Renewable Diesel Feedstocks: Pretreatment and Purification

In recent years, I've had countless conversations with clients looking to transition from fossil fuels to renewable diesel. They often ask the same question: How can we ensure the feedstocks we use deliver consistent, high-quality renewable fuel without harming our equipment or exceeding our budget?

Renewable diesel feedstock pretreatment and purification are critical processes that remove contaminants, protect catalysts, and enable the use of low-cost, sustainable raw materials like waste oils, animal fats, and used cooking oil.

As an engineering solutions provider at Myande Group with over 20 years of experience in edible oil and biofuel processing, I've seen firsthand how optimized pretreatment systems turn diverse, raw feedstocks into clean, high-value fuel inputs. In this post, I’ll walk you through the key stages, technologies, and benefits of renewable diesel feedstock pretreatment and purification.

What Are Renewable Diesel Feedstocks?

Renewable diesel is made from a wide range of feedstocks. Each type presents unique challenges that require customized pretreatment strategies.

The most common feedstocks for renewable diesel include vegetable oils, animal fats, and used cooking oil. Their composition affects process design, purification needs, and end-fuel quality.

🔍 Feedstock Types Overview

Depending on the region and market economics, a plant may rely heavily on low-cost waste oils or focus on high-purity vegetable oils. Either way, pretreatment is essential.

Why Pretreatment Is Essential

Before any renewable feedstock can be converted into diesel, it must be thoroughly cleaned and stabilized.

Pretreatment removes solids, moisture, metals, phospholipids, and free fatty acids to prevent catalyst damage, ensure consistent output, and reduce operating costs.

Without effective pretreatment, hydrotreating catalysts can quickly foul, leading to unplanned shutdowns, reduced fuel yields, and increased hydrogen consumption.

Key Steps in the Pretreatment Process

At Myande, we design pretreatment systems to match each feedstock's specific impurity profile. Here’s a typical process flow:

✅ Renewable Feedstock Pretreatment Flow

We typically use pressure leaf filters, silica-based bleaching agents, and centrifugal drying systems to achieve high throughput and consistent results.

What Happens During Hydrotreating and Final Purification?

Once feedstocks are pretreated, they enter the hydrotreater. This is where the real transformation happens.

Hydrotreating removes oxygen, sulfur, and nitrogen from the feedstock using hydrogen gas, turning triglycerides into paraffinic hydrocarbons—essentially renewable diesel.

🔬 Final Purification Steps

1. Hydrotreating: High-pressure hydrogen reacts with feedstock to eliminate contaminants and convert fats/oils into hydrocarbons.

2. Filtration & Adsorption: Post-treatment polishing removes trace impurities to meet fuel standards like ASTM D975 or EN 15940.

3. Polishing: Adsorbents such as perlite or diatomaceous earth ensure low sulfur and metal levels.

Advanced plants may explore membrane separation or microfluidic technologies to improve efficiency, but traditional methods remain dominant due to their reliability.

Benefits of Effective Pretreatment and Purification

Done right, pretreatment doesn't just clean your feedstock—it transforms your operation.
Effective pretreatment extends catalyst life, reduces maintenance, increases uptime, and allows you to use cheaper, lower-grade feedstocks without compromising fuel quality.

🌟 Key Advantages Table

We've helped clients worldwide upgrade their operations to process even the dirtiest feedstocks—without sacrificing output or reliability.

What is the HVO Pretreatment Process?

The HVO (Hydrotreated Vegetable Oil) process demands especially rigorous pretreatment to protect the sensitive catalysts used in hydrotreating.

The HVO pretreatment process removes solids, phospholipids, metals, chlorides, moisture, and free fatty acids through filtration, degumming, bleaching, and drying.

What is the FAME Process in Biodiesel?

FAME (Fatty Acid Methyl Esters) is the chemical foundation of traditional biodiesel. It’s produced using an entirely different method from renewable diesel.
FAME biodiesel is made through transesterification, where oils react with methanol and a base catalyst to produce methyl esters and glycerol.

🔄 FAME Biodiesel Production Steps
1. Feedstock Pretreatment
Solids and water removed
Free fatty acids neutralized

2. Transesterification
Oils react with methanol and KOH/NaOH
Forms FAME + glycerol

3. Separation & Washing
FAME washed and dried
Glycerol collected as byproduct

4. Quality Testing
Must meet EN 14214 or ASTM D6751 standards

While FAME is widely used, it contains oxygen, is more sensitive to water, and has shorter shelf life compared to HVO.

What is the Difference Between HVO and FAME Biodiesel?

At first glance, both HVO and FAME are biofuels. But dig deeper, and you'll find critical differences in composition, performance, and compatibility.
HVO is a pure hydrocarbon, making it a true diesel substitute, while FAME retains oxygen and requires blending.

⚖️ HVO vs FAME Comparison

Conclusion

Renewable diesel production isn’t just about converting oils into fuel—it’s about engineering a reliable, cost-effective, and sustainable system from start to finish.

At Myande Group, we bring two decades of experience across 800+ global installations to design turnkey renewable diesel pretreatment solutions tailored to your feedstock and capacity needs.

Whether you’re upgrading your feedstock flexibility, reducing costs, or scaling up for the future—our team is here to help you turn renewable potential into performance.