In this work, a new process for achieving the recovery of elemental sulfur by utilizing a fluidized catalytic cracking (FCC) riser reactor for SO_x treatment (FCC-DeSO_x) is proposed. The process leverages the high temperatures and hydrocarbon concentrations in the FCC riser reactor to convert SO_x into H₂S. Subsequently, H₂S, along with the cracked gas, is processed downstream to produce sulfur. Thermodynamic analysis of the key reduction reactions in the FCC-DeSO_x process revealed that complete conversion of SO_x to H₂S is feasible in the dry gas (hydrogen-rich) prelift zone, as well as the upper and lower zones of the riser, upon achieving thermodynamic equilibrium. Experimental studies were conducted to replicate the conditions of these reaction zones using a low concentration of hydrogen gas as the reducing agent. Through process optimization, investigation of the minimum reaction time, and kinetic studies, the potential of this method for the complete reduction of SO_x was further confirmed.

When converting C₅ hydrocarbons to light olefins by catalytic pyrolysis, the generation of low value-added methane will affect the atomic utilization efficiency of C₅ hydrocarbons. To improve the atomic utilization efficiency, different generation pathways of light olefins and methane in the catalytic pyrolysis of C₅ hydrocarbons were analyzed, and the effects of reaction conditions and zeolite types were investigated. Results showed that light olefins were mainly formed by breaking the C₂–C₃ bond in the middle position, while methane was formed by breaking the C₁–C₂ bond at the end. Meanwhile, it was discovered that the hydrogen transfer reaction could be reduced by about 90% by selecting MTT zeolite with 1D topology and FER zeolite with 2D topology under high weight hourly space velocity (WHSV) and high temperature operations, thus leading to the improvement of the light olefins selectivity for the catalytic pyrolysis of n-pentane and 1-pentene to 55.12% and 74.60%, respectively. Moreover, the fraction ratio of terminal C₁–C₂ bond cleavage was reduced, which would reduce the selectivity of methane to 6.63% and 1.83%. Therefore, zeolite with low hydrogen transfer activity and catalytic pyrolysis process with high WHSV will be conducive to maximize light olefins and to decrease methane.

To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent fluidized bed (TFB) FCC unit. The experimental results in the riser indicated that under the condition of low reaction temperature and regenerated catalyst temperature, large catalyst-to-oil weight ratio (C/O) and long reaction time, the gasoline olefin content could be reduced to 20.28 wt%, but there is large octane number loss owing to a great loss in high octane number olefin. Therefore, a novel FCC process using the TFB reactor was proposed to strengthen the aromatization reaction. The reaction performance of TFB reactor were investigated. The result demonstrated that the TFB reactor has more significant effect in reducing olefins and improving aromatics. At the expense of certain gasoline yield, the gasoline olefin content reduced to 23.70 wt%, aromatics content could increase to 26.79 wt% and the RON was up to 91.0. The comparison of reactor structure and fluidization demonstrated that the TFB reactor has higher catalyst bed density. The reaction heat and coke combustion heat was calculated indicating the feasibility of its industrial application of the TFB process.