The scientists from the Federal Research Center Institute of Catalysis, a Siberian Branch of the Russian Academy of Sciences, with support from the Russian Science Foundation, have improved the technology for producing isoalkanes – hydrocarbons used in the manufacture of motor fuels, solvents, cosmetics, and other chemical products. The researchers have developed a new catalytic system based on nickel phosphide and SAPO-11 silicoaluminophosphate zeolite, designed for processing plant-based feedstocks. The use of this catalyst made it possible to significantly lower the solidification temperature of the final product while simultaneously reducing its production energy costs.
Isoalkanes are considered an important component of modern fuels because of their high knock resistance and better performance at low temperatures in comparison with conventional linear hydrocarbons. They can be obtained not only from petroleum but also from renewable feedstocks, such as vegetable oils or food waste. However, this approach has a problem: primary processing produces linear alkanes, which are poorly suited for cold climates due to their high pour point. In some cases, it can reach +20 °C.
To solve this problem, the scientists used a nickel phosphide-based catalyst with the addition of SAPO-11 zeolite – a porous material capable of rearranging the linear molecules into the branched ones. It is this structure that improves the fuel low-temperature properties. Additionally, the researchers modified the system with boron, which helped fine-tune the catalyst’s acidity and reduce the number of side reactions in which part of the feedstock is lost without formation of the desired product.
The main advantage of the new technology is that the processes of oxygen removal from the plant feedstock and isomerization – the conversion of linear hydrocarbons into the branched ones – have been successfully combined into a single stage. Typically, such operations are carried out separately, which requires additional energy and complicates production. Furthermore, unlike common sulfide catalysts, the new system does not require the addition of sulfur to maintain activity, making the process more environmentally friendly.
According to the researchers, the use of SAPO-11 made it possible to lower the pour point of the resulting alkanes to approximately -20 °C, which makes such products suitable for use in regions with cold climates and improves the prospects for industrial production of the renewable fuels from oils and fats.
As a model feedstock, the scientists used methyl palmitate, which is an organic compound derived from palmitic acid and found in many plant and animal fats. This substance is often used in research as a simplified model of vegetable oils. In the future, as the technology is scaled up, it can be replaced with the used cooking oils.
The researchers are now preparing for testing the catalyst on a pilot scale, and plan to produce it in a granular form suitable for industrial use.
