(635b) Additive Solutions for Renewable Fuels and Feedstocks

Increasing pressure from regulatory authorities as well as end-use consumers is driving refiners and fuel producers away from petroleum-derived hydrocarbons and toward more sustainable hydrocarbons that can support a circular economy. A broad mixture of alternative energy sources continues to be developed and commercialized (e.g., electric vehicles, solar panels, wind turbines, etc.), but combustible fuels derived from biological hydrocarbon sources will continue to be a key piece of that energy mixture. Some types of biofuels such as biodiesel (e.g., FAMEs; fatty acid methyl esters) have been known and commercially produced for decades. Other forms of biofuels such as hydrotreated vegetable oil (HVO), also referred to as renewable diesel (RD), are somewhat newer, particularly in US-based markets, but have likewise been produced for many years. Despite their long history, both actual and planned production of biofuels is increasing substantially, and the relative mixture of fuels being produced is also expected to undergo a significant shift in the near term. The Energy Information Agency (EIA) has recently reported that RD production will surpass biodiesel production for the first time ever in 2022, and continue to increase thereafter. Concurrently, conventional ULSD production is projected to decrease as fuel producers shift away from petroleum sources to meet increasing consumer demand. In broad terms, these dynamics are widely acknowledged within the industry, but appear to be gaining momentum as highlighted by the EIA report. While treatment strategies for petroleum-derived fuels have been studied and perfected for decades, the requirements and preferred solutions for biofuels are less well understood. This gap needs to be addressed in order to ensure that the rapid increase in biofuel production and use is accomplished in a safe and reliable manner.

In this paper, we will discuss experimental findings regarding the chemical and physical properties of biofuels and their feedstocks, differences between biofuels/feedstocks and their petroleum-based counterparts, and a variety of chemical treatments that can be used to alter the properties of biofuels and feedstocks. Treatment requirements vary significantly depending on the biomass feedstock, as well as the process conditions (e.g., transesterification versus hydrotreatment). Our goal herein is to provide a broad overview of these differences, as well as an overview of the chemical additives that can be used to ensure that key specifications are met. In some cases, those specifications are prescriptively defined (e.g., conductivity and lubricity requirements outlined in ASTM D975), but in other cases the specifications are subjective and left to individual producers or end users (e.g., cold flow requirements for feedstocks).

Our studies have shown that in many cases the preferred chemical additives used for the treatment of biofuels are substantially similar to those used in petroleum-derived fuels. For example, despite the differences in the chemistry of biofuels and petroleum-derived fuels, the underlying mechanisms required to achieve needed anti-static properties or anti-wear (lubricity) properties do not change depending on the source of the hydrocarbon. Dosage requirements may be different, and those differences will be discussed, but the fundamental role of the chemistry remains the same.

There are other cases, however, where the differences in the chemical properties of the feedstocks and fuels have a more significant impact on the preferred chemical treatments. One example of this relates to cold flow properties (e.g., CFPP, cloud point, pour point). In this case, compositional differences in the feedstocks and fuels can have a significant impact on both the properties of the untreated stream as well as the response of the stream to various treatments. We have found that treatments that may be preferred for use in petroleum-derived streams are not necessarily preferred for use in biologically-derived hydrocarbon streams.

Nalco Water is fortunate to work with a broad customer base and our work in additive solutions for biofuels dates back to the earliest days of biodiesel commercialization. However, in response to shifting market demands, we have placed particular emphasis in this area over the last 2 years. A family of products has been commercialized that is specifically designed to address the needs of this field of application. We believe these products will enable fuel manufacturers both to reliably process biofeedstocks in their operations and generate quality fuels that are suitable for use in consumer markets.

Key areas that will be discussed in this paper include cold flow improvers (e.g., pour point depressants, cloud point depressants, CFPP depressants), conductivity improvers (also known as anti-static additives), lubricity improvers, and antioxidants. Nalco Water is also heavily involved in process-related chemical treatments that are used to facilitate the conversion of biofeedstocks into intermediates and finished fuels, but this work is beyond the scope of the current paper and will be described separately.