Facile synthesis of efficient pentaethylenehexamine-phosphotungstic acid heterogeneous catalysts for oxidative desulfurization

The ultra-deep desulfurization of oil needs to be solved urgently due to various problems,including environmental pollution and environmental protection requirements.Oxidative desulfurization(ODS)was considered to be the most promising technology.The facile synthesis of highly efficient and stable HPW-based heterogeneous catalysts for oxidative desulfurization is still a challenging task.In this paper,pentamethylene hexamine(PEHA)and phosphotungstic acid(HPW)were combined by a simple one-step method to prepare a heterogeneous catalyst of PEHA-HPW for the production of ultra-deep desulfurization fuel oil.The composite material exhibited excellent catalytic activity and high recyclability,which could reach a 100% dibenzothiophene(DBT)removal rate in 30 min and be recycled at least 5 times.Experiments and DFT simulations were used to better examine the ODS mechanism of PEHA-HPW.It was proved that the rich amino groups on the surface of PEHA-HPW play a crucial role.This work provides a simple and feasible way for the manufacture of efficient HPW-based catalysts.

Influence and evaluation of saturated soil shield construction on existing highway

In order to study the shield construction under an existing highway,the initial displacement and the excess pore water pressure solution from Biot consolidation equation were used to derive the analytical solutions of the vertical deformation and pore water pressure of saturated soil caused by the frontal friction and side friction of the cutterhead.In addition,by introducing the layered method and combining it with other theoretical analytical equations,the expressions of total vertical deformation and total pore water pressure caused by tunnel excavation with different overlying materials were obtained.The simulation results on an engineering project showed that the angleαbetween the direction of the road and the propulsion axis of the shield had a significant influence on the surface settlement of the road.When the angleαwas increased,the settlement curve had higher variation;but the variation would not exceed the maximum settlement value above the shield axis.When the road was perpendicular to the shield axis,a critical point of the road bulging and settlement was formed above the incision.Due to the grinding resistance of the cutterhead,the pore water pressure under the roadbed was distributed asymmetrically on both sides of the shield axis.