Supercritical Water Gasification of Lignin and Cellulose Catalyzed with Co-precipitated CeO₂–ZrO₂

Abstract

Lignin and cellulose were gasified at 500 and 600 °C in supercritical water over co-precipitated CeO2–ZrO2 catalyst. The addition of CeO2–ZrO2 improved the gasification efficiency and hydrogen production, and the catalytic effect was more significant at lower temperatures. The H2 yield from cellulose gasification at 500 °C increased by over 2.5 times to 8.50 mol/kg with the presence of CeO2–ZrO2. The gas chromatography-mass spectrometry (GC-MS) analysis showed that the catalyst reduced the content of cyclopentenone and furan derivatives in the aqueous product but increased the content of refractory phenols. We characterized the fresh and the used catalysts with H2-temperature-programmed reduction (H2-TPR), X-ray diffraction (XRD), and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) analysis, showing that CeO2 was the main active component, which catalyzed gasification through redox reactions. ZrO2 enhanced the catalytic activity of CeO2 by lowering the reduction temperature in hydrogen, increasing the dispersion of CeO2, and facilitating H2 adsorption on the catalyst surface.

Hydrogen Production from Supercritical Water Gasification of Lignin and Cellulose with Coprecipitated CuO–ZnO and Fe2O3–Cr2O3

“…Finally, the reactor was opened to collect the used catalyst, which was separated by filtration and dried at 80 °C overnight for further characterization. The schematic diagram of the SCWG system and procedure can be found in our previous study …”

“…The schematic diagram of the SCWG system and procedure can be found in our previous study. 47 Characterization of the Gas and Catalyst. The compositions of the gas product (H 2 , CO, CH 4 , CO 2 , C 2 H 4 , and C 2 H 6 ) were analyzed with an Agilent 7890A gas chromatography instrument equipped with a thermal conductivity detector.…”

Zirconia-Based Solid Acid Catalysts for Biomass Conversion

“…42,48 The acidity feature of ZrO 2 was studied by Chen et al, showing that there are two types of Lewis acid sites (LAS) exhibiting different acid concentrations, strengths, and stabilities. 45 By solid-state 31 P magic angle spinning (MAS) nuclear magnetic resonance (NMR), it is shown that ZrO 2 can possess both LAS and BAS by varying calcination temperatures, determined from the results in different 31 P chemical shifts of the adsorbed trimethylphosphine oxide (TMPO) different sites, 49 as shown in Figure 1.…”

“…To date, zirconia-based catalysts have been involved in a variety of catalytic reactions. For instance, zirconia-based materials are regarded as one of the most promising catalysts in the industrial biodiesel production from vegetable and nonedible oils, which is a hot area for the blue print of long-lasting development of energy. − The modification of zirconia can improve the acidity and accessibility of active sites on surface, enhancing the activity of zirconia-based catalysts in biofuels production. − Meanwhile, the applications of zirconia-based catalysts are spread over the area of syngas production. − Biomass refining reactions including dehydration, isomerization, transferhydrogenation, hydrodesulfurization, alcoholysis, hydrolysis, esterification, and etherfication are also comprehensively studied. − …”

Revealing of Supercritical Water Gasification Process of Lignin by Reactive Force Field Molecular Dynamics Simulations

“…oxole (compound 3) below the 60s during gasification using gas chromatography/mass spectrometry (GC/MS) [51]. On the other hand, the same authors, Cao et al and Miliotti et al have predicted the formation of cyclopentanone (compound 8) and 2-cyclopentanone (compound 9) when treating lignin with supercritical water [51][52][53]. Even if, any of these compounds 8 and 9 can be formed during the present simulations, we believe that these compounds can be extracted through controlled experimental gasification of lignin with supercritical water.…”