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Etherification
Published in Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk, Petroleum Refining, 2019
Mark J. Kaiser, Arno de Klerk, James H. Gary, Glenn E. Hwerk
The reaction network for the etherification of C5 olefins is more complex than that for the reaction of C4 olefins. Of the isoamylenes (methyl butenes), only the olefins where the C=C bond is on a tertiary carbon is reactive for etherification. Thus, 3-methyl-1-butene (3M1B) is unreactive for etherification, despite being a branched olefin. Since this is an acid-catalyzed process, double bond isomerization of 3-methyl-1-butene to 2-methyl-1-butene, or 2-methyl-2-butene, is an advantageous side reaction. Double bond isomerization is not reflected in Figure 34.2, because the etherification reaction shown is with isobutene. Of all the C4 olefin isomers, there is only one branched isomer, isobutene, which makes the reaction network for C4 olefins simpler.
Clean conversion of methanol to high octane components on ZnI2 catalyst
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2020
Weiwei Chen, Rui Zong, Jigang Zhao, Xiaolong Zhou, Chenglie Li
For this purpose, different types of alcohols and olefins, including ethanol, isopropanol, tertbutanol, isopentanol, 2-methyl-2-butene, and 2,3-dimethyl-2-butene, are investigated in this paper. Each of their contents takes 7.5wt% or 25wt% in the feeds, respectively. The results are shown in Figure 1(a and b), indicating all alcohols except ethanol is able to enhance both oil and triptane yields. These results are in line with that reported in the literature (Bercaw et al. 2006). Among these alcohols and olefins, isopentanol is most effective. Yields increased almost 200% for oil products and 88% for triptane, after adding 25% isopenpanol. The products distribution is shown in Figure 2, wherein they are calculated by their carbon number. It is seen that C4 and C7 species are dominant products in gas and oil, respectively, for pure methanol feed. After adding 25% isopropanol, C3 species increases in gas products, while C4 and C5 species increase, respectively, for 25% tertbutanol and isopentanol. The results by GC-MS measurement show propene, isobutene, and 3-methyl-1-butene markedly increase, demonstrating that isopropanol, tertbutanol, and isopentanol are precursors for their corresponding olefins. C5 species and C6 species also increase after adding 2-methyl-2-butene and 2,3-dimethyl-2-butene, respectively.
Can 2-methyl-2-butene and isoprene form clathrate hydrates?
Published in Petroleum Science and Technology, 2018
Kaniki Tumba, Paramespri Naidoo, Amir H. Mohammadi, Deresh Ramjugernath
2-methyl-2-butene and isoprene are valuable chemicals mainly recovered from cracking streams in petroleum refineries. Isoprene is mainly used for the manufacture of synthetic rubber while 2-methyl-2-buteneserves as starting material for many other chemicals (Weitz and Loser 2000). In the presence of other C5 hydrocarbons, these two compounds form close-boiling mixtures which are currently separated by extractive distillation or liquid-liquid extraction. Both techniques require a great amount of energy. Gas hydrate-based separation is generally regarded as a more economic and more environmental friendly alternative to distillation and liquid-liquid extraction. Nevertheless, prior to its use, it must be established whether 2-methyl-2-butene or/and isoprene are hydrate formers. The abilility for either of the two hydrocarbons to form hydrates has not yet been addressed in the literature. In the present study, hydrate dissociation data measurements were undertaken for three systems by means of the well established isochoric pressure search method: 1) methane + water, 2) isoprene + methane + water and 3) 2-methyl-2-butene + methane + water. Methane was included in these systems because it is a well-known help guest for large hydrate formers (Mohammadi, Belandria, & Richon 2009). The possibility of gas hydrate formation was examined through the effect of isoprene or 2-methyl-2-butene (water insoluble chemicals) on methane hydrate dissociation conditions.