An interesting reversal in alkane/alkene adsorption selectivity with pressure is observed: at low pressures the selectivity towards the alkanes is driven by energetic effects while at high pressures the selectivity is towards the alkenes due to entropic effects.
For tri-methyl benzenes, they do have higher selectivity when pressure goes up, but the general trend is, the selectivity drops rapidly as the temperature increases under a particular pressure.
This effect was analyzed in terms of the permeation flux, selectivity, operating pressure and feed velocity.
The advantages of the ultrasonic Hg2+ calibrator are: high accuracy and selectivity, low pressure of HgCl2 stream and very low cost of production.
Based on a simple mathematic model, computer simulations have been carried out which illustrate the relative performance in terms of productivity, selectivity and pressure drop.
When the recycle ratio approaches infinity, the required selectivity and pressure ratio reach their absolute minimum values, which have a simple relationship with that of a single-stage membrane process, as follows: Sn= S1, γn="γ1, where n is the number of stages.
Pressure mainly affected the product selectivity; a higher pressure led to a lower C1 C4 selectivity but enhanced durene formation.
The local thermodynamic efficiency of permeation is a function of membrane selectivity and the pressure ratio across the membrane and is independent of the absolute values of permeabilities and the pressures on either side of the membrane.
Reactor designs for Fischer Tropsch synthesis (FTS) are illustrative for the struggle to combine the process needs concerning selectivity, heat removal, pressure drop and catalyst attrition and separation.
The increased CO2 molar fraction in the binary CO2/N2 mixture decreased the selectivity and saturation pressure to reach a stable equilibrium state.
