The hydrocracking unit is a Class A fire hazard device, which can be susceptible to fire and explosion accidents due to equipment failure. Therefore, it is essential to identify and quantitatively analyze the risk factors. In this paper, qualitative HAZOP, steady-state simulation, dynamic simulation and FTA are combined. Taking process flow of the absorbing-stabilizing system of an actual hydrocracking unit in a refining company as an example, and the quantitative risk analysis is carried out for the deviation of "high column pressure" of the absorption and desorption column and "high column temperature" of the naphtha stabilisation column. With the help of Aspen Plus software, the steady-state and dynamic simulation under dangerous conditions is carried out, and the probability of the consequences of the dangerous accident is calculated by FTA method. The results show that this method can help experts understand the propagation process of the accident, master the safety response time of the personnel, which is conducive to the prevention and timely treatment of accidents, and effectively improve the intrinsic safety level of the hydrocracking units.

Template agent is an essential part in the synthesis of molecular sieves, which has great influence on the physical properties and catalytic properties of molecular sieves. SAPO?34 molecular sieve was synthesized by hydrothermal method using stainless steel tube as crystallization vessel. The effect of PEG?800 addition on crystallinity, morphology and acidity of molecular sieve was investigated, and its MTO catalytic performance was evaluated. The results show that the molecular sieve samples synthesized with TEAOH & PEG?800 as the composite template agent are thin plate?like, the crystallinity and acidity are suitable, and the longest catalytic life is 340 min. When the methanol conversion is above 95%, the selectivity of diolefins is up to 84.0%. It is also found that the thinner the crystal thickness of the lamellar molecular sieve, the better the catalytic performance.

Hierarchical porous Hβ molecular sieve with different structure and acidity were prepared by alkali treatment. XRD, SEM, N₂ physical adsorption and NH₃?TPD characterization methods were used to characterize molecular sieves before and after alkali treatment. With hierarchical porous Hβ molecular sieve as the carrier, the Ru?Hβ bifunctional catalysts were prepared by an equal volume impregnation method, and the benzene hydroalkylation reaction activity and stability were evaluated in a fixed bed reactor.The results show that Hβ molecular sieve can effectively increase the proportion of mesopores after being treated with a proper concentration of alkali, which is beneficial to improve the hydroalkylation activity and stability. At 2 MPa, 210 ℃ and a liquid hourly space velocity of 1 h^-1, when the Ru mass fraction is 0.2% (based on the mass of hierarchical porous Hβ molecular sieve), the dual?functional catalyst composed of hierarchical porous Hβ can achieve effective and stable operation. At the same time, the conversion rate of benzene is 54.32%, the selectivity of cyclohexyl benzene is 71.47%, and the stability of the catalyst does not decrease significantly within 280 h.