采用液相还原法制备纳米零价铁（nZVI），用来去除溶液中的 U （Ⅵ），讨论了溶液pH值、nZVI质量浓度、接触反应时间和温度对去除效果的影响，并从nZVI对U （Ⅵ）的还原角度探讨了还原动力学规律。研究结果表明：nZVI对溶液中的U （Ⅵ...采用液相还原法制备纳米零价铁（nZVI），用来去除溶液中的 U （Ⅵ），讨论了溶液pH值、nZVI质量浓度、接触反应时间和温度对去除效果的影响，并从nZVI对U （Ⅵ）的还原角度探讨了还原动力学规律。研究结果表明：nZVI对溶液中的U （Ⅵ）有很好的去除效果，其去除过程包括还原沉淀和吸附，其中还原过程符合准一级还原动力学模型；溶液pH值对去除效果有明显的影响，在溶液pH值为5.0时，去除率达到最大值96.27％。温度对去除效果有一定的影响，表观速率常数 kobs随反应温度的升高而增大，还原速率与反应温度的关系符合Arrhenius定律，反应活化能 Ea 为16.54 kJ/mol ，低于一般化学反应的活化能（60～250 kJ/mol），表明该反应较易进行。展开更多
A pentane-insoluble mixture of asphaltenes was processed by thermal hydrocracking and catalytic hydrocracking over Ni-Mo/γ-Al2O3 catalyst in a microbatch reactor at 430 ℃.The experimental data of asphaltene conversi...A pentane-insoluble mixture of asphaltenes was processed by thermal hydrocracking and catalytic hydrocracking over Ni-Mo/γ-Al2O3 catalyst in a microbatch reactor at 430 ℃.The experimental data of asphaltene conversion adequately fit second-order kinetics to give the apparent rate constants of 2.435×10-2 and 9.360×10-2 (wt frac)-1 min-1 for the two processes,respectively.A three-lump kinetic model is proposed to evaluate the rate constants for parallel reactions of asphaltenes producing liquid oil (k1) and gas+coke (k3),and consecutive reaction producing gas+coke (k2) from this liquid oil.The evaluated constants for asphaltenes hydrocracking,in the presence and absence of the catalyst,respectively,show that k1 is 2.430×10-2 and 9.355×10-2 (wt frac)-1 min-1,k2 is 2.426×10-2 and 6.347×10-3 min-1,and k3 is 5.416×10-5 and 4.803×10-5 (wt frac)-1 min-1.As compared with the thermal hydrocracking of asphaltenes,the catalytic hydrocracking of asphaltenes promotes liquid production and inhibits coke formation effectively.展开更多
文摘A pentane-insoluble mixture of asphaltenes was processed by thermal hydrocracking and catalytic hydrocracking over Ni-Mo/γ-Al2O3 catalyst in a microbatch reactor at 430 ℃.The experimental data of asphaltene conversion adequately fit second-order kinetics to give the apparent rate constants of 2.435×10-2 and 9.360×10-2 (wt frac)-1 min-1 for the two processes,respectively.A three-lump kinetic model is proposed to evaluate the rate constants for parallel reactions of asphaltenes producing liquid oil (k1) and gas+coke (k3),and consecutive reaction producing gas+coke (k2) from this liquid oil.The evaluated constants for asphaltenes hydrocracking,in the presence and absence of the catalyst,respectively,show that k1 is 2.430×10-2 and 9.355×10-2 (wt frac)-1 min-1,k2 is 2.426×10-2 and 6.347×10-3 min-1,and k3 is 5.416×10-5 and 4.803×10-5 (wt frac)-1 min-1.As compared with the thermal hydrocracking of asphaltenes,the catalytic hydrocracking of asphaltenes promotes liquid production and inhibits coke formation effectively.
