Cumene Dealkylation Research Articles

Preparation and characterization of Pt/HMFI–SBA-15 hybrid catalyst for tetralin transformation

A Pt catalyst supported on a hybrid material, HMFI–SBA-15, was prepared. Both, support and catalyst (Pt/HMFI–SBA-15) were characterized by nitrogen physisorption, small and wide (2 θ) angle XRD patterns, FT-IR, SEM and HRTEM. The acidic properties of the hybrid material were studied by cumene dealkylation and those of the catalyst were studied by FT-IR of adsorbed pyridine. The catalyst, Pt/HMFI–SBA-15, was tested for tetralin transformation at various reaction temperatures 498, 523, 548, 573, 585 and 598 K. Wide-angle XRD and FT-IR in the skeletal region indicate the presence of MFI zeolite fragments incorporated onto SBA-15. The characterization of the acid sites on the support by cumene dealkylation and FT-IR pyridine adsorption revealed the presence of Brönsted acid sites related to the HMFI zeolite fragments in the hybrid materials. For the catalyst, a homogeneous distribution of Pt clusters was found by HRTEM. In the transformation of tetralin, at all the reaction temperatures, the main products were trans + cis-decalins. However, at high reaction temperature ring contraction to spirodecane and dehydrogenation to naphthalene were observed. At 598 K, a maximum of 8% of ring contraction products was obtained.

Ratio of the equilibrium and kinetic acidities of solid catalysts

The feasibility of using the equation log k = const - H0s was examined for solid acid catalysts. Data for the thermoprogrammed dealkylation of cumene showed that the temperature dependence of the strength of the acid sites of the catalyst H0s(T) should be considered in calculating the coefficient . In this case, 1. However, as shown for the isomerization of o-xylene, dimerization of butylenes, dehydration of 2-propanol (2), and the dealkylation of cumene (3), the values found for coefficient are in the range 0.15-0.6 (4) and do not approach 1 as in solution. For example, in the cracking of cumene, an increase in H 0 by six leads to an increase in the rate constant k not by six orders of magnitude but only by a factor of 10. A possible explanation of the low values of is based on the assumption that a proton is not added to the adsorbed molecule but rather polarized hydrogen-bonded complexes are formed (4). In the present work, we have shown that catalytic reactions with proton transfer on the surface in the dealkylation of cumene on acid catalysts may be characterized by "normal" values of 1. In this case, the temperature dependence of the strength of the acid sites of the catalyst is taken into account. Equation (1) clearly reflects the relationship of the equilibrium and kinetic acidities of the catalyst sites and, thus, presupposes a reaction mechanism with consecutive formation of an adsorbed proton-transfer complex with equilibrium constant K s , a transition state with rate constant k, and the reaction products:

Correlation between the strength of the basic sites of catalysts and their activity in the decomposition of 2-methyl-3-butyn-2-ol as a test reaction

A correlation was found between the strength of the basic sites of a series of solid oxides and their activity in the decomposition of 2-methyl-3-butyn-2-ol to give acetylene and acetone as a test reaction. Equations are given for the acidity function H0s and basicity function H–s for individual acidic and basic sites on the solid surface. The basicity of heterogeneous catalysts, similar to their acidity, is an important parameter, which permits us to evaluate their activity in proton transfer reactions. The H – acidity function is the accepted parameter for the strength of basic catalyst sites, while H 0 , the Hammett acidity function, is a parameter of the strength of acidic sites. These functions are determined using standard sets of indicators [1]. The question of how significantly the strength of catalyst sites affects the rate constant of a catalytic reaction is important. Such correlations are found for acidic catalysts, in particular, for the isomerization of o-xylene [1] and the dealkylation of cumene [2]. On the whole, the same tendency is noted for basic catalysts as for acidic catalysts, namely, catalyst activity rises with increasing strength of the basic sites as found, in particular, in the isomerization of 2,3-dimethyl-1-butene [3]. However, there are virtually no data in the literature on the correlation between H– and the rate constants of base-catalyzed reactions. In the present work, we present the relationship between the strength of basic sites of a series of oxides and their activity in the thermoprogrammed decomposition of 2-methyl-3-butyn-2-ol (MBOH), which is commonly used for the testing of both acidic and basic materials [4].

Environmentally friendly solid acid catalyst prepared by modifying TiO2 with cerium sulfate for the removal of volatile organic chemicals

An environmentally friendly solid acid catalyst, Ce(SO4)2/TiO2 was prepared simply by modifying TiO2 with Ce(SO4)2 for acid catalysis of volatile organic chemicals, 2-propanol and cumene. The characterization of prepared catalysts was performed using FTIR, XRD and DSC. The surface area of 7-Ce(SO4)2/TiO2 calcined at 300°C was very high (206.0m2/g) compared to that of unmodified TiO2 (115.2m2/g) due to the interaction between Ce(SO4)2 and TiO2. 7-Ce(SO4)2/TiO2 containing 7wt% Ce(SO4)2 and calcined at 300°C exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acid amounts of catalysts measured by an ammonia chemisorption method. The role of Ce results in an increase in the thermal stability of the surface sulfate species and consequently the acid amount of Ce(SO4)2/TiO2 is increased. The asymmetric stretching frequency of the SO bonds for Ce(SO4)2/TiO2 catalysts was related to the acidic properties and to the catalytic activity for acid catalysis to remove volatile organic chemicals, 2-propanol and cumene.

Physicochemical and Catalytic Properties of NiSO4/CeO2-ZrO2Catalyst Promoted with CeO2for Acid Catalysis

A solid acid catalyst, NiSO4/CeO2-ZrO2 was prepared simply by promoting ZrO2 with CeO2 and supporting nickel sulfate on CeO2-ZrO2. The support of NiSO4 on ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperatures because of the interaction between NiSO4 and ZrO2. The surface area of 10-NiSO4/1-CeO2-ZrO2 promoted with CeO2 and calcined at 600 oC was very high (83 m2/g) compared to that of unpromoted 10-NiSO4/ZrO2 (45 m2/g). This high surface area of 10-NiSO4/1-CeO2-ZrO2 was due to the promoting effect of CeO2 which makes zirconia a stable tetragonal phase as confirmed by XRD. The role of CeO2 was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity of the sample, and high thermal stability of the surface sulfate species. 10-NiSO4/1- CeO2-ZrO2 containing 1 mol% CeO2 and 10 wt% NiSO4, and calcined at 600 oC exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation.

Characterization of Supported NiSO4 and Effect of TiO2–ZrO2 Composition on Catalytic Activity for Acid Catalysis

A series of catalysts, NiSO4/TiO2–ZrO2 having different TiO2–ZrO2 composition, for acid catalysis was prepared by the impregnation method using an aqueous solution of nickel sulfate. The addition of TiO2 to ZrO2 improved the surface area of the catalyst and enhanced its acidity remarkably because of the formation of new acid sites through the charge imbalance of Ti–O–Zr bonding. The binary oxide, TiO2–ZrO2 calcined above 600 °C resulted in the formation of crystalline orthorhombic phase of ZrTiO4. Therefore, NiSO4/TiO2–ZrO2 calcined at 500 °C exhibited a maximum catalytic activity for acid catalysis, and then the catalytic activity decreased with the calcination temperature. The correlation between catalytic activity and acidity held for both reaction, 2-propanol dehydration and cumene dealkylation. NiSO4 supported on 50TiO2–50ZrO2 (TiO2/ZrO2 ratio = 1) among TiO2–ZrO2 binary oxides exhibited the highest catalytic activity for acid catalysis.

Characterization and Acid Catalytic Properties of NiO Supported on ZrO<sub>2</sub> and Modified with MoO<sub>3</sub>

Nickel oxide supported on zirconia and modified with MoO3 for acid catalysis was prepared by drying powdered Ni(OH)2-Zr(OH)4 with ammonium heptamolybdate aqueous solution, followed by calcining in air at high temperature. The characterization of prepared catalysts was performed using FTIR, Raman, XRD, and DSC. MoO3 equal to or less than 15 wt% was dispersed on the surface of catalyst as two-dimensional polymolybdate or monomolybdate, while for MoO3 above 15 wt%, crystalline orthorhombic phase of MoO3 was formed. The high acid strength and acidity were responsible for the Mo=O bond nature of the complex formed by the interaction between MoO3 and ZrO2. The catalytic activity for cumene dealkylation was correlated with the acidity of the catalyst measured by the ammonia chemisorption method

Structural characterization and catalytic activity of molybdenum oxide supported zirconia catalysts

A series of MoO 3/ZrO 2 catalysts with different molybdenum content of 5–30 wt.% MoO 3 were prepared by impregnation method. The prepared catalysts were calcined at 400, 550, 700, 800, and 1000 °C. The structural characteristics were investigated by means of thermal analysis (DTA and TGA), powder X-ray diffraction (XRD) while the textural properties was determined from low temperatures adsorption of N 2 at −196 °C. The surface acidity was measured with nonaqueous titration of n-butylamine in acetonitrile. The catalytic activity was tested by cumene dealkylation and ethanol conversion using the microcatalytic pulse technique. XRD reveals that the samples contain mixture of tetragonal and monoclinic zirconia phases. At low MoO 3 loading, i.e. <15 wt.% MoO 3, MoO 3 was not detected. When the loading of MoO 3 exceeds 15 wt.%, crystalline MoO 3 and Zr(MoO 4) 2 were formed, particularly for the higher calcination temperature products. The incorporation of MoO 3 into ZrO 2 enhanced the surface acidity of the catalysts. It was found that the surface acidity gradually increased as the temperature of thermal treatment was increased from 400 to 550 °C and also with the molybdenum oxide content. This increase in the surface acidity was correlated with the degrees of crystallinity of the samples. The surface area was found to increase with increasing of MoO 3 up to 15 wt.%. Further increase of MoO 3 beyond 15 wt.% led to a decrease of N 2- S BET. The catalytic activity was strongly influenced with the textural, structural properties and surface acidities of the catalysts investigated.

Mesoporous aluminosilicate catalysts from FAU precursor under mild acidic conditions and with Al in totally tetrahedral coordination

Al-SBA-15 mesoporous catalyst with strong Bronsted acid sites and Al stabilized in a totally tetrahedral coordination was synthesized from the addition of hydrothermally aged zeolite Y precursor to SBA-15 synthesis mixture under mildly acidic condition of pH 5.5. The materials possessed surface areas between 690 and 850 m2/g, pore sizes ranging from 5.6 to 7.5 nm and pore volumes up to 1.03 cm3, which were comparable to parent SBA-15 synthesized under similar conditions. As much as 2 wt.% Al was present␣in the most aluminated sample that was investigated, and the Al remained stable in totally tetrahedral coordination, even after calcination at 550 °C. Calcined Al-SBA-15 showed high hydrothermal stability when treated with steam (20% v/v in nitrogen) at 650 °C for 2 h. Textural characteristics are maintained on steam treatment, and very little or no conversion of Al from tetrahedral to octahedral coordination resulted. The Al-SBA-15 mesoporous catalyst showed significant catalytic activity for cumene dealkylation, and activity increased as the amount of zeolite precursor added to the SBA-15 mixture was increased. The catalyst’s activity was not affected by the aging time of the precursor for up to the 24 h aging time investigated. This method of introducing Al and maintaining it in a total tetrahedral coordination is very effective, in comparison to other direct and post synthesis alumination methods reported.

NiO/La2O3-ZrO2/WO3 Catalyst Prepared by Doping ZrO2 with La2O3 and Modifying with WO3 for Acid Catalysis

A series of catalysts, NiO/La 2 O 3 -ZrO 2 /WO 3 , for acid catalysis was prepared by the precipitation and impregnation methods. For the NiO/La 2 O 3 -ZrO 2 /WO 3 samples, no diffraction lines of nickel oxide were observed, indicating good dispersion of nickel oxide on the catalyst surface. The catalyst was amorphous to X-ray diffraction up to 300 °C of calcination temperature, but the tetragonal phase of ZrO 2 and monoclinic phase of WO 3 by the calcination temperatures from 400 °C to 700 C were observed. The role of La 2 O 3 in the catalyst was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity. The high acid strength and high acidity were responsible for the W=O bond nature of complex formed by the modification of ZrO 2 with WO 3 . For 2-propanol dehydration the catalyst calcined at 400 °C exhibited the highest catalytic activity, while for cumene dealkylation the catalyst calcined at 600 °C showed the highest catalytic activity. 25-NiO/5-La203-Zr02/15-W03 exhibited maximum catalytic activities for two reactions due to the effects of WO 3 modifying and La 2 O 3 doping.

New solid superacid catalyst prepared by doping ZrO 2 with Ce and modifying with sulfate and its catalytic activity for acid catalysis

A new solid superacid catalyst, Ce-ZrO 2/SO 4 2− was prepared simply by doping ZrO 2 with Ce and modifying with sulfate simultaneously. The characterization of prepared catalysts was performed using FTIR, XRD and DSC. The surface area of 5Ce-ZrO 2/SO 4 2− calcined at 650 °C was very high (121.2 m 2/g) compared to that of undoped and only sulfated ZrO 2 (56.0 m 2/g). This high surface area of Ce-ZrO 2/SO 4 2− was due to the doping effect of Ce, which makes zirconia a stable tetragonal phase as confirmed by XRD. 5Ce-ZrO 2/SO 4 2− containing 5 wt.% Ce(SO 4) 2 and calcined at 650 °C exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The role of Ce was to form a thermally stable solid solution with zirconia and consequently to give high surface area and acidity of the sample.

Acid–base reactions on alumina-supported niobia

Catalysts containing from 8 to 28% wt. of niobia supported on γ-alumina by impregnation with niobium pentaethoxide solutions were characterized by infrared spectroscopy of adsorbed pyridine as a probe for acidic sites and CO 2 adsorption as a probe for basic sites. The catalysts had their activity measured in isopropanol dehydration at 453 K, 1-butene isomerization at 348 K and in cumene dealkylation at 728 K. The density and strength of the Lewis acid sites and of the basic sites decreased with niobium content. On the other hand, the density of Brønsted acid sites increased in the same direction. Different reactions responded differently to niobium addition. In isopropanol dehydration, the main factor responsible for the observed decrease in catalytic activity was the decrease in concentration of basic sites. Activity for 1-butene isomerization also decreased with niobium addition, but the main factor seemed to be the decrease in concentration of alumina-associated Lewis acidic sites. Evidence from cis-/ trans-2-butene ratio indicated that niobium addition modifies the properties of neighboring aluminum sites. Brønsted acidic sites created by niobium addition are responsible for the development of activity in the cumene dealkylation reaction, but the sites associated with tridimensional niobia species seem to be more effective in this reaction.

Catalytic Activities of Al2O3-promoted NiSO4/TiO2 for Acid Catalysis

A series of catalysts, NiSO4/Al2O3–TiO2, for acid catalysis was prepared by the impregnation method, where support, Al2O3–TiO2 was prepared by the coprecipitation method using a mixed aqueous solution of titanium tetrachloride and aluminum nitrate solution followed by adding an aqueous ammonia solution. The addition of nickel sulfate (or Al2O3) to TiO2 shifted the phase transition of TiO2 from amorphous to anatase to higher temperature because of the interaction between nickel sulfate (or Al2O3) and TiO2. 15-NiSO4/5-Al2O3–TiO2 containing 15 wt% NiSO4 and 5 mol% Al2O3, and calcined at 400°C exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The charge transfer from Ti atoms to the neighboring Al atoms strengthens the Al–O bond between Al and the surface sulfate species. The addition of Al2O3 up to 5 mol% enhanced the acidity, thermal property, and catalytic activities of NiSO4/Al2O3–TiO2 gradually due to the interaction between Al2O3 and TiO2 and consequent formation of Al–O–Ti bond.

Catalytic properties of NiSO4/ZrO2 promoted with Fe2O3 for acid catalysis

A series of catalysts, NiSO4/Fe2O3–ZrO2, for acid catalysis were prepared by the impregnation method, where support, Fe2O3–ZrO2 was prepared by the co-precipitation method using a mixed aqueous solution of zirconium oxychloride and iron nitrate solution followed by adding an aqueous ammonia solution. No diffraction line of nickel sulfate was observed up to 20wt.%, indicating good dispersion of nickel sulfate on the surface of Fe2O3–ZrO2. The addition of nickel sulfate (or Fe2O3) to ZrO2 shifted the phase transition of ZrO2 from amorphous to tetragonal to higher temperature because of the interaction between nickel sulfate (or Fe2O3) and ZrO2. 15-NiSO4/Fe2O3–ZrO2 containing 15wt.% NiSO4 and 5mol% Fe2O3, and calcined at 700°C exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The addition of Fe2O3 up to 5mol% enhanced the acidity, thermal property, and catalytic activities of NiSO4/Fe2O3–ZrO2 gradually due to the interaction between Fe2O3 and ZrO2 and consequent formation of FeOZr bond.

The Effect of Al2O3 Addition on Catalytic Activities of NiSO4/Al2O3-ZrO2 for Acid Catalysis

A series of catalysts, NiSO 4 /Al 2 O 3 -ZrO 2 , for acid catalysis were prepared by the impregnation method, where support, Al 2 O 3 -ZrO 2 was prepared by the coprecipitation method using a mixed aqueous solution of zirconium oxychloride and aluminum nitrate solution followed by adding an aqueous ammonia solution. Characterization of prepared catalysts was performed by using Fourier transform infrared, X-ray diffraction, and differential scanning calorimetry and by measuring surface area. No diffraction line of nickel sulfate was observed up to 20 wt%, indicating good dispersion of nickel sulfate on the surface of Al 2 O 3 -ZrO 2 . The addition of nickel sulfate (or Al 2 O 3 ) to ZrO 2 shifted the phase transition of ZrO 2 from amorphous to tetragonal to higher temperature because of the interaction between nickel sulfate (or Al 2 O 3 ) and ZrO 2 . 10-NiSO 4 /Al 2 O 3 -ZrO 2 containing 10 wt% NiSO 4 and 5 mol% Al 2 O 3 was calcined at 973 K and exhibited maximum catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation. The catalytic activities for both reactions were correlated with the acidity of catalysts measured by the ammonia chemisorption method. The addition of Al 2 O 3 up to 5 mol% gradually enhanced the acidity, thermal property, and catalytic activities of NiSO 4 /Al 2 O 3 -ZrO 2 due to the interaction between Al 2 O 3 and ZrO 2 .

Characterization of NiO-TiO2Modified with WO3and Catalytic Activity for Acid Catalysis

A series of <TEX>$NiO-TiO_2$</TEX>/<TEX>$WO_3$</TEX> catalysts was prepared by drying powdered <TEX>$Ni(OH)_2-Ti(OH)_4$</TEX> with ammonium metatungstate aqueous solution, followed by calcining in air at high temperature. Characterization of prepared catalysts was performed by using FTIR, Raman, XPS, XRD, and DSC and by measuring surface area. Upon the addition of tungsten oxide to titania up to 25 wt%, the specific surface area and acidity of catalysts increased in proportion to the tungsten oxide content due to the interaction between tungsten oxide and titania. Since the -<TEX>$TiO_2$</TEX>/stabilizes the tungsten oxide species, for the samples equal to or less than 25 wt%, tungsten oxide was well dispersed on the surface of titania, but for the samples containing above 25 wt%, the triclinic phase of <TEX>$WO_3$</TEX> was observed at calcination temperature above 400 <TEX>$^{\circ}C$</TEX>. The catalytic activities of 10-NiO-<TEX>$TiO_2$</TEX>/<TEX>$WO_3$</TEX> for 2-propanol dehydration and cumene dealkylation were correlated with the acidity of catalysts measured by ammonia chemisorption method. NiO may attract reactants and enhance the local concentration of reactants near the acid sites, consequently showing the increased catalytic activities.

Acidic properties of nickel sulfate supported on TiO 2–ZrO 2 and catalytic activity for acid catalysis

A series of catalysts, NiSO 4/TiO 2-ZrO 2, was prepared by the impregnation method using an aqueous solution of nickel sulfate. Calcination at 300–600 °C of co-precipitated Ti(OH) 4–Zr(OH) 4 resulted in the formation of an amorphous phase and further heating at 700 °C and above resulted in the formation of crystalline ZrTiO 4 compound. For NiSO 4/TiO 2-ZrO 2 sample, no diffraction line of nickel sulfate was observed up to 30 wt.%, indicating good dispersion of nickel sulfate on the surface of TiO 2–ZrO 2. The addition of nickel sulfate to TiO 2–ZrO 2 shifted the phase transition of ZrTiO 4 from amorphous to orthorhombic to higher temperature because of the interaction between nickel sulfate and ZrTiO 4, and the acid amount of NiSO 4/TiO 2-ZrO 2 increased in proportion to the nickel sulfate content up to 20 wt.% of NiSO 4. The high catalytic activity of NiSO 4/TiO 2-ZrO 2 was related to the increases of acid amount and acid strength due to the addition of NiSO 4. The catalytic activities for both reactions, 2-propanol dehydration and cumene dealkylation, were correlated with the acid amounts of catalysts measured by on ammonia chemisorption method. The asymmetric stretching frequency of the SO bonds for NiSO 4/TiO 2-ZrO 2 samples was related to the acidic properties and to the catalytic activity for acid catalysis. That is, the higher the frequency, the larger the acid amount and catalytic activities for 2-propanol dehydration and cumene dealkylation.

Physicochemical and catalytic characterization of non-hydrothermally synthesized Mg-, Ni- and Mg–Ni-saponite-like materials

Saponite-like materials with Mg 2+ or Ni 2+ ions and their mixture in the octahedral sheet were non-hydrothermally synthesized. Their protonic forms were prepared through deammoniation or by treatment with HCl. The products were characterized by physical methods, gas-phase adsorption of amines and the catalytic transformation of 2-propanol and cumene via pulse and flow methods. The materials have a `house-of-card' texture composed of platelets with small lateral dimensions and exhibit a high surface area and pore volume. Subsequent deammoniation resulted in the formation of non-framework Ni 2+ and possibly Mg 2+ ions. Mg-saponite, prepared in this way, shows predominantly non-framework species formed by tetrahedrally coordinated Al 3+ ions whereas its acid-treated counterpart contains Al 3+ in both framework and non-framework positions. Deammoniated Ni-saponite exhibits a peculiar catalytic behaviour, which manifests itself in the fact that the activity in the 2-propanol decomposition in a pulse experiment is low while under flow conditions it becomes the most active. This is ascribed to generation during the reaction of new acidic centres due to the dissociative adsorption of produced water on site pairs formed by coordinatively unsaturated non-framework Ni 2+ and framework oxygen ions. Cumene conversion tests confirm this explanation. The high activity and stability of acid-treated Mg-saponite in cumene dealkylation underlines its potential use for high-temperature acid-catalyzed reactions. The Brønsted acidity of the saponite-like materials is related to their layer charge, cation exchange capacity and diminished with increasing Ni content, whereas the Lewis acidity increased. Both the gas-phase amine chemisorption and catalytic tests provide the same order of protonic acidity: Mg > MgNi > Ni. The origin of the acidic sites from deammoniation or HCl treatment is discussed.

A correlation between Hammett acidity of catalysts and their activity in temperature-programmed reaction of cumene dealkylation

On the basis of TPR spectra of cumene adsorbed on oxide catalysts, the relationship between Hammett acidity and reciprocal benzene formation temperature (H0 = 32.50 − 18.37 х103/Tm) has been found. Using this relationship, it is possible to estimate a value of H0 for oxide materials in an interval of −5.6 < H0 < −16. The correlation between acidic strength of B-sites and rate constants of heterogeneous catalytic reactions is discussed.

Spectroscopic Studies on ZrO2Modified with MoO3and Activity for Acid Catalysis

Zirconia modified with MoO 3 was prepared by impregnation of powdered Zr(OH) 4 with ammonium heptamolybdate aqueous solution followed by calcining in air at high temperature. Spectroscopic studies on prepared catalysts were performed by using FTIR, Raman, XRD, and DSC and by measuring surface area. Upon the addition of molybdenum oxide to zirconia up to 15 wt%, the specific surface area increased in proportion to the molybdate oxide content, while acidity measured by irreversible chemisorption of ammonia exhibited a maximum value at 3 wt% of MoO 3 . Since the ZrO 2 stabilizes the molybdenum oxide species, for the samples equal to or less than 30 wt%, molybdenum oxide was well dispersed on the surface of zirconia and no phase of crystalline MoO 3 was observed at any calcination temperature above 400 °C. The catalytic activities for cumene dealkylation were roughly correlated with the acidity of catalysts measured by ammonia chemisorption method, while the catalytic activities for 2-propanol dehydration were not correlated with the acidity because weak acid sites are necessary for the reaction.