Chunmei Lu

An investigation on the catalytic capacity of dolomite in transesterification and the calculation of kinetic parameters

The catalytic capacity of dolomite in transesterification was investigated and the kinetic parameters were calculated. The activated dolomites as transesterification catalyst were characterized by X-ray diffraction, nitrogen adsorption and desorption and Hammett indicator method, where the original dolomite was analyzed by thermogravimetric and X-ray fluorescence in advance. Its potential catalytic capacity was validated from aspects of the activated temperature and the reused property, where the reliability of the experimental system was also examined. Then, influences of the catalyst added amount, the mole ratio of methanol to oil, the transesterification temperature and the transesterification time on the catalytic capacity were investigated. Finally, kinetic parameters of the transesterification catalyzed by the activated dolomite were calculated.

Pyrolysis of rice straw with ammonium dihydrogen phosphate: Properties and gaseous potassium release characteristics during combustion of the products.

The effect of ammonium dihydrogen phosphate (NH4H2PO4) on rice straw (RS) carbonization was evaluated at temperatures of 350-650°C. The carbonized products of RS with NH4H2PO4 show higher solid and energy yields, but lower higher heating values than the carbonized RS at every carbonization temperature. The optimum carbonization operation of RS with NH4H2PO4 which has a higher energy yield at a lower solid volume may be determined between 350 and 450°C, and RS with NH4H2PO4 carbonized at 450°C presents better pore properties than carbonized RS. The carbonized products of RS with NH4H2PO4 all have lower gaseous potassium release ratios than those of RS carbonized at the same temperature at combustion temperatures of 700-1000°C by retaining potassium in non-volatile phosphorus compounds with high melting points. It is an effective method for inhibiting the gaseous potassium release during combustion of the carbonized products.

NH3-SCR performance and characterization over magnetic iron-magnesium mixed oxide catalysts

A series of magnetic iron-magnesium mixed oxide catalysts (Fe1−xMgxOz) were synthesized via a novel coprecipitation method with microwave thermal treatment, and their activity in NH3-SCR was tested on a quartz fixedbed reactor. Physical and chemical properties of the catalysts were characterized by X-ray diffraction (XRD), N2-adsorption-desorption, scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS). Fe0.8Mg0.2Oz with excellent N2 selectivity and resistance to SO2 and H2O was validated as the proper SCR catalyst, with the maximum NOx conversion of 99.1% fulfilled at 325 °C. Activity was strongly influenced by the γ-Fe2O3 crystalline phase, and magnesium existed in an amorphous phase and interacted with iron oxide intensively to form solid solution in favor of SCR. For Fe0.8Mg0.2Oz catalyst, optimum pore diameter distribution, appropriate surface area, pore volume and abundant lattice oxygen on the surface could be guaranteed, which is good for the diffusion process and enhances the activity.

Iron-manganese-magnesium mixed oxides catalysts for selective catalytic reduction of NO x with NH3

SCR activity at low temperature over iron oxide catalyst was prominently optimized by adding manganese and magnesium. Fe0.7Mn0.15Mg0.15Oz(n(Mn)/[n(Fe)+n(Mn)+n(Mg)])=0.15 and n(Mg)/[n(Fe)+n(Mn)+n(Mg)]=0.15) presented better performance in the low temperature SCR and NOx conversion of 90% could be achieved over 125 °C. Meanwhile, part of manganese and magnesium oxides were highly dispersed on the catalyst surface in an amorphous phase to react with iron oxide to form solid solution. Manganese and magnesium dopants could optimize the pore structure and distribution of γ-Fe2O3 to enhance the surface area and pore volume. Moreover, O2 participated in SCR reaction at a faster rate than NH3. In addition, the effect of SO2 was proved to be irreversible, whereas the inhibition of H2O could be rapidly removed after its removal.

A Thermogravimetric Analysis of Co-combustion Characteristics of Biomass and Coal in an O2/CO2Atmosphere

Co-combustion characteristics of two coals and two biomass are investigated through thermogravimetric method in O2/CO2 atmosphere. Characteristic parameters of coal combustion deduced from TG-DTG curves show that, at the O2 concentration of 20%, substitution of CO2 for N2 brings about delay in ignition, exaltation in burnout, and drop in combustion integration parameter. To improve performances of coal combustion in O2/CO2 atmosphere, biomass is added to form co-combustion. The difficulty of coal combustion in O2/CO2 atmosphere can be effectively reduced at a co-combustion ratio of 20%. Activation energy during the coal combustion process is evidently reduced with the addition of biomass.

Reactivation Properties of Carbide Slag as a CO2 Sorbent During Calcination/Carbonation Cycles

The carbide slag from polyvinyl chloride production as industry hazardous wastes was proposed as CO2 sorbent at high temperature in calcium looping cycle. The cyclic CO2 capture behavior and the microstructure characteristics of the carbide slag as one of the typical calcium-based industrial wastes during the multiple calcination/carbonation cycles. Also, the comparisons between the carbide slag and the natural limestone in cyclic CO2 capture behavior were made. XRD analysis demonstrates that the predominating constituent of the carbide slag is Ca(OH)2. The carbonation temperature ranging from 650 to 700°C is favourable to cyclic carbonation of the carbide slag. The cyclic carbonation conversions of the carbide slag is lower than that of the limestone before a certain time, but the situation is converse after that time in a thermogravimetric analyzer. The carbide slag has better cyclic CO2 capture capacity. The carbonation conversion of the carbide slag retains 0.28 after 100 calcination/carbonation cycles, while the two limestones achieve 0.08 and 0.14 respectively at the same reaction conditions in a dual fixed-bed reactor. The microstructure of the carbide slag by SEM reveals the reason why it possesses better CO2 capture capacity.

Experimental Study and Mechanism Analysis of Modified Limestone by Red Mud for Improving Desulfurization

Red mud is a type of solid waste generated during alumina production from bauxite, and how to dispose and utilize red mud in a large scale is yet a question with no satisfied answer. This paper attempts to use red mud as a kind of additive to modify the limestone. The enhancement of the sulfation reaction of limestone by red mud (two kinds of Bayer process red mud and one kind of sintering process red mud) are studied by a tube furnace reactor. The calcination and sulfation process and kinetics are investigated in a thermogravimetric (TG) analyzer. The results show that red mud can effectively improve the desulfurization performance of limestone in the whole temperature range (1,073–1,373K). Sulfur capacity of limestone (means quality of SO2 which can be retained by 100mg of limestone) can be increased by 25.73, 7.17 and 15.31% while the utilization of calcium can be increased from 39.68 to 64.13%, 60.61 and 61.16% after modified by three kinds of red mud under calcium/metallic element (metallic element described here means all metallic elements which can play a catalytic effect on the sulfation process, including the Na, K, Fe, Ti) ratio being 15, at the temperature of 1,173K. The structure of limestone modified by red mud is interlaced and tridimensional which is conducive to the sulfation reaction. The phase composition analysis measured by XRD of modified limestone sulfated at high temperature shows that there are correspondingly more sulphates for silicate and aluminate complexes of calcium existing in the products. Temperature, calcium/metallic element ratio and particle diameter are important factors as for the sulfation reaction. The optimum results can be obtained as calcium/metallic element ratio being 15. Calcination characteristic of limestone modified by red mud shows a migration to lower temperature direction. The enhancement of sulfation by doping red mud is more pronounced once the product layer has been formed and consequently the promoting effect of red mud becomes greater once the sulfation reaction becomes diffusion controlled. This study indicates that red mud from alumina plant is a favorable additive for improving the desulfurization performance of limestone, and the effect of red mud on limestone’s desulfurization activity is due to superposition of improvement in solid-state ionic diffusion and surface chemical reaction.

Microcalorimetric Study of the Screening Specific Promoter Bacteria of Nutrient Drug

The power vs. time curves of the promoter bacteria of a nutrient drug were determined by using a 2277 Thermal Activity Monitor (Sweden). A new experimental model of bacterial growth were established. The growth rate constant, heat output and optimum concentration of specific promoter bacterial of nutrient drug were calculated.