Study on the Catalyst for Catalytic Cracking of Light Gasoline to Produce Propylene

The catalytic cracking of a FCC gasoline fraction （IBP--75℃） provided by the refinery No. 2 of Fushun Petrochemical Company was carried out in a continuous fixed fluidized bed reaction apparatus in the laboratory, using the modified HZSM-5 as the catalyst. The effects of the reaction temperature and loading of lanthanum on the modified HZSM-5 catalyst on the FCC product distribution were investigated. The results showed that the yield of propylene was as high as 39.28% and the yield of aromatics reached 23.57% when the loading of La in the HZSM-5 catalyst was about 8%, when the reaction was carried under atmospheric pressure and at a reaction temperature of 500~550℃and a spatial velocity of 4.5 h^-1. The yield of aromatics dropped by 6.29% during catalytic cracking of gasoline in the presence of the zeolitic catalyst modified with 8% La.

Microstructure,mechanical properties and corrosion resistance of as-cast and as-extruded Mg-4Zn-1La magnesium alloy

Microstructure,mechanical properties and corrosion resistance of as-cast and as-extruded Mg-4 wt%Zn-1 wt%La magnesium alloys were investigated.The alloys were produced by low-pressure die casting method and extruded at 350℃after homogenization at 400℃for 24 h.The results show that the as-cast alloy mainly consists of primaryα-Mg matrix and Mg-Zn-La ternary second phases(also called T-Phase)along grain boundaries and isolated spherical particles inside the grains.After extrusion at350℃,the average grain size decreases by 81%due to dynamic recrystallization mechanism and T-phase particles are distributed along the extrusion direction.The elongation,yield strength and tensile strength of the as-cast Mg-4Zn-1La alloy increase by 179%,90%and 40%,respectively,as a result of the extrusion process.The as-extruded Mg-4Zn-1La alloy shows better corrosion resistance than the as-cast alloy due to increased grain boundaries and decreased content of T-phase.

Cu-Mn catalysts modified by rare earth lantnaum for low temperature water-gas shift reaction

The Cu-Mn catalysts doped with different amounts of lanthanum（La） for water-gas shift reaction（WGSR） were prepared, and characterized by X-ray diffraction（XRD）, temperature-programmed reduction（TPR）, temperature-programmed reduction of oxidized surfaces（s-TPR）, temperature-programmed desorption of CO_2（CO_2-TPD）, infrared spectrum（FT-IR） and X-ray photoelectron spectroscopy（XPS）. Catalytic activities were tested for a water-gas shift reaction. The results showed that the introduction of 0.5 mol.% La could significantly improve the catalyst activity for low-temperature shift reaction compared with the undoped catalyst, which might be from the introduction of La making the Cu and Mn components distribute uniformly and the synergistic effect between Cu and Mn increasing the dispersion of Cu on the surface of the catalyst. The apparent CuO phases besides Cu_（1.5）Mn_（1.5）O_4 were found in the samples with at least 3.0 mol.% La content, and the basic sites increased with the increasing of La contents at a decreased rate. With excessive La doping, La particles would aggregate and cover some active sites, resulting in that Mn could not effectively inhibit the gathering together and growing up of Cu crystalline grain, and decreased the dispersion of Cu on the surface, which resulted in the poor activity of the catalyst for WGSR.