Performance of mesoporous HZSM-5 and Silicalite-1 coated mesoporous HZSM-5 catalysts for deoxygenation of straw fast pyrolysis vapors

Abstract

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

“…Wheat straw with a particle size of 0.1-0.25 mm was used as feedstock. Its properties were reported in more detail in earlier work [58]. The moisture content (as received) was 7.1 wt%, and the volatiles, fixed carbon, and ash on a dry basis (d.b.)…”

“…The repeated injection over an empty catalyst reactor or SiC indicated a high reproducibility of the results [58]. While the reported results at constant catalyst temperatures were obtained from single test runs (16 injections), the tests with variable catalyst temperatures were performed in duplicate and the presented results constitute the averaged values.…”

“…At the higher temperatures, the extent of vapor deoxygenation increased and very low yields of AC and MPH resulted ( Table 2). It is further worth noting that the carbon balance closure increased from 80% at 450 • C to 100% at 600 • C, which suggests that the missing carbon at low catalyst activity constitutes heavy matter, which did not reach the detectors and was deposited in the system [58,59]. With an increase in constant catalyst temperature from 450 to 550 • C, the carbon yield of GC-detectable vapors increased from 21.5 to 23.7%, before it decreased at higher temperatures of 600 • C (21.6%).…”

“…The helium flowrate was 60 mL/min and the split ratio at the GC injection port was 56:1. The micro-pyrolyzer and the gas chromatographic conditions were described in more detail in earlier work [58]. The pyrolysis reactor temperature was controlled to 530 • C, and 0.59 ± 0.01 mg biomass was placed into stainless steel sample cups, secured with quartz wool, and subsequently dropped into the pyrolysis zone by the autosampler.…”

“…Once catalyst testing was completed, the reactor was allowed to cool before removing the catalyst. The spent catalyst was emptied into alumina crucibles and the coke was combusted in a thermogravimetric analyzer (Netzsch STA449 F1 coupled with QMS 403 D Aëolos ® ), according to conditions described previously [58].…”