Isobutene trimer

Catalytic test. The catalytic behavior was evaluated for the gas phase isobutene trimerization reaction using a fixed bed reactor, with dimensions of 2 cm of diameter and 55 cm of length respectively. The operation conditions and evaluation procedure were as follows the catalyst was activated at 400°C in flowing air (1 ml/s) during 8 hours. After the activation treatment, temperature was lowered to 40°C and a mixture of isobutane/isobutene 72 28 w/w was feed. The GHSV value was varied to 8, 16, 32 and 64 h respectively. The average time of reaction was 11 h. The time of reactor stabilization after the beginning of the catalytic evaluation was 2 h. 

Isobutanethiol. See 2-Methyl-1-propanethiol Isobutanoic acid. See Isobutyric acid isobutanol HP, Isobutanol. See Isobutyl alcohol Isobutanolamine Isobutanol-2 amine. See Aminomethyl propanol Isobutene. See Isobutylene Isobutene homopolymer Isobutene polymer. See Polyisobutene Isobutene trimer. See Triisobutylene Isobutenol. See Methallyl alcohol Isobutenyl chloride. See 3-Chloro-2-methylpropene... 

Synonyms Isobutene trimer Propene, 2-methyl-, trimer... 

An alternative method for separating the hutenes is hy extracting isobutene (due to its higher reactivity) in cold sulfuric acid, which polymerizes it to di- and triisohutylene. The dimer and trimer of isobutene have high octane ratings and are added to the gasoline pool. 

Cold Acid A process for polymerizing isobutene, mainly into dimers and trimers, for making high-octane gasoline blending components. It is catalyzed by 60 to 70 percent sulfuric acid at 25 to 35°C. Developed by the Shell Companies. See also Hot Acid. 

In this work, the performance of two green acid catalysts, a Ti02 synthesized by the sol-gel method and sulfated in situ was compared with a traditional NiY zeolite in the trimerization of isobutene. The reaction was carried out at mild conditions atmospheric pressure and 40°C of temperature. The results obtained in the catalytic evaluation showed higher conversion and stability as well as a better selectivity to tri-isobutylene for the sulfated titania catalyst with respect to the NiY zeolite. 

Several authors suggest the use of the NiY zeolite and Ni/Si-Al as catalysts for the oligomerization of isobutene [7-9]. The aim of this work is to compare the performance of two different green acid catalysts in situ sulfated Ti02 synthesized by the sol-gel method [22] with NiY zeolite, in the gas phase trimerization of isobutene at mild pressure and temperature conditions atmospheric pressure and 40°C, in terms of activity, selectivity and stability. 

Gas Phase Trimerization of Isobutene Using Green Catalysts 61... 

Isobutylene is more reactive than n-butene and has several industrial uses. It undergoes dimerization and trimerization reactions when heated in the presence of sulfuric acid. Isobutylene dimer and trimers are use for alkylation. Polymerization of isobutene produces polyisobutenes. Polyisobutenes tend to be soft and tacky, and do not set completely when used. This makes polyisobutenes ideal for caulking, sealing, adhesive, and lubricant applications. Butyl rubber is a co-polymer of isobutylene and isoprene containing 98% isobutene and 2% isoprene. 

The absorption step occurs at a temperature of about 68° to 104° F. and whatever pressure is necessary to maintain the hydrocarbon feed in the liquid phase. When using a 65% acid about 90 to 95% of the isobutene is absorbed. Polymerization takes place at a temperature of 200° to 220° F., producing approximately 75 to 80% dimer, the rest trimer. Thus about 67% of the isobutene in the feed is converted to iso-octenes. 

With trimers, he observed that 75-83 percent of the trimer depolyalky-lated. He rationalized further that dimers could behave similarly this is a moot point, because yields of alkylate from butene monomers and dimers are identical when the alkylate formed during chain termination is considered. It was observed (Phillips Petroleum Comp>any, 1946) that Isobutene-butene copolymer yielded alkylate identical to that from the monomers. 

Artemisinin has been converted in two steps into the stable trioxane isobutene dimer 41. Reactions at the linking unit leave the trioxane fragments intact and allow the synthesis of a variety of dimers that possess desirable pharmacological properties <03JMC1060>. 10-Bromoalkyl and 10-aminoalkyl derivatives of deoxoartemisinin have been prepared and used to form dimers and a trimer in which artemisinin residues are linked through alkylamide and alkylthio functions <03JMC987>. 

Concerning the possible causes of the premature cessation of polymerisation in most systems characterised by direct initiation, we believe that the accumulation of anions derived from the Lewis acid is the most important sin e factor responsible. We have already discussed the possible reactions giving rise to an increasing concentration of these anions in the case of direct initiation by the neutral Lewis acid. To these must be added the formation of carbenium ions which cannot propa te either because they are sterical-ly hindered, as in the case of isobutene unsaturated dimers and trimers , or because they are too stable to attack the monomer, as in the case of termination by formation of allylic cations. The accumulation of these species is inevitably accompanied an equivalent rise in anion concentration. Whatever the origin(s) of this rise, a higher anion concentration can determine various detrimental effects on the survivd of active species ... 

The main bytproducts of MTBE cracking are dimethyl ether obtained by methanol dehydration, the dimer and trimer of isobutene, and t-butyi alcohol resulting Grom the polymerization and hydration of the olefin. 

Typically these compounds have their origin in alkenes possesssing a single double bond emanating from the petrochemical industry, such as propene, isobutene and their polymers, diisobutene and propene trimer. The uses of ethene to produce 4-ethylphenol and of propene to give 4-hydroxycumene are not reviewed here, reference having been made to the latter in the introductory chapter on the preparation of resorcinol and hydroquinone. 

Silica-alumina-nickel oxide, amorphous to X-rays, with a high ratio of Si02/ AI2O3 was found to be a suitable catalyst for dimerizing isobutene into a- and P-di-isobutene with high selectivity and was also useful for oligomerizing propene to dimers and trimers. ... 

The remaining components are common to many refinery streams, and thus isobutene and w-butenes may be derived from either source. Isobutene is generally recovered from the butadiene-free raffinate by chemical means. For example, by contacting the mixture with 65% sulphuric acid, r-butanol is formed in the acid phase, from which fairly pure isobutene (for butyl rubber ) may be regenerated. Alternatively, the isobutene within the mixed C4 stream may be converted directly to the dimer and trimer by contact with solid acidic catalysts, to viscous polybutenes by treatment with Lewis acid catalysts, or to a /-butyl ether (section 12.9.3). The reported 1993 U.S. production of isobutene was about 500 kt, but this refers only to isolated material (including dehydration of Arco s co-product /-butanol) derivatives possibly consumed 7-8 Mt in the U.S. compared with roughly 2Mt in Europe. 

Isobutene oligomerization is of increasing interest not only for i-butene utilization and separation, which gained considerable attention because of the worldwide trend in fuel reformulation, but also for the production of isobutene oligomers such as trimers. 

Alcantara, R., Alcantara, E., Canoira, L., Franco, M. J., Herrera, M., Navarro, A. (2000). Trimerization of isobutene over Amberlyst-15 catalyst. Reactive and Functional Polymers, 45, 19-27. 

Trimers and higher isobutene oligomers were obtained by C4 fraction oligomerization in the presence of CUSO4 and AICI3, respectively [16]. 

Early studies on isobutene oligomerization have revealed that this olefin dimerizes selectively to give a mixture of 77 and 18 (Eq. (17)) in the presence of an 0x0 acid such as sulfuric and phosphoric acids. However, selective synthesis of isobutene oligomers higher than the trimer has not been possible to date. A detailed... 

Recently we examined the possibility of selectively synthesizing the isobutene tetramer (IB4.) and trimer (IB3) by the reaction of two isobutene dimers (IBj) or isobutene dimer with isobutene (IB), respectively ... 

With vinyl monomers other than isobutene, attempts to prepare selectively trimers or tetramers from linear dimers have been unsuccessful thus far. The linear dimer of styrene (7) was expected to give an unsaturated tetramer 27, when dimerized by an 0x0 acid (Eq. (23)). However, the oligomerization of 1 with CF3SO3H or AcClO in benzene at 50 °C resulted in a mixture of oligomers with cyclic terminals, consisting... 

---