Molecular sieve processes

Fig. 2. Molecular sieve process where Kl is a molecular sieve sorbent bed ( ), the adsorption system and (-), the regeneration system.

Natural gas from MESA s wells flows into a gathering system where pressure is increased to 7 bar (100 psig). Multiple booster stations raise it to 34 bar (500 psig) before gas enters the plant for separation. When gas enters the LNG recovery unit, its pressure must be raised again to 66 bar (950 psig). It is then subjected to a molecular sieve process for moisture removal. A series of heat exchangers lowers the temperature to -34°C (-30°E). 

The molecular sieve process uses synthetically manufactured. solid crystalline zeolite in a dry bed to remove gas impurities. The crystalline... 

Molecular Sieve Processes for the Isolation of n-Alkanes from Hydrocarbon Mixtures... 

A decisive step of the molecular sieves processes is the desorption of the n-alkanes from the loaded sieve. Various procedures are in use in industry [13]. 

FIG. 1 Operating principle of the Molex molecular sieve process. 

MS-2 A molecular sieving processes for separating branched-chain aliphatic hydrocarbons from unbranched ones by selective adsorption on a zeolite. Developed by the British Petroleum Company in the 1970s but not commercialized. 

Oxidation of lignin can occur through chemical or biochemical means (25). Oxidation, especially in the presence of alkali, is a promising approach when the oxidizing agent can be air or oxygen obtained by a molecular sieve process (26,27). 

It appears that temperatures in the range of 500.to 670 K for the adsorption of n-paraffins in the 560-740 K boiling range on type 5A molecular sieves should be considered for investigating the combination supercritical fluid volatility amplification-vapor phase molecular sieve process. The pressure of operation will be governed by the critical pressures of potential solvents with critical temperatures in this range. The supercritical solvent of choice should not be adsorbable on type 5A molecular sieves and should not be expensive. 

The combination supercritical fluid volatility amplification-molecular sieve process has the potential for producing two valuable products simultaneously from gas oil-lube oil petroleum stocks. In a flow-through molecular sieve bed, the leading adsorption front operates in the lean molecular sieve loading range, providing the conditions needed for the n-paraffin removal needed to produce low pour lube oil, while the trailing adsorption... 

Derivation By fractional distillation from petroleum (molecular sieve process). 

Normal Paraffin-Based Olefins, Detergent range -paraffins are currently isolated from refinery streams by molecular sieve processes (see ADSORPTION, LIQUID separation) and converted to olefins by two methods. In the process developed by Universal Oil Products and practiced by Enichem and Mitsubishi Petrochemical, a -paraffin of the desired chain length is dehydrogenated using the Pacol process in a catalytic fixed-bed reactor in the presence of excess hydrogen at low pressure and moderately high temperature. The product after adsorptive separation is a linear, random, primarily internal olefin. Shell formedy produced olefins by chlorination—dehydrochlorination. Typically, C —C14 -paraffins are chlorinated in a fluidized bed at 300°C with low conversion (10—15%) to limit dichloroalkane and trichloroalkane formation. Unreacted paraffin is recycled after distillation and the predominant monochloroalkane is dehydrochlorinated at 300°C over a catalyst such as nickel acetate [373-02-4]. The product is a linear, random, primarily internal olefin. 

Source S. J. Miller, New Molecular Sieve Process for Lube Dewaxing by Wax Isomerization, Paper presented at the Symposium on New Catalytic Chemistry Utilizing Molecular Sieves, 206th National Meeting of the American Chemical Society, Aug 23-27, 1993. Table copyrighted by the Chevron Corporation and used with permission. 

Source S. J. Miller, New Molecular Sieve Process for Lube Dewaxing by Wax Isomerization, Microporous Materials 2 439—149 (1994). With permission. 

FIGURE 12.5-5 Beigbeu Forschang caibon molecular-sieve process for nitrogen production. (From Ref. 12.5-9, copyright McGraw-Hill Inc., reprinted with permission.)... 

Here Eg ms is the activation energy for diffusion in the molecular sieving process for CMS membranes. Nguyen et al. reported that the CMS membrane presents reasonable sieving effect for gas molecules with different kinetic diameters, which suggests that the CMS membrane is predominantly micro-porous with no major contribution from Knudsen diffusion or viscous flow in its overall mass transfer. ... 

Initially, when regenerative heating of the bed starts, very little solvent is desorbed, but much of the water (about 87%) is desorbed. The circulating gas is first passed through a cooler and then a separate chiller for the condensation or freezing of the water. Subsequently the gas is passed to the chiller where the water is condensed or frozen. From 1 to 1.8% water is recovered. This process is simpler than the molecular sieves process. 

Figura 12-28. Molecular sieve process for purification of inert gas used in anneaiing operations. Fnm dale (195 ...

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