Decarbonisation Technology November 2026 issue

basis, the fatty-acid chain length distribution determines the final application of the deoxygenated oil. Additionally, the degree and position of unsaturation and free fatty acid content affect the processing. Compositional differences influence paraffin distribution, hydrogen consumption, and the extent of downstream conversion necessary to achieve required product properties. Therefore, no universal processing solution can be assumed, and process parameters such as catalyst loadings, temperatures, pressures, and flow rates must be evaluated on a case-by-case basis, especially for new feedstocks. In this context, laboratory-scale high throughput testing is valuable to reduce development risk and identify suitable operating windows. One potentially interesting feedstock is field cress, a winter-hardy oilseed crop being developed as a source of renewable plant oil for Nordic agricultural conditions (see Figure 1 ) ( Abreha, et al., 2025 ). While more common feedstocks such as used cooking oil and similar vegetable oil-derived wastes are dominated by C18 fatty acids, field cress oil is characterised by a high proportion of very-long-chain fatty acids, particularly erucic acid (C22:1), which often accounts for approximately 22-33% of total fatty acids. This compositional feature is expected to shift the post-deoxygenation paraffin distribution towards higher boiling products, which are at the very heavy end or even outside of the diesel range. In addition, these paraffins increase DW demand to meet winter cloud-point targets. At the same time, excessive cracking must be avoided to minimise yield losses. These competing requirements make field cress a particularly relevant example for feedstock- specific process optimisation. High throughput equipment is well suited to this task because it enables parallelised catalyst screening under controlled conditions. For instance, different temperatures can be applied, and different ratios of DW and HC catalyst stacks can be loaded in the second stage and evaluated simultaneously. In this study, high throughput equipment was used to identify suitable operating windows for the conversion of a mixture of field cress and rapeseed oil via HDO and DW/HC. It was found that HDO

12 xHDO

16 x

VO/HVO

C 1 -C 20 , HO, CO x

Online GC

Gas-liquid separation

4 x DW/HC

DW HC

Liquid sample

Oine analysis

performance directly affects downstream DW/ HC, since insufficient removal of heteroatoms hampers the activity of noble metal catalysts. This illustrates that close monitoring of HDO efficiency is needed in refinery settings to maintain stable operation and achieve target fuel specifications. Testing equipment and protocol • Collaboration and setup: hte GmbH and VAROPreem executed a lab campaign on a high throughput trickle-bed platform (see Figure 2 ) to mimic a typical refinery configuration, consisting of HDO for deep heteroatom removal (stage 1), followed by sweet DW/HC to meet cold-flow targets (stage 2). A key element of the approach was to operate both HDO and sweet DW/HC simultaneously in the same high throughput unit and in parallel reactors, in combination with a coordinated experimental plan across experimental variables. This compresses weeks of sequential pilot testing into approximately two on-stream weeks and significantly reduces overhead and sample logistics. • Feed : The feed was a mixture of 20 wt% field cress oil and 80 wt% rapeseed oil. Sulphur was dosed in the form of dimethyl disulphide (approximately 500 ppm) to maintain sulphide functionality during hydrotreating. • Experimental details: The unit comprised 16 individually heated trickle-bed reactors with individual gas-liquid separation. Stage 1: HDO (12 positions). Commercially Figure 2 (A) Schematic of 16-fold high throughput system and (B) catalyst loading diagram used in this study