Production of renewable fuels by blending bio-oil with alcohols and upgrading under supercritical conditions

The work studied a non-catalytic upgrading of fast pyrolysis bio-oil by blending under supercritical conditions using methanol,ethanol and isopropanol as solvent and hydrogen donor.Characterisation of the bio-oil and the upgraded bio-oils was carried out including moisture content,elemental content,pH,heating value,gas chromatography-mass spectrometry(GCMS),Fourier transform infrared radiation,13C nuclear magnetic resonance spectroscopy,and thermogravimetric analysis to evaluate the effects of blending and supercritical reactions.The GCMS analysis indicated that the supercritical methanol reaction removed the acids in the bio-oil consequently the pH increased from 2.39 in the crude bio-oil to 4.04 after the supercritical methanol reaction.The ester contents increased by 87.49% after the supercritical methanol reaction indicating ester formation could be the major deacidification mechanism for reducing the acidity of the bio-oil and improving its pH value.Simply blending crude bio-oil with isopropanol was effective in increasing the C and H content,reducing the O content and increasing the heating value to 27.55 from 17.51 MJ·kg^-1 in the crude bio-oil.After the supercritical isopropanol reaction,the heating value o f the liquid product slightly further increased to 28.85 MJ·kg^-1.

Experimental and theoretical study of microwave enhanced catalytic hydrodesulfurization of thiophene in a continuous-flow reactor

Hydrodesulfiirization(HDS)of thiophene,as a gasoline model oil,over an industrial Ni-Mo/Al2O3 catalyst was investigated in a continuous system under microwave irradiation.The HDS efficiency was much higher(5%-14%)under microwave irradiation than conventional heating.It was proved that the reaction was enhanced by both microwave thermal and non-thermal effects.Microwave selective heating caused hot spots inside the catalyst,thus improved the reaction rate.From the analysis of the non-thermal effect,the molecular collisions were significantly increased under microwave irradiation.However,instead of being reduced,the apparent activation energy increased.This may be due to the microwave treatment hindering the adsorption though upright S-bind(η1)and enhancing the parallel adsorption(η5),both adsorptions were considered to favor to the direct desulfurization route and the hydrogenation route respectively.Therefore,the HDS process was considered to proceed along the hydrogenation route under microwave irradiation.

A review on catalytic & non-catalytic bio-oil upgrading in supercritical fluids

This review article summarizes the key published research on the topic of bio-oil upgrading using catalytic and non-catalytic supercritical fluid(SCF)conditions.The precious metal catalysts Pd,Ru and Pt on various supports are frequently chosen for catalytic bio-oil upgrading in SCFs.This is reportedly due to their favourable catalytic activity during the process including hydrotreating,hydrocracking,and esterification,which leads to improvements in liquid yield,heating value,and pH of the upgraded bio-oil.Due to the costs associated with precious metal catalysts,some researchers have opted for non-precious metal catalysts such as acidic HZSM-5 which can promote esterification in supercritical ethanol.On the other hand,SCFs have been effectively used to upgrade crude bio-oil without a catalyst.Supercritical methanol,ethanol,and water are most commonly used and demonstrate catalyst like activities such as facilitating esterification reactions and reducing solid yield by alcoholysis and hydrolysis,respectively.