IF钢加硅脱氧生产实践

对IF钢加硅和加铝脱氧升温效果进行了理论计算和现场实验对比,热力学理论计算表明,100 kg的铝粒脱氧可使270 t钢水升温12.35℃,但在实际生产中升温平均值为10.29℃;同样加入等质量的硅,其理论升温量为11.1℃,实际升温平均值为8.81℃。IF钢增硅主要来自于脱氧后钢中的Als对渣中SiO_(2)的还原。通过实际生产发现,在转炉加入硅铁,成品增硅量最少,正常情况下控制硅铁的加入量不大于150 kg,基本能保证钢水硅不超内控标准,而且进站钢水氧含量与RH处理结束时钢水中的硅含量成反比关系。

Study on ReactiveAdsorption Desulfurization of Model Gasoline on Ni/ZnO-HY Adsorbent

The reactive adsorption desulfurization of model gasoline was carried out on Ni/ZnO-HY adsorbent.The Ni/ZnO-HY adsorbent was characterized by N2adsorption-desorption test(BET),X-ray diffractometry(XRD),and temperature-programmed reduction(TPR)analysis.The test results have demonstrated that HY-zeolite is a feasible support for Ni/ZnO components used in reactive adsorption desulfurization.The results of XRD and TPR analyses showed that most of nickel element was present as Ni2+species with only a small part existing as Ni3+species,and the Ni2+species had interactions with HY-zeolite.Under the conditions of this study,which specified a 50% ratio of HY-zeolite in the adsorbent,a Zn/Ni molar ratio of 10,and a reduction temperature of 400℃,the Ni/ZnO-HY adsorbent showed the best desulfurization performance.The sulfur capacity of Ni/ZnO-HY adsorbent could be recovered to 92.19% of the fresh one after being subjected to regeneration at 500℃,and could be maintained at 82.17% of the fresh one after 5 regeneration cycles.

Effects of Surface Defects on Adsorption of CO and Methyl Groups on Rutile TiO_(2)(110)

The interaction of reactants with catalysts has always been an important subject for catalytic reactions.As a promising catalyst with versatile applications,titania has been intensively studied for decades.In this work we have investigated the role of bridge bonded oxygen vacancy(O_(v))in methyl groups and carbon monoxide(CO)adsorption on rutile TiO_(2)(110)(R-TiO_(2)(110))with the temperature programmed desorption technique.The results show a clear different tendency of the desorption of methyl groups adsorbed on bridge bonded oxygen(O_(b)),and CO molecules on the five coordinate Ti^(4+)sites(Ti_(5c))as the Ovconcentration changes,suggesting that the surface defects may have crucial influence on the absorption of species on different sites of R-TiO_(2)(110).

Role of Reduced Defects for Coupling Reactions of Acetaldehyde on Anatase TiO2（001）-（1×4） Surface

The chemistry of acetaldehyde (CH3CHO) adsorbed on the anatase TiO2(001)-(1×4) surface has been investigated by temperature-programmed desorption (TPD) method. Our experimental results provide the direct evidence that the perfect lattice sites on the anatase TiO2(001)-(1×4) surface are quite inert for the reaction of CH3CHO, but the reduced defect sites on the surface are active for the thermally driven reductive carbon-carbon coupling reactions of CH3CHO to produce 2-butanone and butene. We propose that the coupling reactions of CH3CHO on the anatase TiO2(001)-(1×4) surface should undergo through the adsorption of paired CH3CHO molecules at the reduced defect sites, since the existing reduced Ti pairs provide the suitable adsorption sites.

Activity and Adsorption Behavior of Oxygen on Rutile TiO_(2)(110)

The activity and adsorption behavior of oxygen on rutile TiO_(2)(110)(RTiO_(2)(110))were investigated using the temperature programmed desorption(TPD)method with methanol(CH_(3)OH)as the probe molecule.By controlling the coverage of molecular O_(2) on the surface via increasing or decreasing O_(2) exposure,two chemisorbed O_(2)species on the surface are confirmed,one at the bridging oxygen vacancy(Ov)site(O_(2)^(2-)/Ov)and the other at the five-fold coordinated titanium(Ti_(5c))site(O^(2-)/Ti_(5c)).At low O_(2)exposure,O^(2-)/Ov is the main species on the surface,which only leads to the O-H bond cleavage of CH_(3)OH,producing methoxy groups(CHgO).However,after the Ov sites are nearly filled by O_(2) at about 0.1 L O_(2) exposure,O_(2)/Tisc species begins to appear on R-TiO_(2)(110)surface,resulting in the formation of formaldehyde(CH_(2)O)via the reaction of O_(2)/Tisc species with CH_(3)OH or CH3O to break the C-H bond at low surface temperature.Moreover,the yield of CH_(2)O increases linearly with that of H_(2)O.In addition,when the 1 L O_(2)covered surface is irradiated with 355 nm UV irradiation to desorb and dissociate O_(2)/Ti_(5c) species,the yield of CH_(2)O decreases linearly with that of H_(2)O.Further analysis suggests that the charge state of O_(2)/Ti_(5c) may not change as the exposure of O_(2)changes on the R-TiO_(2)(110) surface,and O_(2) is most likely to adsorb on the Ti_(5c)sites in the form of O_(2)^(2-),not O_(2)^(-),The result not only advances our understanding on the adsorption state of O_(2) on TiO_(2),but also provides clues for low temperature C-H bond activation with O_(2) on TiO_(2).

Reaction heat-driven CO2 desorption during CO oxidation on Au(997) at low temperatures

Adsorption and reaction of CO and CO2 were studied on oxygen-covered Au（997） surfaces by means of temperature- programmed desorption/reaction spectroscopy. Oxygen atoms （O（a）） on Au（997） enhances the CO2 adsorption and stabilizes the adsorbed COe（a）, and the stabilization effect also depends on the CO2（a） coverage and involved Au sites. CO2（a） desorp- tion is the rate-limiting step for the CO＋O（a） reaction to produce CO2 on Au（997） at 105 K and exhibits complex behaviors, including the desorption of CO2（a） upon CO exposures at 105 K and the desorption of O（a）-stabilized CO2（a） at elevated temperatures. The desorption of CO2（a） from the surface upon CO exposures at 105 K to produce gaseous CO2 depends on the surface reaction extent and involves the reaction heat-driven CO2（a） desorption channel. CO＋O（a） reaction proceeds more easily with weakly-bound oxygen adatoms at the （111） terraces than strongly-bound oxygen adatoms at the （111） steps. These re- sults reveal complex rate-limiting COe（a） desorption behaviors during CO＋O（a） reaction on Au surfaces at low temperatures which provide novel information on the fundamental understanding of Au catalysis.