Tandem beds catalysis for aviation fuel from aqueous phase bio-oil: synergistic ketonization-HDO toward high-density cycloalkanes.

The decarbonization of aviation urgently demands efficient pathways to produce renewable jet fuels meeting stringent ASTM D7566 specifications. Current hydrodeoxygenation (HDO) of aqueous phase bio-oil (APBO) suffers from low carbon efficiency (<40%) and undesired short-chain hydrocarbons, due to its high acidity, water content, and low-carbon oxygenates. Herein, we propose a tandem catalytic strategy using a dual-bed system to achieve precise fraction-based conversion of APBO into jet-range hydrocarbons. The first bed, 10Ni/CeZrOx, leverages synergistic Lewis acid-base pairs and highly dispersed Ni sites to catalyze carboxylic acid ketonization, completely converting acetic acid and furans into C8+ ketones at 280°C and WHSV = 1h-1 while suppressing decarboxylation (gas yield ≤ 13.5%). The second bed, PtNiCo/β, facilitates deep hydrodeoxygenation via Pt-Ni-Co alloy-enabled H2 dissociation and Brønsted acid-mediated deoxygenation, attaining > 89.7% conversion of cyclopentanone and guaiacol under 280°C and WHSV = 2h-1. Notably, the integrated systemdemonstrates remarkable synergy: conversion of refractory oxygenates exceeds 90% (a 23-25% gain over single catalysts), C8-C16 hydrocarbon yield reaches 70.2% with > 85% carbon efficiency, and cycloalkanes selectivity attains 80.8%-ideal for high-density jet fuel-while aromatics are suppressed to 4.0%. Gas byproducts are minimized to 1.6% (>80% reduction), and coke formation is markedly lowered (5.1% weight loss shifted to 400-700°C). Operated under mild conditions (280°C, 3 MPa H2), this approach offers a scalable and carbon-conserving route to sustainable aviation fuel (SAF), overcoming key limitations of conventional APBO upgrading.