Ni/HZSM-5 catalyst preparation by deposition-precipitation. Part 2. Catalytic hydrodeoxygenation reactions of lignin model compounds in organic and aqueous systems

• Published in: Applied catalysis. A, General Vol. 562; pp. 294 - 309
• Main Authors: Barton, R.R., Carrier, M., Segura, C., Fierro, J.L.G., Park, S., Lamb, H.H., Escalona, N., Peretti, S.W.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-07-2018; Elsevier Science SA; Elsevier
• Subjects: Aqueous environments; Aqueous solutions; Catalysis; Catalysts; Catalytic activity; Catalytic converters; Chemical Sciences; Conversion; Cyclohexane; Dehydration; Deoxygenation; Depolymerization; Deposition; Deposition-Precipitation; Dodecane; Ethylbenzene; Hydrodeoxygenation; HZSM-5; Lignin; Nickel; Reaction time; Selectivity; Series & special reports; Silicon dioxide; Sodium hydroxide; Zeolites; Depolymerization; Deposition-Precipitation; Lignin; Hydrodeoxygenation; HZSM-5
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2018.06.012

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•Effect of excess deposition-precipitation times on catalyst properties and model compound hydrodeoxygenation was studied.•Ni(15)/HZSM-5 with 16 h DP time and calcined at 673 K had high intrinsic rates and high selectivity.•Selectivity towards aromatic products was highest in neutral aqueous environments.•Ni/HZSM-5 from deposition-precipitation is a promising catalyst for lignin cleavage at low temperature.
Nickel metal supported on HZSM-5 (zeolite) is a promising catalyst for lignin depolymerization. In this work, the ability of catalysts prepared via deposition-precipitation (DP) to perform hydrodeoxygenation (HDO) on two lignin model compounds in organic and aqueous solvents was evaluated; guaiacol in dodecane and 2-phenoxy-1-phenylethanol (PPE) in aqueous solutions. All Ni/HZSM-5 catalysts were capable of guaiacol HDO into cyclohexane at 523 K. The role of the HZSM-5 acid sites was confirmed by comparison with Ni/SiO2 (inert support) which exhibited incomplete deoxygenation of guaiacol due to the inability to perform the cyclohexanol dehydration step. The catalyst prepared with 15 wt% Ni, a DP time of 16 h, and a calcination temperature of 673 K (Ni(15)/HZSM-5 DP16_Cal673), performed the guaiacol conversion with the greatest selectivity towards HDO products, with an intrinsic rate ratio (HDO rate to conversion rate) of 0.31, and 90% selectivity to cyclohexane. Catalytic activity and selectivity of Ni/HZSM-5 (15 wt%) in aqueous environments (water and 0.1 M NaOH solution) was confirmed using PPE reactions at 523 K. After 30 min reaction time in water, Ni/HZSM-5 exhibited ∼100% conversion of PPE, and good yield of the desired products; ethylbenzene and phenol (∼35% and 23% of initial carbon, respectively). Ni/HZSM-5 in NaOH solution resulted in significantly higher ring saturation compared to the Ni/HZSM-5 in water or the NaOH solution control.