Optimizing Renewable Diesel Production with Advanced Pretreatment
- Amelia Reid and Kristina Thompson
- 1 hour ago
- 5 min read
Solving feedstock challenges with diatomaceous earth and perlite.
As the 2026 Renewable Fuel Standard quotas come into full effect, biofuel refineries are under pressure to ramp up production while maintaining peak operational efficiency. Feedstock variability, however, is a hindrance to optimal throughput. As feedstock blends evolve to meet new regulations and economic realities, producers must manage a wide spectrum of inconsistent contaminant profiles. These fluctuating inputs can contain unpredictable levels of phospholipids, soaps and polyethylene that can quickly “blind” filters and halt production. For modern refineries, the solution to this volatility lies in advanced-pretreatment strategies using high-performance mineral filter aids and innovative filterable adsorbents like Celite®, Kenite®, Harborlite® and CynerSorb®.
The 2026 RFS Mandate: A Race for Throughput
The U.S. EPA’s RFS program has set the bar high for 2026, demanding higher renewable volume obligations (RVOs) than ever before. For refiners, these quotas demand maximum throughput. In the world of renewable diesel, throughput is often dictated by the pretreatment stage. Unlike traditional petroleum, renewable feedstocks are biological and inconsistent. If a refinery cannot process these feedstocks at scale, they risk falling short of their blending mandates and facing significant financial penalties.
The primary threat to this throughput is filter blinding. When processing waste fats and oils, contaminants ranging from phospholipids and soaps to polyethylene and trace metals can quickly form a thin, impermeable layer over filters. This “blinding” causes pressure to spike and flow rates to plummet, forcing frequent shutdowns for cleaning. To survive in the 2026 regulatory environment, refineries and feedstock pretreaters must move away from reactive maintenance and toward proactive filtration chemistry.
Power of Pretreatment with Perlite, DE
Imerys has developed mineral-based filter aids and filterable adsorbents specifically designed to solve the unique operational challenges facing the biofuels market. The goal of diatomaceous earth (DE) and perlite filter aids in the advanced-pretreatment stage is to create a porous and permeable filter cake that can trap high volumes of contaminants without sacrificing flow.
DE remains the gold standard for high-clarity filtration. Composed of the fossilized remains of diatoms, DE possesses an intricate, honeycomb-like structure. This unique morphology provides a massive internal surface area that is highly effective at capturing microscopic solids suspended in liquid. By removing these elements during pretreatment, DE protects the expensive downstream catalysts used in the hydrotreating process, extending their lifespan and ensuring the final fuel meets rigorous standards.
As feedstocks become “dirtier” and more viscous, however, perlite becomes a powerful part of the mineral toolkit. Perlite is a volcanic glass that, when heated, expands to many times its original volume. Imerys’ perlite filter aids are characterized by their lightweight, jagged structure. This makes them exceptionally effective at handling gelatinous contaminants found in recycled waste oils. Perlite creates a bulky, incompressible filter cake that maintains high porosity even under the high-pressure conditions required to move thick tallow or used cooking oil (UCO) through a system. Because perlite is lighter than DE, it also offers a density advantage, often requiring less material by weight to achieve the same volume of filtration.
Adjustable Permeability, Dosage for Feedstock Variability
In the volatile biofuels market, the ability to pivot between different feedstocks without significant mechanical reconfiguration is a competitive advantage. Diatomite and perlite filter aids provide this agility through adjustable permeability and variable dosage rates. Because waste-based feedstocks like UCO and tallow vary significantly in contamination levels, a one-size-fits-all filtration approach can lead to inefficiencies or potential system failure.
By selecting specific grades, producers can dictate the porosity of the filter cake, ensuring that even the most viscous, impurity-laden oils maintain a steady flow. The flexibility extends to real-time dosage adjustments to the body feed. When sensors or lab results detect an uptick in aggressive contaminants, operators can immediately increase the dosage of mineral aid to create a more rigid cake that prevents these particles from slowing production cycles. Conversely, for cleaner batches, reducing the dosage minimizes material costs and waste volume. This control allows refineries to maximize their throughput and protect downstream assets, providing the operational resilience needed to meet aggressive 2026 quotas while processing the widest possible variety of low-cost, high-impurity feedstocks.
Minerals Engineered for Biofuels: The Imerys Portfolio
Imerys’ innovative approach to feedstock pretreatment addresses the industry’s evolving needs through a comprehensive suite of tailor-made filtration solutions. Leveraging over a century of expertise, Imerys helps plant operators navigate complex business constraints and optimize system performance. Our extensive portfolio includes DE filter aids Celite® and Kenite® as well as perlite-derived Harborlite®. By providing the necessary flexibility to manage varying contaminant profiles across a wide range of permeability requirements, these solutions effectively reduce waste-disposal costs while ensuring maximum clarity.
The portfolio is further enhanced by CynerSorb®, a unique family of filterable adsorbents designed to overcome the limitations of conventional pretreatment. CynerSorb employs a multilayered removal strategy: a DE substrate for superior solid-liquid separation, a silica-gel layer to adsorb soluble contaminants, and chelating chemistry to transform impurities into filterable species. By eliminating the poor filtration functionality of traditional adsorbents, contaminants can be removed without excessive waste. These improvements can lead to substantial annual cost savings, potentially reaching six to seven figures for some facilities, offering a promising financial outlook. Systems utilizing high-permeability CynerSorb® can decrease total powder-dosage rates by 50 percent or more. This reduction leads to significantly higher yields, fewer filter cycles and a dramatic decrease in waste cake, providing the operational resilience required to meet aggressive production targets.
The Imerys Advantage: World-Class Technical Support, Partnership
While high-performance minerals are the foundation of successful pretreatment, the complexities of modern biofuel refining require more than just a drop-in product. They require a partnership. Imerys distinguishes itself in the global market through a robust technical-support infrastructure that bridges the gap between mineral science and industrial application. For biofuel and feedstock producers, Imerys provides a deep bench of scientists, application engineers and filtration specialists who work directly with plant personnel to customize solutions.
This technical support begins with comprehensive feedstock characterization and lab-scale testing. Given the extreme variability of modern feedstocks, Imerys specialists conduct detailed filtration tests to determine the optimal filter-aid blend for a specific facility’s unique contamination profile. This prevents the costly trial-and-error approach that many refineries suffer when switching to lower-quality oils. By simulating plant conditions in the lab, Imerys can recommend the precise combination of filter aids to achieve the desired flow rate and clarity at the lowest possible dosage.
At the Imerys Technology Center in Johns Creek, Georgia, scientists are engineering the next generation of CynerSorb® to target one of the industry’s toughest hurdles—advanced phosphorus removal. Developed in direct response to urgent requests from market players struggling to eliminate forms of phosphorus notoriously resistant to traditional chemical and physical methods, this project highlights the Imerys R&D philosophy. We don’t just supply minerals—we collaborate hand-in-hand with our partners to pioneer solutions for their most pressing technical challenges.
Beyond the lab, application engineers visit refineries to analyze the entire filtration circuit from the precoat tanks and body-feed systems to the filter presses or leaf filters themselves. During these audits, they identify mechanical bottlenecks, calibrate dosing equipment and train operators on how to adjust filter-aid ratios in response to changing feedstock indicators. This ground-level support is critical for maintaining high-speed production cycles. If a refinery experiences an unexpected spike in pressure or a decline in clarity, Imerys’ global network ensures that technical expertise is available to diagnose the issue quickly. In an industry where a single day of downtime can cost hundreds of thousands of dollars, the value of having a dedicated technical partner cannot be overstated.
The success of the renewable diesel industry hinges on the ability to turn waste oils into high-quality energy. Changing feedstock blends is inevitable, but the operational risks they pose are manageable. Through the strategic use of Imerys minerals, refiners can overcome the threat of filter blinding, protect their downstream assets and maximize throughput. In doing so, they do more than just meet RFS quotas—they build a resilient, efficient and truly renewable future for global transport.
Authors:
Amelia Reid
Scientist, Imerys
Kristina Thompson
Marketing Manager, Imerys
