Oxidative Desulfurization Using Polyoxometalates

Novel polyoxometalate silica nano-sized spheres: efficient catalysts for olefin oxidation and the deep desulfurization process

A novel method to prepare silica nano-sized particles incorporating polyoxometalates was developed leading to a new efficient heterogeneous oxidative catalyst.

Tris(hydroxymethyl)aminomethane modified layered double hydroxides greatly facilitate polyoxometalate intercalation

The Na₃[PW₁₂O₄₀] intercalated tris(hydroxymethyl)aminomethane (Tris)-modified LDH is prepared for the first time without the necessity of degassing CO₂, resulting in the formation of a new intercalated assembly of Tris-LDH-PW₁₂ under mild conditions.

Ultrasound-assisted oxidative desulfurization of liquid fuels and its industrial application

Latest environmental regulations require a very deep desulfurization to meet the ultra-low sulfur diesel (ULSD, 15 ppm sulfur) specifications. Due to the disadvantages of hydrotreating technology on the slashing production conditions, costs and safety as well as environmental protection, the ultrasound-assisted oxidative desulfurization (UAOD) as an alternative technology has been developed. UAOD process selectively oxidizes sulfur in common thiophenes in diesel to sulfoxides and sulfones which can be removed via selective adsorption or extractant. SulphCo has successfully used a 5000 barrel/day mobile "Sonocracking" unit to duplicate on a commercial scale its proprietary process that applies ultrasonics at relatively low temperatures and pressures. The UAOD technology estimate capital costs less than half the cost of a new high-pressure hydrotreater. The physical and chemical mechanisms of UAOD process are illustrated, and the effective factors, such as ultrasonic frequency and power, oxidants, catalysts, phase-transfer agent, extractant and adsorbent, on reaction kinetics and product recovery are discussed in this review.

A new concept of desulfurization: the electrochemically driven and green conversion of SO2 to NaHSO4 in aqueous solution

A new concept of desulfurization was developed by designing a series of electrochemical reactions to drive an SO2 absorption-and-conversion process in aqueous solution, hence the SO2 in gas was eventually converted to a valuable chemical of NaHSO4. A model experiment of chemically substantiating this concept includes two steps: (I) absorption of SO2 gas by aqueous solution and oxidation of the absorbed SO2 to SO4(2-) by air and (II) transformation of the SO4(2-) to NaHSO4. The experiment demonstrated that in Step I, the cathodic reduction of 02 from ambient air scavenged the H+ released due to the SO2 absorption and its further oxidation, which thereby were accelerated. Meanwhile H2O2 as a cathodic product further enhanced the SO2 oxidation. In Step II, the anodic oxidation of H2O supplied H+ and allowed the NaHSO4 formation through balances of electrons and mass. Thereafter, a pH range of 5.0-6.0 for the SO2 oxidation was optimized, and an electrochemically driven process for the SO2 conversion to NaHSO4 was proposed. Sustainability evaluation indicated that this concept complies with the principles of green chemistry and potentially enables the SO2 conversion from flue gas to NaHSO4 as a value-added process.