Quan Sheng Liu

Effect of precipitator on the texture and activity of copper-manganese mixed oxide catalysts for the water gas shift reaction

Copper-manganese mixed oxides were synthesized by co-precipitation with either KOH or NaOH as precipitators from CuSO4·5H2O and MnSO4·H2O as starting materials. The as-synthesized samples were tested for the water gas shift reaction and characterized by XRD, low temperature N2 absorption/desorption, TG and TPR. The obtained end precipitate consists mainly of Mn3O4 and Cu2+1O for samples prepared using NaOH as the precipitator whereas Cu4SO4(OH)6·H2O is obtained for the samples using KOH as the precipitator. Both the end precipitates prepared with NaOH and KOH as precipitators are converted to Cu1.5Mn1.5O4 after calcination, and reduced to Cu and MnO after the water gas shift reaction. Drastic differences are observed in their catalytic properties for the water gas shift reaction. The dry samples are composed of Mn3O4 and Cu2+1O when using NaOH as a precipitator and these samples maintain a relatively high texture stability and composition uniformity which ensure higher activity and thermal stability. However, for the layered structure of Cu4SO4(OH)6ċH2O and the amorphous manganese oxide, the composition of the dry samples prepared with KOH as a precipitator shows that the samples undergo a complex evolution during calcination resulting in a weakening of the synergistic effect between copper and manganese. Therefore, under the water gas shift reaction conditions the stability of the texture and composition uniformity of the KOH precipitated sample decrease greatly, which leads to a decrease in activity and thermal stability. The present comprehensive study results show that the Cu-Mn mixed oxide prepared using NaOH as a precipitator has significantly higher texture stability and catalytic activity than that prepared using KOH as a precipitator, and present excellent thermal stability.

Effect of inorganic acid elution on microcrystalline structure and spontaneous combustion tendency of Shengli lignite

Abstract XRD, Raman, XPS and FT-IR were used to examine microcrystalline structure changes of Shengli lignite eluted by inorganic acid (HCl, H2SO4 and HCl-HF). By adopting a designed surface adsorption instrument-GC, the samples were oxidized at low temperature through pulse method to investigate their oxygen adsorption under different temperatures. Via low-temperature oxidation, TG/DTG and fixed bed combustion tests, the spontaneous combustion tendency of coal samples were investigated. The results show that the removal of minerals increases the degree of order and graphitization of the coal structure. Compared with raw coal, oxygen absorption of inorganic acid elution samples decreases obviously. With the increase of adsorption temperature, oxygen absorption capacity increases significantly, but decreases with the increasing level of removed minerals, which reduces spontaneous combustion tendency of the treated coal.

Effects of La-Doping on the Structure and Performance of Copper-Manganese Oxides for the Water-Gas Shift Reaction

By using copper manganese sulfated and lanthanum nitrate as raw materials, and NaOH as precipitating agent, the copper-manganese-lanthanum mixed oxides were prepared through co-precipitation method. The catalyst samples were characterized by XRD, TPR and TPD, and the catalytic properties on water gas shift (WGS) reaction were studied. The results show that, La doping didn’t change the crystal structure, but the sample crystallinity was deteriorated. Cu-Mn/La-0.5 sample reduction temperature was low and the adsorption quantity of activated CO2 was large, which implied that copper and manganese components have good metal synergic effect, lower temperature activity and thermal stability.

Macerals of Shengli Lignite in Inner Mongolia of China and Their Combustion Reactivity

The macerals, including fusinitic coal containing 72.20% inertinite and xyloid coal containing 91.43% huminite, were separated from Shengli lignite using an optical microscope, and their combustion reactivity was examined by thermogravimetric analysis. Several combustion parameters, including ignition and burnout indices, were analyzed, and the combustion kinetics of the samples were calculated by regression. Fusinitic coal presented a porous structure, while xyloid coal presented a compact structure. The specific surface area of fusinitic coal was 2.5 times larger than that of xyloid coal, and the light-off temperature of the former was higher than that of the latter. However, the overall combustion reactivity of fusinitic coal was better than that of xyloid coal. The combustion processes of fusinitic and xyloid coals can be accurately described by both the homogeneous model and the shrinking core model. The features of xyloid coal agree with the shrinking core model when its conversion rate is 10%–90%. The activation energy of fusinitic coal during combustion can be divided into three phases, with the middle phase featuring the highest energy. The activation energy of xyloid coal is lower than that of fusinitic coal in the light-off phase, which may explain the low light-off temperature of this coal.

The Effect of the Precipitator Concentration on the Activity of Mesoporous Cu-Ce-La Mixed Oxide Catalyst for Water-Gas Shift Catalyst

Cu-Ce-La mixed oxide catalysts were prepared by co-precipitation methods with a series of precipitator concentration and characterized using X-ray diffraction, BET, TPR, and catalytic reaction for the water-gas shift. The Cu-Ce-La mixed oxide prepared by 4.0 mol/L NaOH concentration presented the highest activity and thermal stability. the precipitator concentration influence the activity of catalyst via the stability of crystal structure and mesoporous structure. La3+ or Ce4+ substituted copper ion of CeO2 framework during reaction process. The concentration of precipitator can control pore diameter of catalyst in synthetical process. The raising of precipitator concentration, from 0.5 to 2.0 mol/L, lead to enhancing of synergistic effects between CuO and CeO2.

Effect of Alkali Precipitateing Agent on the Activity and Stability of Copper-Manganese Mixed-Oxides for the Water Gas Shift Reaction

This paper reports the effect of alkali precipitating agents, i.e. KOH and NaOH, on activity and stability of Cu-Mn based catalysts for the water gas shift (WGS) reaction. Structural and texture characteristics of the catalysts were characterized by low temperature N2 adsorption, X-Ray Diffraction (XRD) and TPR techniques. The XRD and low temperature N2 adsorption results showed the two types of precipitators produced different Cu-Mn phases during precipitation and drying. The KOH precipitator resulted in partial precipitation of copper ion and formation of hydrate basic copper sulfate, Cu4SO4(OH)6•H2O after drying; while the NaOH precipitator led to a completed precipitation of Cu ion and formation of relatively stable Cu2+1O and Mn3O4 crystals after drying. These phases formed after precipitation by the KOH and NaOH, however, experienced the same phase change during calcination and activation, namely, they first changed to Cu1.5Mn1.5O4 in calcination followed by the formation of microcrystalline Cu and MnO phases during activation. The Cu-Mn WGS catalysts prepared by the NaOH was found to have larger surface area and more content of Cu and MnO phases after activation, which might be the reasons of higher activity and better stability of the Cu-Mn catalyst.

Effect of the Ration of Cu to Mn on the Activity and Stability of Copper-Manganese Mixed-Oxides for the Water Gas Shift Reaction

The effects of Cu/Mn ratio on the activity and stability of Cu-Mn catalysts for the water-gas shift reaction (WGSR) were investigated. Activity tests showed that the Cu-Mn catalyst while the ration of Cu to Mn is 1:1 displayed higher activity and better stability than that of others catalysts. The BET , XRD and TPR results revealed that the Cu-Mn catalyst while the ration of Cu to Mn is 1:1 led to higher surface area, a more stable catalyst structure and suitable reduction performance, in turn leading to better catalytic behavior for the Cu-Mn catalyst.

Copper-Based Mixed Oxides Catalyst of Water-Gas Shift Reaction for Fuel Cells: The Role of Alkali Charge

The effects of alkali charge on the activity and stability of copper-based mixed oxides catalyst for the water-gas shift reaction (WGSR) were investigated. Activity tests showed that the copper-based mixed oxides catalyst while the 2[NaOH]/[Cu2++Mn2+] is above 1.2 displayed higher activity and better stability than that of others catalysts. The BET , XRD and TPR results revealed that the Cu-Mn catalyst while the 2[NaOH]/[Cu2++Mn2+] is above 1.2 led to higher surface area, a more stable catalyst structure and suitable reduction performance, in turn leading to better catalytic behavior for the Cu-Mn catalyst.

Influence of Pyrolysis Temperature on the Gaseous Products of Lignite

Temperature-programmed pyrolysis of SL-lignite from Xilinhaote was investigated. The solid and gaseous pyrolysates were analyzed by means of gas chromatography(GC) and X-ray diffraction(XRD). The weight percents of surface moisture, ash, C, H and S increase with increasing the pyrolysis temperature in solid pyrolysates, while the volatile matter is contrary. The cracking reaction occurs before 600°C, the consolidation reaction happens between 600°C and 650°C, while the polycondensation or secondary reaction appears after 650°C. Calcium sulfide is formed by the process of decomposition of calcium sulphates at 900°C. The solid pyrolysates become more graphitic with increasing the pyrolysis temperature.