Ultra-Deep Desulfurization of Real Diesel Using Two-Layer Silica Gels under Mild Conditions

Abstract

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.

Synthesis and characterization of AFe2O4 (A: Ni, Co, Mg)–silica nanocomposites and their application for the removal of dibenzothiophene (DBT) by an adsorption process: kinetics, isotherms and experimental design

“…In addition, in cycle 3, the removal efficiency has reached below 50%. [54][55][56][57][58][59][60][61] Based on the statistical investigations, the optimal conditions for ADS were adsorbent dosage of 7.82 g per 50 ml of the model fuel and a contact time of 32 min. However, selecting suitable adsorbents is regarded an essential challenge in ADS.…”

Desulfurization Kinetics and Regeneration of Silica Gel-Supported TiO2 Extrudates for Reactive Adsorptive Desulfurization of Real Diesel

“…Interestingly, compared to the powdered TiO 2 /SiO 2 , although with decreased surface areas (273, 286, and 280 m 2 /g for extrudates and 340 m 2 /g for powder), the extrudates showed higher sulfur uptake per square meter basis, likely due to the synergetic effect of well-dispersed alumina on the desulfurization of TiO 2 /SiO 2 . Alumina can behave as a Lewis acid and contribute to higher catalytic oxidation activity and sulfone uptake. ,, …”

“…Alumina can behave as a Lewis acid and contribute to higher catalytic oxidation activity and sulfone uptake. 25,28,57 3.3. Dynamic Desulfurization of Real Diesel in Fixed Bed.…”

“…The reported desulfurization adsorbents include modified molecular sieves, activated carbon, activated metal oxides, ionic liquids (ILs), metal–organic frameworks (MOFs), boron nitride, and so forth. As a class of industrial adsorbents, titanium dioxide could provide Lewis acid sites, which were generated by its precursors during calcination in air and significantly impacted the sulfur uptake. , Besides, the loading of titanium dioxide onto porous substrates with high surface area (like alumina, silica, molecular sieves, or activated carbon) provided a feasible route to enhance the number of accessible adsorptive sites. Hussain et al studied the ADS of model and jet fuels over Ag/TiO x –SiO 2 and reported that the introduction of TiO 2 not only increased the Lewis acidity of adsorbent but also improved the dispersion of silver oxide, resulting in abundant adsorptive sites to capture sulfur.…”

Zeolite Stabilized Isolated Molybdenum Species for Catalytic Oxidative Desulfurization

“…据报道, 高空间位阻的硫化物如 二苯并噻吩更容易通过 ODS 去除 [12][13][14][15][16] . 氧化脱硫反应 中使用的催化剂种类繁多, 比如杂多酸体系 [16] 、金属有 机体系 [17][18] 以及负载型催化剂等 [19][20] , 其中负载型氧化 钼催化剂表现出优异的催化性能 [13,[21][22][23][24] .…”