INFORM April 2025

BIODIESEL

inform April 2025, Vol. 36 (4) • 25

but involves high capital and energy costs and produces fatty acid distillate (FAD), requiring further downstream operations. Chemical neutralization (also Super Degumming or Chemical Refining) reduces FFA by forming soap. It is typically applied to feedstocks with FFA amounts below two weight per cent, like soybean or rapeseed oil. Since the resulting neutral oil is trapped in a soapstock byproduct, this process causes high product losses or troublesome recovery downstream. Glycerolysis involves reacting high quality glycerol with FFA to form glycerides at high temperatures and under vac uum, driving up energy and capital costs substantially. It is mainly used for high FFA feedstocks like FAD. As the product is subjected to high temperatures for an extended period, tar formation and color increase are common issues. Acid-catalyzed esterification converts FFA to FAME. It is commonly used for high and medium concentration FFA oils

and fats such as used cooking oil (UCO), animal fats, distillates, and the like. However, it has significant indirect costs due to equipment corrosion, high methanol dosage and rectification costs, in addition to undesirable side reactions. Finally, many producers operate an additional integrated alcoholic neutralization (AN) process to one or more of the four main processes described above. It reduces the require ment for FFA reduction in any of the prior processes by using the alkaline glycerol byproduct of the transesterification to neutralize residual FFA in the feedstock. INTRODUCING A NEW ENZYMATIC CONCEPT To overcome the limitations and challenges associated with existing pretreatment process technologies, Novonesis and BR Process partnered to develop a new, patent pending, enzymatic pretreatment known as Eversa® Advance. This

Methanol and Catalyst

Main Pretreatment Stripping/ Neutralization/

FFA < 2 wt% if AN FFA < 0.2 wt% if no AN

Neutralized oil FFA < 0.2 wt%

Alcoholic Neutralization (AN)

Crude biodiesel product

Feedstock oil

Alkaline Transesterification

Glycerolysis/ Esterification

Sidestreams

Neutral crude glycerin

Main AN process

Alkaline crude glycerin

Crude Glycerin

An example of a general biodiesel processing scheme with pretreatment options. The choice of main pretreatment must accommodate the incoming feedstock FFA concentration. Source: Novonesis.

Methanol addition for feedstocks with FFA >10 wt%

Base catalyst