Natural Gas processing by the use of New Membrane Materials

As we are now approaching the end of the project, we are happy to announce that we we have succesfully achieved a high, maintained selectivity CO2/CH4 with good margin (> 30) but we have still not reached the goal for permeaance at high pressures for the flat sheet membranes (0.3 m3(STP)/m2.h.bar). During the last year the membrane were also coated on hollow fibers, and then higher permeance (0.25 m3(STP)/m2.h.bar)was achieved while still maintaining high selectivity (37). The membrane has also been teste d for durability over long time for exposure to impurities like H2S, methanol and higher hydrocarbons - the material does not degrade and maintain performance - this is very incouraging. The collaboration with the two companies Statoil and Petrobras is ve ry good, and during the last year there has been very good discussions on the potential membrane process solution as well. We have successfully fulfilled the goals set out for the project, and are currently discussing a follow-up project with the partners Statoil and Petrobras in order to move check out the potential of moving even closer to a demonstration of the technology.

The idea is to develop further a CO2-selective membrane which can withstand the high pressures used for natural gas sweetening, while keeping the good separation properties already documented for CO2-CH4 separation on lab-scale and lower pressures. The du rability of the material over time is also crucial for the membrane separation, and will be documented when exposed to trace impurities in various amounts. From analysis of these results, any pretreatment of the gas which may be needed will be recommended . In parallell with the experimental tests, simulations will be performed to document efficiency of the integrated membrane process. Last but not least, an assessment of the membrane process towards commercialization will be conducted. The Innovation proj ect is a follow up of a KMB-project where the membrane was developed and tested on lab-scale. Further optimization is needed. The current membrane is a membrane prepared from polyvinylamine (PVAm) and polyvinylalcohol (PVA) in a certain blend ratio. The s upport material is polysulfone (PSf). The transport mechanism of CO2 through the membrane is based on both solution-diffusion and facilitated transport caused by the fixed amine carrier in the PVAm. This will enhance the permeation of CO2, while the perme ation of CH4 will be more restricted, and will be retained on the high pressure side of the membrane. Both the support and the selective membrane itself may need to be mechanically strengthened to tolerate the high pressures. Two high pressure test rigs are available for the project, one for permeation measurements and one for long term durability measurements. The experimental rig for permeation can easily be modified to be placed on a skid and transported to a test site for exposure to real gas. Bench marking of the separation properties will be done using commercially available cellulose acetate (CA) membrane, to which the PVAm-PVA membrane will be compared.