Isobutene Oligomerization Research Articles

Highly efficient trimerization of isobutene over silica supported chloroaluminate ionic liquid using C4 feed

A series of silica, glass and molecular sieves supported chloroaluminate ionic liquids (ILs) were prepared and their catalytic performance on the trimerization of isobutene based on C4 mixture was investigated. Interestingly, it was found that the carrier played a key role in the reaction route. Among these supported catalysts, silica supported chloroaluminate ionic liquid was highly efficient for the trimerization of isobutene. X-ray photoelectron spectroscopy (XPS) and differential scanning calorimetry (DSC) characterizations suggested that the synergy between Al2Cl7− anion and silica induced the catalytic activity for isobutene oligomerization due to the strong interaction between ILs and silanol group. The reaction conditions including loading amount, temperature, reactant concentration, and space velocity for the isobutene oligomerization were optimized. Ultimately, complete conversion of isobutene and 91.4% selectivity of trimers were obtained over the IL/silica (30wt.%) catalyst at mild conditions. Moreover, catalyst stability and deactivation were preliminarily studied.

Oligomerization of Izobutene in the Presence of Ionic Liquid – Based Catalysts

In the petrochemical industry, the C4 stream including isobutene is an important raw material that can be upgraded. Oligomerization of isobutene is a very promising reaction, as the hydrogenation products of dimers and trimers, obtained from isobutene, can be used as gasoline and diesel additives, respectively. In the present paper, our results concerning the use of Bronsted acidic ionic liquids as oligomerization catalysts are presented. The ionic liquids were supported on silica. Most of the solid catalysts were reused several times without loss of activity. By the proper choice of the ionic liquid and reaction conditions, good selectivity towards either C8 or C12+ products could be achieved.

Selective Isobutene Oligomerization by Mesoporous MSU-SBEA Catalysts

Hydrolytically stable mesostructured aluminosilicates assembled from protozeolitic precursors are examined as acid catalysts in the isobutene oligomerization reaction. Steady state conversions as high as 80% at 60 °C are achieved, depending on the isobutene:butane feed composition and space velocity. Most notably, the product selectivity to dimeric C8= and trimeric C12= olefins is readily fine-tuned simply by changing the feed composition. Undesirable high molecular weight oligomers are not produced in any case. The superior catalytic performance of the mesostructured aluminosilicates in comparison to commercial USY and BEA zeolites is clearly established. The improvement in catalytic performance is attributed to a combination of textural and acidic properties, as judged by N2 adsorption and pyridine adsorption studies.

Etherification of glycerol by isobutylene: Tuning the product composition

Etherification of glycerol by isobutylene was conducted in a batch mode using acidic and partially neutralized Amberlyst-15 ionic resin, p-toluenesulfonic acid, silicotungstic acid, cesium salt of silicotungstic acid, and ionic liquid containing sulfonic acid groups. All the catalysts are comparable in terms of the initial rate of glycerol conversion into mono-ether (except cesium salt of heteropolyacid), but differ substantially with respect to the yields of higher ethers of glycerol. Ionic liquid and heteropolyacid are immiscible/insoluble in higher ethers of glycerol. As a result they have unique capability of suppressing the formation of tri-ether during the initial stage of glycerol conversion. Acidic Amberlyst-15 in the form of fine powder has the highest activity per unit weight for glycerol etherification and relatively high activity in isobutene oligomerization. Partial exchange of acidic protons with cations Na +, Ag +, Mg 2+, and Al 3+ decreases the rates of all the processes, but isobutylene oligomerization is suppressed more efficiently. Ag +- and Al 3+-modified Amberlyst demonstrates higher yields of tri-ether and has specific pattern of interaction with gaseous isobutene distinctive to other metal-substituted Amberlysts.

Oligomerization of isobutene with a beta-zeolite membrane: Effect of the acid properties of the catalytic membrane

Isobutene oligomerization was performed using a ceramic membrane with a film of zeolite beta, where three different zeolite molar ratios SiO 2/Al 2O 3 were evaluated. The reaction was studied in a membrane reactor within the 373–423 K temperature range. Analyses of the reaction products suggest a complex pattern of isobutene dimerization and isomerization and the main reaction product was 2,2,4-trimethypentane (2,2,4 TMP) for all catalytic tests conducted.

Preferential oligomerization of isobutene in a mixture of isobutene and 1-butene over sodium-modified 12-tungstosilicic acid supported on silica

Modification of 15 wt% H 4SiW 12O 40/SiO 2 with Na + ions was investigated. Na-modified H 4SiW 12O 40/SiO 2 showed higher selectivity for isobutene oligomerization in the preferential oligomerization of isobutene in an equimolar mixture of isobutene and 1-butene than the unmodified one and the selectivity increased with an increase in the Na + ion content. The highest selectivity (∼97%) was achieved by using Na 3HSiW 12O 40/SiO 2. The activity decreased with an increase in the Na + ion content. Unmodified H 4SiW 12O 40/SiO 2 had two kinds of acid sites with different acid strengths (medium and strong acid sites) on the outermost surface as revealed by temperature-programmed desorption of benzonitrile. However, the strong acid sites were eliminated by modification with alkaline metal cations; for example, Na 3HSiW 12O 40/SiO 2 had a negligible amount of strong acid sites. Thus, we concluded that the absence of strong acid sites on the outermost surface is the reason for the high selectivity. Li 3HSiW 12O 40/SiO 2 and K 3HSiW 12O 40/SiO 2 also exhibited high selectivity for isobutene oligomerization with activities comparable to that of Na 3HSiW 12O 40/SiO 2.

Trimerization of Isobutene Over Solid Acid Catalysts

Oligomerization of isobutene is a very promising reaction not only for the production of isobutene oligomers such as trimers but also for the separation of isobutene from C4 mixtures. Several solid acid catalysts have been applied for the continuous oligomerization of isobutene in liquid phase. This review analyzes the trimerization of isobutene over various solid acid catalysts such as zeolites, oxides (zirconias and titanias) and acid resins. Trimers selectivity increases with increasing isobutene conversion, irrespective of catalysts such as zeolites and acid resins. Very stable operation with high trimers selectivity is accomplished with WOx/ZrO2 catalyst having tetragonal zirconia or various zeolite catalysts with high Lewis acid site-to-Bronsted acid site ratio (LA/BA ratio). For a good performance, acid resins should be macroporous and strong acid (sulphonic acid group) with high acid concentration. Inorganic catalysts are superior to acid resins because the deactivated inorganic materials can be regenerated by simple calcination. The WOx/ZrO2 catalyst may be applied to a commercial process because about several thousand tons of isobutene can be oligomerized per one ton of zirconia catalyst in a catalytic cycle without regeneration. The oligomerization of isobutene may be improved further because the reaction has been started only recently and no research has been done for the optimization of the reaction and catalysts. It is expected to develop a new inorganic catalyst having suitable acidity, LA/BA ratio and phase, etc. by further research. The isobutene trimers, with or without hydrogenation, may be used for various purposes, and the importance of this trimerization reaction will be increased considering the expected surplus of isobutene due to the banned use of methyl-tert-butyl ether.

IMPROVED SELECTIVITY TO C8-OLEFINS FOR ISOBUTENE OLIGOMERIZATION ON NIO-W2O3/Al2O3 CATALYSTS

Isobutene oligomerization on W2O3/Al2O3 and NiO-W2O3/Al2O3 catalysts (20 wt.% W2O3 and 5 wt.% NiO) was studied. The catalysts were prepared by impregnating ammonium tungstanate and nickel nitrate on a γ-alumina sol-gel support. The XRD patterns of the samples calcined at 500°C show the presence of large W2O3 conglomerates on the W2O3/Al2O3 sample and smaller ones on the NiO-W2O3/Al2O3 catalyst. Pyridine-FT-IR absorption spectra study shows a higher acidity on the nickel-containing sample. The isobutene oligomerization was carried out in a gas-phase flow reactor (50°–150°C), and selectivity as high as 100% to the formation of the olefins fraction was obtained. The role of NiO coordinating the π-allyl adsorption of the olefins as well as its role to the high selectivity were discussed.

Oligomerization of isobutene over aluminum chloride-loaded USY zeolite catalysts

Oligomerization of isobutene has been investigated over AlCl3-loaded USY zeolite catalysts in order to produce triisobutenes or remove/separate isobutene from C4 streams. Stable isobutene conversion and high selectivity for trimers and tetramers were attained over the modified zeolite with high ratio of Lewis acid site-to-Bronsted acid site, suggesting that a potential trimerization catalyst can be obtained easily by loading a Lewis acid into an acidic zeolite catalyst. This catalyst can be facially produced by physical mixing and can be easily restored its activity after deactivation by simple calcinations.

Oligomerization of Isobutene Catalyzed by Iron(III) Chloride Ionic Liquids

The oligomerization of isobutene catalyzed by ionic liquids containing FeCl4− and Fe2Cl7− was conducted in an autoclave. The conversion of isobutene was above 83 wt%, and the selectivity of diisobutene plus triisobutene was above 75% when the mole ratio of FeCl3 to [(C2H5)3NH]Cl ranged from 1.2:1 to 2:1. The addition of cuprous chloride to the ionic liquid increased the conversion of isobutene and the selectivity of diisobutene plus triisobutene. The latter reached 90% at the mole ratio of CuCl to [(C2H5)3NH]Cl-1.5FeCl3 of 0.25:1. The reaction pathway of the oligomerization of isobutene catalyzed by iron(III) chloride ionic liquids was explained by the carbonium ion mechanism.

NiO–W 2O 3/Al 2O 3 catalysts for the production of ecological gasoline: Effect of both NiO and the preparation method on the isobutene oligomerization selectivity

The results obtained for the oligomerization of C 4 olefins in order to produce high octane ecological gasoline by using NiO–W 2O 3/Al 2O 3 catalysts prepared by both the wetness impregnation and sol–gel methods, are reported. High selectivity towards C 8 = olefins, avoiding the formation of heavier olefinic products, as well as an excellent stability were reached by means of the NiO–W 2O 3/Al 2O 3 impregnated catalyst. The characterization of the catalysts by XRD, total specific surface area and FTIR pyridine adsorption are also reported.

Preferential oligomerization of isobutene in mixtures of isobutene and 1-butene over 12-tungstosilicic acid supported on silica

Abstract Preferential oligomerization of isobutene in a mixture of isobutene and 1-butene (molar ratio of 1:1) over H 4 SiW 12 O 40 /SiO 2 was investigated with different loadings of H 4 SiW 12 O 40 . The catalytic performance of H 4 SiW 12 O 40 /SiO 2 was compared with those of typical solid acids, such as H-β, SiO 2 -Al 2 O 3 , and SO 4 2− /ZrO 2 . H 4 SiW 12 O 40 /SiO 2 was superior in activity and selectivity for isobutene oligomerization (defined as the fraction of isobutene converted against the total conversion) compared to other catalysts. The activity was sensitive to the H 4 SiW 12 O 40 loading on SiO 2 , reaching a maximum at around 40 wt.%, due to the change in the acid amount of the outermost surface as determined by temperature-programmed desorption of benzonitrile. The selectivity for isobutene oligomerization also changed with the H 4 SiW 12 O 40 loading. The highest selectivity (∼95%) was achieved using 10 wt.% H 4 SiW 12 O 40 /SiO 2 at 293 K, due to the absence of strong acid sites on the outermost surface. In the conversion of linear butene (1- and 2-butene), an induction period occurred when 10 wt.% H 4 SiW 12 O 40 /SiO 2 was used, because linear butene cannot adsorb on the acid sites when isobutene is present in the reaction mixture.

One pot preparation of NiO/ZrO 2 sulfated catalysts and its evaluation for the isobutene oligomerization

The synthesis of NiO/ZrO 2 sulfated catalysts prepared by the one pot method (sol–gel) is reported. Specific surface areas comprised between 52 and 108 m 2/g were obtained. XRD patterns showed the presence of monoclinic and tetragonal zirconia phases. FTIR-pyridine absorption spectra show the presence of Lewis and Brönsted sites in sulfated zirconia but only Lewis sites in nickel zirconia sulfated catalysts. A good correlation between the amount of adsorbed pyridine and the catalytic activity for the isopropanol dehydration was observed. However, an opposite effect was observed for the isobutene oligomerization, where the catalysts with the lower acidity showed the higher activity. The role of Ni +2 diminishing the deactivation rate forming π-allylic bonds with the olefins is discussed.

Effect of Butadiene in Catalytic Trimerization of Isobutene Using Commercial C4Feeds

Catalytic oligomerization of isobutene to produce triisobutenes has been performed over a cation-exchange resin (Amberlyst-35) by using commercial C4 feeds. The catalytic activity in the oligomerization was retained without deactivation up to 90 h of reaction in a simulated reaction feed without butadiene, but its activity was significantly affected by the presence of butadiene in commercial C4 feeds. The isobutene conversion with time-on-stream was significantly decreased in the presence of butadiene, indicating the catalyst deactivation by butadiene. However, the stable activity for trimerization was accomplished when the oligomerization was carried out after eliminating butadiene by hydrogenation of the feeds. This work demonstrates that butadiene plays a role as a catalyst poison on the solid acid catalyst, so that its removal in the reactant feed is essential for practical application of trimerization.

Oligomerization of isobutene over dealuminated Y zeolite catalysts

Abstract Oligomerization of isobutene to produce oligomers such as trimers and tetramers has been investigated over dealuminated Y zeolite catalysts that were obtained by calcination at temperatures in the range of 500–700 °C in the presence of steam. Relatively stable isobutene conversion and high selectivity for trimers and tetramers are attained over a dealuminated Y zeolite by steam-treatment at 600 °C. The observed stable performance with the increased selectivity is attributed to the high concentration of Lewis acid sites. Moreover, a deactivated catalyst can be regenerated easily by simple calcination in air. The present study demonstrates that a steamed zeolite having high concentration of Lewis acid sites, even with decreased crystallinity and porosity, is one of the potential catalysts to exhibit stable and high conversion, high selectivity (for trimers and tetramers) and facile regeneration for the oligomerization of isobutene. However, the contribution of a strong or new acid site for the stable catalysis cannot be ruled out.

Trimerization of Isobutene over Solid Acid Catalysts under Wide Reaction Conditions

Oligomerization of isobutene has been investigated using a few solid acid catalysts in order to produce efficiently triisobutenes that are useful chemical feedstocks for heavy alkylates and neo-acids. Several reaction conditions such as space velocity and isobutene concentration are evaluated, and a few cation exchange resins with various acid capacities were compared in the reaction. High trimers selectivity and high conversion can be obtained over a catalyst containing high acid capacity at low space velocity and relatively low isobutene concentration. The stability of a catalyst for the reaction is high when the acid capacity of the catalyst is high (for example Amberlyst-35).

Trimerization of isobutene over a zeolite beta catalyst

Oligomerization of isobutene has been investigated using several zeolite catalysts to produce triisobutenes that are useful as chemical feedstocks. Stable isobutene conversion and high selectivity for trimers are attained over a beta zeolite with high concentration of Lewis acid sites. Isobutene is quantitatively oligomerized over a beta zeolite with selectivity for trimers > 50 % up to 100 h at a high isobutene WHSV of 10 h −1. Moreover, a deactivated catalyst can be easily regenerated by calcining in flowing air. Zeolite beta's high stability, quantitative conversion, high selectivity, and facile regeneration make it an attractive potential catalyst for isobutene trimerization.

Trimerization of isobutene over zeolite catalysts: Remarkable performance over a ferrierite zeolite

Abstract Oligomerization of isobutene has been investigated using several zeolites in order to produce triisobutenes that are useful chemical feedstocks for heavy alkylates and neo-acids. Stable isobutene conversion and high selectivity for trimers are obtained over a ferrierite zeolite at high temperature and low space velocity. Trimers selectivity increases with increasing isobutene conversion. Isobutene is quantitatively oligomerized over a ferrierite catalyst with selectivity for trimers higher than 60% up to 50 h at high isobutene WHSV of 10 h −1 . Moreover, a deactivated catalyst can be regenerated easily by calcining in flowing air. The ferrierite zeolite is one of the potential catalysts for the isobutene trimerization showing high stability, quantitative conversion, high selectivity and easy regeneration.

Trimerization of isobutene over cation exchange resins: Effect of physical properties of the resins and reaction conditions

Oligomerization of isobutene has been investigated using several cation exchange resins in order to produce triisobutenes that are useful feedstock for heavy alkylates and neo-acids. Trimers selectivity increases with increasing isobutene conversion. High isobutene conversion is obtained at high temperature and low space velocity by using macroporous cation exchange resins that have high concentration of sulfonic acid groups. Under selected conditions (viz., isobutene WHSV: 10 h −1; temperature: 70 °C; catalyst: Amberlyst-35), the isobutene is quantitatively oligomerized with higher than or equal to 70% selectivity for trimers. The wet resin catalysts containing water or ethanol are very stable for the oligomerization up to about 70 h contrary to the gradual decrease in the conversion with dehydrated catalysts.

Surface-appropriate lipophobicity—Application in isobutene oligomerization over Teflon-modified silica-supported 12-silicotungstic acid

A series of silica-supported 12-silicotungstic acid catalysts (H 4SiW 12O 40, abbreviated as HSiW), modified with various loadings of Teflon (HSiW/SiO 2-Teflon), were prepared by an impregnation method. The surface properties of the catalysts were studied by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), BET, infrared (IR) spectroscopy, NH 3-TPD and the Drop Shape Analysis (DSA). SEM results combined with energy-dispersive X-ray (EDX) measurements of HSiW/SiO 2-Teflon revealed that F-compound (Teflon) is effectively coated on the catalyst surface. The contact angles for water and oil of 50 wt% HSiW/SiO 2 and HSiW/SiO 2-Teflon indicate that HSiW/SiO 2-Teflon catalyst enhances not only the surface hydrophobicity but also the surface lipophobicity by means of the addition of Teflon. Silica-supported 12-silicotungstic acid modified with Teflon exhibits higher C 8 = selectivity and longer lifetime than that of silica-supported 12-silicotungstic acid in isobutene oligomerization. Thus, surface-appropriate lipophobicity of catalysts may be effective for decreasing the interaction between coke precursors and the catalyst surface and for removing deposited coke more easily.