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植物焦炭氧化中的平行反应及其动力学解析 总被引:1,自引:0,他引:1
通过建立多组分平行反应模型和开展非线性动力学解析, 理论上探索植物焦炭氧化中的平行反应以及其对焦炭氧化反应活性影响的机制. 运用高温管式炉并通入高纯氮气制备植物焦炭, 热处理温度分别设定为450、520和800 ℃. 运用同步热分析仪开展空气气氛中植物焦炭线性升温氧化实验, 并通过对热重和质量损失速率实验数据进行拟合以获取焦炭氧化动力学参数值. 解析结果证实, 对于低中热处理温度(450和520 ℃)制得的焦炭, 其质量损失速率及对应的热流率曲线的变化特征主要是由残留木质素、无定形碳及粗脂肪和粗蛋白等其它反应物质的平行氧化反应叠加而成; 当热处理温度达到800 ℃时, 焦炭中活性物质基本为无定形碳, 氧化则可简化为无定形碳的单步反应. 残留木质素氧化反应的活化能最低, 范围为86~147 kJ·mol-1, 相应的温度作用区间为300~480 ℃; 无定形碳的活化能为174~208 kJ·mol-1, 反应温度在370~520 ℃之间; 其它物质的反应活化能为214~225 kJ·mol-1, 温度作用区间在420~510 ℃之间. 焦炭的氧化活性主要由残留木质素含量决定. 随着热处理温度升高, 残留木质素含量降低, 同时另两个反应组分的氧化活化能均有所增大, 导致焦炭的氧化反应活性下降. 相似文献
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李小平 《高等学校化学学报》1991,12(9):1256-1258
在化学反应动力学中,质量作用定律占有重要的地位,通常认为,该定律仅适用于理想的反应体系,并假定,一旦反应在平衡条件下遵循质量作用定律,那么在非平衡条件下也应遵循该定律,但根据最近的研究结果,平衡条件下的理想反应体系,在非平衡条件下可能变成非理想体系,换言之,非平衡性可能引起非理想性,这表明,非平衡条件下的(基元)反应并不总是遵守质量作用定律,本文利用文献的一些结果,并结合1个具体反应模型,研究了山非平衡性引起对质量作用定律的偏离,结果表明,非平衡性本身对反应动力学规律有重要影响,对化学反应动力学的研究亦具有一定启发作用。 相似文献
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The chemical reactions and kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate were studied in the presence of hydrogen over a supported palladium catalyst in the gaseous phase at the typical coupling reaction conditions. The experiments were performed in a continuous flow fixed-bed reactor. The results indicated that hydrogen only reacts with ethyl nitrite to form ethanol, and kinetic studies revealed that the rate-determining step is the surface reaction of adsorbed hydrogen and the ethoxy radical (EtO-). A kinetic model is proposed and a comparison of the observed and calculated conversions showed that the rate expressions are of rather high confidence. 相似文献
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Fandong Meng Genhui Xu Zhenhua Pa DuState Key Laboratory of C Chemical Technology Tianjin University Tianjin China Luoyang Petrochemical Engineering Corporation Luoyang China 《天然气化学杂志》2002,(Z2)
The chemical reactions and kinetics of the catalytic coupling reaction of carbon monoxide to diethyl oxalate were studied in the presence of hydrogen over a supported palladium catalyst in the gaseous phase at the typical coupling reaction conditions. The experiments were performed in a continuous flow fixed-bed reactor. The results indicated that hydrogen only reacts with ethyl nitrite to form ethanol, and kinetic studies revealed that the rate-determining step is the surface reaction of adsorbed hydrogen and the ethoxy radical (EtO-). A kinetic model is proposed and a comparison of the observed and calculated conversions showed that the rate expressions are of rather high confidence. 相似文献
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运用对流-扩散模型研究了流动注射分析系统中的化学动力学,基于无化学反应时试样分散的浓度分布公式,运用数学归纳法导出了在一定条件下一级和二级反应的产物浓度分布公式,所得解析解便于计算机模拟产物生成曲线。解释了双峰的产生,并讨论了相关的动力学信息。 相似文献
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Armenise I. Capitelli M. Colonna G. Koudriavtsev N. Smetanin V. 《Plasma Chemistry and Plasma Processing》1995,15(3):501-528
Plasma Chemistry and Plasma Processing - Nonequilibrium nitrogen dissociation-recombination kinetics in the boundary layer and on the surface of a solid body during hypersonic flow. the subsequent... 相似文献
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Margarita Baeva 《Plasma Chemistry and Plasma Processing》2016,36(1):151-167
Effects caused by thermal and chemical nonequilibrium in free-burning arcs in argon are presented and discussed. The results cover a range of arc currents between 100 and 200 A, interelectrode distance of 5–10 mm, and a variation of the electrode material and the shape of the cathode tip. The results obtained show that nonequilibrium in the near-electrode regions has a strong impact on the distributions of temperatures, electric conductivity and current density, and the arc voltage. Departure from chemical nonequilibrium in the vicinity of the cathode as a result of transport processes is indicated. Moreover, overpopulation of the atomic ground state close to the arc axis, under population of the excited states in the arc periphery with respect to the equilibrium values, axial dependence of the off-axis maximum of the radial emission coefficient of Ar I at 696.5 nm, and enhanced population of the Ar (1s4) resonance level due to trapping of resonance radiation in the arc periphery are considered. 相似文献
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Kinetics and Catalysis - A method for solving the inverse problem of chemical kinetics based on stationary data for chemical reactions proceeding according to nonideal kinetic laws in an isothermal... 相似文献
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Russian Journal of General Chemistry - One of the difficulties encountered in solving direct and inverse chemical kinetics problems is the complexity of studying multidimensional systems of... 相似文献
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Patiño P. Sánchez N. Suhr H. Hernández N. 《Plasma Chemistry and Plasma Processing》1999,19(2):241-254
The oxidation of 13 liquid olefins with either high-voltage or radio frequency (RF) glow discharges has been studied. The reactions were carried out by making the oxygen plasma reach the low vapor pressure substrate. Product formation has proved to be selective—epoxides, aldehydes, ketones, and low quantities of carboxylic acids being the most important species. Fragmentation products were only observed in the traps of the RF system for the most volatile olefin of this study. This indicates that, except for this case, the most relevant interaction of this study has been the heterogeneous reaction of the plasma with the liquid. Total conversion, i.e., mass transformed against initial mass of substrate, has been studied as a function of temperature of the liquid and oxygen flow rate in the reactor, this ranging from 15 to 53.6 mmol/hr in the high-voltage system and 13 to 270 mmol/hr in the RF device. The optimum conversions were 27 to 99%. A correlation between these results and the behavior of the O(
3
P) population in the discharge allows us to conclude that this is the most relevant species to the oxidation process. A discussion relating the structures of the olefins with the composition of the mixtures produced by the oxidation is also presented. 相似文献
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A linear algebraic characterization for sets of independent reactions, independent reaction numbers, conservation laws and resistant groups for both equilibrium and kinetic systems is suggested. Basing on the ranks of two stochiometric matrices N and M, these concepts are discussed and formulas given for setting up of independent sets of equilibrium and kinetic equations. The difference in the definition of independent reaction numbers for these two types of systems is pointed out. A brief consideration is devoted to the transformations of equilibrium and kinetic equations induced by transformation from one set of linearly independent reactions to another. Finally the conservation laws are formulated as chemical invariants within the N, M framework. 相似文献
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分析和总结了催化剂催化有机化学反应的4种基本方式,包括建立电子流动通道、改变电子流动属性、加强电子流动能力和稳定电子流动结果。本文旨在揭示有机化学反应中催化剂作用的本质,以便学生更加深刻理解并掌握有机化学反应。 相似文献
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Russian Journal of Applied Chemistry - A technique has been developed for determining the stage rate constants of chemical reactions proceeding in an isothermal gradientless reactor according to... 相似文献
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QunCHEN RongHE ZhanGangLIANG XuChangXU ChangHeCHEN 《中国化学快报》2005,16(3):393-396
Five coal char samples were burnt in thermobalance with ramp heating rate of 30 K/min. The pore structure of these char samples was studied through mercury intrusion method. Combined with the kinetic theory of gases, the data of surface area was used in fitting the results. As a result, the kinetic triplet was given. The analysis showed that five char samples share almost the same intrinsic activation energy of the overall reaction. The phenomenological implication of the derived combustion rate equation was given. 相似文献
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Margarita Baeva 《Plasma Chemistry and Plasma Processing》2017,37(3):513-530
The widespread application of electric arcs is closely related to the continuous research interest over the course of many years. The present survey is concerned with chemical and excitation nonequilibrium in atmospheric pressure argon plasma generated between a sharpened tungsten cathode and a flat copper anode at current levels of 35–200 A. Advanced fully nonequilibrium modelling is applied to simulate the combination of the wall-confined arc plasma column and the open region in front of the anode in a self-consistent manner in order to pay tribute to the tremendous research work that E. Pfender has done. The new modelling results are presented along with experimental and modelling results of the studies of E. Pfender and his group and other works of relevance. 相似文献
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T. Ozawa 《Journal of Thermal Analysis and Calorimetry》2000,60(3):887-894
Theoretical consideration has been made of the non-isothermal kinetics of consecutive reactions based on the superposition
principle. In the model the first reaction product reacts to form the final product and the two reactions proceed independently.
The amount of the first reaction product and the production rate of the final product have been obtained as a function of
time for isothermal cases and as a function of the reduced times for non-isothermal cases.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献