Reaction Of 1-hexene Research Articles

Raman spectroscopic investigation of phase changes and reactivity of 1-pentadecene under high-pressure and high-temperature conditions.

The phase changes and reactivity of 1-pentadecene (C15H30) were investigated using Raman spectroscopy under high-pressure and high-temperature conditions using diamond anvil cells. At room temperature, the phase changes from liquid phase to solid phase I, and solid phase I to solid phase II were observed at 0.3GPa and 4.1GPa, respectively. Another phase change to form phase III progressed at approximately 10GPa, and a partial irreversible chemical reaction was observed after decompression from 15.7GPa. Under high-pressure and high-temperature conditions, the irreversible chemical reaction extensively progressed from the solid phase at 180°C, 1.8GPa, and at 210°C, 5.4GPa. The selective reduction of the Raman peak intensities corresponding to sp2 carbon indicated the progression of an addition reaction similar to that observed in the 1-hexene reaction. A new CC stretching mode appeared, which was attributed to the non-terminal CC bond and was more evident at higher pressures. As the chemical reaction progressed from the liquid phase, a gradual reduction of the CC stretching mode peak was observed upon increasing the temperature at approximately 1.0GPa, indicating the occurrence of a partial chemical reaction.

Novel titanium-containing precursors for the fabrication of hierarchical TS-1 and the enhanced catalytic performance for olefins

Hierarchical TS-1 zeolites with high catalytic activities toward 1-hexene epoxidation were successfully synthesized by using novel titanium-containing precursors. The precursors were prepared by o/m/p-dihydroxybenzene with tetrabutyl titanate, which not only promote the uniform distribution of titanium sources and reduce the aggregation of Ti species, but also contribute to regulating the coordination state of Ti species and increasing the frameworks Ti contents. TS-m/p-DHB-48h zeolites display excellent catalytic performance in the epoxidation reaction of 1-hexene, and the conversion improved by 41.9 % and 34.7 %, respectively. The hierarchical zeolites also exhibit superior 1,2-epoxyhexane selectivity, which will greatly improve the efficiency of industrial production.

MCM-22 zeolite-based system to produce jet fuel from the 1-hexene oligomerization

The oligomerization of light olefins is an alternative for generating clean liquid fuels. In this study, the MCM-22 zeolite featuring a partially disordered layered structure with framework combined 10 membered ring (10 MR) was discussed for 1-hexene oligomerization. MCM-22 and Y zeolite were compared to investigate the influences of the framework and acidity strength on the activity and yield in the 1-hexene oligomerization. The results indicated that the MCM-22 zeolite was an efficient catalyst for oligomerization compared to Y zeolite. The MCM-22 zeolite was characterized in detail by NMR, Py-FTIR, and TG analyses. The catalytic performance and deactivation properties of MCM-22 zeolite in the oligomerization reaction of 1-hexene were investigated. Structure–activity relationships were established through the kinetic study. Although the density of strong acid sites was essential for the oligomerization of 1-hexene, the presence of low pressure was also necessary for the formation of dimers. Thus, MCM-22 zeolite demonstrates a substantial improvement in initial conversion and catalyst lifespan for 1-hexene oligomerization.

Esterification of 1-hexene and acetic acid using resin-supported phosphotungstic acid catalysts

As an atom economy technology, the direct esterification reaction of olefins plays a significant role in the production of organic esters. In this work, a series of resin-supported HPW catalysts were prepared using D101, D152, RM027, and A15 as the carriers, and they were used to prepare 1-methylpentyl acetate by the esterification of 1-hexene and acetic acid. The composition, structure, morphology, acid content, and other parameters of catalysts were characterized. In the esterification reaction, the activity order of catalysts is as follows: 20.0%HPW/A15 > 20.0%HPW/D101 > 20.0%HPW/D152 > 20.0%HPW/RM027. It depends on the acid strength of the carrier, the interaction between the carrier and HPW, and the HPW content. Moreover, it can be concluded that the weak acid resin carrier is completely inactive for the esterification reaction of 1-hexene, and the ratio of acetic acid to 1-hexene has a significant influence on the product selectivity. When n (acetic acid)/n (1-hexene) = 2, the optimum 1-methylpentyl acetate selectivity is 38.2%. Results of repeated experiments confirm that the stability of the active constituent is related to the type of functional groups on the carrier. Graphical Abstracts. 1-Methylpentyl acetate was successfully prepared by the direct esterification of 1-hexene and acetic acid using resin-supported HPW catalysts. The catalytic activity depends on the HPW content, the acid strength of the resin, and the interaction between HPW with the carrier, while the stability of the active constituent is related to the type of functional groups on the carriers.

Application of liquid-phase plasma for the production of hydrogen and carbon from the plasma-induced cracking of liquid hydrocarbons

A study was conducted on the decomposition reaction of liquid hydrocarbons induced by liquid plasma and photocatalyst. This study is to obtain useful resources by recycling waste liquid-hydrocarbons. Titanium dioxide and TiO2-doped with a metal (and nitrogen atoms) were used as photocatalysts individually in the study. First, H2 and carbon were simultaneously produced in the decomposition reaction of liquid hexane and benzene induced by liquid plasma. Notably, only H2 was obtained as a gaseous product, and no carbon dioxide was produced in this reaction. However, when photocatalyst was injected into this decomposition, the corresponding reactivity improved. In particular, the amount of H2 and carbon produced increased in the order of: the amount of H2 and carbon produced with N/Ni/TiO2 > Ni/TiO2 > TiO2 photocatalyst, respectively, when the photocatalyst was added in an equal amount to the reactant of the decomposition. The highest carbon yield and hydrogen evolution under these experimental conditions were about 1 %/(g∙h) and about 180 L/(g∙h), respectively. This order is because the strong visible light generated by liquid plasma discharge improved the photoreactivity of the N/Ni/TiO2 photocatalyst that has a high sensitivity to visible light and narrow band gap. Carbon particles produced from the decomposition reaction of liquid hexane and benzene, respectively, induced by liquid plasma and photocatalyst were small and uniform, with a size of 10 nm or less. In addition, the BET surface area of the carbon produced in this reaction was greater than 500 m2/g, and the properties of the carbon particles were almost the same regardless of the lapse of reaction time. Hence, this decomposition reaction of liquid hexane and benzene, respectively, induced by liquid plasma and photocatalyst was judged to be forming an efficient technology that can simultaneously obtain high-purity hydrogen energy and useful basic materials from liquid hydrocarbons.

Acyl-Nω-methylserotonins and Branched-chain Acylserotonins in Lemon and Other Citrus Seeds-New Lipids with Antioxidant Properties and Potential Pharmacological Applications.

We have found 15 previously unknown compounds in seeds of lemon and other citrus species, such as tangerine, grapefruit and pomelo. The structure of these compounds was characterized by HR–MS spectrometry, fluorescence spectroscopy and chemical synthesis. These compounds were predominantly long-chain (C20–C25), saturated acyl-Nω-methylserotonins with the main contribution of C22 and C24 homologues, usually accounting for about 40% and 30% of all acylserotonins, respectively. The other, previously undescribed, minor compounds were branched-chain acylserotonins, as well as normal-chain acylserotonins, recently found in baobab seed oil. Within the seed, acylserotonins were found nearly exclusively in the inner seed coat, where probably their biosynthesis proceeds. On the other hand, lemon seedlings contained only trace amounts of these compounds that were not found in adult leaves. The compounds identified in the present studies were shown to have antioxidant properties in vitro, using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. In the investigated reaction in hexane, Me-C22 and Me-C24-serotonins were less active than n-C22 and n-C24-serotonins and δ-tocopherol, while branched-chain acylserotonins (iso-C21 and -C25) showed higher antioxidant activity than all the normal-chain compounds. On the other hand, all these compounds showed a similar but considerably lower antioxidant activity in acetonitrile than in hexane.

Zinc Ammonio-dodecaborates: Synthesis, Lewis Acid Strength, and Reactivity.

Two series of zinc salts, [EtZn][A] and Zn[A]2, with weakly coordinating anions [A]- as counterions have been prepared, and their activities as catalysts for hydrosilylation reactions of 1-hexene, benzophenone, and acetophenone have been investigated. The counterions and per- and partially chlorinated 1-ammonio-closo-dodecaborate anions [Me3NB12Cl11]- [1]-, [Pr3NB12H5Cl6]- [2]-, [Bu3NB12H4Cl7]- [3]-, and [Hex3NB12H5Cl6]- [4]- were chosen as potential and more readily available alternatives to carborate anions such as [CHB11Cl11]- and [HexCB11Cl11]-. The basicity of anion [4]- was determined as being close to that of the triflimide anion [N(SO2CF3)2]-, and the fluoride ion affinities (FIAs) of compounds [EtZn][2] and Zn[2]2 are lower than those of the Lewis acids B(C6F5)3 and Zn[HexCB11Cl11]2. The higher anion basicity and the resulting lower Lewis acidity of the zinc centers result in low activity in 1-hexene hydrosilylation catalysis and only moderate activity in the hydrosilylation catalysis of benzophenone and acetophenone.

Brønsted acid properties of hydrodesulfuriaztion catalysts for minimizing the loss of octane number: A DFT and microkinetic study

In order to reduce the loss of octane number during HDS process by enhancing the isomerization ability of HDS catalysts, the catalysis performance of 1-hexene isomerization on different introduced Brønsted acid are studied based on density functional theory (DFT) and microkinetic method. The influence of acid strength and acid density on the adsorption and reaction of 1-hexene are investigated. There is obviously weaker adsorption strength of thiophene (the representation of sulfide in fluid catalytic cracking gasoline) than 1-hexene on Brønsted acid, which indicates thiophene hardly affect the 1-hexene isomerization process. The reaction rate of 1-hexene isomerization on strong Brønsted acid (HZSM-5/Al zeolite) is about 10 4 times higher than that on weak Brønsted acid (HZSM-5/B zeolite). The increasing of Brønsted acid density would bring the slight reduction of acid strength, which makes the 1-hexene isomerization reaction rate is slightly decreased, and the reaction rate on HZSM-5/2Al drops to about 76% of that on HZSM-5/Al. Through comparison, it is found that the reaction rate of 1-hexene isomerization at the strong Brønsted acid reaction center is about 10 5 times that of 1-hexene hydrogenation saturation reaction rate at previous reported sulfur vacancy. Thus, it could be theoretically clarified that the introduction of strong Brønsted acid active centers in the support of HDS catalysts is beneficial to the isomerization of n-olefins, which providing the theoretical guidance to design the catalysts with minimizing octane number loss during the HDS process of FCC gasoline. • Increasing B acid density leads to the reduction of B acid strength. • The rate of isomerization on HZSM-5/Al zeolite is about 10 4 times higher than that on HZSM-5/B zeolite. • Increasing B acid density slightly reduces the 1-hexene isomerization rate. • Introduction of strong B acid site in the HDS catalysts is beneficial to maintain octane number.

Complejos (η6-Arene)-tricarbonylchromium(0) complexes used in olefin hydroformylation reaction with syngas

Aldehydes are compounds with a great scientific interest in its chemical applications, especially to consider a raw material in many industrially and process for manufacturing secondary products, such as, solvents, biodegradable detergents, pharmaceuticals, surfactants, lubricants, other. In this paper we describe the use of commercial chromium carbonyl: [Cr(CO)6] (1), [Cr(CO)3(η6-C6H6)](2a), [Cr(CO)3(η6-C6H5CH3)] (2b), [Cr(CO)3(η6-C8H8O2)] (2c) y [Cr(CO)3(η6-C7H8)] (3), as catalytic precursors in hydroformylation reactions of 1-hexene and cyclohexene with syngas CO/H2 and CO2/H2 in homogeneous phase. In all cases, the reactions conditions (temperature, pressure, CO/H2 ratio, solvents, substrate/catalyst ratio) were optimized and additionally, the catalytic activity was studied employing excess ligands condition or mercury test to verify the homogeneity in the catalytic system. Under optimal conditions, a high percent yield and good selectivity for linear versus branched aldehydes, and for the CO2/H2 system, all the catalysts showed moderate conversion towards linear, branched aldehydes and alcohols with and without NaCl.

Synthesis of hierarchically porous zeolite TS-1 with small crystal size and its performance of 1-hexene epoxidation reaction

TS-1 is a typical microporous zeolite, which is hindering the timely diffusion of reaction products and is likely to cause secondary side reactions in heterogeneous catalytic reaction due to the micropore size. However, zeolite TS-1 with hierarchical pores of micropores and mesoporous/macropores can solve this problem to a great extent. In view of this, hierarchical zeolite TS-1 is synthesized by using tetrapropylammonium hydroxide (TPAOH) as structure directing agent and polyacrylamide (PAM) as a hierarchical pore-directing template. The texture property of hierarchical TS-1 can be optimized by changing the amount of PAM in the synthesis gel. With the increase of PAM content, the pore volume and specific surface area of the hierarchical zeolite TS-1 increases. Compared with the conventional TS-1, the hierarchical TS-1 samples have obvious pore size distribution in the range of 20–80 nm. It is interesting that the particle size of TS-1 decreases after adding PAM. When the hierarchical TS-1 is applied to the epoxidation reaction of 1-hexene with H 2 O 2 , the selectivity of the desired product 1,2-epoxyhexane is significantly increased. • Hierarchical zeolite TS-1 with small crystal size has been synthesized by using PAM as template. • The texture property of hierarchical TS-1 can be controlled by changing the amount of PAM. • The selectivity of 1,2-epoxyhexane was greatly improved in 1-hexene epoxidation with H 2 O 2 catalyzed by hierarchical TS-1.

Effect of ammonium salt on the distribution of titanium species in the synthesis of TS-1 zeolites

Titanium silicalite (TS-1) zeolites with different distribution of Ti species were synthesized through altering different amounts of (NH4)2SO4 as crystallization-mediating agent. The distribution of titanium species of TS-1-X samples (X represents the molar ratio of (NH4)2SO4 to SiO2) was systematically investigated via ICP-AES, FT-IR, UV-vis, UV-Raman and other techniques. The TS-1-X zeolite samples were applied in the epoxidation of 1-hexene reaction. It was found that the appropriate amount of ammonium salt not only facilitated the enrichment of titanium species from liquid phase to solid phase and promoted the incorporation of Ti into the MFI skeleton, but also resulted in the formation of uniformly small TS-1 crystals due to the inhibition of rapid growth of crystals. However, much more amounts of (NH4)2SO4 led to the formation of extra-framework Ti, including anatase TiO2 and amorphous Ti species. Meanwhile it promoted the rapid growth of grain resulting in larger TS-1 crystals. Ti-rich TS-1 sample synthesized with molar ratio of (NH4)2SO4 to SiO2 of 0.2 exhibited higher conversion of 1-hexene (42%) and effective utilization of H2O2 (81.8%). In addition, the effect of ammonium salt's composition on the properties of TS-1 was investigated by experiments and characterizations. It was found that ammonium salt could regulate the process of crystallization through its own anion and changing pH of the synthesis gel.

Synthesis of a Ni Complex Chelated by a [2.2]Paracyclophane-Functionalized Diimine Ligand and Its Catalytic Activity for Olefin Oligomerization.

A diimine ligand having two [2.2]paracyclophanyl substituents at the N atoms (L1) was prepared from the reaction of amino[2.2]paracyclophane with acenaphtenequinone. The ligand reacts with NiBr2(dme) (dme: 1,2-dimethoxyethane) to form the dibromonickel complex with (R,R) and (S,S) configuration, NiBr2(L1). The structure of the complex was confirmed by X-ray crystallography. NiBr2(L1) catalyzes oligomerization of ethylene in the presence of methylaluminoxane (MAO) co-catalyst at 10–50 °C to form a mixture of 1- and 2-butenes after 3 h. The reactions for 6 h and 8 h at 25 °C causes further increase of 2-butene formed via isomerization of 1-butene and formation of hexenes. Reaction of 1-hexene catalyzed by NiBr2(L1)–MAO produces 2-hexene via isomerization and C12 and C18 hydrocarbons via oligomerization. Consumption of 1-hexene of the reaction obeys first-order kinetics. The kinetic parameters were obtained to be ΔG‡ = 93.6 kJ mol−1, ΔH‡ = 63.0 kJ mol−1, and ΔS‡ = −112 J mol−1deg−1. NiBr2(L1) catalyzes co-dimerization of ethylene and 1-hexene to form C8 hydrocarbons with higher rate and selectivity than the tetramerization of ethylene.

Activation of C–H bonds of normal alkanes in sulfuric acid solutions of Mn(III)/Mn(II)

One of the most important directions of establishing the mechanisms of activation of C–H bonds, both in saturated and aromatic hydrocarbons in aqueous and sulfuric acid solutions of oxidants, metal complexes and radicals, is to study the kinetics of reactions and the influence of temperature, environment, nature of reagents, etc. The study of mechanisms is important for the development of technologies for processing hydrocarbons into products with high added value. In this work, to determine the nature of limiting stages and mechanisms of reactions of one group of saturated hydrocarbons, normal alkanes, we use the dependences of substrate selectivity (relative rate constants) on their characteristics: ionization potentials, energy and number of primary and secondary C–H bonds. To determine the nature of the limiting stages of reactions of normal alkanes, the correlations between the logarithms of substrate selectivity of alkanes reactions in H2SO4 solutions with one of the most active manganese(III) ions and molecule properties or C–H bond type were studied by the method of correlation analysis. Comparison of the obtained results with quantum-chemically calculated enthalpy changes of different possible variants of the course of this elementary reaction allowed to clarify the mechanism and propose tests to perform the mechanism of the slow limiting stage. It is shown that for alkanes (ethane, pentane, hexane, heptane, octane) the linear dependence with the ionization potential is most accurately performed, the least accurate is the correlation with the number of secondary C–H bonds, which indicates the electron abstraction in the slow limiting stage. For the shorter pentane – octane series, correlation dependences on both the number of secondary C–H bonds and the ionization potentials are performed with almost equal accuracy, which makes it impossible to establish the nature of the slow stage. The results of quantum-chemical calculations of hexane reactions in Mn(III)/Mn(II)–H2SO4 solutions showed that the most favorable are the electron abstraction by manganese(III) and subsequent proton transfer or homolysis of the C–H bond under the action of bisulfate radical, which is likely formed in the oxidation of sulfuric acid by manganese(III).

Polyvinyl alcohol templated synthese of hierarchical SAPO-11

This work reports that the polyvinyl alcohol successfully templates the intracrystal mesoporous structure of hierarchical SAPO-11 molecular sieves. The structures of prepared hierarchical SAPO-11 materials and a conventional SAPO-11 simultaneously synthesized are characterized by X-ray diffraction, N2 adsorption/desorption, scanning electron microscopy and high resolution transmission electron microscopy. The characterizations demonstrate that this synthesized hierarchical SAPO-11 possesses a mesopore structure with a much regular pore size distribution. Importantly, these mesopores are intracrystal but not intercrystal. The bifuntional isomerization catalyst with this hierarchical SAPO-11 as support shows a high selectivity in hydroisomerization reaction of hexane, evidencing that the catalytic selectivity is improved by introduction of mesopore structure into the SAPO-11 crystal. The templating mechanism of polyvinyl alcohol in formation of mesopores is well discussed at the ending. This work provides a potential template to prepare hierarchical catalyst materials.

Study of catalytic activity on hydrogenation reactions of 1-hexene by RuCl2(Py)4 and RuCl2(DMSO)2(NC5H4CO2Na)2 supported on functionalized MCM-48

Two hybrid catalysts were synthesized: (I) from dichlorotetrakis(pyridine)ruthenium(II) [RuCl2(Py)4] and (II) cisdichlorobis (dimetylsulfoxide)bis(sodiumnicotinate)ruthenium(II) [RuCl2(DMSO)2(NC5H4CO2Na)2] supported on MCM-48 functionalized, using post-synthesis method with [3-(2-aminoethylamino)propyl]trimethoxysilane and triethoxymethylsilane as anchoring and passivation ligands, respectively. The catalysts were characterized using infrared spectroscopy (FTIR), mass spectrometry (MS), thermogravimetric analysis (TGA-DSC), nitrogen adsorptiondesorption, scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX). Studies of catalytic activity were carried out in hydrogenation reactions and the reactions parameters (time, temperature, substrate/catalyst ratio and H2 pressure) were optimized. Supported complexes are chemiospecific to produce hexane and showed 100% conversion under optimal conditions. Catalysts were reused up to five times with a decrease about 30% of catalytic activity.

Oligomerization reactions of 1-hexene with metallocene catalysts: Detailed data on reaction chemistry and kinetics

The paper describes oligomerization reactions of 1-hexene with catalysts derived from three metallocene complexes, Cp2ZrCl2, (CH3-Cp)2ZrCl2 and (n-C4H9-Cp)2ZrCl2, and two types of methylalumoxane. Gas chromatographic analysis of oligomers provides detailed information on the chemical structure of individual oligomer molecules, the chemical mechanism and kinetics of early stages of the oligomerization reactions.

Highly active mono and bis-ligated iminopyridyl nickel catalysts for 1-hexene reactions

A series of mono- and bis-ligated iminopyridyl Ni(II) catalysts were prepared and characterized. The activation of these Ni(II) complexes with methylaluminoxane generated the toluene alkylation by the hexene monomers, dimers and trimmers with high activities using only 1-hexene as feedstock. Most interestingly, The bis-ligated iminopyridyl Ni(II) catalysts demonstrated much better thermal stability and showed higher activities at high temperature than the mono-ligated iminopyridyl Ni(II) catalysts. The mono-ligated and bis-ligated iminopyridyl Ni(II) catalysts also influenced the products distribution.

Aqueous-biphasic hydroformylation of 1-hexene catalyzed by the complex HCo(CO)[P(o-C6H4SO3Na)

The water soluble cobalt complex HCo(CO)[P(o-C6H4SO-3Na)]3 was used as catalyst precursor for the biphasic aqueous hydroformylation of 1-hexene. The complex was synthesized by reductive carbonylation of CoCl2.6H2O in the presence of o-TPPTS ([P(o-C6H4SO3Na)]3) under nitrogen atmosphere and characterized by FTIR, 1H NMR and 31P {1H} NMR, 13C NMR, DEPT – 135, COSY, HSQC, MS (ESI). The catalytic activity of the complex in the biphasic hydroformylation reaction of 1-hexene was evaluated under moderate reaction conditions. The pressure and temperature were varied from 4137 – 7584 kPa (600-1100 psi) of syngas and from 353 – 383 K (80 – 110 °C), respectively. The 1-hexene concentration was varied from 0.021-0,11M and the catalyst from 4x10-4 - 1.1x10-3 M. The best conversion at 363 K and 7584 kPa and 7.5 h was 62% with selectivity towards aldehydes (heptanal and 2-methyl-hexanal) of 66% to with l/b ratio of 2.6. The recycling of the catalytic precursor after four successive times, did not show any loss on the activity, having selectivity towards aldehyde up to 60%.

Two-fold interpenetrating btc based cobaltous coordination polymer: A promising catalyst for solvent free oxidation of 1-hexene

This work describes the synthesis of a new 2-D coordination polymer (CP), [Co3(btc)2(dmp)8]n (btc = 1,3,5-benzenetricarboxylate and dmp = 3,5-dimethylpyrazole) and its catalytic activity towards the oxidation reaction of 1-hexene to form oxygenated compounds under solvent free condition. Structural analysis reveals that Co(II) cations in this polymeric compound are linked by btc3- anions with alternate tetrahedral/octahedral coordination forming a two-fold interpenetrated 3-connected hcb underlying net. Electronic spectrum of the cobaltous polymer has been calculated using TDDFT/B3LYP method for making the appropriate assignments of electronic transitions. Catalytic results show good conversions of the starting material to oxygenated products with high selectivities for 1,2-epoxyhexane and 1-hexanal.

Creation of surface catalytic active sites on tungsten oxide(s) and a study of the catalytic behavior in isopropanol and 1-hexene reactions

Catalytically active sites formed after the partial reduction of tungsten trioxide using hydrogen gas at different reduction temperatures were studied by measuring the catalytic activity of the system in reactions with isopropanol and 1-hexene. These reactions were activated by either metal, acid, or acid-metal (bifunctional) functionalities. The identification of the chemical composition of the specific catalytic active sites was achieved by in situ characterization of the system using the XPS-UPS surface technique carried out at the same time as the experimental catalytic measurements. Tungsten trioxide species possess acidic character before applying the reduction treatment. However, when WO3 is reduced to WO2 a metallic character is obtained, imparting the delocalization of π electrons over the tungsten atoms located along the C-axis of the deformed rutile structure of WO2. Changes in the spin–orbit coupling of W(4f) and the structure of the density of states (DOS) at the Fermi level confirmed the development of metallic properties. The bonding of active H, obtained from the dissociation of molecular hydrogen during the reduction procedure, to the oxygen surface sites results in a build-up of Bronsted W-OH acid functionalities. Therefore, a metal–acid bifunctional catalyst is obtained on the surface of the sample in the form of WO2−x(OH)y/TiO2. Titanium dioxide is utilized as a support to mechanically strengthen the catalyst and enhance the surface area.