Coupling Hydrogenation of Guaiacol with In Situ Hydrogen Production by Glycerol Aqueous Reforming over Ni/Al2O3 and Ni-X/Al2O3 (X = Cu, Mo, P) Catalysts

Abstract

Biomass-derived liquids, such as bio-oil obtained by fast pyrolysis, can be a valuable source of fuels and chemicals. However, these liquids have high oxygen and water content, needing further upgrading typically involving hydrotreating using H2 at high pressure and temperature. The harsh reaction conditions and use of expensive H2 have hindered the progress of this technology and led to the search for alternative processes. In this work, hydrogenation in aqueous phase is investigated using in-situ produced hydrogen from reforming of glycerol, a low-value by-product from biodiesel production, over Ni-based catalysts. Guaiacol was selected as a bio-oil model compound and high conversion (95%) to phenol and aromatic ring hydrogenation products was obtained over Ni/γ-Al2O3 at 250 °C and 2-h reaction time. Seventy percent selectivity to cyclohexanol and cyclohexanone was achieved at this condition. Hydrogenation capacity of P and Mo modified Ni/γ-Al2O3 was inhibited because more hydrogen undergoes methanation, while Cu showed a good performance in suppressing methane formation. These results demonstrate the feasibility of coupling aqueous phase reforming of glycerol with bio-oil hydrogenation, enabling the reaction to be carried out at lower temperatures and pressures and without the need for molecular H2.

Cobalt–Graphene Catalyst for Selective Hydrodeoxygenation of Guaiacol to Cyclohexanol

“…Currently, catalytic hydrodeoxygenation (HDO) is considered the most efficient approach for upgrading biomass derivatives, and the development of cost-effective catalysts is key to this process [3]. As a main component of biomass, lignin is a planted polymer composed of phenylpropanoid building units that potentially provide renewable six-ring compounds [4]. Given the complex structure of lignin, guaiacol (GUA; 2-methoxyphenol), which contains two common oxygenate groups in lignin: methoxy (C aryl -OCH 3 ) and phenolic (C aryl -OH) groups, is extensively used as a lignin model compound in catalytic studies of lignin derivatives [5].…”

Renewable Hydrogen Fuel from Photofermentation of Glycerol: Enhanced Reviews

“…However, of all such sources of hydrogen, fossil fuels still hold the largest share as feedstock at (96%) and the remaining percentage are from electrolysis (3.9%) and other by-product sources of hydrogen (0.1%) [10,11]. But attention is shifting towards renewable sources and processes of producing hydrogen as a result of environmental hazards, climate change, and global warming inflicted by non-renewables [12]. A typical renewable process of hydrogen production is the Photofermentation (PF) of biomass [2,13].…”

Effect of Water and Glycerol in Deoxygenation of Coconut Oil over Bimetallic NiCo/SAPO-11 Nanocatalyst under N2 Atmosphere

“…In 2002, the pioneer work [ 16 ] applied glycerol into the system to generate in-situ H 2 for the reaction. However, the hydrogen production is always accompanied by several side reactions, such as methanol decomposition, water gas shift reaction, and methanation [ 17 , 18 , 19 , 20 ]. Therefore, the hydrogen yield is highly related to the performance of the catalysts which actively involves for the C–C, C–H, and C–O bonds scission, especially the cleavage of the C–H bond.…”

“…Therefore, the hydrogen yield is highly related to the performance of the catalysts which actively involves for the C–C, C–H, and C–O bonds scission, especially the cleavage of the C–H bond. The development of bimetallic catalysts such as Ni-Cu [ 17 , 18 ] or Ni-Co [ 19 ] is an efficient way to control the selectivity as the second metal can affect metal particle sizes or strengthen metal-support interaction to improve water gas shift reaction or inhibit methanation reaction.…”