38. Recovery of VOC from Offshore and Onshore Shuttle Tankers Using Structured Y-Type Zeolite Membranes

The emissions of volatile organic compounds (VOCs) from onshore and offshore facilities are studied and an alternative technology for the recovery of methane and propane by the use of membrane technology is explored. Permeation tests were carried out with a zeolite membrane consisting of an α—Al₂O₃ support. The permeance of nitrogen, carbon dioxide, helium, methane and propane through the membrane at varying pressures was determined. The permeance of CH₄ was in the range of 1.44 × 10⁻⁶–3.41 × 10⁻⁶ mols⁻¹m⁻²Pa⁻¹ and a CH₄/C₃H₈ selectivity of 3.3 at 293 K was obtained. The molar flux of the gases was found to have an average linear regression coefficient value R² of 0.9892. On the basis of the results obtained it can be concluded that separation of the hydrocarbon gases can be achieved with the zeolite membrane. The main mechanism governing the flow of gases through the zeolite membrane was molecular sieving although there is evidence of deviation from this mechanism. To achieve higher selectivity of the target gas there is need for further modification of the membrane. The morphology of the membrane was determined using the scanning electron microscope, which showed the pore size of the membrane and the support layer.