Butene Feedstock

Prior to 1960 benzene was the only feed used to produce maleie anhydride. From 1962, however, the Petrotex Chemical Corporation began to use n-butene feed in its plant in Houston, Texas.  

Note Early naphthalene and benzene oxidation catalysts often contained alkali metal promoters. Commercial benzene oxidation catalysts were shown to contain a p-bronze phase (NaiO-V2O4 5V2O5 or NajO MoOj-SViOs) with other mixed oxide compounds such as V9Mo504o.The p-bronze could possibly stabilize the other active compounds and limit loss of molybdena during operation. M. Najbar, Preparation of Catalysts IV,, Elsevier, Amsterdam, 1987, p. 217. 

The -butene feed was supplied by the dehydrogenation of n-butane and the plant began the trend to develop oxidation processes using aliphatic petrochemical hydrocarbons. The main incentive, of course, was to use surplus C4 hydrocarbon from steam cracking. This not only used a cheap by-product gas, but the reaction was less complicated because the straight-chain C4 molecule contained fewer carbon atoms tlm aromatic benzene. 

The mixed vanadium pentoxide/phosphorous pentoxide (with niobium, copper, lithium promoters) catalyst used by Petrotex was, at the time, a further step change in the catalyst types used for hydrocarbon oxidatiom It also eventually contributed to a better understanding of the catalyst structures used in oxidation reactions. The catalyst must have evolved from the accumulated experience obtained with a variety of mixed oxide catalysts and had a composition similar to that shown in Table 4.8. Distillers patented a molybdenum triox-ide/phosphorous pentoxide catalyst, and the Atlantic Refining Company took out a patent for a vanadium pentoxide/phosphorous pentoxide catalyst specifically for butene-2 oxidation. The vanadiitm pentoxide catalyst gave higher yields. 

TABLE 4.8. Operating Conditions for n-Butene/n-Butane Oxidation. 

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The effect of butene isomer distribution on alkylate composition produced with HF catalyst (21) is shown in Table 1. The alkylate product octane is highest for 2-butene feedstock and lowest for 1-butene isobutylene is intermediate. The fact that the major product from 1-butene is trimethylpentane and not the expected primary product dimethylhexane indicates that significant isomerization of 1-butene has occurred before alkylation. 

The ionic liquid process has a number of advantages over traditional cationic polymerization processes such as the Cosden process, which employs a liquid-phase aluminium(III) chloride catalyst to polymerize butene feedstocks [30]. The separation and removal of the product from the ionic liquid phase as the reaction proceeds allows the polymer to be obtained simply and in a highly pure state. Indeed, the polymer contains so little of the ionic liquid that an aqueous wash step can be dispensed with. This separation also means that further reaction (e.g., isomerization) of the polymer s unsaturated ot-terminus is minimized. In addition to the ease of isolation of the desired product, the ionic liquid is not destroyed by any aqueous washing procedure and so can be reused in subsequent polymerization reactions, resulting in a reduction of operating costs. The ionic liquid technology does not require massive capital investment and is reported to be easily retrofitted to existing Cosden process plants. 

Olefin metathesis is the transition-metal-catalyzed inter- or intramolecular exchange of alkylidene units of alkenes. The metathesis of propene is the most simple example in the presence of a suitable catalyst, an equilibrium mixture of ethene, 2-butene, and unreacted propene is obtained (Eq. 1). This example illustrates one of the most important features of olefin metathesis its reversibility. The metathesis of propene was the first technical process exploiting the olefin metathesis reaction. It is known as the Phillips triolefin process and was run from 1966 till 1972 for the production of 2-butene (feedstock propene) and from 1985 for the production of propene (feedstock ethene and 2-butene, which is nowadays obtained by dimerization of ethene). Typical catalysts are oxides of tungsten, molybdenum or rhenium supported on silica or alumina [ 1 ]. 

Butadiene (> 98%w/w) 20 ooo longtons Catalytic dehydrogenation of n-butenes feedstock of liquid mixed hydrocarbon stream containing 80.5 mol % n-butenes, 11.5 mol % n-butane, and 1 mol % of higher hydrocarbons. 

Technology for hydrogenation to normal or iso-butanols or aldoliza-tion and hydrogenation to 2-ethylhexanol exists and has been widely licensed. One version of the SELECTOR Technology has been licensed to produce a mixture of alcohols (predominantly 2 propylheptanol) from an n-butene feedstock and another version to produce higher alcohols (up to C15) from Fischer Tropsch produced olefins. 

Among the resins tested, the Amberlyst XN-IOIO/BF3 catalyst system appeared to be the most selective one, producing the best alkylate quality. This catalyst showed much less difference among different butene feedstocks than conventional HF and H2SO4 alkylation catalysts. In addition, its alkylate quality was improved as the temperature was decreased, reaching a plateau at about 0°C at which an alkylate with a R( I clear of... 

Similarly, after blending about 30vol.% of propylene with cis-2-butene, the RON loss was less than 1 number. With H2SO4 alkylation, similar amounts of propylene would lead to a RON about 1.5 lower. Table 12.10 summarizes the estimated impact of feedstock variation on RON relative to a pure cis-2-butene feedstock for the AlkyClean process and liquid acid technologies. Based on these results, it can be concluded that our new SAC technology is less sensitive to feedstock variation regarding product quality than either liquid acid technology. 

On a propylene feedstock, very substantial amounts of isobutylene are found in the reactor effluent. On a n-butene feedstock, attractive yields of polypropylene are obtained as well as iso-butylene. 

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