Consolidated Vacuum Sublimation Module: a Purification Apparatus and Process for Solid-Phase Materials

 

A consolidated Vacuum Sublimation Module [cVSM] provides engineering improvements over conventional sublimation apparatus. As implied, the cVSM is structurally modular and it comprises: valve stem unit, valve/Collector/jacket unit, lower glass body, FKM seals, threaded PTFE bushing, and an internal glass cartridge [see US patent 7794694]. In association with the cVSM, a batch sublimation process was developed to purify solid-phase materials such as ferrocene, perylene, oxalic acid, and pentachlorobenzene.

To effect sublimation, the lower glass body is controllably heated to establish a vertical temperature gradient. The temperature gradient along the [evacuated] lower body surface was measured versus input electric power. At steady state, an input of ~37 watts generated +530K at z=0 and +314K near z=95 mm. When operated with natural cooling, the starting material recovery was typically ≥95 mass%. Design features of said Module include: concentric multi-tubular geometry, elongated tapered Collector, positively compressed seals, natural Collector cooling, minimal power consumption, transparency, and glovebox compatibility. The [static vacuum] leakage of an empty cVSM measured <20 ppmv of air per hour. Lastly, the prototype Module has been moderately scaled-up and demonstrated.