Laboratory Fluorinated By-Products Analyser

The Hydrofluoric (HF) Alkylation process catalytically combines C3 – C5 olefins with isobutene to produce motor fuel alkylate. There is an increasing demand for alkylate because of its properties as a low-sulphur, highoctane blending component for unleaded and reformulated gasoline. The products of the process contain traces of HF and organofluoride by-product compounds. Elevated levels of residual fluorinated byproducts in process streams can cause serious problems in refinery operations including corrosion, catalyst poisoning, downtime, and lost production. Fluorinated by-products are removed by catalytic decomposition at 177 – 220 °C to HF and olefins. The HF released during this decomposition step is removed by adsorption on a bed of alumina forming aluminium fluoride. This step reduces total fluoride levels from approximately 100 – 400 ppm down to low ppm levels in the motor fuel alkylate.

OI Analytical’s (USA) FBA 5320 is a laboratory fluorinated by-products analyser (FBA) designed to detect and measure total fluorinated contaminants (HF and organofluoride compounds) in liquid propane, liquid butane, and motor fuel alkylate from the HF alkylation process. The analyser is based on an Agilent 7890 gas chromatograph equipped with an automated liquid sampling valve for sample introduction, a packed-inlet injection port, a stainless steel column, and a 5320 Electrolytic Conductivity Detector (ELCD) configured for fluoride detection. The FBA 5320 accurately detects total fluoride concentrations in the low parts-per-million (ppm) range. The FBA 5320 is typically calibrated with a calibration gas mixture (e.g. 3- fluoropropane in n-Butane) or using a sample from a C4 process stream analysed by the Wickbold Method (ASTM D 7284). The measurement range of the FBA 5320 is 0.02 to 100ppm-F.