Requirements and Solutions for the Pretreatment of  HVO Feedstocks

Abstract

Hydrotreated Vegetable Oils (HVO) and Hydoprocessed Esters and Fatty Acids (HEFA) are premium quality biofuels that are produced via hydrotreatment of renewable (waste) feedstocks from vegetable and animal origin. HVO/HEFA production is increasing rapidly worldwide and this is supported by several growth drivers. HVO/HEFA has a better functionality compared to classical biodiesel based on fatty acid methyl esters (FAME)  and it is fully compatible with mineral diesel. HVO/HEFA fractions can also be used as sustainable aviation fuel (SAF). All major (European) airlines have recently announced that they will start using increasing volumes of SAF on voluntary basis in anticipation of a future compulsory SAF proportion. Initially, HVO was mainly produced from food-grade oils (e.g. palm oil, soybean oil). However for sustainability but also economical & political reasons, producers are increasingly looking for alternative (lower quality – non food) feedstocks such as UCO, waste animal fats, by-products from edible/technical oil refining, distillation pitches and even non-glyceride feedstocks. 
Independent of the applied technology, all HVO feedstocks need to be pre-treated before they can enter the hydrotreatment process. Specific pre-treated feedstock specifications depend on the HVO technology provider. In general, the pre-treatment is necessary to remove impurities such as P and metals but also nitrogen and chlorine containing components in order to increase the HVO catalyst life time and to avoid corrosion problems in the plant.
Pre-treatment of ‘good quality’ feedstocks (vegetable oils, used cooking oils, some animal fats) is pretty straightforward and can be accomplished by a series of processes that are already known from the edible oil refining processes. Proper pre-treatment of lower quality feedstocks is much more challenging and requires a more complex, multi-stage process that consists of a series of dedicated unit operations. HVO/HEFA producers are very interested in such efficient pre-treatment processes as their availability and industrial applicability will finally determine if/to which extend a given low quality feedstock can be used which will directly impact the economical viability of their HVO plant.