Yongmin Zhang

Aqueous 30% H2O2 in hexafluoro-2-propanol (HFIP) is described as a facile, selective and efficient oxidant for the conversion of sulfides to sulfoxides under neutral conditions. The nitrogen center of the pyridine molecule and the carbon–carbon double bond are shown to not be affected by the reagent system used. The oxidation of glycosyl sulfides to glycosyl sulfoxides was achieved in very high yield at room temperature.

Fluid catalytic cracking (FCC) is the workhorse of modern crude oil refinery. Its regenerator plays a critical role in optimizing the overall profitability by efficiently restoring the catalyst activity and enhancing the heat balance in the riser reactor. Improvement in the device metallurgy and process operations have enabled industrial regenerators to operate at high temperatures with a better coke burning rate and longer operating cycle. Today, the carbon content of regenerated catalyst has drastically reduced to less than 0.1 wt.%. However, the unit is still plagued with operational complexities and insufficient understanding of the underlying dynamic, multiscale intricacies. Recent process-intensification strategies provide insights into regenerator performance improvement potentials. In this review, the importance of the uniform distribution of spent catalysts through structural modification and operational manipulations of the catalyst distributor is discussed. The knowledge of the role of baffles in enhancing excellent gas–solid interaction has been increasing, but skepticism due to its complex hydrodynamic effects on gas–solid flows fends off operators from its application, a critical evaluation of its implication in the regenerators is covered. The understanding of the contribution of air/steam distributor design and feed gas injection techniques for even contact with spent catalyst leading to the improvement in FCC performance is also investigated. The reliability of FCC components is equally a big concern, as unplanned shutdown and enormous economic losses are being witnessed due to device failure. To this end, mitigation approaches to damaging afterburn and high-temperature erosion problems with respect to process control and geometric adjustment in the bed, freeboard, cyclone separators and collection ducts are explored. Emission limits for fluid catalytic cracking unit (FCCU) and products are consistently ratcheting downward; the commingled turnkey solutions to reducing pollutants generation are also reviewed.

Abstract Ultra‐long‐chain amidobetaine surfactants have become one of the hot topics recently, but the influence of the hydrophilic head group on the aggregation behaviors and the correlation between surface activities and thickening ability have been less documented. In this work, comparative studies on the effect of the hydrophilic group on Krafft temperature ( T K ), surface activities and rheological behaviors of erucyl amidobetaines with sulfonate, hydroxyl‐sulfonate or carboxylate were examined. Compared to the sulfobetaines, the carboxybetaine is more water‐soluble; the addition of an hydroxyl group onto the head group of sulfobetaine increases water‐solubility leading to a lower T K . Unexpectedly, the nature of the head groups has little effect on the critical micelle concentration and thickening ability of these surfactants. The packing parameter prediction verifies the formation of wormlike micelles which accounts for the strong thickening ability of the surfactant aqueous solutions.

Shock waves in water have many applications, such as lithotripsy, sterilization, weapons, and so on. Underwater electrical wire explosion can be utilized to produce shock waves with fast front and short duration time efficiently. In order to amplify the energy of shock waves, energetic materials (EMs) were considered. In this paper, Al, Cu, Mo, and W wires with EM covers were designed and tested. The results showed that wire explosion ignited the EMs, which in turn affected the process of wire explosion. As a result, the duration time of shock waves was elongated.