Consumption of ethylene

Table 2. United States Consumption of Ethylene Glycol-Based Automotive Antifreeze ...

Global demand for ethylene is expected to increase from 79 million tons in 1997 to 114 million tons in 2005. In 1998, the U.S. consumption of ethylene was approximately 52 billion pounds. Eigure 7-2 shows the breakdown of the 1998 U.S. ethylene consumption. ... 

Table 27 Consumption of ethylene as function of catalyst concentration and temperature107 ... 

Ethylene is obtained by catalytic cracking of naphtha. It is one of the key petrochemical commodities worldwide used mostly in the production of polyethylene, ethyl benzene, ethylene oxide and others. The consumption of ethylene for the production of alcohols and other surfactant raw materials represents less than 10% of the total end uses of ethylene on a worldwide basis. 

Another interesting recent development in styrene technology which will affect future consumption of ethylene relates to new methods for increasing conversion in the dehydrogenation of ethylbenzene. Several years ago, Scientific Design pioneered a technique for increasing conversion in this reaction. The net result was a marked decrease in the capital investment required for styrene plants. The present trend is to-... 

Almost any naphthenic or parallflnic hydrocarbon heavier then methane can he steam-cracked to yield elhylene. The preferred feedstock in the United Slates has been ethane and/or propane recovered from natural gas. or from the volatile fractions of petroleum. However, because of longterm uncertainties pertaining to natural gas, many producers have been turning to heavier petroleum fractions, such as gas oils, as feedstock. The consumption of ethylene throughout the free world is estimated to be about 40 x 10 pounds per year,... 

The first kinetic studies were made by Hay and coworkers l71,l72). They found that the rate of polymerization of ethylene was independent of the concentration of TMEDA and concluded that the active initiating species is n-butyllithium which is neither complexed nor self-associated initiator efficiences were reported to be less than 50 %. The rate of consumption of ethylene was found to be proportional to the concentrations of ethylene and n-butyllithium. 

In 1999, U.S. consumption of ethylene glycol totaled 5.5 billion lb. Of that, 1.5 billion lb (28%) was used in the production of polyester bottles, primarily for soft drinks. Polyester fiber applications accounted for 1.4 billion lb (26%), primarily for the textile industry. Polyester film and miscellaneous applications consumed another 0.4 billion lb (7%). Antifreeze applications have held steady at approximately 1.6 billion lb over the last 20 years, and have become relatively less important with time than the polyester applications. This trend is expected to hold in the future. Increased demand for polyester bottles is expected to fuel growth in the United States, and bottle and textile applications are expected to fuel growth in other areas of the world. 

This difference in mechanism is clearly demonstrated by substituting bifunctional catalysts for acidic catalysts (29). The introduction of platinum in MFI catalysts leads to a large decrease in the rate of ethylbenzene disproportionation (divided by 6), which is due to a large consumption of ethylene by hydrogenation as shown by the large increase in the rate of dealkylation. On the other hand, the introduction of platinum in MOR catalysts leads to a limited change in the rates of disproportionation and dealkylation. 

In most industrially relevant reacting systems, one main reaction typically makes the desired products and several side reactions make byproducts. The specific rate of production or consumption of a particular component in such a reaction set depends upon the stoichiometry and the rates. For example, assume that the main reaction for making vinyl acetate, Eq. (4.4.1, proceeds with a rate r< (mol/L s) and that the side reaction, Eq. (4.8), proceeds with rate r2 (mol/L s). Then the net consumption of ethylene is (-l)r1 - (-1 )r2 (mol/L s). Similarly, the net consumption of oxygen is (-0.5)fi + (— 3)r2, and the net production of water is (l)r-, + (2)ra. For a given chemistry (stoichiometry), our ability to control the production or consumption of any one component in the reactor is thus limited to how well we can influence the various rates. This boils down to manipulating the reactor temperature and/ or the concentrations of the dominant components. Occasionally, the reaction volume for liquid-phase reactions or the pressure for gas-phase reactions can also be manipulated for overall production control. These are the fundamentals of reactor control. 

To a very small extent EB undergoes alkylation to diphenylethane. The DEB and TEB can be easily recovered by transalkylation with benzene to EB, so they can be considered useful products. Conversely, the formation of olefins and other alkylbenzenes heavily affects the efficiency of the process by increasing the specific consumption of ethylene and benzene and reducing the EB quality. 

Ethylene. Ayres has reported 2) on the costs of ethylene production (based on 1950 construction costs) from propane at four cents per gallon, as shown in Table XV. The consumption of ethylene by the chemical industry has been reviewed by Aries and Copulsky ). 

Table IV summarizes percent consumption of ethylene consequent upon reaction of the pure substrate and three of its mixtures with propane with six different ratios of N(4S). Table V summarizes analogous data for propane. The data for mixtures given in the two Tables are derived from the same sets of experiments. Table VI summarizes apparent relative specific rates of consumption, kr2H4/kc.,Hs These ratios were calculated by means of Equation 14, the expression which would be appropriate...

Uses for 1984 and figures for production, capacities and consumption of ethylene glycol in Western Europe, the United States and Japan are given in Table 7.9. 

Consequently, for two molecules of ethylene oxide formed according to Eq. (V.52), two adsorbed oxygen atoms are formed, whereby one molecule C2H4 is oxidized to CO2 and HgO. Then the yield of ethylene oxide with respect to the consumption of ethylene is in fair agreement with the experimental results obtained by Imre 49). 

Use an excess of benzene (4 1 to 5 1) to improve the selectivity. Consider complete consumption of ethylene. 

A Different Global Optimum for a Different Objective Imagine further that xylene is now the desired component and not toluene, and that we also wish to minimize the consumption of ethylene. How do we achieve this new objective and is our old design still appropriate If it is possible to compute a set of achievable available concentrations, for many reactor configurations, then a change in objective function is easily incorporated into the new analysis. 

Figure 3. Rate of consumption of ethylene as a function of time. Experimental conditions P(C2H4) = 10.8 PSI ( ), 20.8 PSI ( ), 30.5 PSI ( ), T = 25 C. Symbols are experimental data and the line corresponds to the kinetic model (see text below).

The consumption of ethylene clearly shows an induction period, which may be associated with the formation of the first reactant-chromium complexes, followed by a deactivation process, which leads to an almost stationary rate of comsumption of ethylene. It is clear from... 

Figure 4 represents the rate of consumption of ethylene for different temperatures. As it can be seen, the global activity increases with temperature. The rate of deactivation also increases with temperature. 

On the other hand, studying the tertiary amine-catalyzed reaction of acetic acid with ethylene oxide in n-butanol, Bazant et al. found a pseudo-zero order for the consumption of ethylene oxide ... 

Thus, Samsonova et al. studying the kinetics of the triethylamine-catalyzed reaction of terephthalic acid, in the bulk under a pressure of ethylene oxide, found a third-order relation for the consumption of ethylene oxide ... 

Experimental study of the system showed that reaction (33) is much more rapid than (34) and (35), and it was established that the consumption of ethylene oxide obeys a second-order law ... 

Figure 6.12.3 World consumption of ethylene oxide by end use in 2006. Data from Devanney (2007).

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