Depletion of Liquefied Petroleum Gas from Natural Gas by Zeolite Membranes The depletion of higher alkanes from methane is a key aspect during the conditioning of natural gases or accompanying gases. Membrane technologies could be used as alternative to energy and cost intensive purifications. Against this background the influence of membrane geometry, composition of the gas mixture as well as temperature and pressure was investigated in separation experiments for methane/n-butane mixtures using MFI membranes.