Ethylene, consumption

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. ... 

According to the ethylene consumption rate profile for ethylene/l-hexene copolymerization in figure 1, it indicated that deactivation of active species occurred in the borate system. On the... 

In the process shown in Figure 23-4 the reactor is partially filled with cyclohexane, the medium in which the reaction takes place. The cyclohexane keeps the ethylene, the catalyst, and the polyethylene fluid and in contact with each other it sponges up much of the heat from the exothermic reaction and helps control the rate of ethylene consumption. 

This process produces a wide melt index range by applying innovative catalyst chemistry combined with a sophisticated polymerization process. An all-round catalyst and simple polymerization operation provide easy product changeover that reduces transition time and yields negligible off-spec product from the transition. Mitsui has also developed new catalyst that contributes better morphology of the polymer powder and ethylene consumption. 

Methylalumoxane (3.32 g) and the Step 4 product (38.2 pmol) were thoroughly mixed and placed in a burette. A stirred 1-liter Buchi autoclave reactor was charged with 150 ml of toluene and methylalumoxane, and the Step 4 product mixture added the aluminium/zirconium ratio was 300. The reaction was conducted under an ethylene pressure of 0.3 bar at 20°C for 2 hours. The reactor was then purged with nitrogen to remove ethylene, and the reactor temperature was raised to 80°C. Thereafter 2.85 bar of ethylene pressure was applied, and the polymerization was conducted for 30 minutes while maintaining the ethylene pressure and temperature at this level. The ethylene consumption was 0.7082 mol, and the product was isolated having a MP = 127°C. 

Figure 1. Effect of HCl upon the selectivity of the alkylation reaction. Selectivity based on ethylene consumption and defined as ([C6HU] +...

Comparing the reaction rate, i.e. ethylene consumption with the pH value, both plotted against the mole ratio ([Cu"]/[Cu ] -i- [Cu ]), i.e., the degree of oxidation of the catalyst solution, it has been shown that a reduction in the reaction rate and the pH value occurs at the same degree of oxidation, depending on the Cl/Cu ratio (Figure 1). This point is in fact consistent with the neutralization of the copper oxychloride while the reaction according to eq. (7) proceeds [6, 12, 13, 46], and is very important for the operation of the Wacker process (see Section 2.4.1.4.1). 

In both cases, under open-circuit operation (I = 0, no electrochemical rate), there is a catalytic rate, ro, of ethylene consumption for oxidation to CO2 (Fig. 47) or of 1 -butene consumption owing to reduction to butane and isomerization to cis-2-butene and trans-2-butene (Fig. 47). 

Figure 1. The average degree of polymerization of the product, n, is a function of the relative rates of ethylene consumption and transfer. By invoking the steady-state assumption, it can be shown that the average degree of polymerization is governed by the competitive rates of propagation and transfer.

In the presence of ethylene oxide, formaldehyde, and acetaldehyde, the rate of ethylene consumption remains unchanged. There is also no inhibition of ethylene oxide formation at its gas-phase concentration of about 1%. This is probably due to the blocking off of the most active surface sites. 

The most important example of this reaction is the formation of ethylene oxide (Eqn. 1), over Ag-catalysts which displaced the two-step chlorohydrine route (Eqn. 2). Ethylene oxide is used in the production of ethylene glycol, antifreeze, polyesters and surfactants, and accounts for 18% of U.S. ethylene consumption (Figure 3). ... 

Ethylene reacts in the presence of benzene in a 2 1 benzene to ethylene ratio. The rate of ethylene consumption... 

Since ethenolysis leads to selective formation of terminal double bonds, the determination of the catalyst activity is possible. For this purpose we developed a special apparatus which allows time-dependent measurements of ethylene consumption by means of a mass-flow controller [12]. Based on these measurements we calculated the catalyst turn-over frequency (TOF). 

Vlasova, N. N., Matkovskii, P. Y, Yenikolopyan, N. S., Papoyan, A. T, Vostorgov, B. Y, and Sergeyev, V. 1.1985. Effect of various factors on the kinetics of ethylene consumption during its polymerization on the surface of kaolin particles treated with organo-aluminum compounds. Polymer Science USSR 27 2380-2385. 

Figure 274 Successive reactivation of Cp 2Nd(BH4)THF/BEM toward ethylene consumption with addition of new crops of BEM (an arrow corresponds to a new addition of 50 equiv BEM).

Figure 3.1 shows the chromium atom in a Cr(VI) oxidation state, but the chromium center needs to be reduced in order to produce an ethylene polymerization center. Ihis reduction step can be carried out using hydrogen, carbon monoxide or ethylene. Ihe most common method is to use the ethylene that is present in an ethylene polymerization reactor. The time required to carry out this reduction process within the polymerization reactor results in a delay in ethylene consumption once the oxidized chromium species is exposed to ethylene. This delay is usually several minutes, depending on the specific catalyst composition, and is referred to as an induction period. 

Polymerization. Slurry polymerization was performed in a 1 1 autoclave under a constant pressure of ethylene. A prescribed amount of AlBt, and 500 ml of n-hexane were introduced into the reactor in a nitrogen stream. 1-Hexene was also introduced in the case of copolymerization. After evacuation, ethylene was introduced at the polymerization temperature. Polymerization was started by breaking the glass ampoule containing the prescribed amount of catalyst. The rate of polymerization was determined from the rate of ethylene consumption, measured by a hot-wire flowmeter with a personal computer directly connected to it through A/D converter. Details of polymerization procedures were described elsewhere . 

The sulfur-containing additive may be expected to have a dual influence, both electronic and steric. The increase in electron density at the transition-metal center may prevent coordination of the a-olefins this effect must necessarily have a bearing on the coordination of the ethylene itself, decreasing the rate of ethylene consumption. On the other hand, very bulky sulfur ligands may block the coordination site effectively enough to make it accessible only for the small ethylene molecule, but not for the higher a-olefins. 

Equation (5-3) is a very general expression for the rate of ethylene consumption, given the mechanism of Reactions (5-D)-(5-G). The first term ofthis rate equation (ki [C2H4][H2]) is the rate at which ethylene disappears in Reaction (5-D), and the second term (k2- / i 3/ 2 4[C2H4][H2]) is the rate at which ethylene disappears in Reaction (5-E). 

To apply the long-chain approximation to the preceding ethylene hydrogenation mechanism, we write a rate expression that includes only the rate of ethylene consumption in the propagation steps, i.e., in the steps that carry the chain. 

However, more recently, ethylene production in China has been on the rise. For example, in 2003, China s output of ethylene increased by 15%, to 3.44 million tonnes, according to the State Statistical Bureau. Ethylene consumption in the same period rose by 14%, to 3.45 million tonnes. Output of purified terephthalic acid - a key raw material in the production of many petrochemical derivatives and plastics - rose by 10%, to reach 1.47 million tonnes, while the production of benzene increased 16%, to 1.16 million tonnes. 

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