Column deactivation techniques selectivity

Propane aromatization reaction (at 550°C) was carried out at atmospheric pressure in a continuous flow quartz reactor (id 13 mm), using a propane-nitrogen mixture (33.3 mol-% propane) as a feed with a space velocity of 3100 cm g h". The catalytic activity and selectivity were measured as a function of time-on-stream (up to about 6.7 + 0.2 h). The reaction products were analyzed by an on-line GC with FID, using Poropak-Q (3 mm x 3 m) and Benton-34 (5%) and dinonylphthalate (5%) on Chromosorb-W (3 mm x 5 m) columns. The activity and selectivity data at different space velocities in the absence of catalyst deactivation (i.e. initial activity/selectivity) at 550°C were obtained by the square pulse technique by passing the reaction mixture at different space velocities over fresh catalyst for a short period (2-5 min) under steady state and then replacing the reactant mixture by pure Nj during the product analysis by the GC. 

Sulfur Mustard stability in nonpolar solvents has been determined by GC and GC-MS methods. The situation is more complex for Lewisite because GC methods generally involve derivatization with thiols, and are also complicated by the fact that Lewisite and its hydrolysis products give the same compound after derivatization. The solution to this problem can be found by measuring Lewisite without derivatization. In a study reported by Down in 2005 [63], toluene was selected as the extraction solvent because Lewisite slowly decomposed in other organic solvents, such as acetone and hexane. Thermal oligomerization in the injection port was prevented by on-column injection and a deactivated guard column was used to prevent the well-known problems of memory effects and column deterioration that occur with Lewisite. The extracts were analysed by GC-AED and GC-MS with both electron and chemical ionization [63]. More GC-MS techniques will be described in Chapter 4 with respect to the numerous degradation products of Sulfur Mustard. 

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