Catalyst testing for renewable fuels and chemicals The possibilities and best practices to run renewable feedstocks in high throughput units are presented
Giada Innocenti, Kai Dannenbauer, Jochen Berg, Xavier Sanz and Ioan-Teodor Trotus hte GmbH
W orldwide sustainability goals are calling for a major redesign of the petrochemical and chem- ical industries. The net-zero CO₂ emission goals set for the next decade require such industries to improve their efficiency and start relying on different raw materials. Selected resources need to be either renewable, such as vegetable oils, animal fats, and sugars, or recycled, such as pyrolysis oil or used cooking oil. Additionally, they need to be widely available and not food competitive. Food competition makes using most of the feedstocks that are well-characterised and commercially ready (vegetable oils) challenging in the long term. Thus, the need to test feedstocks deemed more challenging, such as pyrolysis oil, will become very relevant soon. The use of such feedstocks will also perfectly match the concepts of a circular economy that aim to use the wastes of one industry as feedstocks for another. However, such types of feedstocks are currently not close to commercial implemen- tation and require additional developmental work.¹ State-of-the-art tools are required to fill the gap in the development and optimisation work required for the effi - cient conversion of renewable raw materials. High through- put experimentation technology can be employed to test many reactors in parallel under relevant process conditions. Experimental data can be generated at an unprecedented rate, enabling acceleration of process development, the quick choice of the most economically productive catalytic system from many options available, the development of new catalysts, or simply the execution of proof-of-concept studies. This type of testing is very important in fluid cata - lytic cracking and hydroprocessing to evaluate the perfor- mances of different catalytic systems.² High throughput experimentation enables a quick and effective exploration of the experimental space. It can be easily associated with design of experiment (DOE) to get the most out of a limited number of tests. Regardless of the feedstock and the experimental plan to be run on a high throughput unit, preparation and vali- dation are key. It is important to make sure that liquid, gas, and H₂ recovery are 100% to ensure high data quality and reproducibility. The renewable resources discussed here are vegetable oils (VO) and pyrolysis oil (PO). These two feedstocks are
at very different technological development stages, as they present different challenges associated with their use.¹ VO hydrotreatment in laboratory-scale units VOs are, in general, mixtures of triglycerides. A triglyceride molecule is composed of three fatty acids esterified with a molecule of glycerol. Fatty acids have an even number of car- bon atoms, most often arranged as chains between 16 and 20 atoms long, and a variable number of unsaturation (typi - cally 1 to 3 double bonds). VOs contain up to 15% O, which can be removed by hydrodeoxygenation (HDO) or decarbon- ylation (DCN)/decarboxylation (DCX) (see Figure 1 ). The S and N content is usually very low (up to 30 ppm). Contaminants such as P and Si, whose concentra- tion depends on feedstock derivation, can cause catalyst
Saturation of C C
Breakage of C O
O
O
Propane
O
O
O
H
H
O
+
O
O
O
O
HO
O
3
O
O
Triglyceride
Saturated triglyceride Free fatty acid (FFA)
Hydrodeoxygenation (HDO)
+
3 H
HO
+
2 H O
O
Decarbonylation (DCN)
+ H
HO
+ H O + CO
O
Decarboxylation (DCX)
HO
+ CO
O
Figure 1 Simplified reaction schema of triglycerides conversion to paraffins. The fatty acids can be generated by breaking a C-O bond of the triglyceride. The generated fatty acid can then undergo hydrodeoxygenation, decarbonylation, or decarboxylation. These last three reactions can also happen on the triglyceride itself or any residual diglyceride or monoglyceride
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PTQ Q4 2023
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