(532bc) Liquid-Phase Alkylation of Biomass-Derived Phenols over Zeolites for the Production of Jet-Fuel Range Aromatics

The research into the development of bio-jet fuel production technologies is being emphasized due to increasing demand for jet fuel and global climate change. Although the conventional technologies such as bio-alcohols-to-jet or vegetable oils-to-jet were successfully demonstrated in pilot scale reactors, the high price and limited availability of these feedstocks are significant challenges for the commercialization. In contrast, the biomass pyrolysis oil can be easily produced from the cheap and abundant biomass resources such as agricultural wastes or byproducts. In order to realize the pyrolysis oil-based jet fuel technology, the key catalytic step is to increase the carbon numbers of pyrolysis oil compounds (mainly <C6) to jet-fuel range C8-C15 products. In this work, we investigated the alkylation of 2-methoxyphenol, i.e., guaiacol, with 2-propanol (IPA) over zeolite catalysts as a model reaction for the upgrading of biomass pyrolysis oil to jet-fuel precursors. A range of zeolites, including medium (ZSM-5, MCM-22) and large pore (Beta and Y) with various Si/Al ratios, layered zeolite (MCM-36, ITQ-2) as well as Lewis acidic alumina were prepared, and their structure-activity relationships for guaiacol alkylation were thoroughly investigated under various process conditions. During the alkylation of guaiacol with 2-propanol, three competing reactions occurred simultaneously, including the desired 1) C-alkylation and 2) trans-alkylation and the undesired 3) O-alkylation reaction. Overall, we found that zeolite acidity, pore structure and hydrophobicity as well as the process variables such as temperature and the type of alcohol (e.g., primary vs. secondary) play a crucial role in maximizing the desired C-alkylation product selectivity.