Production of bio-based chemicals, fuels and energy are essential in the current climate environment. Hydrotreatment of renewable platform chemical furfural yields many valuable products, such as furfuryl alcohol and 2-methylfuran (MF). MF has excellent properties for use as a gasoline octane booster to replace current fossil methyl tert-butyl ether and ethyl tert-butyl ether. The current CuCr-catalyst in furfural hydrotreatment is toxic and new and selective catalysts are required.
In this dissertation, noble metal free and non-toxic catalysts were prepared for production of MF. Metal catalyst options chosen for this work were copper, nickel and iron. High yields (up to 60%) of MF were achieved with the prepared catalysts in liquid phase batch reactor experiments in short reaction time (1 - 2 h). High temperature (230 °C) and high hydrogen partial pressure (40 bar) were optimal for MF produc-tion, and the most optimal metal combinations were copper-nickel and copper-iron. Active metals were tested in MF production on various activated carbon supports and a mesoporous carbon material (CMK-3). Deep characterization was performed to obtain data of beneficial catalyst characteristics for MF production. Production of MF was enhanced by small metal particle size, small pore volume and higher acidity. These enhancements suppressed the production of competitive products and side reactions, and increased the selectivity towards 2-methylfuran.
Solvents may also react in furfural hydrotreatment. The applied 2-propanol can react through catalytic transfer hydrogenation (CTH) offering hydrogen for hydrotreatment reactions and producing acetone. The solvent can also dehydrogenate to acetone and hydrogen. Acetone formation mechanisms were studied with the prepared catalysts. The acetone formation was metal dependent: with nickel and copper acetone formation occurred through CTH while with iron also dehydrogenation took place.
Hydrogen solubility in the reaction media is important for the process and especially in scaling up pro-cesses. Hydrogen solubilities in furfural and 2-propanol were measured and observed to increase as a function of temperature (50 - 200 °C) and pressure (50 - 125 bar). Hydrogen solubility in 2-propanol was observed almost three times higher to solubility in furfural. By way of example, at 200 °C and 125 bar hydrogen mole fraction in 2-propanol and furfural was measured to be 0.064 and 0.038 respectively. The solubility data was modelled with PC-SAFT model and the model predicted the hydrogen solubility data well.
This dissertation offers a MF selectivity optimized and fast noble metal free catalyst alternative for the current catalyst, new data of hydrogen solubility in the reaction media and optimized carbon support characteristics for the production of MF.
|Translated title of the contribution||Carbon Catalysts in Biofuel Production: from Furfural to 2-Methylfuran|
- , Supervisor
- , Advisor
- Juha Lehtonen, Advisor
|Publication status||Published - 2019|
|MoE publication type||G5 Doctoral dissertation (article)|
- furfural, 2-methylfuran, activated carbon, mesoporous carbon, hydrotreatment