To develop dynamic ultra-deep catalytic adsorptive desulfurization (CADS) of real diesel using ultra-stable and lowcost silica gel-supported TiO 2 is the aim of the work. A two-stage dynamic breakthrough model was built to describe the CADS process, varied with H/R ratio and O/S ratio. The desulfurization capacity reached 1.3 mg-S/g-A at the breakthrough concentration of 5 ppm-S. Various types of silica gel were screened as the substrate for TiO 2 , and the textural/ acidic properties and CADS capacity were correlated in high relevancy. The effectiveness of diverse oxidants on CADS and the oxidation path were elucidated via combined experiment/simulation. Adsorption enthalpy derived from fitted isotherm data was calculated as 33.4 kJ/mol. The TiO 2 /silica gel-based sorbent demonstrated remarkable recyclability/ stability in 10 cycles. An effective and economic route to eliminate the trace amount of stubborn sulfur compounds in low-sulfur diesel is provided, which can be potentially implemented as the final polishing step for ultra-clean diesel production.

Desulfurization kinetics and regeneration of silica gel-supported TiO2 extrudates were explored for the reactive adsorptive desulfurization (RADS) process in this work. RADS using TiO2/SiO2 extrudates with varied particle sizes was evaluated. The textural and chemical properties of molded adsorbents were well maintained after extrusion, with a negligible decrease (<0.97%) in the desulfurization capacity for 50 ppm low-sulfur diesel. The RADS of trilobed TiO2/SiO2 was well described with a first-order adsorption kinetic model of ln­(C) = −9.42 × 10–3 t + 3.84, and TiO2/SiO2 extrudates with smaller particle size may provide larger external surface area and shorter diffusion path. The impacts of packing density and weight hour space velocity (WHSV) on fixed-bed dynamic RADS were discussed. The desorption of adsorbed diesel can be well presented by a first-order model, where the total diesel yield of the RADS process reached above 99.5% at a nitrogen purging temperature ≥150 °C. The effects of solvent structure, polarity, and alkalinity on adsorbent regeneration were further illustrated. This work provides an insight into the aspects of kinetics and regeneration of molded adsorbents to pave the way for industrial fixed-bed desulfurization processes.

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