Catalytic conversion of acetol over HZSM-5 catalysts – influence of Si/Al ratio and introduction of mesoporosity

Counteracting Rapid Catalyst Deactivation by Concomitant Temperature Increase during Catalytic Upgrading of Biomass Pyrolysis Vapors Using Solid Acid Catalysts

“…Temperature ( Using P/HZSM-5/γ-Al 2 O 3 , the gas yields increased from 21.3 C% at 450 • C to 38.8 C% at 600 • C. Simultaneously, the yield of unreactive light C 1 -C 3 alkanes increased from 0.04 to 0.66 C% and the yield of valuable C 2 -C 3 alkenes increased from 1.9 to 9.3 C%. Operating at higher catalyst temperatures increased the cumulative yield of MAR at B:C~4 from 1.6 to 3.8 C%, and led to an increased yield of CO, polyaromatics, and coke (Table 2), in agreement with the literature [34]. At the higher temperatures, the extent of vapor deoxygenation increased and very low yields of AC and MPH resulted ( Table 2).…”

“…By increasing the temperature at a higher rate between 450 and 500 • C following temperature profile II (Figure 9b), the breakthrough of highly oxygenated compounds could be reversed earlier, at B:C~0.75, and continue to decrease when increasing the temperature to 600 • C. When maintaining the catalyst temperature at 600 • C during the last seven injections (B:C = 3.5-5.0), the yield of oxygen-free hydrocarbons slightly decreased and the yield of compounds with two oxygen atoms slightly increased (Figure 9b). The initially accelerated temperature increase in profile II aimed to mirror the rapid decrease in catalyst acidity due to coking [30,34], and resulted in a decrease in the oxygen content of the accumulated vapors from 20.8 to 18.5% due to a slightly increased yield of oxygen-free HC and a decreased yield of two-oxygen-containing products (Figure 11). An important benefit of the presented strategy is that it allows operation at higher B:C ratios without leading to a pronounced increase in oxygen content (Figure 11).…”

“…However, significant carbon losses to coke and gas occur at the initial upgrading period over a freshly regenerated catalyst [27]. The initially high rate of coke deposition is followed by a much lower rate of coke deposition [30,[32][33][34][35]. Based on this, regenerating the catalyst incompletely, in order to reduce the initial carbon losses to coke and benefit from a lower coking rate compared to upgrading over a fresh catalyst, was suggested [32].…”

Boron-Modified Mesoporous ZSM-5 for the Conversion of Pyrolysis Vapors from LDPE and Mixed Polyolefins: Maximizing the C2–C4 Olefin Yield with Minimal Carbon Footprint

“…For a run number of ∼50, the coke per surface area was 14 μg/m 2 and it increased to 22 μg/m 2 after 200 runs. This indicates an initially steeper build-up of coke, which then deflects with more feed being converted over the zeolite due to loss in catalyst activity. , The coke yield might therefore follow an exponential decay function, similar to what was observed for ethylene and propylene.…”

Catalytic transformations of glycerol via hydroxyacetone into nitrogen heterocycles of industrial interest

“…These functional features enable acetol to participate in different organic reactions, such as the Mannich reaction [90] or some aldolic condensations [91]. Besides that, acetol can be applied to produce other chemicals such as olefins, acetone and furan derivatives [92], acetic acid [93], lactic acid [94,95], and, especially, it is a crucial intermediate when producing propylene glycol [96]. Newly, acetol has been proposed as a platform molecule for the electrocatalytic synthesis of acetone, 1,2-propanediol, and 2-propanol [97] and even a recent study describe acetol as a high-performance fuel for electrochemical oxidation in a direct alkaline liquid fuel cell [98].…”