Separation of C1-C15 Alkanes with a Disk-Shaped Aluminum Column Employing Mesoporous AAO as the Stationary Phase

A new type of gas chromatographic (GC) column employing a mesoporous anodic aluminum oxide (AAO) layer as the stationary phase was developed. The gas fluidic channels were fabricated on both sides of an aluminum disk via a mechanical stamping process. The tops of the gas fluidic channels were sealed with a thick aluminum foil and a thin glass liner. The cross section of this fluidic channel is triangular in shape and consists of two aluminum surfaces and one glass surface. The diameter of the aluminum disk is 8.7 cm, and the length of the GC column is 6.0 m. The AAO layer was grown on the aluminum surface and had an average pore diameter of 50 nm and a specific surface area of 4.13 m² g^-1. The thickness of the AAO stationary phase ranged from 6-150 μm. Although thin AAO is insufficient for separating light alkanes, methane and ethane can be separated with a resolution of 4.25 using a 150 μm thick AAO stationary phase at room temperature in less than 100 s. C₁ to C₁₅ alkanes can be completely separated within 20 min when using a temperature program ramped from room temperature to 350 °C. Some limitations of this preliminary design, such as peak broadening probably arising from the triangular cross section, not yet being suitable for polar compounds, and the lack of a stationary phase on one-third of the column surface are discussed.