MTBE catalysis

Acid catalysis by titanium silicate molecular sieves another area characterized by recent major progress. Whereas only two categories of acid-catalyzed reactions (the Beckmann rearrangement and MTBE synthesis) were included in the review by Notari in 1996 (33), the list has grown significantly since then. In view of the presence of weak Lewis acid sites on the surfaces of these catalysts, they can be used for reactions that require such weak acidity. 

Synthesis gas is also the precursor to MTBE via methanol. The process requires isobutylene as well. Ethyl alcohol is made by direct, catalyzed hydration of ethylene. The route to isopropyl alcohol historically used to be solely indirect hydration of propylene, which occurs at much lower pressures and temperatures than the direct method, but advances in catalysis now make the direct route competitive. 

There has been an enormous technological interest in tertfa/j-butanol (tBA) dehydration during the past thirty years, first as a primary route to methyl te/f-butyl ether (MTBE) (1) and more recently for the production of isooctane and polyisobutylene (2). A number of commercializable processes have been developed for isobutylene manufacture (eq 1) in both the USA and Japan (3,4). These processes typically involve either vapor-phase tBA dehydration over a silica-alumina catalyst at 260-370°C, or liquid-phase processing utilizing either homogenous (sulfonic acid), or solid acid catalysis (e.g. acidic cationic resins). More recently, tBA dehydration has been examined using silica-supported heteropoly acids (5), montmorillonite clays (6), titanosilicates (7), as well as the use of compressed liquid water (8). 

Esterification and etherification may be accomplished by catalysis with mineral adds of BF3 the reaction of isobutylene with methanol to make MTBE is catalyzed by a sulfonated ion exchange resin. 

IFP Methyl tertiary butyl ether (MTBE) FCC and steam-cracker C4 cuts and methanol CATACOL technology ensures high MTBE yields by combining catalysis and distillation separation 21 1996... 

Abstract This chapter explores the role of abiotic reactions such as acid catalysis (hydrolysis) as well as the adsorption of methyl tert-butyl ether (MTBE) and other fuel oxygenates in environmental issues as the remediation of these substances is notoriously difficult. First of all, these methods are briefly classified with other abiotic technologies. The suitability of hydrolysis and adsorption for the remediation of water contaminated by fuel oxygenates is then discussed in detail, with information being provided about the principle of the reactions, potential catalysts and sorbents, limitations of the reactions, and practical implications. To conclude, the possible application of hydrolysis and adsorption in combination with other remediation techniques is also examined. 

The acid catalysis of MTBE plays an important role in many different areas of application. The key aspect is the synthesis of MTBE using solid acid catalysts since it has become the most important fuel oxygenate in the world. As this reaction is reversible, the cleavage of MTBE is used to gain pure isobutene, a basic chemical required for various products. Furthermore, the hydrolysis of MTBE has been investigated regarding its role in environmental chemistry. Besides its prominence in analysis, the use of this reaction in the treatment of contaminated water is discussed. 

In this paper we describe some recent work done by Shell Research (which is submitted to the Tripartite Group) on the effects of gasoline composition and properties on vehicle emissions. In addition the manufacture of MTBE, a relatively new gasoline component and a major feature of US reformulated gasoline is reviewed. Catalysts appear to play an important role in both gasoline manufacture (illustrated for MTBE production) and gasoline end use (exhaust catalysis). 

As already mentioned, control of vrater content is of great importance in enzyme catalysis. Studies on Pseudomonas sp. lipase have also revealed a strong influence of the vrater content of the reaction medium [70]. In order to compare the enzyme activity and selectivity as a fonction of the vrater present in solvents of different polarities, it is necessary to use the vrater activity a in these solvents. We used the method of vrater activity equilibration over saturated salt solutions [71] and could demonstrate that, in contrast to MTBE, which is commonly used for this type of reaction, the enantiosdectivity of the lipase is less influenced either by the water content or the temperature when the reaction is performed in [BMIM][(CFjS02)2N]. 

Catalytic Distillation Catalytic or reactive distillation is another example of the use of a hybrid reactor and combines catalysis and distillation in one column/reactor. Usually, we have a two-phase process with gas and liquid flowing in countercurrent mode. This requires special catalysts and packings, for example, monoliths, as in case of a fixed-bed flooding of the reactor would occur at high flow rates. In industry, catalytic distillation is already used for the production of MTBE (methyl tert-butyl ether), an important octane booster (Figure 4.10.77 DeGarmo, Parulekar, and Pinjala, 1992), cumene (DeGarmo, Parulekar, and Pinjala, 1992), and ethylbenzene (Podrebarac, Ng, and Rempel, 1997). 

Salomon, M.A., Coronas, J., Menendez, M. and Santamaria, J. (2000) Synthesis of MTBE in zeolite membrane reactors. Applied Catalysis A General, 200,201-210. 

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