How to Mitigate the Risks Due to the Implementation of New Technologies

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Refining Catalyst risk

Another important factor impacting the risk assessment is the nature of the catalysts used in the process. Two types of catalysts exist: homogeneous and heterogeneous catalysts. Homogeneous catalysts are soluble in the reaction medium, while heterogeneous catalysts are solid catalysts that convert liquid or gas feedstocks. A comparison of heterogeneous and homogeneous catalysts is provided in the Table 2. Factors, such as diffusion limitations, poison sensitivity and poor mechanistic understanding, increase the risk when implementing processes employing heterogeneous catalysts.

In the oil & refining industry, over 90 per cent of the products will come in contact with solid heterogeneous catalysts. The catalyst may consist of several components, such as zeolite, metals and binder. Often the catalyst is dual-functional in that the acidic function, provided by the zeolite, catalyzes cracking and isomerization reactions, and the metal function catalyzes hydrogenation reactions, as is the case of hydrocracking catalysts. This, tied to the variability of the composition of the crude oil fractions, increases the risk of implementing new technologies in refineries.

Catalyst Risk and Biofuels

In the biodiesel industry, vegetable oil – typically sourced from soybeans in the United States, consists of triacylglycerides, also called triglycerides, which are reacted with methanol with a catalyst to produce Fatty Acid Methyl Esters (FAME) and glycerol.

This reaction is called transesterification. The fatty acid methyl esters constitute the biodiesel. The catalyst used in this process is sodium or potassium hydroxide, which is dissolved in the alcohol. The sodium hydroxide is charged as flakes of 99 per cent+ purity; the potassium hydroxide is also charged as flakes but its purity is 90-92 per cent with the remainder being crystalline water. Although based on economics, sodium methoxide solutions can be delivered to the plant, thereby avoiding mixing the hydroxide with the methanol at the plant site.

The feedstock is typically soybean oil of high purity. These free fatty acids can be troublesome at higher concentrations, since they react with sodium hydroxide and form soap and water via saponification, leading to catalyst consumption. High free fatty acid content requires an acid-catalyzed esterification pretreatment step.

Comparison of the properties of the sodium hydroxide catalyst to the list in Table 2, shows that these catalysts are consistent with those of homogeneous catalysts. They are in the same phase as the reaction medium. Further, the catalyst chemical composition and structure are known and the reaction mechanism is well understood. Consequently, the risk when implementing this technology is substantially reduced.

Start-up companies in the biofuels industry in particular have to deal with higher levels of risk, since programs, which test new concepts in catalysis or process quite different feedstocks, are often initiated without extensive data – and rapid initial testing is needed to quickly explore the potential of these concepts. Feedstocks being tested are often bio-mass sourced, and have substantially different compositions than conventional crude oils.

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