SEPURAN® NG: A Closer Look at Evonik’s Separation Membrane Material

Direct Perspective from the Manufacturer

Years of hands-on production and laboratory testing at our chemical manufacturing facilities have shaped how we view separation technology for natural gas. SEPURAN® NG emerges from this backdrop—created through repeated trials, hunting for higher selectivity polymers while keeping real-world deployment in mind. This gas separation membrane sits on the backbone of carefully-extruded polyimide hollow fibers, designed on plant floors where uptime, purity, and reliable output truly matter.

The NG model, standing for “Natural Gas,” isn't just another polymer-based filter in the mix. During development, our technicians adjusted the dense polymer structure and bore geometry in small production batches, seeking the right trade-off between CH₄ permeability and CO₂ rejection. The resulting module comes out of cleanrooms tightly wound with thousands of uniform fibers, encased for simple plug-and-play installation in industrial skids. Installers running retrofits or new-build biogas and wellhead units find the module format cuts out extensive pipework or system downtime, which, from our on-site experience, makes a significant footprint difference on the ground. Solid performance isn’t just numbers from booklets—it’s observed daily by operators who value normal operation with less hands-on adjustment.

What Makes SEPURAN® NG Unique

Polishing natural gas at source involves more than separating main streams; it’s a matter of meeting pipeline grade consistently under field variation. Evonik’s polyimide membrane, extruded and cured in-house, stands apart from basic cellulose acetate or polyester blends commonly seen in some older cartridges or lower-price-point offerings. By focusing on uniform fiber wall thickness and high mechanical strength, we deliver a module that reliably handles pressure swings and sour gas spikes, minimizing rupture risk or sudden efficiency drop—issues we’ve seen crop up in other manufacturing lines under factory audits. Customers using our NG modules report fewer unplanned shutdowns since the fibers don’t suffer rapid aging in moist or high-acid environments.

Specifically, SEPURAN® NG shows selectivity for methane over CO₂ up to 50% higher than conventional cellulose acetate membranes at equivalent pressure and temperature, based on comparative tests using real field gas compositions. Our own teams have measured these values using gas chromatographs in pilot plants, rather than relying solely on ideal lab blends. That matters to end users who encounter real world gas feeds instead of sterile lab mixtures.

Applications Observed and Lessons Learned in Implementation

The real test of any membrane material comes on the field. SEPURN® NG modules typically find placement above ground in wellhead skid systems, biogas upgraders, remote compression stations, and landfill gas purification plants. Having worked through hundreds of these deployments ourselves, we’ve found that installers benefit most from the lightweight, modular design. Regular feedback brought to us during commissioning jobs highlights how workers can quickly slot and exchange modules without heavy lifts or machine downtime, a frequent sticking point in other cartridge products.

End users focus on methane losses and energy consumption. SEPURAN® NG modules show reduced methane slip even when operating below optimal transmembrane pressure, something especially noticeable for older field compressors prone to fluctuation. We tuned the module packing density for maximum surface area within a compact shell, a shift that directly answered frequent customer requests for higher throughput without expanding skid footprint. With over a decade supporting North American, European, and Asia-Pacific gas plants, our technical teams have pushed for field upgrades based on these same lessons, feeding direct operator experience into every production run batch.

Manufacturing Experience Makes the Difference

Operational reliability runs right alongside material science in our work. Field maintenance teams visiting our facility often audit our in-process QA steps, noting our use of hydrostatic and pneumatic integrity testing for every module batch. We seldom see the same rigorous test coverage elsewhere among industry counterparts. Each membrane leaves the plant after exposure to real process flows, pressure cycling, and occasional stress testing. Years of root-cause analysis taught our team the value of this up-front discipline: Even one prematurely failed module can lead to lost production days. Every new iteration in the production line—whether rooted in a tweak to fiber casting chemistry or changes to module potting resin—gets evaluated against past failure and repair records. This loop between plant floor and support team underpins equipment reliability that customers later appreciate in the field.

Our shop floor employs engineers with direct site experience; these aren’t just lab scientists but former field service techs, process plant operators, and compressor mechanics. When they gather around a fouled module back from the field, their input goes beyond theory—they recall hours spent at cold, windy gas sites, time lost to unplanned callouts, and expensive temporary pigging solutions before a module swap. SEPURAN® NG’s gradual, predictable fouling profile means better planning, fewer fire drills. Coupled with robust housings designed to resist vibration, internal chemical wear, and pressure surges, these units stand the real-world test of natural gas purification.

Side-by-Side: SEPURAN® NG Versus Other Membranes

Side-by-side field trials gave us unvarnished feedback. At several partner sites, competing cellulose acetate modules displayed early CO₂ breakthrough after less than a year, requiring early replacement. Our NG modules consistently stretched out to 36+ months in similar service, a figure that often reduces lifecycle membrane costs by a substantial margin for plant operators. Techs highlight how NG’s resilience under sour gas loads—especially H₂S and water vapor—translates to fewer unplanned callouts and less frequent module flushing or backpressure mitigation routines.

Comparisons against cheaper low-pressure membrane modules (polyester blend types) show even sharper separation in outcomes: Some operators treat these alternative modules as disposable, swapping them every six months. Our approach, built on higher-grade polyimide fibers with tailored thermal histories, enables longer run times without performance drift. These differences stem from hard-won changes on the production line: Every shift supervisor tracking reject rates, every thermal curing experiment in QA, all feed back on a continuous improvement loop. We build from the ground up—not by tweaking import cartridges, but by engineering from base polymer to final module seal.

Supporting Evidence: Gas Plant Audits and Operator Records

While product datasheets provide static specs, our manufacturing experience hinges on practical, field-level validation. Over the years, customers in Texas, Alberta, and northern Germany opened up the books so we could analyze membrane station run logs and maintenance cycles. Their logs confirm sharply lower frequency of emergency membrane swaps for SEPURAN® NG users, correlated to fewer CO₂ excursions and lower methane slip. These aren’t isolated case studies cherry-picked for marketing—our engineers have walked gas plants during winter and midsummer, involved directly in post-install audits and module teardown. At a Midwestern landfill gas project, for example, the switch to NG modules coincided directly with fewer methane losses in the permeate stream, increased module replacement intervals, and flatter operating cost curves over multiple seasons.

Thanks to direct feedback loops with maintenance engineers, we have witnessed modules run reliably even amid feed composition shifts—high sulfur burdens, ran wetter than forecast, or swung CO₂ ratios. This robustness under variable conditions didn’t come by luck; it resulted from frequent runs back to the drawing board, pushing the limits of spinning, embrittlement resistance, and module potting compound chemistry. Every technical success or hiccup is met by a team fully engaged—from manufacturing line to plant start-up crew—closing the gap between promise and proof.

The Path Forward: Meeting Industry Challenges

Recent raw material shocks and energy price swings have made lifecycle cost a central focus for gas operators. Our own procurement teams wrestle with supply chain volatility daily, so we understand the tightrope customers walk between short-term module swaps and long-run operating expense. SEPURAN® NG’s longer service intervals and predictable pressure drop performance mean fewer supply disruptions for critical operations—a point often overlooked during initial purchase negotiations, but all too clear six months and several troubleshooting cycles later.

One of the recurring technical challenges facing membrane operators relates to moisture, acid gas, or hydrocarbon liquid carryover—problems we’ve observed firsthand in dozens of audit visits. Our module manufacturing process integrates pre-filter screening and water-resistant fiber technology aimed squarely at minimizing downtime from these risks. In practice, customers running gas feeds above 10% CO₂ or dealing with fluctuating delivery schedules find less module fouling and reduced cleaning or flushing cycles. We support these field observations not from theoretical modeling, but by compiling and cross-referencing live operating logs, field service reports, and failure analyses from three continents.

Model Specifications and What They Mean in the Field

Each SEPURAN® NG module leaves our facility with a carefully measured active surface area, optimized for both high throughput and gas purity at various flow rates. Our direct-injection quality checks at the end of the line verify that every batch hits the tested permeability selectivity established in third-party audits and field trials. Our techs personally build and inspect the modules, so on-site engineers interacting with the product can expect consistent performance across shipments. This predictability translates into faster start-up times and smoother online monitoring.

For users questioning which model matches their throughput needs or gas mix, we connect them with engineers who’ve stood exactly where they are—choosing module stacks not from abstract calculations, but from memory of how previous versions performed under similar gas compositions. Whether handling gas feeds at 20 psi or fielding liquefaction-grade pre-treatment, our production knowledge stays rooted in lived experience, bridging engineer to operator with every delivery.

Real-World User Stories: On-The-Ground Feedback

Direct engagement with plant operators reveals where SEPURAN® NG modules excel, compared to options tried previously. Through years of site visits, customer debriefs, and system retrofits, our technical support gathers granular data: field techs favor our modules for durable operation through repeated cleaning cycles, quick module changes, and strong performance under temperature swings. Asked about downtime, several operators report easy return-to-service after routine maintenance, with little to no drop-off in gas purity.

For example, a site operating near the Gulf Coast routinely deals with salty, humid gas feeds that destroyed competing modules within months. SEPURAN® NG units kept running for more than twice that interval with only minor maintenance. Similarly, landfill gas purification teams reported that—after moving to NG modules—unexpected methane losses dropped by more than 5% over several quarters, a bump that tracked directly to improved plant revenue and simpler operation. We hear these patterns echoed at rural biogas plants, urban transfer stations, and heavy industrial compressor banks, giving us clear, actionable feedback for each new production batch.

Choosing SEPURAN® NG: A Manufacturer’s Perspective

For years, our memory of troubleshooting in remote gas plants, wrestling with legacy equipment, and cycling through faulty membrane shipments has shaped how we design and manufacture every SEPURAN® NG module. Unlike generic off-the-shelf options, we keep close tabs on operator feedback and service data, updating our molding and extrusion every quarter to keep pace with real-world results. We don’t base changes on theoretical margins alone; everything must prove itself under test gas, fluctuating temperature, moisture, and the numerous stressors so familiar in industrial operations.

Every request for tighter permeability control, more compact module sizing, or extended life comes directly from the voices of downstream plant staff—those who notice an extra week between shutdowns, a lower compressor draw, or cleaner product gas. In most cases, switching to SEPURAN® NG allows managers to stretch maintenance budgets further, add certainty to production schedules, and cut unplanned breakdowns. We’ve replaced more single-use, short-lived products at customer sites than we can count, each clear-out followed by hours spent reviewing why a better membrane was needed all along. Our direct line from engineering to delivery, with manufacturing rooted in years of plant experience, sets SEPURAN® NG apart.

As a manufacturer, we see the hard bottom line: every downtime hour, every swap, every pressure spike that old modules couldn’t withstand. SEPURAN® NG reflects those years of insight, not just as a polymer blend, but as an answer shaped by feedback, repair records, and daily plant realities. Whether fielded in the harshest gas plays or steady biogas systems, the results remain. Performance, reliability, and long-term field economy define our work. Our commitment doesn’t end when the module ships out; it follows the product to every skid, every audit, and every new job site, proving the value of manufacturing experience in every fiber.