Continual population growth and rapid development in Saudi Arabia elicits a rising demand for their natural gas resources to satisfy domestic energy needs. Conventional separation techniques such as amine scrubbers and other sorbents effectively remove contaminants like CO2 and H2S from natural gas, but these energy-intensive processes require regeneration and skilled operation. A burgeoning technology used in conjunction with these processes to lower energy input and overall cost of natural gas treatment utilizes membranes for gas separations. Membranes suitable for the removal of sour and acid gas species already see success in oil and gas operations, but less-developed membranes that can facilitate the removal of valuable heavy hydrocarbons (C3+) for petrochemical applications offer additional opportunity. This talk describes Aramco’s development of substituted poly(norbornene) [PNB] membranes for enhanced C3+/C1 separations. These efforts began with the synthesis of a systematic series of alkoxysilyl-substituted PNBs using both ring-opening metathesis polymerization (ROMP) and addition-type polymerization (APN) techniques, yielding PNBs with dramatic differences in polymer backbone structure and packing ability. NMR characterization confirmed polymer structure and endo-exo isomerism, which impacted microstructure and yield. X-ray diffraction elucidated increases in inter-chain d-spacing as a function of increasing alkoxy substitution, which suggested increasing free volume in the synthesized materials. Single-gas permeation studies revealed the superior performance of the addition-type alkoxysilyl PNBs and demonstrated a doubling of C3+/C1 selectivity compared to a previously studied trimethylsilyl PNB derivative. Finally, more extensive and realistic permeation studies using various mixed gas feeds allowed for further evaluation and a deeper understanding of these materials’ performance.

Alkoxysilyl poly(norbornene) membranes for enhanced heavy hydrocarbon removal in natural gas separations: Synthesis and performance

254th National Meeting (2017)

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