into the optimisation of catalytic ethanol conversion is gained. High throughput technology A flexible high throughput unit equipped with 16 parallel, individually heated fixed-bed reactors was used to study the conversion of ethanol into different products within the same run over commercial catalysts (for the scheme and unit description, see Innocenti, et al., 2024 ). The schematic loading design of the 16 parallel reactors is shown in Figure 1a. The first eight reactors consisted of 6 mm ID tubes allocated to four different Cu-based catalysts for acetaldehyde production, primarily tested as 1/16 inch extrudates. Each Cu-based catalyst was loaded in two different amounts (1.6 and 3.2g) for space velocity variation (WHSV ethanol = 10 h -1 and 5 h -1 , respectively). Reactors 9-16 featured 16 mm ID tubes for the loading of larger catalyst volumes. Position nine was filled with inert material only, providing a reference for data evaluation. The remaining positions, 10-16, were allocated to ethanol-to- ethylene conversion over different Al 2 O 3 -based extrudates with two of the catalysts also loaded in reduced volumes (4.5 mL vs 9.0 mL) for gas hourly space velocity (GHSV) variation. All reactors shared the same feed (such as composition and flow rates). At the same time, each reactor can be individually brought on-stream via automated feed valve control. Gaseous feeds, such as argon (Ar), used as an internal standard, were metered using mass flow controllers (MFC). Liquid feeds (ethanol and H 2 O) were fed via separate pumps and evaporated prior to final mixing, resulting in the desired gas- phase composition. The gaseous feed mixture is evenly distributed among all reactors on-stream. Since both liquid components are dosed individually, the feed composition can be adjusted fully automatically during operation, allowing for real-time simulation of varying feedstock qualities. Here, pure ethanol and a 1/10 (m/m) mixture of H2 O and ethanol were used as feed while maintaining a constant total ethanol flow rate. Moreover, the setup allows the feeding of synthetic air for catalyst regeneration by combusting carbon deposits that may form during on-stream operations. Downstream, the reactor effluent is diluted
(a) Schematic loading design of the 16 parallel reactors
Cu-based catalysts
Al O -based catalysts
1 2 3
45678 9 10 11 12 13 14 15 16
Acetaldehyde
Ethylene
(b)
Yield target product vs. Conversion
100
Cu: Acetaldehyde w/o H O Cu: Acetaldehyde w/ H O Al O : Ethylene w/o H O Al O : Ethylene w/ H O
80
60
40
20
0 10 20 30 40 50 60 70 80 90 100 Conversion (%) 0
compositions are simulated by changing the H 2 O-to-ethanol ratio. Combining the tests with state-of-the-art online gas chromatography (GC) analysis specifically tuned for oxygenate and olefin quantification enables detailed insight into by-product and side-product formation during the conversion processes. This being the case, these investigations aim to provide a deeper understanding of ethanol valorisation pathways and facilitate the development of more efficient and sustainable processes for producing green chemical intermediates and products. With the help of hte’s most advanced high throughput unit, simultaneous evaluation of both conversion processes, and real-time variations in feedstock quality, valuable insight Figure 1a Schematic loading design for the 16 parallel, mixed-sized reactors tested in ethanol conversion. Reactors 1-8 (blue): Cu- based catalyst for acetaldehyde production; reactor 9 (black): inert as reference for data evaluation; reactors 10-16 (green): Al 2 O 3 -based catalysts for ethylene production. 1b Yield of the corresponding target product plotted over ethanol conversion. Bright colours indicate a pure ethanol feed, while dark colours indicate a 1/10 H 2O/ethanol feed mixture
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