How to Achieve Refinery Flexibility with Effective Renewable Fuel Pretreatment
With international emission reduction targets set under the Paris Agreement, there is increased pressure for the renewable fuels industry to produce lower-carbon intensity transportation fuels. Around the world, industry drivers such as blending obligations set by local governments, targets set by private industries, and regional tax incentives, are sparking the demand for renewable fuels. For refiners looking to tap into the growing demand and optimize production of renewable diesel and sustainable aviation fuel (SAF), sufficient pretreatment of renewable feedstocks is critical to success.
Why is pretreatment necessary when producing renewable fuels?
Feedstocks for renewable fuels can come from a variety of sources, including animal fats, used cooking oil, and yellow grease, depending on availability. The challenge is that phosphorus and other metal contaminants are present at higher levels in renewable feedstocks than in traditional crude oil and can negatively affect refinery performance if not properly removed. In most cases, for optimized hydroprocessing conversion, these contaminants must be reduced to below 10 ppm in total. If not removed, phosphorus and metals can lead to downstream issues resulting in unexpected downtime and lost productivity.
What’s more, contaminated feedstocks can consume refining catalysts at a much higher rate – requiring catalyst replacement more often than the typical two years or more – an expensive and wasteful proposition. Feedstock pretreatment can help ensure catalyst lifespan and reduce the amount of maintenance and turnarounds required at the refinery.
The benefits of Synthetic Amorphous Silica as an adsorbent
The pretreatment process includes:
- Blending the feedstocks
- Filtering out larger particulates
- Degumming with acid (and optional water-washing)
- Impurity adsorption to remove phosphorous- and metal-based species
That final adsorption step is critical for achieving catalyst specifications, but not all adsorbents are created equal. Synthetic Amorphous Silica (SAS), including TRISYL® silica from Grace, is more effective than other adsorbents, such as Bleaching Earth or Diatomaceous Earth (DE), because of its physical and chemical properties, including:
- Moisture content > 60% which attracts polar contaminants more efficiently to the adsorbent’s surface
- No detectable traces of crystalline silica
- The low (undetectable) levels of pro-oxidant metals in SAS avoids the undesired chemical reactions seen with mined materials such as bleaching earth and DE.
- High adsorption capacity and low dosage requirement, resulting in less spent filter cake and lower oil losses when compared to BLEACHING EARTH or DE
In a recent webinar presented by Biodiesel Magazine and Grace, our biofuel experts, Chelsea Grimes and Natalia Krupkin, explore in more detail why renewable fuel feedstock pretreatment is the key to refinery flexibility and the six ways you can realize savings when switching to TRISYL® silica adsorbents.