The objective of this work is to explore ultra-deep oxidative desulfurization (ODS) of real diesel using two-layer silica gels as both the guard adsorbent and oxidation catalyst under mild conditions. A series of commercial silica gels were screened for ODS in the presence of cumene hydrogen peroxide, with the dibenzothiophene conversion varying diversely from 1.2 to 99.8%. The best silica gel SC-2 is capable of treating >375 cm3 of simulated diesel per gram of catalyst with ∼3 ppmw S at 373 K. Fairly trace Ti species of ∼0.02 wt % in silica gel was detected and quantified by inductively coupled plasma, which was identified as the major Lewis acidic species correlating to the high ODS conversion. Moreover, the effects of real diesel composition, including model aromatics, olefin, oxygen fuel additive, and trace organonitrogen compounds, on ODS using silica gel were investigated, where nitrogen compounds, such as indole, were identified as major inhibitors, even at a low concentration of 150 ppmw. Accordingly, guard adsorbents were investigated for adsorptive denitrogenation prior to ODS, the N-capacity followed the order of SC-2 ∼ AC > Al2O3 > 13X. The layered-bed combination for deep desulfurization was optimized to be 5 and 2.5 mg/mL of SC-2, respectively, as the guard adsorbent and oxidation catalyst. The matrix is capable of processing deep-desulfurized diesel below 10 ppm with the total sulfur capacity of up to 4.2 mg-S/g. The process using two-layer commercial silica gel beds provides a new path for ultra-deep oxidative desulfurization of diesel under mild conditions.

In this work, the effective ultra‐deep catalytic adsorptive desulfurization (CADS) using titanium‐silica gel (Ti‐SG) adsorbent at low Ti loading (<1 wt.%) was investigated. The superior CADS capacity (37.3 mg‐S/g‐A) and high TOF value (432 h−1) for dibenzothiophene (DBT) of Ti‐SG adsorbent were achieved at Ti loading of 0.6% with high dispersion and low titanium coordination. The rate equation of catalytic DBT oxidation was described as rDBT=N2kK[]CHP[]DBT, where the TiOOR was determined as the intermediate to enable the DBT oxidation to form the corresponding sulfone (DBTO2). The effectiveness of CADS using Ti‐SG adsorbents was verified in real diesels with varied sulfur concentrations and O/S ratios in the dynamic adsorption and multicycle regeneration. This work provides insights on using low‐cost bifunctional catalytic adsorbents at low Ti loadings for effective CADS to realize ultra‐deep desulfurization of transportation fuels.

In this work, the effective ultra-deep catalytic adsorptive desulfurization (CADS) using Ti-silica gel adsorbent at low Ti loading range (< 1%) was investigated. The superior CADS capacity (37.3 mg-S/g-A) and high TOF value (432 h-1) for dibenzothiophene (DBT) were achieved at 0.6% of Ti loading with high dispersion and low Ti coordination. The catalytic oxidation of DBT conformed to the pseudo-first-order kinetic model, and the corresponding rate equation was well described as , where the TiOOR is determined as the intermediate to enable the DBT oxidation to the corresponding sulfone (DBTO2). The effectiveness of CADS using Ti-SG was verified in various real low-sulfur diesels with varied sulfur concentrations and O/S ratios in the dynamic fixed-bed adsorption and multi-cycle regenerations. This work provides insights on using low-cost bifunctional catalytic adsorbents at low Ti loading for effective CADS to realize ultra-deep desulfurization of transportation fuels.