This Small Business Innovation Research (SBIR) Phase II project proposes to develop a novel membrane for a broad spectrum of hydrocarbon separations. The initial focus of the project is the development of a selective membrane for efficient separation of hydrocarbons from methane in natural gas processing and separation of hydrocarbons from hydrogen in refinery applications. The chemically robust polymeric membrane will be of a composite configuration comprised of a hollow fiber porous support with a superimposed several hundred angstroms thick separation layer. The nano-structured morphology of the separation layer will enable selective fractionation of hydrocarbon molecules.
The broader/commercial impact of this project is the reduction of energy consumption currently used in separation and purification of hydrocarbons found in oil and gas. In addition, if successful, petrochemical industries will reduce emissions of green house gases, including methane and carbon dioxide. The membrane will effect molecular level separation of hydrocarbons and will be capable of operation in harsh environments and at high temperatures. The initial market for this technology is the recovery of natural gas and hydrocarbon liquids from the associated natural gas in remote geographic locations (gas generated during oil production) that is currently flared. Development of the proposed technology will enable recovery of the methane and high value hydrocarbons at the well with extensive economic and environmental benefits. The membrane is expected to find further utility in high value gas and liquid separation applications including hydrogen recovery from refinery fuel gas, olefin/paraffin separation, and generic hydrocarbon fractionation.
Hydrocarbon separations are at the core of the chemical and petrochemical industries and are carried out almost exclusively by distillation or deep refrigeration. These processes are energy intensive and do not scale down efficiently which can lead to underutilization of hydrocarbon feedstock. For example, a number of hydrogen containing streams in refineries are currently used as a fuel due to the lack of efficient hydrogen/hydrocarbon separation technology. Large volumes of natural gas generated during oil production (associated petroleum gas) are flared due to the lack of an efficient separation technology that can treat the gas at the wellhead. Membrane technology can be energy efficient and it is highly compact. The technology is ideally suited for the treatment of natural gas at isolated geographic locations and on off shore platforms. However, the poor separation efficiency and the lack of chemical durability have limited membrane utilization in hydrocarbon separation applications to date. The overall objective of this NSF SBIR program was to develop a comprehensive membrane separation platform for a broad spectrum of hydrocarbon separations. This objective was successfully accomplished by developing a novel composite polymeric membrane comprised of an ultra-thin separation layer formed from a nanostructured polymer superimposed on a porous hollow fiber substrate formed from the engineering polymer poly(ether ether ketone), PEEK. The composite membrane exhibits hydrocarbon permeation characteristics inverse to the hydrocarbon molecule size, i.e., the membrane permeates larger hydrocarbon molecules faster than smaller hydrocarbons, as opposed to conventional glassy polymeric gas separation membranes that preferentially permeate smaller molecules. The membrane structure and its hydrocarbon separation characteristics are shown schematically in Figure 1. The composite membrane exhibits exceptional hydrocarbon separation characteristics. In Phase II of the program, PoroGen Corporation, PGC, has successfully optimized and scaled up the novel composite hollow fiber membrane preparation. Commercial size membrane modules were constructed and their separation performance evaluated. The technology is ready for field demonstrations. The membrane process design and economic analysis was completed. The analysis indicates that the membrane process utilizing the novel composite hollow fiber membrane is more economical in terms of capital cost and operating costs as compared to the conventional refrigeration process.
