2,3-Dimethylbutane, supercritical

Figure 9 Rate constants for electron attachment to CO2 vs. the free energy of reaction in different fluids 0—2,2,4-trimethylpentane [126], —2,2-dimethylbutane [139], O— TMS [126], —supercritical ethane [99],...

In this study, C16-C32 wax distillate is separated into n-paraffin and denormal oil fractions by vapor phase contacting with type 5A molecular sieves. 2,2,4-Trimethylpentane (isooctane), 2,2-dimethylbutane, and 2-methylpentane are each used as the supercritical fluid. Recovery of n-paraffins from the molecular sieves is accomplished by contacting with nitrogen or ammonia gas. 

A test was made with 2,3-dimethylbutane as the supercritical solvent it has a lower critical temperature than 2,2,4-trimethyl-pentane. Operating at a temperature of 508-512 K, a pressure of 4.10-4.37 MPa, a molecular sieve/oil ratio of 6.39, and a solvent/ oil ratio of 21.3, the molecular sieve capacity attained is 5.73 g/100 g of molecular sieves (as compared to 3.2 g/100 g of molecular sieves with 2,2,4-trimethylpentane at 550 K). The n-paraffin content of the wax distillate was reduced by 88% to a level of 2 wt %, giving a pour point of 266 K. The yield of denormal oil was lower (63%) and the n-paraffin content of the desorbate was lower (44%) at this lower temperature level. This is probably due to increased capillary condensation. Conversely, operation at temperatures greater than 550 K should produce less capillary condensation and purer n-paraffin product. It would be interesting to try supercritical solvents with critical temperatures in the 600-670 K range. 

Figure 11. Molecular sieve selectivity for supercritical-fluid—molecular-sieve extraction (O) 2,2,4-trimethylpentane (9) 2,3-dimethylbutane...

Figure 4.4-6 Ratio of mono- to polychlorides produced in the free radical chlorination of 2,3-dimethylbutane (23DMB), neopentane, and cyclohexane in conventional and supercritical fluid solvents as a function of inverse viscosity at 40 °C (data taken from References SO and 51).

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