Investigation On The Upgrading Of Phenolic Bio-oil Etherification

In this work,using methanol as methylation reagent,the performances of alumina supported alkali metal and alkaline-earth metal catalysts on the alkylation of alkylphenols,alkoxyphenols,and their mixtures were studied.Some of the main conclusions are as follows:Phenol and methylphenol can high efficiently be converted to O-alkylation products over alkali metal modified Al2O3 catalysts.Specifically,under the catalysis of Cs2CO3/AA,the conversion of phenol reaches to the highest value of 90.4wt%with high anisole selectivity of 96.1area%.However,neither the conversion nor the selectivity to any product is satisfactory for the alkylation of methoxyphenol over Cs2CO3/AA.Additionally,none of the adjustment on reaction temperature,space velocity,or Cs loading amount can effectively improve the conversion of guaiacol or the selectivity to O-alkylation product over Cs2CO3/AA.The reason is speculated as the more complex ways of adsorptions of methoxyphenols than that of methylphenols.The co-alkylation of a binary phenolic mixture with equal molar ratio of o-cresol and guaiacol are investigated,under the catalysis of KNO3/AA.The results show that there exists a synergistic effect in the reaction system,and under this effect,the conversion of methylphenol is inhibited,while the selectivity to O-alkylation product of methylanisole is promoted.If the proportion of o-cresol is increased or decreased,the selectivity to C-alkylation product of dimethylphenol is severely improved.The increase of temperature in the range of 380-420? makes the selectivity to methyl anisole increased and meanwhile decreases the content of dimethoxybenzene.An optimal reaction reaction temperature is determined as 400?.With increasing space velocity,the O-alkylation product of methylanisole from o-cresol increases,while the O-alkylation product of dimethoxybenzene and all C-alkylation products decreases contrarily.It means that a higher space velocity is advantageous for decreasing the overall polarity of the product oil.The co-alkylation of a five-component phenolic mixture with equal molar ratio and a real phenolic-oil are investigated,under the catalysis of KNO3/AA and Cs2CO3/AA.The results show that compared with the effect of Cs2CO3/AA,more O-alkylation products are generated over KNO3/AA,though C-alkylation products are still most abundant.The composition of the phenolic-oil is much simplified after treatment by alkylation with methanol over KNO3/AA at 400?.The predominant components in the product oil are alkyl phenols,such as o-cresol,p-cresol and dimethylphenol,with some aryl ethers of anisole,o-methylanisole,and p-methylanisole.Particularly,the alkoxyphenols in the product oil almost disappeared after treatment.Based on the obtained results and regulations,a novel process for phenolic-oil upgrading is put forward.In this process,the phenolic-oil is first treated by alkylation with methanol to produce alkyl phenols high selectively,with a low fraction of aryl ethers and no existence of alkoxy phenols.The obtained alkyl phenols is to be further treated by second time of alkylation with methanol for producing aryl ethers high selectively,due to the free of alkoxy phenols.