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Crude Oil Refining—Part 2
Published in Hussein K. Abdel-Aal, Economic Analysis of Oil and Gas Engineering Operations, 2021
Alylation is the process that produces gasoline-range compounds from the combination of light C3-C5 olefins (mainly a mixture of propylene and butylene) with isobutene. The highly exothermic reaction is carried out in the presence of a strong acid catalyst, either sulfuric acid or hydrofluoric acid. World alkylation capacity is currently 2.1 million b/d [1]. The alkylate product is composed of a mixture of high-octane, branched-chain paraffinic hydrocarbons. Alkylate is a premium clean gasoline blending with octane number depending upon the type of feedstocks and operating conditions. Research efforts are directed toward the development of environmentally acceptable solid superacids capable of replacing HF and H2SO4.
Membrane Processing
Published in John J. McKetta, Unit Operations Handbook, 2018
Nafion has also found use as a catalyst. Superacids such as magic acid, a system containing antimony fluoride and fluorosulfonic acid, have useful catalytic properties in the synthesis of organic chemicals. Wide applicability of superacids encouraged efforts to prepare them in the solid phase by absorbing antimony fluoride and fluorosulfonic acid on supports such as fluorinated graphite or a fluorinated polyolefin resin. Nafion has been used as a catalyst for various reactions involving superacids. Nafion (in the hydrogen ion form) was found to have higher catalytic activity than other solid-phase superacid catalysts for gas-phase alkylation of benzene and alkylbenzenes. Nafion is also used as a catalyst in the isomerization ofm-xylene, for Friedel-Craft reactions of toluene and phenol with alkylchioroformates and oxalates.
Introduction to Chemical Reactivity
Published in Caroline Desgranges, Jerome Delhommelle, A Mole of Chemistry, 2020
Caroline Desgranges, Jerome Delhommelle
In the 1960s, Olah develops the famous “magic acid” for which he is awarded the Nobel Prize in chemistry in 1994 “for his contribution to carbocation chemistry”. “The name magic acid for the FSO3H-SbF5 system was given by J. Lukas, a German post-doctoral fellow working with me in Cleveland in the sixties who after a laboratory party put remainders of a Christmas candle into the acid. The candle dissolved and the resulting solution gave an excellent NMR spectrum of the tert-butyl cation. This observation understandably evokes much interest and hence he named the acid ‘magic’.” Olah shows that it is then possible to create carbocations using superacids! These acids are stronger than mineral acids like highly concentrated sulfuric acid, meaning that the lifespan of a carbocation will be long enough to study it! Indeed, since they are in very acidic systems, they cannot recombine with any bases as these cannot exist! This allows Olah to assemble molecules, disassemble them and even change their structure using carbocations. Indeed, a tremendous advance enabled by superacidic hydrocarbon chemistry is the achievement of efficient low-temperature isomerization reactions of alkanes. This, in turn, opens the door to new methods for methane functionalization, higher hydrocarbons synthesis and environmentally adaptable alkylation reactions. He also adds that “Superacidic systems are not limited to solution chemistry. Solid superacids, possessing both Brönsted and Lewis acid sites, are of increasing significance. They range from supported or intercalated systems, to highly acidic perfluorinated resinsulfonic acids (such as Nafion-H and its analogues), to certain zeolites (such as H-ZSM-5).”
Esterification of high acidity vegetable oil catalyzed by tin-based catalysts with different sulfate contents: contribution of homogeneous catalysis
Published in Chemical Engineering Communications, 2019
Camila O. P. Teixeira, Kelly C. N. R. Pedro, Thais L. A. P. Fernandes, Cristiane A. Henriques, Fatima M. Z. Zotin
Superacid catalysts such as sulfated ZrO2 and SnO2 have been successfully applied in various reactions (Lam et al., 2009; Furuta et al., 2004a; Xie et al., 2012; Chavan et al., 1996; Moreno et al., 2011; Alaya and Rabah, 2013), including esterification, due to the presence of a high number of strong acid sites which promotes unique catalytic activities. Compared with sulfated zirconia, catalyst extensively used in esterification reactions, sulfated tin oxide presents similar or stronger acid strength, which may reflect in a good catalytic activity (Furuta et al., 2004b).