and flow rate while the removal efficiency increased with increasing absorbance material bed height, pH and feeding temperature. Statistical model is achieved to find an expression relates the overall operating parameters with the removal efficiency for each metal ions used in this investigation in a general equation (each one alone). The samples of (IRH) remaining after using it in the removal of (Mg, Mn and Mo) heavy metal ions above from Simulated Synthetic Aqueous Solutions (SSAS) to investigate the capitalized of it in different methods. Different benefits possess which are: remove the three toxic heavy metals ions contaminated the water, get rid of agricultural waste (IRH), in the same time, produce light and more benefit hydrocarbons from n-heptane isomerization using a type Y-zeolite catalyst synthesis from remaining (IRH) and prepare a cheap and active rodenticide.

Utilization of Iraqi Rice Husk in the Removal of Heavy Metals from Wastewater

This study deals with the potential of Iraqi Rice Husk (IRH) for the removal of nine heavy metal pollutants which are Al, As, Cd, Cr, Cu, Fe, Ni, Pb and Zn ions from industrial wastewater using different design parameters by the adsorption process. Samples were taken of the IRH remaining after being used for the removal of the nine metal ions above from aqueous solutions using different methods. One of these methods was the preparation of a promoted type Y-zeolite catalyst which was compared with normally type Y-zeolite catalyst prepared from IRH alone and tested in the process of n-heptane isomerization under different temperatures. Another method involved the study of IRH as a rodenticide directly without any pre-treatment. The results show that the promoted type Y-zeolite catalyst by Cd +2 , Cr +6 , Cu +2 , Fe +3 , Ni +2 and Zn +2 ions gives a higher conversion and better selectivity of n-heptane isomerization than the normal type Y-zeolite catalyst and the IRH which had previously adsorbed Al +3 , As +5 , Zn +2 and Pb +2 from an aqueous solution and also showed good behavior as a rodenticide.

Hydrocarbon Fractions Obtained from Recycling of Waste Materials

Pyrolysis of contaminated waste plastics was carried out in a laboratory scale batch reactor at 450 °C under nitrogen atmosphere. Raw materials were original high density polyethylene (HDPE) and waste motor oil flasks from industrial sector. Volatile products were passed through a fixed catalyst bed with temperature of 350 °C. In the experiments Y-zeolite, β-zeolite, HZSM-5, Co/Mo and Ni/Mo catalysts were used. Three product fractions were obtained: gas, liquid and heavy oil. Catalysts had mainly effect on the gas and liquid yields, the amount of the residue did not show significant differences in the case of the same raw material. By pyrolysis of contaminated raw material higher volatile product yield could be observed compared to pyrolysis of the original raw material. Catalysts increased gas yields and had influence on the composition of products. Most significant effect could be observed in the case of Y-zeolite and β-zeolite catalysts. Contaminant level of liquid products could be decreased in case of thermo-catalytic pyrolysis, which is a key property for further application of the pyrolysis products.

Fluid catalytic cracking of biomass pyrolysis vapors

Catalytic cracking of pyrolysis oils/vapors offers the opportunity of producing bio-oils which can potentially be coprocessed with petroleum feedstocks in today’s oil refinery to produce transportation fuel and chemicals. Catalyst properties and process conditions are critical in producing and maximizing desired product. In our studies, catalyst matrix (kaolin) and two commercial fluid catalytic cracking (FCC) catalysts, FCC-H and FCC-L, with different Y-zeolite contents were investigated. The catalytic cracking of hybrid poplar wood was conducted in a 50-mm bench-scale bubbling fluidized-bed pyrolysis reactor at 465°C with a weight hourly space velocity of 1.5 h−1. The results showed that the yields and quality of the bio-oils was a function of the Y-zeolite content of the catalyst. The char/coke yield was highest for the higher Y-zeolite catalyst. The organic liquid yields decreased inversely with increase in zeolite content of the catalyst whereas the water and gas yields increased. Analysis of the oils by both Fourier-transform infrared and 13C-nuclear magnetic resonance indicated that the catalyst with higher zeolite content (FCC-H) was efficient in the removal of compounds like levoglucosan, carboxylic acids and the conversion of methoxylated phenols to substituted phenols and benzenediols. The cracking of pyrolysis products by kaolin suggests that the activity of the FCC catalyst on biomass pyrolysis vapors can be attributed to both Y-zeolite and matrix. The FCC-H catalyst produced much more improved oil. The oil was low in oxygen (22.67 wt.%), high in energy (29.79 MJ/kg) and relatively stable over a 12-month storage period.

Pyrolysis of latex gloves in the presence of Y-zeolite

In this study we have investigated the possibility of processing waste rubber gloves using pyrolysis. Y-zeolite catalyst was employed to upgrade the pyrolysis products to give higher yields of valuable aromatic compounds such as toluene and xylenes. The composition of the pyrolysis products was determined using gas chromatography with linked mass spectrometry (GC-MS), gas chromatograph equipped with a flame ionization detector (GC-FID), gas chromatograph fitted with dual thermal conductivity detectors (GC-TCD), and Fourier Transform Infra-Red Spectrometry (FT-IR). It was found that when rubber gloves were pyrolysed in the absence of a catalyst, the pyrolysis oil consisted mainly of limonene and oligomers of polyisoprene. When Y-zeolite was added to the reaction system, the yields of toluene, xylene, methylbenzenes, ethylbenzenes, and naphthalenes increased dramatically. The Y-zeolite also catalysed the decomposition of limonene, which was absent from the catalytic pyrolysis products. The presence of the Y-zeolite catalyst also increased the yield of hydrocarbon gases. The tests were carried out at both 380 degrees C and 480 degrees C and it was found that the higher reaction temperature led to increased yields of all the major compounds, both in the presence and absence of the Y-zeolite catalyst.

Catalytic Functionalities of H-β-Zeolite-Supported Molybdenum Hydrotreating Catalysts

Catalysts containing 2−12 wt % Mo and 1−5 wt % Co or Ni were prepared using commercial H-β-zeolite as a support. The support as well as various catalysts were characterized by X-ray diffraction (XRD), BET surface area, temperature-programmed reduction (TPR), and in situ oxygen chemisorption in the sulfided state. The XRD studies indicated that the crystallinity of β-zeolite decreases rapidly at higher loadings of molybdenum, and there is no evidence for the presence of crystalline Mo phases below 10 wt % Mo loading. At higher loadings, however, MoO3/MoS2 may be present in small quantities. The BET surface area analysis indicated that molybdenum is well-dispersed up to 6 wt % Mo loading in both oxide and sulfide states. The oxygen uptakes increased up to 6 wt % Mo and then decreased at higher loadings. The crystallite sizes evaluated by oxygen chemisorption are small, indicating that MoS2 is well-dispersed on the support up to 6 wt % Mo. The TPR results indicated that a Co or Ni promoter helps decrease the temperature of the Mo reduction. TPR results indicated that two molybdenum phases with differing reduction behavior exist before and after 6% Mo loading. Catalytic activities for HDS, HYD, and HCK followed the same trend as oxygen uptake. A comparison with γ-Al2O3 indicated that the β-zeolite support imparts superior HYD activities in Mo, CoMo, and NiMo catalysts. Y-zeolite catalysts exhibit higher HDS activities but lower HYD activities than β-zeolite-supported catalysts.